JP2012008374A - Developing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device which causes no deviation in toner density on a developing sleeve even when images having high image area are continuously output, reduces scattering of toner to a photoreceptor drum due to rise in internal pressure of a collection conveyance path using a simple method, maintains a compact size, has excellent assemblability, and prevents a filter from clogging.SOLUTION: A filter 5 for passing air without passing toner is provided above a feed conveyance path 2a. A suction duct 35 is disposed below the developing sleeve 11 for letting out a pressure within a feed conveyance path 2b externally to the apparatus. An opening 36 is provided in a partition member 37 between the collection conveyance path and the suction duct for ventilating the collection conveyance path and the suction duct.

Description

本発明は、複写機、ファクシミリ、プリンタ等に用いられる現像装置に係り、詳しくは、トナーと磁性キャリアからなる二成分現像剤を用いる現像装置及びこれを用いた画像形成装置に関するものである。   The present invention relates to a developing device used for a copying machine, a facsimile, a printer, and the like, and more particularly to a developing device using a two-component developer composed of toner and a magnetic carrier and an image forming apparatus using the same.

従来、上記現像装置の一つとして、現像剤担持体の軸方向に現像剤を搬送しながら現像剤担持体に現像剤を供給する供給搬送路と、現像剤を攪拌しながら供給搬送路とは逆方向に搬送する攪拌搬送路とを設けて、現像剤を循環させるものが知られている。このような現像装置において、現像領域を通過した現像剤担持体上の現像剤を供給搬送路で回収すると、現像領域でトナーが消費された現像剤と供給搬送路内の現像剤とが混ざり、供給搬送路の下流側ほど現像領域を通過した現像剤が多くなる。このため、供給搬送路の下流側ほど現像剤担持体に供給する現像剤のトナー濃度が低下し、搬送方向上流側と下流側とで画像濃度が異なるという問題があった。   Conventionally, as one of the developing devices, a supply conveyance path for supplying a developer to the developer carrying body while conveying the developer in the axial direction of the developer carrying body and a supply conveyance path for stirring the developer are: There is known an agitating / conveying path that conveys the developer in the reverse direction to circulate the developer. In such a developing device, when the developer on the developer carrying member that has passed through the development area is collected in the supply conveyance path, the developer in which the toner has been consumed in the development area and the developer in the supply conveyance path are mixed, The more developer that has passed through the development area, the more downstream the supply conveyance path. For this reason, there is a problem that the toner density of the developer supplied to the developer carrier decreases toward the downstream side of the supply conveyance path, and the image density differs between the upstream side and the downstream side in the conveyance direction.

この問題は、特許文献１に記載の現像装置のように、供給搬送路及び攪拌搬送路とは別に現像剤を回収する回収搬送路を設けることで解決できる。この現像装置では、現像剤担持体に現像剤を供給する供給搬送路と、供給搬送路の下方に配置され供給搬送路と反対方向に現像剤を搬送する攪拌搬送路と、現像剤担持体の下方に配置され現像剤担持体から現像剤を回収しながら供給搬送路と同方向に現像剤を搬送する回収搬送路とを備えている。供給搬送路、回収搬送路及び攪拌搬送路は、それぞれ仕切り部材によって仕切られており、攪拌搬送路の下流側端部の供給搬送路との仕切り部材には、供給搬送路に攪拌した現像剤を受け渡す開口部を設けている。また、供給搬送路の下流側端部の攪拌搬送路との仕切り部材には攪拌搬送路に余剰現像剤を受け渡す開口部、回収搬送路の下流側端部の攪拌搬送路との仕切り部材には攪拌搬送路に回収現像剤を受け渡す開口部をそれぞれ設けて、現像剤を循環させている。このように、現像剤担持体への現像剤の供給と回収との機能を分離して行うことにより、現像剤担持体に供給する現像剤のトナー濃度が一定となり、濃度ムラの発生を防止することができる。   This problem can be solved by providing a recovery conveyance path that collects the developer separately from the supply conveyance path and the agitation conveyance path, as in the developing device described in Japanese Patent Application Laid-Open No. 2005-228867. In this developing device, a supply conveyance path for supplying the developer to the developer carrying member, a stirring conveyance path that is disposed below the supply conveyance path and conveys the developer in a direction opposite to the supply conveyance path, and a developer carrying member A recovery conveyance path that is disposed below and conveys the developer in the same direction as the supply conveyance path while collecting the developer from the developer carrying member is provided. The supply conveyance path, the recovery conveyance path, and the agitation conveyance path are each partitioned by a partition member, and the developer agitated in the supply conveyance path is supplied to the partition member with the supply conveyance path at the downstream end of the agitation conveyance path. A passing opening is provided. Also, the partition member for the agitating and conveying path at the downstream end of the supply conveying path is an opening for delivering the excess developer to the agitating and conveying path, and the partitioning member for the agitating and conveying path at the downstream end of the collecting and conveying path. Each has an opening for delivering the collected developer to the agitation transport path to circulate the developer. In this way, by separately performing the functions of supplying and collecting the developer to the developer carrying member, the toner concentration of the developer supplied to the developer carrying member becomes constant, and density unevenness is prevented. be able to.

また、一般的に現像装置では、現像剤担持体の回転により発生した気流により周辺空気が装置内に吸い込まれて装置内の内圧が上昇し、装置内外の圧力差によって、装置内に浮遊するトナーが、例えば現像スリーブと装置筐体の間の僅かな隙間から装置外へ飛散してしまうという不具合がある。装置内の内圧の上昇を抑えるために、特許文献２では、装置に設けた圧抜き用穴を真空吸引装置に連結することで圧力を逃がしている。しかし、真空ポンプは大型かつ高コストであり、商品の魅力を下げることになる。特許文献３には、現像装置の内圧上昇を抑えて現像装置から感光体ドラムへのトナー飛散を抑制するものとして、トナーを通過させず空気を通過させるフィルタを設けた現像装置が記載されている。これは、フィルタを介して現像装置内の気流を装置外に排出して現像装置内の内圧の上昇を抑えると共に、浮遊するトナーを気流に乗せてフィルタで捕集することで、現像装置から感光体ドラムへのトナー飛散を抑制するものである。また、フィルタは、十分な通気を確保すると共に、フィルタの目詰まりをし難くするために、現像装置の上側に設置し、効率よく現像装置内の気流を装置外に排出して内圧の上昇を抑えている。   In general, in a developing apparatus, the ambient air is sucked into the apparatus due to the air flow generated by the rotation of the developer carrier, and the internal pressure in the apparatus rises, and the toner floating in the apparatus due to the pressure difference between the inside and outside of the apparatus. However, for example, there is a problem that the image is scattered outside the apparatus from a slight gap between the developing sleeve and the apparatus housing. In order to suppress an increase in internal pressure in the apparatus, in Patent Document 2, the pressure is released by connecting a pressure relief hole provided in the apparatus to a vacuum suction device. However, the vacuum pump is large and expensive, which reduces the attractiveness of the product. Patent Document 3 describes a developing device provided with a filter that does not allow toner to pass therethrough and suppresses toner scattering from the developing device to the photosensitive drum by suppressing an increase in internal pressure of the developing device. . This is because the air current in the developing device is discharged out of the device through the filter to suppress the increase in the internal pressure in the developing device, and the floating toner is placed on the air current and collected by the filter, so This suppresses toner scattering to the body drum. In addition, the filter is installed on the upper side of the developing device to ensure sufficient ventilation and to prevent clogging of the filter, and the internal air pressure is increased by efficiently discharging the air flow in the developing device to the outside. It is suppressed.

しかし、特許文献１の構成と特許文献３の構成を組み合わせても、開口部が現像剤の通り道となるために、攪拌搬送路の内圧が装置内上方の供給搬送路に速やかに通気せず、結局攪拌搬送路の内圧が上昇してしまう。そこで、特許文献４では、この問題を解決するために、攪拌搬送路と供給搬送路の間に連通する２つの開口部に加えて、別な開口部を、現像剤を供給搬送路から攪拌搬送路に移動させるための開口部よりも下流側かつ上方に配置している。この別な開口部によって、現像装置内で現像剤が偏り状態にならず、攪拌搬送路から現像装置上方に設けられたフィルタへの通気が確保される。また、特許文献５では現像装置のトナー補給口に接続したトナー搬送部に圧抜き用フィルタを設置している。この構成を特許文献１の構成に適用すれば、回収搬送路及び攪拌搬送路と現像装置上部との間で気流が通らなくても、回収搬送路に通じたトナー補給口及び圧抜き用フィルタを介してトナー補給口付近の内圧を外側に逃がすことができる。特許文献６では以上の問題点を踏まえ、特許文献１の構成において、回収搬送路及び攪拌搬送路の内圧を開放するために、攪拌搬送路及び供給搬送路に接続するトナー搬送部を現像装置に一体形成している。   However, even if the configuration of Patent Document 1 and the configuration of Patent Document 3 are combined, the opening serves as a passage for the developer, so the internal pressure of the stirring transport path does not quickly vent into the supply transport path above the apparatus, Eventually, the internal pressure of the stirring and conveying path will increase. Therefore, in Patent Document 4, in order to solve this problem, in addition to the two openings communicating between the agitation conveyance path and the supply conveyance path, another opening is agitated and conveyed from the supply conveyance path. It arrange | positions downstream from the opening part for moving to a path | route, and upper direction. With this other opening, the developer is not biased in the developing device, and the ventilation from the stirring conveyance path to the filter provided above the developing device is ensured. Further, in Patent Document 5, a pressure release filter is installed in a toner transport unit connected to a toner supply port of a developing device. If this configuration is applied to the configuration of Patent Document 1, the toner replenishing port and the depressurizing filter connected to the recovery conveyance path can be provided without airflow between the recovery conveyance path and the agitation conveyance path and the upper part of the developing device. The internal pressure near the toner supply port can be released to the outside. In Patent Document 6, based on the above problems, in the configuration of Patent Document 1, in order to release the internal pressure of the recovery transport path and the stirring transport path, a toner transport unit connected to the stirring transport path and the supply transport path is provided in the developing device. It is integrally formed.

本発明は、画像面積が高い画像を連続して出力しても現像スリーブ上のトナー濃度偏差が生じず、回収搬送路の内圧上昇による感光体ドラムへのトナー飛散をより簡単な方法で低減させ、コンパクトなサイズを維持し、良好な組み立て性が実現され、かつフィルタが目詰まりしない現像装置及び画像形成装置を提供することを目的とする。   According to the present invention, even if images having a large image area are continuously output, the toner density deviation on the developing sleeve does not occur, and toner scattering to the photosensitive drum due to an increase in the internal pressure of the recovery conveyance path can be reduced by a simpler method. Another object of the present invention is to provide a developing device and an image forming apparatus that maintain a compact size, achieve good assembly, and do not clog a filter.

この課題は、本発明によれば、トナーと磁性キャリアとからなる現像剤を担持して回転により潜像担持体との対向部まで搬送する現像剤担持体と、該現像剤担持体の軸線方向に沿って現像剤を攪拌搬送して該現像剤担持体に供給する第１現像剤攪拌搬送手段を有する第１現像剤搬送路と、該第１現像剤攪拌搬送手段よりも下方に配置され該潜像担持体との対向部通過後の該現像剤担持体から現像剤を回収して、該第１現像剤攪拌搬送手段と同方向に搬送する第２現像剤攪拌搬送手段を有する第２現像剤搬送路と、該第１現像剤攪拌搬送手段よりも下方に配置され、該第１現像剤攪拌搬送手段により該現像剤担持体に供給されずに該第１現像剤搬送路の搬送方向下流部まで搬送された現像剤と、該第２現像剤攪拌搬送手段により該現像剤担持体から回収され該第２現像剤搬送路の搬送方向下流部まで搬送された現像剤との供給を受け、該第１現像剤攪拌搬送手段と逆方向に現像剤を攪拌搬送して下流側で該第１現像剤攪拌搬送手段に受け渡す第３現像剤攪拌搬送手段を有する第３現像剤搬送路とを有し、該第１現像剤搬送路の搬送方向下流部から該第３現像剤搬送路の搬送方向上流部に現像剤を供給するための第１現像剤供給用開口部と、該第２現像剤搬送路の搬送方向下流部から該第３現像剤搬送路の搬送方向上流部に現像剤を供給するための第２現像剤供給用開口部と、該第３現像剤搬送路の搬送方向下流部から該第１現像剤搬送路の搬送方向上流部に現像剤を供給するための第３現像剤供給用開口部とを有し、該第１現像剤搬送路、該第２現像剤搬送路及び該第３現像剤搬送路は仕切り部材により仕切られる現像装置において、トナーを通過させずに空気を通過させるフィルタが該第１現像剤搬送路の上方に設けられ、画像形成装置の外側に通じた通気路が、該現像剤担持体の下部に設けられ、該第２現像剤搬送路と該通気路は仕切り部材により仕切られ、該第２現像剤搬送路と該通気路を通気するための通気用開口部が、該第２現像剤搬送路と該通気路との該仕切り部材に設けられることによって解決される。   According to the present invention, there is provided a developer carrier that carries a developer composed of toner and a magnetic carrier and conveys the developer to a portion facing the latent image carrier, and an axial direction of the developer carrier. A first developer conveying path having first developer agitating and conveying means for agitating and conveying the developer and supplying the developer to the developer carrying member, and disposed below the first developer agitating and conveying means. Second developer having a second developer agitating and conveying means for recovering the developer from the developer carrying body after passing through the portion facing the latent image carrier and conveying it in the same direction as the first developer agitating and conveying means. A developer conveying path and a lower position than the first developer agitating / conveying means, and the first developer agitating / conveying means is not supplied to the developer carrier by the first developer agitating / conveying means; And the developer carrying member by the second developer stirring and conveying means. The developer collected and transported to the downstream part in the transport direction of the second developer transport path is supplied, and the developer is stirred and transported in the direction opposite to the first developer stirring and transporting means, and the developer is transported downstream. A third developer conveying path having third developer agitating / conveying means to be transferred to the first developer agitating / conveying means, and the third developer conveying path from a downstream portion of the first developer conveying path in the conveying direction. A first developer supply opening for supplying a developer to an upstream portion in the transport direction of the first developer, and development from a downstream portion in the transport direction of the second developer transport path to an upstream portion in the transport direction of the third developer transport path A second developer supply opening for supplying the developer, and a second developer supply passage for supplying the developer from the downstream in the transport direction of the third developer transport path to the upstream in the transport direction of the first developer transport path. 3 developer supply openings, the first developer transport path, the second developer transport path, and the third developer transport path In the developing device partitioned by the partition member, a filter that allows air to pass without passing through the toner is provided above the first developer transport path, and an air passage that leads to the outside of the image forming apparatus has the developer carrying Provided in a lower portion of the body, the second developer conveyance path and the ventilation path are partitioned by a partition member, and a ventilation opening for ventilating the second developer conveyance path and the ventilation path includes the second developer conveyance path. The problem is solved by providing the partition member between the developer conveyance path and the ventilation path.

また、上記通気路は、トナーを通過させずに空気を通過させるフィルタと、上記通気路内部の空間を吸引する吸引手段とに接続していると好ましい。
さらに、上記通気用開口部は、上記現像剤担持体の長手方向に見て、現像剤が汲み上げられる範囲の外側に位置すると好ましい。 Further, it is preferable that the air passage is connected to a filter that allows air to pass through without passing toner, and a suction unit that sucks a space inside the air passage.
Further, it is preferable that the vent opening is located outside the range in which the developer is pumped up as viewed in the longitudinal direction of the developer carrier.

また、上記通気用開口部は、上記第２現像剤攪拌搬送手段の回転中心よりも上部に位置すると好ましい。
さらに、上記通気用開口部は、上記第２現像剤搬送路の搬送方向下流側であって、上記通気路の気流搬送方向の最上流部に配置されると好ましい。
また、本発明に従う画像形成装置は前述した現像装置を備えると好ましい。 Further, it is preferable that the vent opening is located above the rotation center of the second developer agitating / conveying means.
Further, it is preferable that the ventilation opening is disposed on the downstream side in the conveyance direction of the second developer conveyance path and at the most upstream portion in the airflow conveyance direction of the ventilation path.
The image forming apparatus according to the present invention preferably includes the developing device described above.

本発明によれば、現像装置の供給搬送路の上部に設けられたフィルタを介して供給搬送路における内圧が装置外に開放されると共に、回収搬送路における内圧が開口部を介して吸引ダクトに導かれ、吸引ダクトから装置外へ開放されるため、回収搬送路における内圧の上昇も効果的に抑制される。従って、回収搬送路から感光体ドラムへのトナー飛散を長期にわたって低減することができる。また、フィルタも目詰まりし難くなる。また、構造の最も簡単な回収搬送路に開口部を１つ増設するだけで良いため、装置の構造が簡単になり、装置の小型化と良好な組み立て性が実現される。さらに、回収搬送路と開口部及び吸引ダクトとの位置が近いため、回収搬送路の内圧を装置外へ効果的に排出することができる。   According to the present invention, the internal pressure in the supply conveyance path is released to the outside of the apparatus via the filter provided in the upper part of the supply conveyance path of the developing device, and the internal pressure in the recovery conveyance path is applied to the suction duct via the opening. Since it is guided and opened from the suction duct to the outside of the apparatus, an increase in the internal pressure in the recovery conveyance path is also effectively suppressed. Accordingly, it is possible to reduce toner scattering from the recovery conveyance path to the photosensitive drum over a long period of time. Also, the filter is less likely to be clogged. Further, since it is only necessary to add one opening to the recovery conveyance path having the simplest structure, the structure of the apparatus is simplified, and the apparatus can be reduced in size and can be easily assembled. Furthermore, since the positions of the collection conveyance path, the opening, and the suction duct are close, the internal pressure of the collection conveyance path can be effectively discharged out of the apparatus.

本実施形態に係る画像形成装置の要部の概略構成図である。1 is a schematic configuration diagram of a main part of an image forming apparatus according to an embodiment. 現像装置の概略構成を示す断面図である。It is sectional drawing which shows schematic structure of a developing device. 回収搬送路の搬送方向下流部における回収搬送路と攪拌搬送路との断面図である。It is sectional drawing of the collection conveyance path and the stirring conveyance path in the conveyance direction downstream part of a collection conveyance path. 現像装置の供給搬送路の搬送方向上流部における断面図である。It is sectional drawing in the conveyance direction upstream part of the supply conveyance path of a developing device. 現像装置の供給搬送路の搬送方向下流部における断面図である。FIG. 7 is a cross-sectional view of a downstream portion in a transport direction of a supply transport path of the developing device. 現像装置の供給搬送路の搬送方向下流部における断面図である。FIG. 7 is a cross-sectional view of a downstream portion in a transport direction of a supply transport path of the developing device. 現像装置内における現像剤の流れの模式図である。It is a schematic diagram of the flow of the developer in the developing device. 供給搬送路と攪拌搬送路の長手方向の断面図である。It is sectional drawing of the longitudinal direction of a supply conveyance path and a stirring conveyance path. 供給搬送路と攪拌搬送路の長手方向の断面図であり、開口部２ｆがトナーで塞がれた状態を示す。It is sectional drawing of the longitudinal direction of a supply conveyance path and a stirring conveyance path, and shows the state by which the opening part 2f was block | closed with the toner. 回収搬送路の内圧とトナー濃度の関係を示す図である。FIG. 6 is a diagram illustrating a relationship between an internal pressure of a recovery conveyance path and a toner concentration. 現像スリーブ手前側近傍位置の粉塵量とトナー濃度の関係を示す図である。FIG. 6 is a diagram illustrating a relationship between a dust amount near a position near the developing sleeve and a toner density. 本発明との比較例であり、特許文献４の現像装置内における現像剤の流れの模式図である。It is a comparative example with this invention, and is a schematic diagram of the flow of the developer in the developing device of Patent Document 4. 本発明との別な比較例であり、特許文献５のトナー搬送部及び圧抜き用フィルタを有する現像装置の断面図である。FIG. 10 is a cross-sectional view of a developing device that is another comparative example with the present invention and that includes a toner transport unit and a pressure relief filter of Patent Document 5. 本発明との別な比較例であり、特許文献６の攪拌搬送路及び供給搬送路に接続するトナー搬送部が一体形成されている現像装置の断面図である。FIG. 10 is a cross-sectional view of a developing device that is another comparative example with the present invention and in which a toner transport unit connected to the stirring transport path and the supply transport path of Patent Document 6 is integrally formed.

以下、本発明を画像形成装置に適用した一実施形態について説明する。図１は、本実施形態に係る画像形成装置の要部の概略構成図である。画像形成装置は、潜像担持体である感光体ドラム１００の周囲に、帯電装置２１、現像装置１、中間転写装置２３、クリーニング装置２８等が配設されている。現像装置１は、例えばイエロー、マゼンタ、シアン、ブラックのトナーを有し、画像形成装置内には各色に対応する画像形成部が設けられている。また、これらの下方には露光装置２２が設けられている。また、中間転写装置２３の側方には２次転写装置２５と定着装置２７とが設けられている。   Hereinafter, an embodiment in which the present invention is applied to an image forming apparatus will be described. FIG. 1 is a schematic configuration diagram of a main part of the image forming apparatus according to the present embodiment. In the image forming apparatus, a charging device 21, a developing device 1, an intermediate transfer device 23, a cleaning device 28, and the like are disposed around a photosensitive drum 100 that is a latent image carrier. The developing device 1 has, for example, yellow, magenta, cyan, and black toner, and an image forming unit corresponding to each color is provided in the image forming device. An exposure device 22 is provided below these. Further, a secondary transfer device 25 and a fixing device 27 are provided on the side of the intermediate transfer device 23.

感光体ドラム１００は、図中反時計回りに回転しながら、帯電装置２１で一様に帯電され、露光装置２２よりレーザーのような発光素子によって情報信号を露光されて静電潜像を形成される。感光体ドラム１００上の静電潜像は、現像装置１によりトナー像化され、形成されたトナー像は中間転写装置２３によって中間転写ベルト２４の上に転写される。中間転写ベルト２４上には、図示しない他の現像装置によるトナー像も転写可能であり、異なる色のトナーを重ねたカラー画像を作成することもできる。中間転写ベルト２４上のトナー像は２次転写装置２５によって転写紙２６の上に転写され、更に定着装置２７にて定着して永久画像を得る。感光体ドラム１００上の転写残トナーはクリーニング装置２８により除去され、感光体ドラム１００は次の画像形成に供される。   The photosensitive drum 100 is uniformly charged by the charging device 21 while rotating counterclockwise in the figure, and an information signal is exposed by a light emitting element such as a laser from the exposure device 22 to form an electrostatic latent image. The The electrostatic latent image on the photosensitive drum 100 is converted into a toner image by the developing device 1, and the formed toner image is transferred onto the intermediate transfer belt 24 by the intermediate transfer device 23. A toner image by another developing device (not shown) can be transferred onto the intermediate transfer belt 24, and a color image in which different color toners are superimposed can be created. The toner image on the intermediate transfer belt 24 is transferred onto the transfer paper 26 by the secondary transfer device 25 and further fixed by the fixing device 27 to obtain a permanent image. The transfer residual toner on the photosensitive drum 100 is removed by the cleaning device 28, and the photosensitive drum 100 is used for the next image formation.

図２は、現像装置の概略構成を示す断面図である。この現像装置１は、２成分現像剤を収容した現像容器２を備え、感光体ドラム１００と対面した現像容器２の開口部に、現像剤担持体としての現像スリーブ１１が感光体ドラム１００と所定の間隔を開けて回転自在に設置されている。現像スリーブ１１は非磁性材料の円筒部材からなり、矢印の方向に回転する感光体ドラム１００に対して、対向部が同方向に移動する向きに回転する。現像スリーブ１１の内側には磁界発生手段のマグネットローラが、現像スリーブ１１の回転に対して非回転に配置されている。マグネットローラは５つの磁極Ｎ１、Ｓ１、Ｎ２、Ｎ３、Ｓ２を有している。現像スリーブ１１上方の現像容器２の部分には磁性部材の規制ブレード３０が取付けられ、この規制ブレード３０は、マグネットローラの鉛直方向最上点に略位置した磁極Ｓ２の近傍に向けて、現像スリーブ１１と非接触に配置されている。   FIG. 2 is a cross-sectional view illustrating a schematic configuration of the developing device. The developing device 1 includes a developing container 2 containing a two-component developer, and a developing sleeve 11 serving as a developer carrying member is formed with a predetermined distance from the photosensitive drum 100 at an opening of the developing container 2 facing the photosensitive drum 100. It is installed so as to be freely rotatable with an interval of. The developing sleeve 11 is made of a cylindrical member made of a non-magnetic material, and rotates in a direction in which the facing portion moves in the same direction with respect to the photosensitive drum 100 rotating in the direction of the arrow. Inside the developing sleeve 11, a magnet roller as a magnetic field generating means is arranged so as not to rotate with respect to the rotation of the developing sleeve 11. The magnet roller has five magnetic poles N1, S1, N2, N3, and S2. A magnetic member regulating blade 30 is attached to the portion of the developing container 2 above the developing sleeve 11, and the regulating blade 30 is directed toward the vicinity of the magnetic pole S <b> 2 that is substantially positioned at the uppermost point in the vertical direction of the magnet roller. And arranged in non-contact.

現像容器２内には第１現像剤攪拌搬送手段である供給スクリュー４、第２現像剤攪拌搬送手段である回収スクリュー６、第３現像剤攪拌搬送手段である攪拌スクリュー７をそれぞれ収容する第１現像剤搬送路としての供給搬送路２ａ、第２現像剤搬送路としての回収搬送路２ｂ、第３現像剤搬送路としての攪拌搬送路２ｃの３つの現像剤搬送路が設けられている。供給搬送路２ａと攪拌搬送路２ｃとは、斜め上下方向に配置されている。また、回収搬送路２ｂは、現像スリーブ１１の現像領域下流側で、攪拌搬送路２ｃと略水平な側方に配置されている。   The developer container 2 contains a first supply screw 4 as a first developer stirring and conveying means, a recovery screw 6 as a second developer stirring and conveying means, and a first stirring screw 7 as a third developer stirring and conveying means. There are provided three developer conveyance paths: a supply conveyance path 2a as a developer conveyance path, a recovery conveyance path 2b as a second developer conveyance path, and an agitation conveyance path 2c as a third developer conveyance path. The supply conveyance path 2a and the agitation conveyance path 2c are arranged obliquely in the vertical direction. Further, the collection conveyance path 2b is disposed on the downstream side of the developing region of the developing sleeve 11 and on a side substantially horizontal to the stirring conveyance path 2c.

現像容器２内に収容された２成分現像剤は、供給スクリュー４、回収スクリュー７、攪拌スクリュー６の撹拌、搬送により供給搬送路２ａ、回収搬送路２ｂ、攪拌搬送路２ｃを循環搬送されながら、供給搬送路２ａより現像スリーブ１１に供給される。現像スリーブ１１に供給された現像剤は、マグネットローラの磁極Ｎ２により現像スリーブ１１上に汲み上げられる。現像スリーブ１１の回転にともない、現像スリーブ１１上を磁極Ｓ２から磁極Ｎ１、磁極Ｎ１から磁極Ｓ１と搬送され、現像スリーブ１１と感光ドラム１００とが対向した現像領域にいたる。その搬送の途上で現像剤は、規制ブレード３０により磁極Ｓ２と共同して磁気的に層厚を規制され、現像スリーブ１１上に現像剤の薄層が形成される。現像スリーブ１１内の現像領域に位置されたマグネットローラの磁極Ｓ１は現像主極であり、現像領域に搬送された現像剤は、磁極Ｓ１によって穂立ちして感光ドラム１００の表面に接触し、感光ドラム１００の表面に形成された静電潜像を現像する。潜像を現像した現像剤は、現像スリーブ１１の回転にともない現像領域を通過し、搬送極Ｎ３を経て現像容器２内に戻され、磁極Ｎ２、Ｎ３の反発磁界により現像スリーブ１１から離脱し、回収スクリュー６により回収搬送路２ｂに回収される。   The two-component developer accommodated in the developing container 2 is circulated and conveyed through the supply conveyance path 2a, the collection conveyance path 2b, and the agitation conveyance path 2c by stirring and conveyance of the supply screw 4, the recovery screw 7 and the stirring screw 6. The toner is supplied to the developing sleeve 11 from the supply conveyance path 2a. The developer supplied to the developing sleeve 11 is pumped onto the developing sleeve 11 by the magnetic pole N2 of the magnet roller. As the developing sleeve 11 rotates, the developing sleeve 11 is conveyed from the magnetic pole S2 to the magnetic pole N1 and from the magnetic pole N1 to the magnetic pole S1, and reaches the developing area where the developing sleeve 11 and the photosensitive drum 100 face each other. During the conveyance, the developer is magnetically regulated by the regulating blade 30 in cooperation with the magnetic pole S2, and a thin layer of developer is formed on the developing sleeve 11. The magnetic pole S1 of the magnet roller located in the developing area in the developing sleeve 11 is a developing main pole, and the developer conveyed to the developing area rises by the magnetic pole S1 and comes into contact with the surface of the photosensitive drum 100, and is exposed to light. The electrostatic latent image formed on the surface of the drum 100 is developed. The developer that has developed the latent image passes through the developing region as the developing sleeve 11 rotates, returns to the developing container 2 through the transport pole N3, and is separated from the developing sleeve 11 by the repulsive magnetic field of the magnetic poles N2 and N3. It is collected in the collection conveyance path 2b by the collection screw 6.

また、装置内で発生した内圧は、供給搬送路２ａの上方に設置された、トナーの通過を阻止し空気の通過のみを許容するフィルタ５を介して装置外に排出される。
供給搬送路２ａと斜め下方の回収搬送路２ｂとは第１仕切り部材３１によって仕切られている。 The internal pressure generated in the apparatus is discharged outside the apparatus through a filter 5 installed above the supply conveyance path 2a that prevents the passage of toner and allows only the passage of air.
The supply conveyance path 2 a and the collection conveyance path 2 b obliquely below are partitioned by a first partition member 31.

回収搬送路２ｂと側方に配置される攪拌搬送路２ｃとは第２仕切り部材３２によって仕切られているが、回収搬送路２ｂの回収スクリュー６による搬送方向下流部には、回収された現像剤を攪拌搬送路２ｃに供給するための現像剤供給用開口部が設けられている。図３は、回収スクリュー６による搬送方向下流部における回収搬送路２ｂと攪拌搬送路２ｃとの断面図であり、回収搬送路２ｂと攪拌搬送路２ｃとを連通する開口部２ｄが設けられている。   The collection conveyance path 2b and the agitating conveyance path 2c arranged on the side are partitioned by the second partition member 32, but the collected developer is located downstream in the conveyance direction by the collection screw 6 of the collection conveyance path 2b. Is provided with a developer supply opening for supplying the toner to the agitating and conveying path 2c. FIG. 3 is a cross-sectional view of the collection conveyance path 2b and the agitation conveyance path 2c at the downstream portion in the conveyance direction by the collection screw 6, and an opening 2d that connects the collection conveyance path 2b and the agitation conveyance path 2c is provided. .

また、供給搬送路２ａと斜め下方に配置される攪拌搬送路２ｃとは第３仕切り部材３３により仕切られているが、供給搬送路２ａの供給スクリュー４による搬送方向上流部と下流部には、現像剤を供給するための現像剤供給用開口部が設けられている。図４は、供給スクリュー４による搬送方向上流部における現像装置１の断面図であり、第３仕切り部材３３に攪拌搬送路２ｃと供給搬送路２ａとを連通する開口部２ｅが設けられており、現像剤は攪拌スクリュー７の回転によって供給搬送路２ａに持ち上げられる。また、図５は、供給スクリュー４による搬送方向下流部における現像装置１の断面図であり、第３仕切り部材３３に攪拌搬送路２ｃと供給搬送路２ａとを連通する開口部２ｆが設けられている。図５に示すように、開口部２ｆはある水準（高さ）で設けられており、この水準を越えた現像剤は開口部２ｆを介して攪拌搬送路２ｃに戻される。現像剤は、供給搬送路２ａの最下流部に向かって供給スクリュー４による搬送力を受けるが、現像剤が搬送力によって下流側でパッキングされることはなく、現像剤の水準は、開口部２ｆの水準と、供給スクリュー４の搬送力及び現像スリーブ１１の搬送力とによって決まるある水準になる。   Further, the supply conveyance path 2a and the agitation conveyance path 2c disposed obliquely below are partitioned by the third partition member 33, but in the upstream and downstream parts in the conveyance direction by the supply screw 4 of the supply conveyance path 2a, A developer supply opening for supplying the developer is provided. FIG. 4 is a cross-sectional view of the developing device 1 at the upstream portion in the conveyance direction by the supply screw 4, and the third partition member 33 is provided with an opening 2e that communicates the agitation conveyance path 2c and the supply conveyance path 2a. The developer is lifted to the supply conveyance path 2 a by the rotation of the stirring screw 7. FIG. 5 is a cross-sectional view of the developing device 1 at a downstream portion in the conveyance direction by the supply screw 4. The third partition member 33 is provided with an opening 2 f that communicates the agitation conveyance path 2 c and the supply conveyance path 2 a. Yes. As shown in FIG. 5, the opening 2f is provided at a certain level (height), and the developer exceeding this level is returned to the stirring and conveying path 2c through the opening 2f. The developer receives a conveying force by the supply screw 4 toward the most downstream portion of the supply conveying path 2a, but the developer is not packed downstream by the conveying force, and the level of the developer is the opening 2f. And a certain level determined by the conveying force of the supply screw 4 and the conveying force of the developing sleeve 11.

本発明の特徴部として、現像スリーブ１１近傍及び回収搬送路２ｂにおける飛散トナーを雰囲気ごと吸引して装置外に排出する通気路としての吸引ダクト３５が、現像スリーブ１１の下方に配置されている。吸引ダクト３５は、画像形成装置の外装カバー近くに設置された、トナーを通過させずに空気を通過させるフィルタ（不図示）及び吸引手段としてのファン（不図示）に接続され、現像装置１から画像形成装置の外側に通じている。吸引ダクト３５内部の空間は、このファンによって吸引されており、飛散トナーを含む空気は、ファンの手前に設置されたこのフィルタを通り、飛散トナーはフィルタに吸着され、最終的に空気のみ画像形成装置外へ排出されるようになっている。ここで、画像形成装置の外装カバー近くに設置されたフィルタは、その設計の自由度が大きく、小型化が求められる現像装置のフィルタよりも大きいものを使用することができる。   As a feature of the present invention, a suction duct 35 is disposed below the developing sleeve 11 as a ventilation path for sucking the scattered toner in the vicinity of the developing sleeve 11 and in the collecting and conveying path 2b together with the atmosphere and discharging it to the outside of the apparatus. The suction duct 35 is connected to a filter (not shown) installed near the exterior cover of the image forming apparatus that allows air to pass therethrough and a fan (not shown) as suction means. It leads to the outside of the image forming apparatus. The space inside the suction duct 35 is sucked by this fan, and air containing scattered toner passes through this filter installed in front of the fan, and the scattered toner is adsorbed by the filter, and finally only air forms an image. It is designed to be discharged out of the device. Here, the filter installed near the exterior cover of the image forming apparatus has a large degree of freedom in design, and a filter larger than the filter of the developing device that is required to be downsized can be used.

また、図６に示すように、現像装置の供給搬送路２ｂの搬送方向下流部において、吸引ダクト３５と回収搬送路２ｂとの第４仕切り部材３７には、飛散トナーを含む空気を回収搬送路２ｂから吸引ダクト３５に通気するための通気用開口部としての開口部３６が少なくとも１つ形成されており、これにより吸引ダクト３５と回収搬送路２ｂは連通している。ここで、開口部３６は、現像スリーブ１１の長手方向に見て、現像剤が汲み上げられる範囲の外側に位置するのが好ましい。開口部３６が現像剤が汲み上げられる幅よりも外側になければ、現像スリーブ１１から回収搬送路２ｂへ落ちる現像剤がそのまま吸引ダクト３５内に落ちてしまい、吸引ダクト３５に落ちた現像剤は、有効に利用されずに無駄になるだけでなく、場合によっては開口部３６を塞いで気流を遮断してしまうからである。同様に、開口部３６は、回収スクリュー６の回転中心よりも上部に位置するのが好ましい。上部にないと回収スクリュー６によって回転搬送された現像剤が、やはり開口部３６を介して吸引ダクト３５内に落ちてしまうからである。   In addition, as shown in FIG. 6, in the downstream portion in the transport direction of the supply transport path 2b of the developing device, air containing scattered toner is collected into the recovery transport path in the fourth partition member 37 of the suction duct 35 and the recovery transport path 2b. At least one opening 36 as a ventilation opening for ventilating the suction duct 35 from 2b is formed, whereby the suction duct 35 and the recovery conveyance path 2b communicate with each other. Here, the opening 36 is preferably located outside the range in which the developer is pumped up as viewed in the longitudinal direction of the developing sleeve 11. If the opening 36 is not outside of the width where the developer is pumped up, the developer falling from the developing sleeve 11 to the collection conveyance path 2b falls into the suction duct 35 as it is, and the developer dropped into the suction duct 35 is This is because it is not used effectively but is wasted, and in some cases, the opening 36 is blocked to block the airflow. Similarly, the opening 36 is preferably located above the rotation center of the recovery screw 6. This is because the developer rotated and conveyed by the recovery screw 6 falls into the suction duct 35 through the opening 36 if it is not at the upper part.

このように開口部３６の位置を画定することによって、回収搬送路２ｂで発生した圧力が開口部３６及び吸引ダクト３５を介して画像形成装置外へ排出されるため、現像スリーブ１１下部及び回収搬送路２ｂにおいて内圧が上昇せず、回収搬送路２ｂから感光体ドラム１００へのトナー飛散が増大することもない。さらに、開口部３６が現像剤で塞がることが無いので、長期にわたって回収搬送路２ｂから感光体ドラム１００へのトナー飛散を抑制することができる。   By defining the position of the opening 36 in this way, the pressure generated in the collection conveyance path 2b is discharged out of the image forming apparatus through the opening 36 and the suction duct 35. The internal pressure does not increase in the path 2b, and toner scattering from the recovery conveyance path 2b to the photosensitive drum 100 does not increase. Furthermore, since the opening 36 is not blocked by the developer, it is possible to suppress toner scattering from the collection conveyance path 2b to the photosensitive drum 100 over a long period of time.

次に、３つの現像剤搬送路内での現像剤の循環について説明する。
図７は、現像装置１内での現像剤の流れの模式図である。図７中の各矢印は現像剤の移動方向を示している。攪拌搬送路２ｃから現像剤の供給を受けた供給搬送路２ａでは、現像スリーブ１１に現像剤を供給しながら、供給スクリュー４の搬送方向下流側に現像剤を搬送する。そして、現像スリーブ１１に供給されずに供給搬送路２ａの搬送方向下流部まで搬送された余剰現像剤は第３仕切り部材３３に設けられた第１現像剤供給用開口部としての開口部２ｆより攪拌搬送路２ｃに供給される。 Next, the circulation of the developer in the three developer conveyance paths will be described.
FIG. 7 is a schematic view of the developer flow in the developing device 1. Each arrow in FIG. 7 indicates the moving direction of the developer. In the supply conveyance path 2 a that receives the developer supplied from the agitation conveyance path 2 c, the developer is conveyed downstream in the conveyance direction of the supply screw 4 while supplying the developer to the developing sleeve 11. The surplus developer conveyed to the downstream side in the conveyance direction of the supply conveyance path 2 a without being supplied to the developing sleeve 11 is from an opening 2 f as a first developer supply opening provided in the third partition member 33. It is supplied to the agitation transport path 2c.

また、回収スクリュー６により現像スリーブ１１から回収搬送路２ｂに回収され、供給搬送路２ａの現像剤と同方向に搬送方向下流部まで搬送された回収現像剤は第２仕切り部材３２に設けられた第２現像剤供給用開口部としての開口部２ｄより攪拌搬送路２ｃに供給される。   Further, the recovered developer that is recovered from the developing sleeve 11 to the recovery transport path 2b by the recovery screw 6 and transported to the downstream portion in the transport direction in the same direction as the developer in the supply transport path 2a is provided in the second partition member 32. The developer is supplied to the stirring and conveying path 2c from the opening 2d as the second developer supply opening.

攪拌搬送路２ｃでは、供給された余剰現像剤と回収現像剤とを攪拌スクリュー７により攪拌し、回収搬送路２ｂ及び供給搬送路２ａの現像剤と逆方向に搬送する。そして、攪拌搬送路２ｃの搬送方向下流側に搬送された現像剤は、第３仕切り部材３３に設けられた第３現像剤供給用開口部としての開口部２ｅより供給搬送路２ａの搬送方向上流部に供給される。   In the agitation transport path 2c, the supplied surplus developer and recovered developer are stirred by the stirring screw 7, and transported in the opposite direction to the developer in the recovery transport path 2b and the supply transport path 2a. The developer conveyed downstream in the conveyance direction of the agitation conveyance path 2 c is upstream in the conveyance direction of the supply conveyance path 2 a from the opening 2 e serving as the third developer supply opening provided in the third partition member 33. Supplied to the department.

以上のように、現像剤は、３つの搬送室２ａ，２ｂ，２ｃ内と現像スリーブ１１上を図中矢印の方向に移動し、現像剤と同じく現像装置１内の空気の流れも矢印のように移動する。さらに、フィルタ５から現像装置１外に排出される空気流れと、開口部３６及び吸引ダクト３５を介して現像装置１外に排気される空気流れも存在する。第４仕切り部材３７における開口部３６により、回収搬送路２ｂと吸引ダクト３５は連通しており、吸引ダクト３５内の空間は図中点線矢印の方向にファン（不図示）によって引かれているため、吸引ダクト３５及び回収搬送路２ｂ内の飛散トナーを含んだ空気はフィルタ（不図示）を介して画像形成装置外へと排出される。   As described above, the developer moves in the three conveyance chambers 2a, 2b, and 2c and on the developing sleeve 11 in the direction of the arrow in the figure, and the flow of air in the developing device 1 is as indicated by the arrow as in the case of the developer. Move to. Further, there are an air flow discharged from the filter 5 to the outside of the developing device 1 and an air flow exhausted to the outside of the developing device 1 through the opening 36 and the suction duct 35. The collection conveyance path 2b and the suction duct 35 communicate with each other through the opening 36 in the fourth partition member 37, and the space in the suction duct 35 is drawn by a fan (not shown) in the direction of the dotted arrow in the figure. The air containing the scattered toner in the suction duct 35 and the collection conveyance path 2b is discharged out of the image forming apparatus through a filter (not shown).

また、開口部３６は、回収搬送路２ｂの搬送方向下流側であって、吸引ダクト３５の気流搬送方向の最上流部に配置されるのが好ましい。回収搬送路２ｂでは現像剤と空気が搬送される下流側ほど内圧が高くなり易いため、この位置に開口部３６を設けることで、開口部３６及び吸引ダクト３５を介して回収搬送路２ｂの内圧を効率的に画像形成装置外へ逃がすことができる。   Further, the opening 36 is preferably disposed on the downstream side in the transport direction of the collection transport path 2b and at the most upstream portion in the airflow transport direction of the suction duct 35. In the collection conveyance path 2b, the internal pressure tends to increase toward the downstream side where the developer and air are conveyed. Therefore, by providing the opening 36 at this position, the internal pressure of the collection conveyance path 2b is set via the opening 36 and the suction duct 35. Can be efficiently released to the outside of the image forming apparatus.

このように、フィルタ５により供給搬送路２ａにおける内圧を逃がし、開口部３６及び吸引ダクト３５により回収搬送路２ｂにおける内圧を逃がすことができるため、現像装置内に収容された現像剤によって各開口部が十分に連通していない場合でも、現像装置の内圧を効果的に逃がすことができる。   As described above, the internal pressure in the supply conveyance path 2a can be released by the filter 5 and the internal pressure in the recovery conveyance path 2b can be released by the opening 36 and the suction duct 35. Therefore, each opening is formed by the developer contained in the developing device. Even when there is not sufficient communication, the internal pressure of the developing device can be effectively released.

また、攪拌搬送路２ｃの下方には、トナー濃度センサ（不図示）が設けられ、センサ出力により不図示のトナー補給制御装置を作動し、トナー収容部（不図示）からトナー補給を行っている。攪拌搬送路２ｃでは攪拌スクリュー７によって、必要に応じてトナー補給口３から補給されるトナーを、回収現像剤及び余剰現像剤と攪拌しながら搬送方向下流側へ搬送する。トナーを補給する際には攪拌スクリュー７の上流にて補給すると補給から現像までの攪拌時間を長くとれるので良い。   A toner concentration sensor (not shown) is provided below the agitation transport path 2c, and a toner supply control device (not shown) is operated by the sensor output to supply toner from a toner container (not shown). . In the agitating and conveying path 2c, the toner replenished from the toner replenishing port 3 as necessary is conveyed by the agitating screw 7 to the downstream side in the conveying direction while being agitated with the collected developer and the surplus developer. When replenishing toner, replenishing upstream of the agitation screw 7 can increase the agitation time from replenishment to development.

このように現像装置１では、供給搬送路２ａと回収搬送路２ｂとを備え、現像剤の供給と回収とを異なる現像剤搬送路で行うので、現像済みの現像剤が供給搬送路２ａに混入することがない。よって、供給搬送路２ａの搬送方向下流側ほど現像スリーブ１１に供給される現像剤のトナー濃度が低下することを防止することができる。また、回収搬送路２ｂと攪拌搬送路２ｃとを備え、現像剤の回収と攪拌とを異なる現像剤搬送路で行うので、現像済みの現像剤が攪拌の途中に落ちることがない。よって、十分に攪拌がなされた現像剤が供給搬送路２ａに供給されるため、供給搬送路２ａに供給される現像剤が攪拌不足となることを防止することができる。このように、供給搬送路２ａ内の現像剤のトナー濃度が低下することを防止し、供給搬送路２ａ内の現像剤が攪拌不足となることを防止することができるので現像時の画像濃度を一定にすることができる。   As described above, the developing device 1 includes the supply conveyance path 2a and the collection conveyance path 2b, and the developer is supplied and collected in different developer conveyance paths, so that the developed developer is mixed into the supply conveyance path 2a. There is nothing to do. Therefore, it is possible to prevent the toner concentration of the developer supplied to the developing sleeve 11 from decreasing toward the downstream side of the supply conveyance path 2a in the conveyance direction. Further, since the recovery conveyance path 2b and the agitation conveyance path 2c are provided and the developer is collected and stirred in different developer conveyance paths, the developed developer does not fall during the agitation. Therefore, since the sufficiently stirred developer is supplied to the supply conveyance path 2a, it is possible to prevent the developer supplied to the supply conveyance path 2a from being insufficiently stirred. In this way, the toner density of the developer in the supply conveyance path 2a can be prevented from decreasing, and the developer in the supply conveyance path 2a can be prevented from being insufficiently stirred, so the image density during development can be reduced. Can be constant.

また、図４に示す供給搬送路２ａの搬送方向上流部では、斜め下方に配置される攪拌搬送路２ｃから上方の供給搬送路２ａへ現像剤を供給するものである。この現像剤の受け渡しは、攪拌スクリュー７の回転で現像剤を押し込むことにより、現像剤を盛り上がらせて開口部２ｅより現像剤を溢れさせて供給搬送路２ａに現像剤を供給するものである。このような現像剤の移動は、現像剤に対してストレスを与えることになり、現像剤の寿命低下の一因となる。現像装置１では、供給搬送路２ａを攪拌搬送路２ｃの斜め上方になるように配置することにより、供給搬送路２ａを攪拌搬送路２ｃの垂直上方に設け、現像剤を持ち上げるものに比べて、上方への現像剤の移動における現像剤のストレスを軽減することができる。   Further, in the upstream portion in the conveyance direction of the supply conveyance path 2a shown in FIG. 4, the developer is supplied from the stirring conveyance path 2c disposed obliquely downward to the upper supply conveyance path 2a. In the delivery of the developer, the developer is pushed up by the rotation of the stirring screw 7 so that the developer is raised and overflows from the opening 2e to supply the developer to the supply conveyance path 2a. Such movement of the developer gives stress to the developer and contributes to a decrease in the life of the developer. In the developing device 1, the supply conveyance path 2a is disposed so as to be obliquely above the agitation conveyance path 2c, so that the supply conveyance path 2a is provided vertically above the agitation conveyance path 2c, and the developer is lifted, It is possible to reduce the developer stress in the upward movement of the developer.

しかしながら、このような構成において本発明のような開口部３６が無いと、現像剤の供給搬送路２ａ内でのバランスによっては、現像装置の回収搬送路２ｂ及び攪拌搬送路２ｃで発生した内圧が下がらなくなることがある。   However, in such a configuration, if there is no opening 36 as in the present invention, the internal pressure generated in the recovery conveyance path 2b and the agitation conveyance path 2c of the developing device depends on the balance in the developer supply conveyance path 2a. May not go down.

供給搬送路２ａと攪拌搬送路２ｃの長手方向の断面図は図８に示されるようになっている。一般に、現像剤の流動性の変化とトナー濃度の変化により現像装置内の現像剤の分布は変化するため、図９に示すような現像剤分布になり得る。図９に示すように開口部２ｆが現像剤によって完全に塞がれてしまうと、回収搬送路２ｂ及び攪拌搬送路２ｃで発生した内圧が装置上方のフィルタ５まで達することができず、回収搬送路２ｂと現像スリーブ１１の間のギャップを介して、回収搬送路２ｂから感光体ドラム１００へのトナー飛散が発生又は増大してしまう。   A longitudinal sectional view of the supply conveyance path 2a and the agitation conveyance path 2c is as shown in FIG. In general, the developer distribution in the developing device changes due to the change in the fluidity of the developer and the change in the toner concentration, so that the developer distribution as shown in FIG. 9 can be obtained. As shown in FIG. 9, when the opening 2f is completely blocked by the developer, the internal pressure generated in the collection conveyance path 2b and the stirring conveyance path 2c cannot reach the filter 5 above the apparatus, and the collection conveyance Through the gap between the path 2 b and the developing sleeve 11, toner scattering from the recovery conveyance path 2 b to the photosensitive drum 100 occurs or increases.

本発明によれば、前述のように現像装置に吸引ダクト３５及び開口部３６を設けることで、この問題を解決することができる。現像装置に吸引ダクト３５及び開口部３６を設けることによる効果を以下のようにして比較・検証した。   According to the present invention, this problem can be solved by providing the developing device with the suction duct 35 and the opening 36 as described above. The effects of providing the suction duct 35 and the opening 36 in the developing device were compared and verified as follows.

カラーコピー機として「Ｉｍａｇｉｏ ＭＰ Ｃ７５００」（商品名：株式会社リコー製）を使用し、この現像装置に吸引ダクトを追加して、吸引ダクトと回収搬送路の間の仕切り部材に現像スリーブの手前側端部の直下位置で５ｍｍ角の開口部を形成し、現像剤排出スクリューを取り外し、本発明の実施例の現像装置とした。また、比較例として、単に吸引ダクトと回収搬送路の間の仕切り部材の穴を塞いだものを使用した。また、吸引ダクトとして「Ｄ２Ｘ−０５ＴＬ」（商品名：日本電産株式会社製）を使用して、現像装置の奥側から吸引ダクトを吸引した。現像装置には、カラーコピー機に同梱されたブラック現像剤をセットし、トナーは同様に同梱されたブラックトナー「ｉｍａｇｉｏ ＭＰ Ｐトナーブラック Ｃ７５００」（商品名：株式会社リコー製）を使用した。   “Imagio MP C7500” (trade name: manufactured by Ricoh Co., Ltd.) is used as a color copier, a suction duct is added to this developing device, and the front side of the developing sleeve is placed on the partition member between the suction duct and the collection conveyance path An opening of 5 mm square was formed at a position directly below the end, the developer discharge screw was removed, and the developing device of the example of the present invention was obtained. Further, as a comparative example, the one in which the hole of the partition member between the suction duct and the collection conveyance path is simply closed is used. Further, “D2X-05TL” (trade name: manufactured by Nidec Corporation) was used as the suction duct, and the suction duct was sucked from the back side of the developing device. The black developer supplied with the color copier was set in the developing device, and the black toner “image MP P Toner Black C7500” (trade name: manufactured by Ricoh Co., Ltd.) was also used as the toner. .

この現像装置において、各スクリューと現像スリーブを回転駆動させ、トナーを足しながら、現像剤のトナー濃度に対する現像装置の内圧とトナー飛散量を測定した。トナー濃度が上昇すると、現像剤の嵩が増えるので、図９に示すような現像剤状態になり、内圧の上昇とトナー飛散が生じ易い。トナーをトナー補給口から追加し、スクリューにより現像装置内の現像剤を１分間攪拌し、次の１分間攪拌時の内圧測定値とトナー飛散量測定値を平均して比較した。   In this developing device, each screw and developing sleeve were rotationally driven, and while adding toner, the internal pressure of the developing device and the amount of scattered toner with respect to the toner concentration of the developer were measured. When the toner concentration is increased, the bulk of the developer is increased, so that the developer state as shown in FIG. 9 is obtained, and the internal pressure is increased and the toner is likely to be scattered. Toner was added from the toner replenishing port, the developer in the developing device was stirred for 1 minute with a screw, and the measured internal pressure value and the measured toner scattering amount during the next 1 minute stirring were averaged and compared.

現像スリーブ手前側（回収搬送路２ｂの下流部、画像形成装置本体手前側）の現像装置内圧は、回収搬送路の、現像スリーブ手前端部の直下位置から約１０ｍｍ手前の位置であって、回収スクリュー６の真上位置に開口部を開け、その位置の圧力を「精密デジタル圧力計 ＧＣ１５」（商品名：長野計器株式会社製）を使用して測定した。
現像スリーブ近傍のトナー飛散量は、現像スリーブの手前側端部に向かって水平に５０ｍｍ離れた位置で、「デジタル粉塵計 ＤｕｓｔＴｒａｋ Ｍｏｄｅｌ ８５２０」（商品名：ＴＳＩ社製）を使用して測定した。 The internal pressure of the developing device on the front side of the developing sleeve (the downstream side of the collection conveyance path 2b, the front side of the image forming apparatus main body) is approximately 10 mm before the position immediately below the front end of the development sleeve in the collection conveyance path. An opening was opened at a position directly above the screw 6, and the pressure at that position was measured using "Precision Digital Pressure Gauge GC15" (trade name: manufactured by Nagano Keiki Co., Ltd.).
The toner scattering amount in the vicinity of the developing sleeve was measured by using “Digital Dust Meter DustTrak Model 8520” (trade name: manufactured by TSI) at a position horizontally spaced 50 mm toward the front end of the developing sleeve.

測定結果として、回収搬送路の内圧とトナー濃度の関係を図１０に、現像スリーブ手前側近傍位置の粉塵量とトナー濃度の関係を図１１にそれぞれ示す。図示のように、実施例における吸引ダクトと回収搬送路の間の仕切り部材に開口部を形成した構成では、飛散トナーを含む空気をこの開口部を介して吸引ダクトに導き、トナーをフィルタ（不図示）で吸着して、空気のみを現像装置及び画像形成装置外へ排出するため、トナー濃度上昇時でも現像装置内圧とトナー飛散量の上昇は共に抑制されていた。しかしながら、比較例である吸引ダクトと回収搬送路の間の仕切り部材に開口部が形成されていない構成では、トナー濃度が１０重量％以上になると現像装置内圧は上昇し、トナー飛散量も増大していた。このように、本発明によればトナー濃度上昇時でも従来よりも現像装置内圧が抑えられ、トナー飛散量も上昇しないことが判明した。   As a measurement result, FIG. 10 shows the relationship between the internal pressure of the collection conveyance path and the toner concentration, and FIG. 11 shows the relationship between the dust amount near the developing sleeve front side and the toner concentration. As shown in the drawing, in the configuration in which an opening is formed in the partition member between the suction duct and the collection conveyance path in the embodiment, air containing scattered toner is guided to the suction duct through this opening, and the toner is filtered (not filtered). In the drawing, only air is discharged to the outside of the developing device and the image forming apparatus. Therefore, both the increase in the internal pressure of the developing device and the amount of scattered toner are suppressed even when the toner concentration is increased. However, in the configuration in which the opening portion is not formed in the partition member between the suction duct and the collection conveyance path, which is a comparative example, when the toner concentration becomes 10% by weight or more, the internal pressure of the developing device increases and the amount of toner scattering increases. It was. Thus, according to the present invention, it has been found that even when the toner concentration is increased, the internal pressure of the developing device can be suppressed more than before, and the amount of scattered toner is not increased.

なお、特許文献４、特許文献５及び特許文献６は本発明と同様の課題を解決しようとしているが、それぞれ次のような問題を残している。
図１２は、本発明との比較例として特許文献４の現像装置の構成を示す図である。図示のように、攪拌搬送路２ｃと供給搬送路２ａを連通する３つの開口部が設けられているため、装置は比較的複雑となり、現像装置の組み立ての工数が増大してしまう。一方、本発明の現像装置１の構成を示す図７では、攪拌搬送路２ｃと供給搬送路２ａを連通する開口部は２つで足りるため、現像装置１の組み立てはより容易である。また、回収搬送路２ｂと開口部２ｇとの位置が遠いため、回収搬送路２ｂの現像スリーブ位置での内圧を十分に抜き難い。一方、本発明の現像装置１の構成を示す図６では、回収搬送路２ｂと開口部３６及び吸引ダクト３５との位置が近いため、回収搬送路２ｂにおける内圧を十分に抜くことができる。 In addition, although patent document 4, patent document 5, and patent document 6 are going to solve the subject similar to this invention, the following problems remain, respectively.
FIG. 12 is a diagram showing a configuration of a developing device of Patent Document 4 as a comparative example with the present invention. As shown in the figure, since three openings for communicating the agitation conveyance path 2c and the supply conveyance path 2a are provided, the apparatus becomes relatively complicated, and the number of steps for assembling the developing device increases. On the other hand, in FIG. 7 showing the configuration of the developing device 1 of the present invention, since only two openings are required to communicate the agitation transport path 2c and the supply transport path 2a, the assembly of the developing apparatus 1 is easier. Further, since the positions of the collection conveyance path 2b and the opening 2g are far from each other, it is difficult to sufficiently release the internal pressure at the developing sleeve position of the collection conveyance path 2b. On the other hand, in FIG. 6 showing the configuration of the developing device 1 of the present invention, the internal position of the collection conveyance path 2b can be sufficiently released because the collection conveyance path 2b is close to the opening 36 and the suction duct 35.

図１３は、本発明との別な比較例として、特許文献５に記載されたような、現像装置のトナー補給口３に接続する、圧抜き用フィルタ５ａを有するトナー搬送部１２０を備えた現像装置を示している。回収搬送路２ｂにおいて発生した圧力はトナー補給口３及びトナー搬送部１２０のフィルタ５ａを介して現像装置の外部に排出される。しかし、現像剤を上方へ持ち上げる必要のある現像装置で図９の状態となると、現像装置内の空気が流通しないため、特許文献５の現像装置よりも遥かに内圧が高まる。よって、トナー補給口３を通じて装置外に空気を逃がす場合、トナー混じりの空気の排気量が増え、フィルタが早く寿命に達してしまう。また、特許文献５では狭い空間に小さいフィルタを配置するのでフィルタの目詰まりが発生し易いが、本発明では、大きめのフィルタ５及び吸引ダクト３５の大きい排出口に備えられた大きめのフィルタ（不図示）を使用するので、これらのフィルタの目詰まりが生じ難い。また、回収搬送路２ｂと攪拌搬送路２ｃに設けられたトナー補給口３との位置が遠いため、回収搬送路２ｂの現像スリーブ位置での内圧を十分に抜き難い。   FIG. 13 shows, as another comparative example with the present invention, a development provided with a toner conveying portion 120 having a pressure relief filter 5a connected to the toner replenishing port 3 of the developing device as described in Patent Document 5. The device is shown. The pressure generated in the recovery conveyance path 2b is discharged to the outside of the developing device through the toner supply port 3 and the filter 5a of the toner conveyance unit 120. However, in the developing device that needs to lift the developer upward, the air in the developing device does not flow when the state shown in FIG. 9 is reached, so that the internal pressure is much higher than that of the developing device of Patent Document 5. Therefore, when air is released to the outside of the apparatus through the toner supply port 3, the exhaust amount of air mixed with toner increases, and the filter reaches the end of its life quickly. Further, in Patent Document 5, since a small filter is arranged in a narrow space, the filter is likely to be clogged. However, in the present invention, the large filter (not large) provided at the large discharge port of the large filter 5 and the suction duct 35 is used. These filters are not easily clogged. Further, since the positions of the collection conveyance path 2b and the toner replenishing port 3 provided in the stirring conveyance path 2c are far from each other, it is difficult to sufficiently release the internal pressure at the developing sleeve position of the collection conveyance path 2b.

図１４は、本発明との比較例として特許文献６の現像装置の構成を示す図である。この現像装置には、トナー搬送部９０が一体形成されており、トナー搬送部９０は、トナーが攪拌搬送路２ｃに自由落下するための直線状の基体９１とそこから水平方向に延在した圧抜き部分９２を有し、基体９１の側面の一部は圧抜き部分９２によって供給搬送路２ａに接続し、圧抜き部分９２内に圧力バイパス経路３ｂが形成されている。圧力バイパス経路３ｂを介して供給搬送路２ａへ導かれた装置内圧は、供給搬送路２ａの大きめの空間により減圧されて、減圧後にフィルタ５を通じて装置外に排出される。トナー補給口３付近で発生した高い内圧は減圧されてからフィルタ５を通過するために、トナーが飛散せずに下方に落ち易く、フィルタ５の目詰まりも発生し難い。しかし、供給搬送路２ａにおける開口が増えている分、やや複雑な構成になっている。また、回収搬送路２ｂとトナー補給口３や圧力バイパス経路３ｂとの位置が遠いため、回収搬送路２ｂの現像スリーブ位置での内圧を十分に抜き難い。   FIG. 14 is a diagram showing a configuration of a developing device of Patent Document 6 as a comparative example with the present invention. In this developing device, a toner transport unit 90 is integrally formed. The toner transport unit 90 has a linear base 91 for allowing the toner to freely fall into the stirring transport path 2c and a pressure extending in the horizontal direction therefrom. A part of the side surface of the base 91 is connected to the supply conveyance path 2 a by the pressure release part 92, and the pressure bypass path 3 b is formed in the pressure release part 92. The internal pressure of the apparatus guided to the supply conveyance path 2a through the pressure bypass path 3b is reduced by the larger space of the supply conveyance path 2a, and is discharged outside the apparatus through the filter 5 after the pressure reduction. Since the high internal pressure generated in the vicinity of the toner replenishing port 3 passes through the filter 5 after being reduced, the toner does not scatter and tends to fall downward, and the filter 5 is not easily clogged. However, since the opening in the supply conveyance path 2a is increased, the configuration is somewhat complicated. In addition, since the positions of the collection conveyance path 2b and the toner replenishing port 3 and the pressure bypass path 3b are far from each other, it is difficult to sufficiently release the internal pressure at the developing sleeve position of the collection conveyance path 2b.

前述のように、現像装置１には、供給搬送路２ａに現像剤、トナー又は空気が通過する開口を４つ（フィルタ５の部分、開口部２ｅ、開口部２ｆ、現像スリーブ１１の部分）有し、回収搬送路２ｂに現像剤、トナー又は空気が通過する開口を２つ（開口部２ｄ、現像スリーブ１１の部分）有し、攪拌搬送路２ｃに現像剤、トナー又は空気が通過する開口を４つ（開口部２ｄ、トナー補給口３、開口部２ｅ、開口部２ｆ）有するものがある。このような現像装置１において、本発明によれば、吸引ダクト３５を設け、最も構造の簡単な回収搬送路２ｂに開口部３６を形成するため、現像装置１は設計が簡単になり、従来よりも単純な構造で実現され、低コストで済む。   As described above, the developing device 1 has four openings through which the developer, toner, or air passes through the supply conveyance path 2a (the filter 5 portion, the opening portion 2e, the opening portion 2f, and the developing sleeve 11 portion). The recovery conveyance path 2b has two openings through which the developer, toner or air passes (the opening 2d and the developing sleeve 11), and the stirring conveyance path 2c has an opening through which the developer, toner or air passes. Some have four (opening 2d, toner supply port 3, opening 2e, and opening 2f). In such a developing device 1, according to the present invention, the suction duct 35 is provided and the opening 36 is formed in the recovery conveyance path 2 b having the simplest structure. Can be realized with a simple structure and can be manufactured at low cost.

１ 現像装置
２ａ 供給搬送路（第１現像剤搬送路）
２ｂ 回収搬送路（第２現像剤搬送路）
２ｃ 攪拌搬送路（第３現像剤搬送路）
２ｄ 開口部（第２現像剤供給用開口部）
２ｅ 開口部（第３現像剤供給用開口部）
２ｆ 開口部（第１現像剤供給用開口部）
３ トナー補給口
４ 供給スクリュー（第１現像剤攪拌搬送手段）
５ フィルタ
６ 回収スクリュー（第２現像剤攪拌搬送手段）
７ 攪拌スクリュー（第３現像剤攪拌搬送手段）
１１ 現像スリーブ（現像剤担持体）
３５ 吸引ダクト（通気路）
３６ 開口部（通気用開口部）
１００ 感光体ドラム（潜像担持体） 1 Developing Device 2a Supply Transport Path (First Developer Transport Path)
2b Collection transport path (second developer transport path)
2c Agitation conveyance path (third developer conveyance path)
2d opening (second developer supply opening)
2e Opening (third developer supply opening)
2f opening (first developer supply opening)
3 Toner supply port 4 Supply screw (first developer agitating and conveying means)
5 Filter 6 Recovery screw (second developer stirring and conveying means)
7 Stirring screw (third developer stirring and conveying means)
11 Development sleeve (developer carrier)
35 Suction duct (ventilation passage)
36 Opening (ventilation opening)
100 Photosensitive drum (latent image carrier)

特開２００１−２９０３６８号公報JP 2001-290368 A 特開昭５６−４６２７２号公報JP 56-46272 A 特開昭６０−５１８６１号公報JP-A-60-51861 特開２００９−１３９４７６号公報JP 2009-139476 A 特開２００６−８４４８７号公報JP 2006-84487 A 特願２０１０−０３７１７９号明細書Japanese Patent Application No. 2010-037179

Claims (6)

トナーと磁性キャリアとからなる現像剤を担持して回転により潜像担持体との対向部まで搬送する現像剤担持体と、
該現像剤担持体の軸線方向に沿って現像剤を攪拌搬送して該現像剤担持体に供給する第１現像剤攪拌搬送手段を有する第１現像剤搬送路と、
該第１現像剤攪拌搬送手段よりも下方に配置され該潜像担持体との対向部通過後の該現像剤担持体から現像剤を回収して、該第１現像剤攪拌搬送手段と同方向に搬送する第２現像剤攪拌搬送手段を有する第２現像剤搬送路と、
該第１現像剤攪拌搬送手段よりも下方に配置され、該第１現像剤攪拌搬送手段により該現像剤担持体に供給されずに該第１現像剤搬送路の搬送方向下流部まで搬送された現像剤と、該第２現像剤攪拌搬送手段により該現像剤担持体から回収され該第２現像剤搬送路の搬送方向下流部まで搬送された現像剤との供給を受け、該第１現像剤攪拌搬送手段と逆方向に現像剤を攪拌搬送して下流側で該第１現像剤攪拌搬送手段に受け渡す第３現像剤攪拌搬送手段を有する第３現像剤搬送路とを有し、
該第１現像剤搬送路の搬送方向下流部から該第３現像剤搬送路の搬送方向上流部に現像剤を供給するための第１現像剤供給用開口部と、該第２現像剤搬送路の搬送方向下流部から該第３現像剤搬送路の搬送方向上流部に現像剤を供給するための第２現像剤供給用開口部と、該第３現像剤搬送路の搬送方向下流部から該第１現像剤搬送路の搬送方向上流部に現像剤を供給するための第３現像剤供給用開口部とを有し、
該第１現像剤搬送路、該第２現像剤搬送路及び該第３現像剤搬送路は仕切り部材により仕切られる現像装置において、
トナーを通過させずに空気を通過させるフィルタが該第１現像剤搬送路の上方に設けられ、
画像形成装置の外側に通じた通気路が、該現像剤担持体の下部に設けられ、
該第２現像剤搬送路と該通気路は仕切り部材により仕切られ、
該第２現像剤搬送路と該通気路を通気するための通気用開口部が、該第２現像剤搬送路と該通気路との該仕切り部材に設けられることを特徴とする現像装置。 A developer carrier that carries a developer composed of toner and a magnetic carrier and conveys the developer to a portion facing the latent image carrier by rotation;
A first developer conveying path having first developer agitating and conveying means for agitating and conveying the developer along the axial direction of the developer carrying member and supplying the developer to the developer carrying member;
The developer is disposed below the first developer agitating / conveying means, and the developer is recovered from the developer carrying body after passing through the portion facing the latent image carrier, and is in the same direction as the first developer agitating / conveying means. A second developer conveying path having a second developer stirring and conveying means for conveying
The first developer agitating / conveying means is disposed below the first developer agitating / conveying means, and is not supplied to the developer carrier by the first developer agitating / conveying means, but is conveyed to the downstream portion in the conveying direction of the first developer conveying path. The first developer is supplied with the developer and the developer collected from the developer carrier by the second developer agitating and conveying means and conveyed to the downstream portion in the conveying direction of the second developer conveying path. A third developer conveying path having third developer agitating and conveying means that agitates and conveys the developer in the opposite direction to the agitating and conveying means and delivers the developer to the first developer agitating and conveying means on the downstream side;
A first developer supply opening for supplying a developer from a downstream part in the transport direction of the first developer transport path to an upstream part in the transport direction of the third developer transport path; and the second developer transport path A second developer supply opening for supplying developer from a downstream portion in the transport direction to an upstream portion in the transport direction of the third developer transport path, and a downstream portion in the transport direction of the third developer transport path. A third developer supply opening for supplying the developer to the upstream portion in the transport direction of the first developer transport path;
In the developing device in which the first developer transport path, the second developer transport path, and the third developer transport path are partitioned by a partition member,
A filter that allows air to pass without passing toner is provided above the first developer transport path;
An air passage leading to the outside of the image forming apparatus is provided at a lower portion of the developer carrier;
The second developer conveyance path and the ventilation path are partitioned by a partition member,
A developing device, wherein a vent opening for venting the second developer transport path and the vent path is provided in the partition member between the second developer transport path and the vent path. 請求項１に記載の現像装置において、上記通気路は、トナーを通過させずに空気を通過させるフィルタと、上記通気路内部の空間を吸引する吸引手段とに接続していることを特徴とする現像装置。   2. The developing device according to claim 1, wherein the air passage is connected to a filter that allows air to pass therethrough and a suction unit that sucks the space inside the air passage. Development device. 請求項１又は２に記載の現像装置において、上記通気用開口部は、上記現像剤担持体の長手方向に見て、現像剤が汲み上げられる範囲の外側に位置することを特徴とする現像装置。   3. The developing device according to claim 1, wherein the ventilation opening is located outside a range in which the developer is pumped up when viewed in the longitudinal direction of the developer carrying member. 請求項１〜３のいずれか一項に記載の現像装置において、上記通気用開口部は、上記第２現像剤攪拌搬送手段の回転中心よりも上部に位置することを特徴とする現像装置。   4. The developing device according to claim 1, wherein the ventilation opening is located above a rotation center of the second developer agitating / conveying means. 5. 請求項１〜４のいずれか一項に記載の現像装置において、上記通気用開口部は、上記第２現像剤搬送路の搬送方向下流側であって、上記通気路の気流搬送方向の最上流部に配置されることを特徴とする現像装置。   5. The developing device according to claim 1, wherein the ventilation opening is downstream in the conveyance direction of the second developer conveyance path and is the most upstream in the air flow conveyance direction of the ventilation path. The developing device is arranged in a portion. 請求項１〜５のいずれか一項に記載の現像装置を備えることを特徴とする画像形成装置。   An image forming apparatus comprising the developing device according to claim 1.

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