JP2012103280A

JP2012103280A - Developing apparatus and image forming apparatus

Info

Publication number: JP2012103280A
Application number: JP2010248911A
Authority: JP
Inventors: Junichi Matsumoto; 純一松本; Tomoya Omura; 知也大村; Yasuo Takuma; 康夫詫間; Yutaka Kikuchi; 裕菊地; Natsumi Matsue; 菜摘松江
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2010-11-05
Filing date: 2010-11-05
Publication date: 2012-05-31

Abstract

PROBLEM TO BE SOLVED: To obtain a developing apparatus stabilizing developer circulation by preventing leaking of air.SOLUTION: The developing apparatus includes: a developing section; a developer storage section 40 arranged outside the developing section for storing a part of the developer; a rotary feeder 50 for ejecting the developer in the developer storage section 40; and a developer conveyance path 31 for transporting the developer ejected from the rotary feeder to the developing section by using air. In this case, the rotary feeder includes: a stator 55 having cylindrical space inside; a developer flow-in hole 56 arranged on the top section side of the stator through which the developer from the developer storage section flows in; a developer ejection hole 57 arranged on the bottom section side of the stator for the developer to be ejected; and a rotor 51 arranged in the space in the stator, having a plurality of blades extending radially from a shaft section, and pivotally supported to be freely rotated. In addition, a developer retaining section 70 is included for retaining the developer in between the developer ejection hole of the rotary feeder and a confluence section 35 where the developer ejected from the developer ejection hole converges with the developer conveyance path 31.

Description

本発明は、トナーとキャリアからなる二成分現像剤を用いた現像装置と、その現像装置を備えた複写機、プリンタ、プロッタ、ファクシミリ、あるいはこれらの複合機等の画像形成装置に関する。 The present invention relates to a developing device using a two-component developer composed of a toner and a carrier, and an image forming apparatus such as a copying machine, a printer, a plotter, a facsimile, or a complex machine including the developing device.

複写機、プリンタ、プロッタ、ファクシミリ、あるいはこれらの複合機等の電子写真方式の画像形成装置においては、感光体等の潜像担持体上に形成した静電潜像を現像するための現像装置を備えており、この現像装置は、例えばトナーとキャリアから成る二成分現像剤を用いて、潜像担持体上の静電潜像を現像剤のトナーで現像して可視化する装置である。
このような二成分現像剤を用いた現像装置では、現像領域で現像処理を終了してトナーが消費された現像剤は回収され、トナーホッパーやトナーカトリッジ等から補給されるトナーと混合、撹拌され、再び現像に供される。また、このような構成の現像装置に用いられる現像剤は、安定したトナー画像を得るために、一定のトナー濃度と帯電量を維持する必要がある。トナー濃度は現像で消費したトナーと補給トナー量により調整され、帯電量はキャリアとトナーとの混合時の摩擦帯電により付与される。そして現像装置は、トナーとキャリアから成る二成分現像剤の撹拌を充分に行い、トナー濃度分布を均一化するとともに、トナーに帯電を付与し、トナー画像の安定化を行っている。 In an electrophotographic image forming apparatus such as a copying machine, a printer, a plotter, a facsimile, or a composite machine of these, a developing device for developing an electrostatic latent image formed on a latent image carrier such as a photosensitive member is provided. The developing device is a device that develops and visualizes an electrostatic latent image on a latent image carrier with toner of a developer using, for example, a two-component developer composed of toner and carrier.
In such a developing device using a two-component developer, the developer that has completed the developing process in the developing region and has consumed the toner is collected, mixed with the toner replenished from the toner hopper, toner cartridge, etc., and stirred. And again subjected to development. Further, the developer used in the developing device having such a configuration needs to maintain a constant toner concentration and charge amount in order to obtain a stable toner image. The toner density is adjusted by the amount of toner consumed during development and the amount of replenished toner, and the charge amount is given by frictional charging during mixing of the carrier and toner. The developing device sufficiently agitates the two-component developer composed of the toner and the carrier to make the toner density distribution uniform, and to charge the toner and stabilize the toner image.

一般的な現像装置では、補給されたトナーが現像剤担持体である現像ローラ（現像スリーブ）に汲み上げられるまでの僅かな時間の間に、２本の現像剤混合攪拌部材（例えばスクリュ）の回転による撹拌効果を利用してトナーの分散及び帯電付与を行っているため、特にトナーの収支が多い場合には補給されたトナーが十分に分散することなく現像ローラに汲み上げられてしまい、地汚れやトナー飛散が発生してしまうという問題があった。 In a general developing device, two developer mixing and agitating members (for example, screws) rotate for a short time until the replenished toner is pumped up to a developing roller (developing sleeve) as a developer carrying member. Since the toner is dispersed and charged by using the stirring effect of the toner, the replenished toner is pumped up to the developing roller without being sufficiently dispersed, particularly when the toner balance is large, There is a problem that toner scattering occurs.

そこで、このような問題を解決するために、現像部から離れた位置に別途撹拌部を設けると共に、現像部と撹拌部とを現像剤循環手段によって接続し、撹拌部で現像剤の状態に応じた撹拌を行うことでトナー濃度及び帯電量を適切に調整した後に、現像剤を現像部に供給する現像装置が提案されている（例えば、特許文献１（特許第３７３４０９６号公報）、特許文献２（特許第３３４９２８６号公報）及び特許文献３（特開平１１−１４３１９６号公報））。
また、本発明者らは先に、上記と同様の構成で、より撹拌性能の優れた撹拌システムを用いた現像装置を提案している（特許文献４（特開２００７−１９３３０１号公報）、特許文献５（特開２００８−２９９２１７号公報）、特許文献６（特開２００８−３５６１号公報）、特許文献７（特開２００９−１０３７５１号公報）。 Therefore, in order to solve such a problem, a separate stirring unit is provided at a position away from the developing unit, and the developing unit and the stirring unit are connected by a developer circulation means, and the stirring unit is used according to the state of the developer. There has been proposed a developing device that appropriately adjusts the toner concentration and the charge amount by performing agitation, and then supplies the developer to the developing unit (for example, Patent Document 1 (Japanese Patent No. 3734096), Patent Document 2). (Japanese Patent No. 3349286) and Patent Document 3 (Japanese Patent Laid-Open No. 11-143196).
Further, the present inventors have previously proposed a developing device using a stirring system having the same configuration as described above and having a higher stirring performance (Patent Document 4 (Japanese Patent Laid-Open No. 2007-193301)). Document 5 (Japanese Patent Laid-Open No. 2008-299217), Patent Document 6 (Japanese Patent Laid-Open No. 2008-3561), and Patent Document 7 (Japanese Patent Laid-Open No. 2009-103751).

上述の先行技術のような、空気（エア）を利用して現像剤を循環させる現像装置においては以下のような課題がある。
現像剤を空気を利用して管内を連続的に搬送する場合、現像装置の主な構成は、現像部、現像剤収納部、現像剤供給部、現像剤循環手段（輸送管、空気供給源）である。この構成では空気の圧力（正圧）と流速とを利用して現像剤を搬送するため、空気搬送元と搬送先（大気圧）との間には差圧が発生する。また、この現像装置は、現像部に送られた現像剤が、現像部から現像剤収納部に回収され、再び搬送される（循環している）ため、現像剤収納部も大気圧である。
従って、現像剤を現像部へ搬送するためには、現像剤供給部と現像剤収納部をシールし、空気供給源の空気が現像剤収容部に洩れないようにする必要がある。空気が洩れると、現像剤を搬送するための圧力が低下して搬送量が十分確保できない。また、空気が現像剤収納部に逆流する（現像剤収容部に圧力がかかる）と、現像剤収容部から現像剤供給部に入る現像剤が逆流する空気によって妨げられ、排出量の低下や、ばらつきが発生する。また、現像剤収納部が流入する空気によって内圧が上昇し、現像部から回収する現像剤の流入を妨げる恐れもある。 A developing device that circulates a developer using air as in the above-described prior art has the following problems.
When the developer is continuously conveyed through the pipe using air, the main configuration of the developing device is as follows: developing unit, developer storage unit, developer supply unit, developer circulation means (transport pipe, air supply source) It is. In this configuration, the developer is transported using the air pressure (positive pressure) and the flow velocity, so that a differential pressure is generated between the air transport source and the transport destination (atmospheric pressure). Further, in this developing device, the developer sent to the developing unit is collected from the developing unit to the developer containing unit and conveyed (circulated) again, so that the developer containing unit is also at atmospheric pressure.
Therefore, in order to transport the developer to the developing unit, it is necessary to seal the developer supply unit and the developer storage unit so that the air from the air supply source does not leak into the developer storage unit. If the air leaks, the pressure for transporting the developer decreases and the transport amount cannot be secured sufficiently. In addition, when air flows back to the developer storage section (pressure is applied to the developer storage section), the developer entering the developer supply section from the developer storage section is hindered by the backflowing air, and the discharge amount decreases, Variation occurs. In addition, the internal pressure rises due to the air flowing into the developer storage unit, which may hinder the inflow of the developer recovered from the development unit.

現像剤供給部を構成する供給装置として一般的に用いられるものに、ロータリフィーダがある。ロータリフィーダは、回転する複数の羽根を持ったロータと、ロータを覆うステータからなり、定量性、制御性に優れた機構であるが、シール性が不足すると上述した空気の逆流が発生する。シール性を確保する方法として、ロータの羽根を弾性体としてステータとの間で食い込みを持たせる方法があるが、経時の劣化（ロータ及びステータの削れ等）が顕著となり実用的ではない。特に、現像剤を構成するキャリアは鉄やフェライトであるため、硬度が高いことからこの方法により耐久性を得ることは困難である。 A rotary feeder is generally used as a supply device constituting the developer supply unit. The rotary feeder is composed of a rotor having a plurality of rotating blades and a stator covering the rotor, and is a mechanism having excellent quantitative and controllability. However, when the sealing property is insufficient, the above-described air backflow occurs. As a method for ensuring the sealing performance, there is a method in which the blades of the rotor are used as an elastic body so that the rotor bites into the stator. In particular, since the carrier constituting the developer is iron or ferrite and has high hardness, it is difficult to obtain durability by this method.

そこで、この課題を解決する方法として、本発明者らは、特許文献５において、ロータととステータの間の隙間（クリアランス）を適正化することで空気の逆流を防止する方法を提案している。しかし、この方法ではロータとステータの加工精度が要求され、コスト高となる。 Thus, as a method for solving this problem, the present inventors have proposed a method for preventing a backflow of air by optimizing a gap (clearance) between the rotor and the stator in Patent Document 5. . However, this method requires processing accuracy of the rotor and the stator, and increases the cost.

また、本発明者らは、特許文献７において、ロータリフィーダのシール性を向上させる手段として、故意に現像剤の一部を排出しないで、ロータとステータのクリアランス部に現像剤を滞留させる方法を提案している。しかし、この方法では、現像剤の一部を排出しないため、ロータリフィーダの容積効率が低下するという課題（副作用）がある。 In addition, in the Patent Document 7, as a means for improving the sealability of the rotary feeder, the present inventors have made a method of retaining the developer in the clearance between the rotor and the stator without intentionally discharging a part of the developer. is suggesting. However, in this method, since a part of the developer is not discharged, there is a problem (side effect) that the volumetric efficiency of the rotary feeder is lowered.

本発明は上記事情に鑑みてなされたものであり、空気供給源（エアポンプ等）からの空気がロータリフィーダへ進入する進入量を大幅に低減すると共に、確実にロータリフィーダ内部の現像剤を排出して容積効率を向上でき、現像剤収容部から現像部に適切なトナー濃度と帯電量を持った現像剤を現像に必要な量だけ連続的に安定供給することができる現像装置を提供することを目的とし、さらには、その現像装置を備えた画像形成装置を提供することを目的とする。 The present invention has been made in view of the above circumstances, and significantly reduces the amount of air entering from the air supply source (such as an air pump) into the rotary feeder and reliably discharges the developer inside the rotary feeder. The present invention provides a developing device that can improve the volumetric efficiency and can stably and stably supply a developer having an appropriate toner concentration and charge amount from the developer accommodating portion to the developing portion in an amount necessary for development. It is another object of the present invention to provide an image forming apparatus including the developing device.

上記の目的を達成するため、本発明では以下のような解決手段を採っている。
本発明の第１の解決手段は、潜像担持体上の潜像を現像する現像部と、前記現像部の外部に設けられ現像剤の一部を収容する現像剤収納部と、前記現像剤収納部の下方に設けられ該現像剤収納部の現像剤を排出するロータリフィーダと、前記ロータリフィーダから排出された現像剤を空気を利用して前記現像部に移送する現像剤搬送経路とを備えた現像装置において、前記ロータリフィーダは、内部に円筒状の空間を有するステータと、該ステータの上部側に設けられ前記現像剤収納部からの現像剤が流入する現像剤流入孔と、前記ステータの下部側に設けられ現像剤が排出される現像剤排出孔と、前記ステータの空間内に配置され軸部から放射状に延びる複数の羽根を有する回転自在に軸支されたロータを備え、前記ロータリフィーダの現像剤排出孔と、該現像剤排出孔から排出された現像剤が前記現像剤搬送経路に合流する位置（合流部）の間に、該現像剤を保持する現像剤保持部を設けたことを特徴とする（請求項１）。 In order to achieve the above object, the present invention employs the following solutions.
According to a first aspect of the present invention, there is provided a developing unit that develops a latent image on a latent image carrier, a developer accommodating unit that is provided outside the developing unit and accommodates a part of the developer, and the developer A rotary feeder provided below the storage unit for discharging the developer in the developer storage unit; and a developer transport path for transferring the developer discharged from the rotary feeder to the development unit using air. In the developing device, the rotary feeder includes a stator having a cylindrical space inside, a developer inflow hole provided on an upper side of the stator, into which the developer from the developer accommodating portion flows, and the stator A rotary feeder rotatably provided with a developer discharge hole provided on the lower side for discharging the developer and a plurality of blades disposed in the space of the stator and extending radially from the shaft portion; Present A developer holding portion for holding the developer is provided between the developer discharge hole and a position (merging portion) where the developer discharged from the developer discharge hole joins the developer transport path. (Claim 1).

本発明の第２の解決手段は、潜像担持体上の潜像を現像する現像部と、前記現像部の外部に設けられ現像剤の一部を収容する現像剤収納部と、前記現像剤収納部の下方に設けられ該現像剤収納部の現像剤を排出するロータリフィーダと、前記ロータリフィーダから排出された現像剤を空気を利用して前記現像部に移送する現像剤搬送経路とを備えた現像装置において、前記ロータリフィーダは、内部に円筒状の空間を有するステータと、該ステータの上部側に設けられ前記現像剤収納部からの現像剤が流入する現像剤流入孔と、前記ステータの下部側に設けられ現像剤が排出される現像剤排出孔と、前記ステータの空間内に配置され軸部から放射状に延びる複数の羽根を有する回転自在に軸支されたロータを備え、前記ロータリフィーダの現像剤排出孔と、該現像剤排出孔から排出された現像剤が前記現像剤搬送経路に合流する位置（合流部）の間に、該現像剤を保持し搬送するスクリュ搬送部を設けたことを特徴とする（請求項２）。 The second solving means of the present invention comprises: a developing unit that develops a latent image on a latent image carrier; a developer accommodating unit that is provided outside the developing unit and accommodates a part of the developer; and the developer A rotary feeder provided below the storage unit for discharging the developer in the developer storage unit; and a developer transport path for transferring the developer discharged from the rotary feeder to the development unit using air. In the developing device, the rotary feeder includes a stator having a cylindrical space inside, a developer inflow hole provided on an upper side of the stator, into which the developer from the developer accommodating portion flows, and the stator A rotary feeder rotatably provided with a developer discharge hole provided on the lower side for discharging the developer and a plurality of blades disposed in the space of the stator and extending radially from the shaft portion; Present A screw transport section for holding and transporting the developer is provided between the developer discharge hole and a position where the developer discharged from the developer discharge hole joins the developer transport path (joining section). It is characterized (claim 2).

本発明の第３の解決手段は、第２の解決手段の現像装置において、前記スクリュ搬送部のスクリュの回転によって搬送される現像剤の理論値の最大値である現像剤搬送能力は、前記ロータリフィーダの現像剤排出量より少なく設定することを特徴とする（請求項３）。
また本発明の第４の解決手段は、第２または第３の解決手段の現像装置において、前記スクリュ搬送部のスクリュは略水平に配置されており、該スクリュにより搬送された現像剤は、前記現像剤搬送経路の搬送路の略垂直に配置された部分で前記空気と合流することを特徴とする。
さらに本発明の第５の解決手段は、第２〜第４のいずれか一つの解決手段の現像装置において、前記スクリュ搬送部の前記ロータリフィーダの現像剤排出部との合流点より上流側に、現像剤を排出する開口部を設けたことを特徴とする（請求項５）。
さらに本発明の第６の解決手段は、第４または第５の解決手段の現像装置において、前記現像剤搬送経路の現像剤と空気との合流部に、フィルタを設置することを特徴とする（請求項６）。
さらに本発明の第７の解決手段は、第２〜第６のいずれか一つの解決手段の現像装置において、前記スクリュ搬送部のスクリュの径、及びスクリュ経路断面を、現像剤搬送方向下流側で小さくすることを特徴とする（請求項７）。 According to a third solving means of the present invention, in the developing device according to the second solving means, the developer conveying ability which is the maximum theoretical value of the developer conveyed by the rotation of the screw of the screw conveying unit is It is set to be smaller than the amount of developer discharged from the feeder (claim 3).
According to a fourth solving means of the present invention, in the developing device of the second or third solving means, the screw of the screw conveying portion is arranged substantially horizontally, and the developer conveyed by the screw is The developer is combined with the air at a portion arranged substantially perpendicular to the conveyance path of the developer conveyance path.
Furthermore, the fifth solving means of the present invention is the developing device according to any one of the second to fourth solving means, upstream of the confluence of the screw conveying part and the developer discharge part of the rotary feeder, An opening for discharging the developer is provided (claim 5).
Further, the sixth solving means of the present invention is characterized in that, in the developing device of the fourth or fifth solving means, a filter is installed at a joining portion of the developer and air in the developer transport path ( Claim 6).
Furthermore, the seventh solving means of the present invention is the developing device of any one of the second to sixth solving means, wherein the screw diameter of the screw conveying portion and the screw path cross section are set on the downstream side in the developer conveying direction. It is characterized in that it is made smaller (claim 7).

本発明の第８の解決手段は、潜像担持体と、該潜像担持体上の潜像を現像して可視化する現像手段を備えた画像形成装置であって、前記現像手段として第１〜第７のいずれか一つの解決手段の現像装置を備えたことを特徴とする（請求項８）。 According to an eighth aspect of the present invention, there is provided an image forming apparatus including a latent image carrier and a developing unit that develops and visualizes the latent image on the latent image carrier. A developing device according to any one of the seventh means is provided (claim 8).

第１の解決手段の現像装置では、ロータリフィーダの現像剤排出孔と、該現像剤排出孔から排出された現像剤が現像剤搬送経路に合流する位置（合流部）の間に、該現像剤を保持する現像剤保持部を設けたことにより、現像剤排出孔から排出された現像剤が現像剤保持部に溜まって、該現像剤保持部に現像剤が充満している状態、あるいは該現像剤保持部の少なくとも一部が現像剤で満たされている状態であると、空気供給源からの空気（エア）が、合流部からロータリフィーダに流れ込むのを防止することができ、空気供給源からの空気を無駄に消費することが無い。よって、空気供給源からの空気がロータリフィーダへ進入する進入量を大幅に低減することができるので、ロータリフィーダの搬送効率が向上し、確実にロータリフィーダ内部の現像剤を排出して容積効率を向上でき、現像剤収容部から現像部に適切なトナー濃度と帯電量を持った現像剤を現像に必要な量だけ連続的に安定供給することができる。 In the developing device of the first solving means, the developer is disposed between the developer discharge hole of the rotary feeder and the position where the developer discharged from the developer discharge hole joins the developer transport path (joining portion). By providing the developer holding portion that holds the developer, the developer discharged from the developer discharge hole is accumulated in the developer holding portion, and the developer holding portion is filled with the developer, or the development When at least a part of the agent holding part is filled with the developer, it is possible to prevent air from the air supply source from flowing into the rotary feeder from the joining part. The air is not consumed wastefully. As a result, the amount of air entering the rotary feeder from the air supply source can be greatly reduced, so that the conveyance efficiency of the rotary feeder is improved and the developer inside the rotary feeder is reliably discharged to increase the volumetric efficiency. The developer having an appropriate toner concentration and charge amount can be continuously and stably supplied from the developer accommodating portion to the developing portion in an amount necessary for development.

第２の解決手段の現像装置では、ロータリフィーダの現像剤排出孔と、該現像剤排出孔から排出された現像剤が現像剤搬送経路に合流する位置（合流部）の間に、該現像剤を保持し搬送するスクリュ搬送部を設けたことにより、現像剤排出孔から排出された現像剤がスクリュ搬送部にに溜まって、該スクリュ搬送部に現像剤が充満している状態、あるいは該スクリュ搬送部の少なくとも一部が現像剤で満たされている状態であると、空気供給源からの空気（エア）が、合流部からロータリフィーダに流れ込むのを防止することができ、空気供給源からの空気を無駄に消費することが無い。よって、空気供給源からの空気がロータリフィーダへ進入する進入量を大幅に低減することができるので、ロータリフィーダの搬送効率が向上し、確実にロータリフィーダ内部の現像剤を排出して容積効率を向上でき、現像剤収容部から現像部に適切なトナー濃度と帯電量を持った現像剤を現像に必要な量だけ連続的に安定供給することができる。また、ロータリフィーダの現像剤排出孔から排出された現像剤は、現像剤搬送経路の合流部にスクリュにより搬送されるため、搬送量が安定化し、搬送量のばらつきを低減することができる。 In the developing device of the second solving means, the developer is disposed between the developer discharge hole of the rotary feeder and the position where the developer discharged from the developer discharge hole joins the developer transport path (joining portion). By providing a screw transport unit that holds and transports the developer, the developer discharged from the developer discharge hole accumulates in the screw transport unit and the screw transport unit is filled with the developer, or the screw When at least a part of the transport unit is filled with the developer, it is possible to prevent air from the air supply source from flowing into the rotary feeder from the junction, and from the air supply source. There is no wasteful consumption of air. As a result, the amount of air entering the rotary feeder from the air supply source can be greatly reduced, so that the conveyance efficiency of the rotary feeder is improved and the developer inside the rotary feeder is reliably discharged to increase the volumetric efficiency. The developer having an appropriate toner concentration and charge amount can be continuously and stably supplied from the developer accommodating portion to the developing portion in an amount necessary for development. Further, since the developer discharged from the developer discharge hole of the rotary feeder is transported by the screw to the joining portion of the developer transport path, the transport amount is stabilized, and variation in the transport amount can be reduced.

第３の解決手段の現像装置では、第２の解決手段の効果に加え、スクリュ搬送部のスクリュの回転によって搬送される現像剤の理論値の最大値である現像剤搬送能力は、ロータリフィーダの現像剤排出量より少なく設定することにより、スクリュによって搬送される現像剤は最大搬送能力（効率を１００％としたときの搬送量）と等しくなり、すなわち、現像剤搬送経路が十分に充填された状態（現像剤で満たされている状態）になるため、確実に空気がロータリフィーダに流れ込むのを防止することができる。 In the developing device of the third solving means, in addition to the effect of the second solving means, the developer conveying ability which is the maximum value of the theoretical value of the developer conveyed by the rotation of the screw of the screw conveying unit is the value of the rotary feeder. By setting it smaller than the developer discharge amount, the developer transported by the screw becomes equal to the maximum transport capacity (the transport amount when the efficiency is 100%), that is, the developer transport path is sufficiently filled. Since the state (state filled with the developer) is reached, it is possible to reliably prevent air from flowing into the rotary feeder.

第４の解決手段の現像装置では、第２または第３の解決手段の効果に加え、スクリュ搬送部のスクリュは略水平に配置されており、該スクリュにより搬送された現像剤は、現像剤搬送経路の搬送路の略垂直に配置された部分で空気と合流するようにしたので、水平の空気搬送経路に現像剤を上方から合流させ空気で搬送する方式に対し、スクリュにより搬送された現像剤を現像剤搬送経路の搬送路の略垂直に配置された部分で空気と合流させた方が、現像剤を加速するために必要な圧力が少なくて済むため、空気による現像剤搬送の負荷を低減でき、省エネルギである。 In the developing device of the fourth solving means, in addition to the effects of the second or third solving means, the screw of the screw conveying portion is arranged substantially horizontally, and the developer conveyed by the screw is transferred to the developer. The developer is transported by a screw compared to the system in which the developer is merged from above into the horizontal air transport path and transported by air because the part is arranged substantially vertically in the transport path of the path. Since the pressure required to accelerate the developer is less when the air is combined with the air at the portion of the developer transport path that is arranged substantially perpendicular to the transport path, the developer transport load by air is reduced. It can save energy.

第５の解決手段の現像装置では、第２〜第４のいずれか一つの解決手段の効果に加え、スクリュ搬送部のロータリフィーダの現像剤排出部との合流点より上流側に、現像剤を排出する開口部を設けたので、メンテナンス等で現像剤を交換する際には、スクリュ搬送部のロータリフィーダの現像剤排出部との合流点より上流側に設けた開口部を開口させ、スクリュを通常と逆回転することにより、スクリュ搬送部内の現像剤を外部に排出することができ、循環経路に残る現像剤量を低減することができる。 In the developing device of the fifth solving means, in addition to the effect of any one of the second to fourth solving means, the developer is introduced upstream of the junction with the developer discharging portion of the rotary feeder of the screw conveying portion. Since the opening for discharging is provided, when replacing the developer for maintenance, etc., the opening provided upstream from the junction with the developer discharging portion of the rotary feeder of the screw conveying portion is opened, and the screw is By rotating in the reverse direction, the developer in the screw conveyance unit can be discharged to the outside, and the amount of developer remaining in the circulation path can be reduced.

第６の解決手段の現像装置では、第４または第５の解決手段の効果に加え、現像剤搬送経路の現像剤と空気との合流部にフィルタを設置したので、フィルタにより、空気供給源（エアポンプ等）側に現像剤が進入するのを防止でき、空気供給源（エアポンプ等）の破損を防止することができる。 In the developing device of the sixth solving means, in addition to the effects of the fourth or fifth solving means, the filter is installed at the joining portion of the developer and air in the developer transport path, so the air supply source ( The developer can be prevented from entering the air pump or the like) side, and the air supply source (air pump or the like) can be prevented from being damaged.

第７の解決手段の現像装置では、第２〜第６のいずれか一つの解決手段の効果に加え、スクリュ搬送部のスクリュの径、及びスクリュ経路断面を、現像剤搬送方向下流側で小さくすることにより、スクリュ径、経路断面を小さくした部位では搬送能力が少なくなるため、現像剤が滞留し、シール効果がより向上するので、より確実に空気がロータリフィーダに流れ込むのを防止することができる。 In the developing device of the seventh solving means, in addition to the effect of any one of the second to sixth solving means, the screw diameter of the screw conveying portion and the screw path cross section are reduced on the downstream side in the developer conveying direction. As a result, the conveying capacity is reduced at the part where the screw diameter and the path cross section are reduced, and therefore the developer stays and the sealing effect is further improved, so that air can be prevented from flowing into the rotary feeder more reliably. .

第８の解決手段の画像形成装置では、現像手段として第１〜７の解決手段のいずれか一つに記載の現像装置を備えたことにより、現像剤の循環、混合、攪拌、帯電の安定化が図れるため、画質や画像濃度の安定化を図ることができる。 In the image forming apparatus of the eighth solving means, the developing device according to any one of the first to seventh solving means is provided as a developing means, so that the circulation, mixing, stirring, and charging of the developer are stabilized. Therefore, image quality and image density can be stabilized.

本発明の一実施例を示す現像装置の概略斜視図である。1 is a schematic perspective view of a developing device showing an embodiment of the present invention. 図１に示す現像装置の現像部（現像器）の概略断面図である。It is a schematic sectional drawing of the image development part (developing device) of the image development apparatus shown in FIG. 図１に示す現像装置の現像剤収容部、ロータリフィーダ、現像剤循環手段の概略を示す概略構成図である。FIG. 2 is a schematic configuration diagram illustrating an outline of a developer accommodating portion, a rotary feeder, and a developer circulation unit of the developing device illustrated in FIG. 1. 従来の現像剤保持部を設けていない現像装置の現像剤収容部、ロータリフィーダ、現像剤循環手段の概略を示す概略構成図である。FIG. 10 is a schematic configuration diagram illustrating an outline of a developer storage unit, a rotary feeder, and a developer circulation unit of a developing device that does not include a conventional developer holding unit. 現像装置のロータリフィーダ、現像剤保持部（スクリュ搬送部）内の現像剤の様子の一例を示す概略要部断面図である。It is a schematic principal part sectional drawing which shows an example of the mode of the developer in the rotary feeder of a developing device, and a developer holding part (screw conveyance part). 本発明の別の実施例を示す現像装置の現像剤収容部、ロータリフィーダ、現像剤循環手段の概略を示す概略構成図である。It is a schematic block diagram which shows the outline of the developer accommodating part of the developing apparatus which shows another Example of this invention, a rotary feeder, and a developer circulation means. 図３及び図６の現像装置で、現像剤を搬送しているときの、エア搬送経路内の圧力のグラフを示す図である。FIG. 7 is a diagram illustrating a graph of pressure in the air conveyance path when the developer is being conveyed in the developing device of FIGS. 3 and 6. 図６に示す現像装置の合流部の構成例を示す概略要部断面図である。FIG. 7 is a schematic cross-sectional view of an essential part showing a configuration example of a merging portion of the developing device shown in FIG. 6. 本発明のさらに別の実施例を示す現像装置の概略要部構成図である。It is a general | schematic principal part block diagram of the developing apparatus which shows another Example of this invention. 本発明のさらに別の実施例を示す現像装置の現像剤収容部、ロータリフィーダ、現像剤循環手段の概略を示す概略構成図である。It is a schematic block diagram which shows the outline of the developer accommodating part of the developing apparatus which shows another Example of this invention, a rotary feeder, and a developer circulation means. 本発明の一実施例を示す画像形成装置の概略構成図である。1 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention.

本発明を実施するための形態について、図示の実施例に基づいて詳細に説明する。 EMBODIMENT OF THE INVENTION The form for implementing this invention is demonstrated in detail based on the Example of illustration.

［実施例１］
｛現像剤循環方式の現像装置の説明｝
図１は本発明の一実施例を示す現像装置の概略斜視図、図２は図１に示す現像装置の現像部（現像器）の概略断面図、図３は図１に示す現像装置の現像剤収容部、ロータリフィーダ、現像剤循環手段の概略を示す概略構成図である。
図１、図２に示すように、現像装置３の現像部１０は、現像器を構成するケーシング１５を有しており、ケーシング１５の内部には螺旋状のフィンを有する２つの搬送スクリュ１１，１２と、現像ローラ１３とが回転自在に設けられている。現像ローラ１３は、回転する円筒状の現像スリーブと、その現像スリーブの内部に固定配置された複数の磁石（または複数の磁極が着磁されたマグネットローラ）で構成されている。
現像装置３のケーシング１５の内部にはトナーとキャリアを混合した２成分現像剤が収納されており、この現像剤は搬送スクリュ１１の回転により図２の手前側から奥側に向けて搬送され、この一部が現像ローラ１３の内部に設けられた図示しない磁石によって現像ローラ１３の表面に吸い上げられて吸着する。現像ローラ１３の表面に吸着した現像剤はドクタブレード１４によってその層厚が均一となるように均された後、潜像担持体である感光体ドラム２に接することで感光体ドラム２上に形成された静電潜像をトナーで現像して顕像化し、トナー像を形成する。 [Example 1]
{Description of developer circulation type developing device}
1 is a schematic perspective view of a developing device showing an embodiment of the present invention, FIG. 2 is a schematic sectional view of a developing section (developing device) of the developing device shown in FIG. 1, and FIG. 3 is a development of the developing device shown in FIG. It is a schematic block diagram which shows the outline of an agent accommodating part, a rotary feeder, and a developer circulation means.
As shown in FIGS. 1 and 2, the developing unit 10 of the developing device 3 includes a casing 15 that constitutes a developing device, and two casing screws 11 having spiral fins inside the casing 15, 12 and a developing roller 13 are rotatably provided. The developing roller 13 includes a rotating cylindrical developing sleeve and a plurality of magnets (or a magnet roller having a plurality of magnetic poles magnetized) fixedly disposed inside the developing sleeve.
A two-component developer in which toner and carrier are mixed is accommodated in the casing 15 of the developing device 3, and this developer is conveyed from the near side to the far side in FIG. A part of this is sucked and attracted to the surface of the developing roller 13 by a magnet (not shown) provided inside the developing roller 13. The developer adsorbed on the surface of the developing roller 13 is leveled by the doctor blade 14 so that the layer thickness is uniform, and is then formed on the photosensitive drum 2 by contacting the photosensitive drum 2 as a latent image carrier. The electrostatic latent image thus developed is developed with toner to be visualized to form a toner image.

現像後の現像剤は、搬送スクリュ１２の端部に設けられた図示しない孔から循環路３０を経由して現像剤収納部４０の現像剤流入口４３に搬送される。搬送スクリュ１２の現像剤搬送方向最下流位置には図示しないトナー濃度検知手段が配設されており、このトナー濃度検知手段からの検知信号に基づいてトナーカートリッジ２０からトナー補給が行われる。トナーカートリッジ２０からのトナー補給は、モータ２１によってトナー補給路２２内に設けられた図示しない搬送部材（コイル、軸無しスクリュ等）を回転させることにより行われる。トナー補給は現像剤循環経路内において現像剤収納部４０の直前の位置で行われ、現像剤収納部４０では現像後の現像剤と補給されたトナーとが混合され、適切なトナー濃度及び帯電量を有する現像剤となる。 The developed developer is transported from a hole (not shown) provided at the end of the transport screw 12 to the developer inlet 43 of the developer storage section 40 via the circulation path 30. A toner concentration detection unit (not shown) is disposed at the most downstream position in the developer conveyance direction of the conveyance screw 12, and toner is replenished from the toner cartridge 20 based on a detection signal from the toner concentration detection unit. Toner supply from the toner cartridge 20 is performed by rotating a conveyance member (a coil, a shaftless screw, etc.) (not shown) provided in the toner supply path 22 by the motor 21. Toner replenishment is performed in the developer circulation path at a position immediately before the developer storage section 40, and the developer stored in the developer storage section 40 is mixed with the replenished toner to obtain an appropriate toner concentration and charge amount. A developer having

図１、図３に示すように、現像剤収納部４０内の現像剤は、現像剤収納部４０の下部に配設された排出口と連通するロータリフィーダ５０の現像剤流入孔（ステータ５５の円筒状空間に連通する上部側の開口部）５６を経由してロータリフィーダ５０内に運ばれる。ロータリフィーダ５０内に運ばれた現像剤は、ロータリフィーダ５０を構成するステータ５５内に設けられたロータ５１がモータ５３で回転されることにより下方へと運ばれ、ステータ５５の現像剤排出孔（ステータ５５の円筒状空間に連通する下部側の開口部）５７から下方に排出され、現像剤保持部７０に搬送されて保持される。ここで現像剤保持部７０は、現像剤を一時的に滞留させて保持するためのものであり、円管状等の容器でもよいが、図３の例では、現像剤保持部内での現像剤の詰まりを防止するため、現像剤保持部内に搬送用のスクリュ７１を設置したスクリュ搬送部としている。そして、現像剤保持部（スクリュ搬送部）７０内に保持された現像剤は、スクリュ７１により図中左側に移動し、搬送方向下流側の開口部７２から現像剤搬送経路３１の合流部３５に排出される。なお、図１中の符号５２はロータを駆動させるモータ、７５はスクリュ７１を駆動させるモータである。 As shown in FIGS. 1 and 3, the developer in the developer accommodating portion 40 flows into the developer inflow hole (the stator 55 of the stator 55) of the rotary feeder 50 that communicates with the discharge port disposed in the lower portion of the developer accommodating portion 40. It is carried into the rotary feeder 50 via an upper opening 56) communicating with the cylindrical space. The developer transported into the rotary feeder 50 is transported downward when the rotor 51 provided in the stator 55 constituting the rotary feeder 50 is rotated by the motor 53, and the developer discharge hole ( It is discharged downward from a lower opening 57 communicating with the cylindrical space of the stator 55, and is conveyed to and held by the developer holding unit 70. Here, the developer holding unit 70 is for temporarily retaining and holding the developer, and may be a container such as a circular tube, but in the example of FIG. 3, the developer holding unit 70 in the developer holding unit is used. In order to prevent clogging, a screw transport unit is provided in which a transport screw 71 is installed in the developer holding unit. Then, the developer held in the developer holding unit (screw conveyance unit) 70 is moved to the left side in the drawing by the screw 71, and is transferred from the opening 72 on the downstream side in the conveyance direction to the merging unit 35 of the developer conveyance path 31. Discharged. 1 is a motor for driving the rotor, and 75 is a motor for driving the screw 71.

現像剤搬送経路３１の合流部３５には、空気供給源であるエアポンプ６０が空気供給路３１を介して連結されており、現像剤保持部（スクリュ搬送部）７０の開口部７２から合流部３５に排出された現像剤は、エアポンプ６０から発生する空気（エア）の圧力により循環路となる現像剤搬送経路３１内を現像部（現像器）１０に移送され、再び現像部（現像器）１０のケーシング１５内に供給される。 An air pump 60, which is an air supply source, is connected to the merging portion 35 of the developer conveyance path 31 via the air supply path 31, and the merging portion 35 is opened from an opening 72 of the developer holding portion (screw conveyance portion) 70. The developer discharged in the step is transferred to the developing unit (developing unit) 10 through the developer transport path 31 serving as a circulation path by the pressure of air (air) generated from the air pump 60, and is again developed. Is supplied into the casing 15.

以上のように、本発明に係る現像装置３では、現像剤は、現像部（現像器）１０→循環路３０→現像剤収納部４０→ロータリフィーダ５０→現像剤保持部（スクリュ搬送部）７０→合流部３５→現像剤搬送経路（循環路）３１→現像部（現像器）１０と循環され、トナー補給は現像剤循環経路内において現像剤収納部４０の直前の位置で行われ、現像剤収納部４０では現像後の現像剤と補給されたトナーとが混合され、適切なトナー濃度及び帯電量を有する現像剤となるので、現像部（現像器）１０では、常に適切なトナー濃度及び帯電量を有する現像剤による現像を行うことができる。 As described above, in the developing device 3 according to the present invention, the developer is supplied from the developing unit (developing device) 10 → the circulation path 30 → the developer storage unit 40 → the rotary feeder 50 → the developer holding unit (screw conveying unit) 70. → Merging section 35 → Developer transport path (circulation path) 31 → Developer section (developer) 10 is circulated, and toner replenishment is performed at a position immediately before the developer storage section 40 in the developer circulation path. Since the developer after development and the replenished toner are mixed in the storage unit 40 and become a developer having an appropriate toner concentration and charge amount, the development unit (developer) 10 always has an appropriate toner concentration and charge. Development with an amount of developer can be performed.

｛撹拌部（現像剤収容部）及びロータリフィーダの詳細説明｝
次に現像剤収容部４０とロータリフィーダ５０についてより詳細に説明する。図３はロータリフィーダ５０のロータ５１の回転軸に対して垂直な平面で切断したときの現像剤収容部、ロータリフィーダ、現像剤循環手段の概略を示す断面図であり、図３に示すように、現像剤収容部４０内には、攪拌スクリュ４１と、撹拌羽根４２がある。撹拌羽根４２はモータ４５により回転する板状の部材で、図のように、複数の格子状の空間が設けられている。そして攪拌羽根４２の回転により、この格子状の空間の中を現像剤が通過することにより、現像剤が撹拌され、補給されたトナーが現像剤中に分散される。攪拌スクリュ４１は現像剤を上方に動かす向きに回転し、攪拌羽根４２と同じくモータ４５が駆動源である。この攪拌スクリュ４１によって、中心付近の現像剤が上方に持ち上げられ、攪拌羽根４２の回転により、攪拌スクリュ４１の下部に現像剤が入り込む。このように現像剤が、攪拌羽根４２によりせん断されつつ、全体は対流運動を行うことにより、より素早くトナーが現像剤中に分散する仕組みである。このようにして現像剤収容部４０で撹拌された現像剤は、ステータ５５の現像剤流入孔５６を通りロータリフィーダ５０内に入る。 {Detailed description of stirring section (developer storage section) and rotary feeder}
Next, the developer container 40 and the rotary feeder 50 will be described in more detail. FIG. 3 is a cross-sectional view schematically showing the developer accommodating portion, the rotary feeder, and the developer circulating means when cut along a plane perpendicular to the rotation axis of the rotor 51 of the rotary feeder 50. As shown in FIG. The developer container 40 includes a stirring screw 41 and a stirring blade 42. The stirring blade 42 is a plate-like member that is rotated by a motor 45, and a plurality of lattice-like spaces are provided as shown in the figure. The developer passes through the lattice-like space by the rotation of the stirring blade 42, whereby the developer is stirred and the replenished toner is dispersed in the developer. The stirring screw 41 rotates in a direction to move the developer upward, and the motor 45 is a driving source, like the stirring blade 42. The developer near the center is lifted upward by the stirring screw 41, and the developer enters the lower portion of the stirring screw 41 by the rotation of the stirring blade 42. In this way, the developer is sheared by the stirring blade 42 and the whole moves in a convection so that the toner is more quickly dispersed in the developer. The developer agitated in the developer container 40 in this way enters the rotary feeder 50 through the developer inflow hole 56 of the stator 55.

ロータリフィーダ５０は、内部に円筒状の空間を有するステータ５５と、該ステータの上部側に設けられた開口部であり現像剤収納部４０からの現像剤が流入する現像剤流入孔５６と、ステータ５５の下部側に設けられた開口部であり現像剤が排出される現像剤排出孔５７と、ステータ５５の空間内に配置され軸部（回転軸）から放射状に延びる複数の羽根を有する回転自在に軸支されたロータ５１を備えている。このロータリフィーダ５０のロータ５１は、図１に示すように、回転軸をステータ５５の側壁に回転自在に軸支され、その回転軸の一方側がモータ５２と連結されて、図３中ではモータ５２によって回転軸を中心に時計回りに回転される。 The rotary feeder 50 includes a stator 55 having a cylindrical space inside, a developer inflow hole 56 that is an opening provided on the upper side of the stator and into which developer from the developer storage unit 40 flows, and a stator. A developer discharge hole 57 that is an opening provided on the lower side of 55 and through which the developer is discharged, and a plurality of blades that are arranged in the space of the stator 55 and extend radially from the shaft portion (rotary shaft). The rotor 51 is supported on the shaft. As shown in FIG. 1, the rotor 51 of the rotary feeder 50 is rotatably supported by a rotating shaft on the side wall of the stator 55, and one side of the rotating shaft is connected to the motor 52. Is rotated clockwise about the rotation axis.

このように、ロータリフィーダ５０は複数の羽を持つロータ５１と、ロータを覆うステータ５５から構成され、現像剤収納部４０から自重によって落下してくる現像剤を下方に定量排出する役割と、現像剤収納部４０と現像剤搬送経路３１のエア合流部３５の圧力差を維持するシール機能の役割がある。しかしながら、「発明の解決しようとする課題」で述べたとおり、ロータ５１とステータ５５には、わずかな隙間があるため、エアポンプ６０のエアの一部がこの隙間を通り現像剤収納部４０に流れ込んでしまう。このエアの漏れを防止するためには、ロータ５１の羽根とステータ５５の間の隙間（クリアランス）をできるだけ小さくすることが好ましいが、寸法精度を考慮すると限界がある。また、この方法では、ロータとステータの加工精度が要求され、コスト高となる。
また、別の方法としては、ロータ５１の羽根の枚数を増やすことが考えられ、ロータ５１の羽根の枚数を増やすことで、羽根とステータ５５の近接部が増えるため、空気抵抗が増し、漏れを低減（シール性を高く）することができる。しかし、ロータ５１の羽根の枚数を増やすと、羽根の厚みの分、ロータ５１内の現像剤の充填量が減ってしまい、同じ量の現像剤を搬送するためには、ロータ５１の外径を大きくする必要があり、ロータリフィーダ５０が大型化するという問題がある。 As described above, the rotary feeder 50 is composed of the rotor 51 having a plurality of blades and the stator 55 covering the rotor. The rotary feeder 50 has a role of quantitatively discharging the developer falling from its developer weight 40 by its own weight downward, and developing. There is a role of a sealing function for maintaining a pressure difference between the agent storage section 40 and the air merging section 35 of the developer transport path 31. However, as described in “Problems to be Solved by the Invention”, since there is a slight gap between the rotor 51 and the stator 55, a part of the air of the air pump 60 flows into the developer accommodating portion 40 through this gap. It will end up. In order to prevent this air leakage, it is preferable to make the gap (clearance) between the blades of the rotor 51 and the stator 55 as small as possible, but there is a limit in consideration of dimensional accuracy. In addition, this method requires processing accuracy of the rotor and the stator, and increases the cost.
Another method is to increase the number of blades of the rotor 51. By increasing the number of blades of the rotor 51, the proximity of the blades and the stator 55 increases. Reduction (high sealing performance) can be achieved. However, if the number of blades of the rotor 51 is increased, the amount of developer filling in the rotor 51 is reduced by the thickness of the blades. To transport the same amount of developer, the outer diameter of the rotor 51 is reduced. There is a problem that the rotary feeder 50 needs to be enlarged and the rotary feeder 50 becomes larger.

そこで本発明では、上記のような従来構成を用いずに、エアポンプ６０からの空気がロータリフィーダ５０へ進入する進入量を大幅に低減すると共に、確実にロータリフィーダ内部の現像剤を排出して容積効率を向上でき、現像剤収容部４０から現像部１０に適切なトナー濃度と帯電量を持った現像剤を現像に必要な量だけ連続的に安定供給することができる現像装置を実現するものであり、その解決手段として、ロータリフィーダ５０の現像剤排出孔５７と、該現像剤排出孔５７から排出された現像剤が現像剤搬送経路３１に合流する位置（合流部３５）の間に、現像剤を保持する現像剤保持部７０を設けている。なお、前述したように図３の例では、現像剤保持部７０はスクリュ搬送部で構成されている。以下、現像剤保持部（スクリュ搬送部）についてより詳しく説明する。 Therefore, in the present invention, without using the conventional configuration as described above, the amount of the air from the air pump 60 entering the rotary feeder 50 is significantly reduced, and the developer inside the rotary feeder is reliably discharged to increase the volume. It is possible to improve the efficiency, and to realize a developing device capable of continuously and stably supplying a developer having an appropriate toner concentration and charge amount from the developer containing unit 40 to the developing unit 10 in an amount necessary for development. As a solution, there is a development between the developer discharge hole 57 of the rotary feeder 50 and the position where the developer discharged from the developer discharge hole 57 joins the developer transport path 31 (joining portion 35). A developer holding unit 70 for holding the developer is provided. As described above, in the example of FIG. 3, the developer holding unit 70 is configured by a screw conveying unit. Hereinafter, the developer holding unit (screw conveyance unit) will be described in more detail.

｛現像剤保持部（スクリュ搬送部）の説明｝
本発明の特徴は、ロータリフィーダ５０と現像剤搬送経路３１の合流部３５の間に、現像剤保持部７０を設けたことである。
ここで、図４に示すような現像剤保持部７０を設けていない従来の合流部３５のみの構成では、エアがロータリフィーダ部に流れ易いが、図３に示すように現像剤保持部（スクリュ搬送部）７０を設けた場合には、現像剤保持部（スクリュ搬送部）７０には、現像剤排出孔５７から排出された現像剤が現像剤保持部（スクリュ搬送部）７０内に溜まって、該現像剤保持部（スクリュ搬送部）７０に現像剤が充満している状態、あるいは該現像剤保持部（スクリュ搬送部）７０の少なくとも一部が現像剤で満たされている状態となるため、現像剤がシールの役割をもつことができるため、エアが合流部３５からロータリフィーダ側に、流れにくくなっている。したがって、ロータリフィーダ５０の現像剤排出孔５７からの落下現像剤をエアが妨げることが無いため、排出現像剤量が安定化する。また、ロータリフィーダ側に漏れるエアを大幅に低減できるので、使用するエアの量も低減することができる。また、現像部１０への搬送のみにエアを使用することができるため、ロータリフィーダ部への漏れを考慮して、過剰にエアポンプ６０のエア流量を設定する必要が無くなる。 {Description of developer holding unit (screw conveying unit)}
A feature of the present invention is that a developer holding unit 70 is provided between the rotary feeder 50 and the merging unit 35 of the developer transport path 31.
Here, in the configuration of only the conventional merging portion 35 in which the developer holding portion 70 is not provided as shown in FIG. 4, the air easily flows to the rotary feeder portion. However, as shown in FIG. When the transport unit 70 is provided, the developer discharged from the developer discharge hole 57 is accumulated in the developer holding unit (screw transport unit) 70 in the developer holding unit (screw transport unit) 70. The developer holding unit (screw conveyance unit) 70 is filled with the developer, or at least a part of the developer holding unit (screw conveyance unit) 70 is filled with the developer. Since the developer can serve as a seal, it is difficult for air to flow from the merging portion 35 to the rotary feeder side. Therefore, air does not interfere with the developer dropped from the developer discharge hole 57 of the rotary feeder 50, and the discharged developer amount is stabilized. Further, since the air leaking to the rotary feeder side can be greatly reduced, the amount of air used can also be reduced. Further, since air can be used only for conveyance to the developing unit 10, it is not necessary to set the air flow rate of the air pump 60 excessively in consideration of leakage to the rotary feeder unit.

なお、図３の例では、現像剤保持部（スクリュ搬送部）７０内には、スクリュ７１が設置されており、スクリュ７１の回転により、現像剤保持部（スクリュ搬送部）７０内に保持されている現像剤を図中左方向に搬送し、搬送方向下流側に設けた開口部７２から、現像剤搬送経路（循環路）３１との合流部３５に現像剤を落下させている。このようにスクリュ７１を用いることで現像剤搬送量が安定化し、搬送量のばらつきを低減することができので、循環現像剤量の定量性も保たれている。 In the example of FIG. 3, a screw 71 is installed in the developer holding unit (screw conveyance unit) 70, and is held in the developer holding unit (screw conveyance unit) 70 by the rotation of the screw 71. The developer is transported to the left in the drawing, and the developer is dropped from the opening 72 provided on the downstream side in the transport direction to the junction 35 with the developer transport path (circulation path) 31. By using the screw 71 in this way, the developer conveyance amount is stabilized, and variations in the conveyance amount can be reduced, so that the quantitativeness of the circulating developer amount is also maintained.

次に現像剤保持部（スクリュ搬送部）７０のスクリュ７１の設定値について説明する。
図のようなスクリュ７１によって現像剤を搬送する場合、現像剤の搬送能力（最大搬送能力）は、スクリュ７１の断面積、羽のピッチ、回転数によって決まる。断面積はスクリュの軸及び、羽（スパイラル）の断面積を除いた面積である。
断面積をＡ（ｃｍ²）、ピッチをＰ（ｃｍ）、回転数をＮ（ｒｐｍ）、効率をα、現像剤のかさ密度をρ（ｇ／ｃｍ³）とすると、搬送量能力Ｍ１（ｇ／ｓ）は、
Ｍ１＝ρ×α×Ａ×（Ｐ×Ｎ／６０）（１）
で表される。 Next, the set value of the screw 71 of the developer holding unit (screw conveying unit) 70 will be described.
When the developer is transported by the screw 71 as shown in the figure, the developer transport capability (maximum transport capability) is determined by the cross-sectional area of the screw 71, the blade pitch, and the rotational speed. The cross-sectional area is the area excluding the screw shaft and the cross-sectional area of the wing (spiral).
When the cross-sectional area is A (cm ² ), the pitch is P (cm), the rotation speed is N (rpm), the efficiency is α, and the bulk density of the developer is ρ (g / cm ³ ), the conveyance capacity M1 (g / S)
M1 = ρ × α × A × (P × N / 60) (1)
It is represented by

上記の式（１）で効率αを１としたときが、スクリュ７１の最大搬送能力である。ここでロータリフィーダ５０の現像剤排出量をＭ２としたとき、Ｍ１＜Ｍ２となるように、スクリュ７１及びロータリフィーダ５０のパラメータを設定することが本発明の特徴である。ロータリフィーダ５０の現像剤排出量はロータ５１の大きさ、回転数等で設定可能である。このように設定すると、ロータリフィーダ５０の現像剤排出量に比べスクリュ７１の現像剤搬送能力が低いため、スクリュ７１は常に効率１、すなわち現像剤保持部７０が完全に充填された状態（現像剤で満たされている状態）で搬送されることになるため、エアの漏れを確実に防止することが可能となる。 When the efficiency α is 1 in the above formula (1), the maximum conveying capacity of the screw 71 is shown. Here, when the developer discharge amount of the rotary feeder 50 is M2, the parameters of the screw 71 and the rotary feeder 50 are set so that M1 <M2. The developer discharge amount of the rotary feeder 50 can be set by the size of the rotor 51, the number of rotations, and the like. With this setting, since the developer transport capability of the screw 71 is lower than the developer discharge amount of the rotary feeder 50, the screw 71 is always in the efficiency 1, that is, the state in which the developer holding portion 70 is completely filled (developer Therefore, it is possible to reliably prevent air leakage.

ここで、図５にロータリフィーダ５０、現像剤保持部（スクリュ搬送部）７０内の現像剤の様子の一例を示す。図示の様に現像剤保持部（スクリュ搬送部）７０が現像剤でほぼ満たされているため、合流部３５からエアがロータリフィーダ５０に進入するのを防止している。なお、ロータリフィーダ５０の現像剤排出量が、スクリュ７１の現像剤搬送量より多い場合は、図示のように現像剤の一部が現像剤保持部（スクリュ搬送部）７０に落下せず、ロータ５１の回転によって上部に戻される。 Here, FIG. 5 shows an example of the state of the developer in the rotary feeder 50 and the developer holding unit (screw conveying unit) 70. As shown in the drawing, since the developer holding part (screw conveying part) 70 is almost filled with the developer, air is prevented from entering the rotary feeder 50 from the junction part 35. When the developer discharge amount of the rotary feeder 50 is larger than the developer conveyance amount of the screw 71, a part of the developer does not fall to the developer holding unit (screw conveyance unit) 70 as illustrated, and the rotor It is returned to the upper part by the rotation of 51.

［実施例２］
次に本発明に係る現像装置の別の実施例について説明する。
図６は本発明の別の実施例を示す現像装置の現像剤収容部、ロータリフィーダ、現像剤循環手段の概略を示す概略構成図である。
本実施例の現像装置の基本的な構成は実施例１と同様であるが、本実施例では、現像剤保持部（ここではスクリュ搬送部とする）７０のスクリュ７１は略水平に配置されており、該スクリュ７１により搬送された現像剤が、現像剤搬送経路３１の搬送路の略垂直に配置された部分でエアポンプ６０からのエアと合流するように合流部３５を設けたものである。 [Example 2]
Next, another embodiment of the developing device according to the present invention will be described.
FIG. 6 is a schematic configuration diagram showing an outline of a developer accommodating portion, a rotary feeder, and a developer circulating means of a developing device according to another embodiment of the present invention.
The basic configuration of the developing device of the present embodiment is the same as that of the first embodiment, but in this embodiment, the screw 71 of the developer holding portion (here, referred to as a screw conveying portion) 70 is disposed substantially horizontally. The joining portion 35 is provided so that the developer transported by the screw 71 joins the air from the air pump 60 at a portion arranged substantially perpendicular to the transport path of the developer transport path 31.

スクリュ搬送部７０から合流部３５に現像剤を搬送し、エアと混合し現像剤を搬送する場合、図３のように現像剤のスクリュ搬送部７０からの落下が垂直方向でエアの方向が水平である場合に比べ、図６のように現像剤の落下方向に対しエアの方向も垂直にすると、現像剤を加速するために必要な圧力が低くなることが分かった。図７に、図３及び図６の現像装置で、現像剤を搬送しているときの、エア搬送経路内の圧力のグラフを示す。圧力の測定は、現像剤搬送経路３１に圧力計を取り付け測定した。 When the developer is transported from the screw transport unit 70 to the joining unit 35 and mixed with air to transport the developer, the developer falls from the screw transport unit 70 in the vertical direction and the air direction is horizontal as shown in FIG. As shown in FIG. 6, when the direction of the air is also perpendicular to the direction of dropping of the developer as shown in FIG. FIG. 7 shows a graph of the pressure in the air conveyance path when the developer is conveyed in the developing device of FIGS. 3 and 6. The pressure was measured by attaching a pressure gauge to the developer transport path 31.

図６の装置のように、スクリュ７１により搬送された現像剤を現像剤搬送経路３１の搬送路の略垂直に配置された部分でエアと合流させた方が、現像剤を加速するために必要なエアの圧力が少なくて済むため、エアによる現像剤搬送の負荷を低減でき、省エネルギである。 As in the apparatus of FIG. 6, it is necessary for the developer conveyed by the screw 71 to merge with air at a portion disposed substantially perpendicular to the conveyance path of the developer conveyance path 31 in order to accelerate the developer. Since the air pressure is small, the load of conveying the developer by air can be reduced and energy is saved.

次に図８は、図６のように、スクリュ搬送部７０のスクリュ７１は略水平に配置されており、該スクリュ７１により搬送された現像剤が、現像剤搬送経路３１の搬送路の略垂直に配置された部分でエアポンプ６０からのエアと合流するように合流部３５を設けた場合の、現像装置の合流部の構成例を示す概略要部断面図である。 Next, in FIG. 8, as shown in FIG. 6, the screw 71 of the screw conveyance unit 70 is arranged substantially horizontally, and the developer conveyed by the screw 71 is substantially perpendicular to the conveyance path of the developer conveyance path 31. FIG. 6 is a schematic cross-sectional view of an essential part showing a configuration example of a merging portion of the developing device when a merging portion 35 is provided so as to merge with air from the air pump 60 at a portion arranged in the position.

図６のように、スクリュ７１により搬送された現像剤を、現像剤搬送経路３１の搬送路の略垂直に配置された部分の合流部３５でエアと合流させる場合、装置が停止し、エアポンプ６０が停止すると、垂直部の搬送経路内の現像剤が自重により合流部３５に落下するため、空気供給路３１を通ってエアポンプ６０に現像剤が進入し易い。
そこで図８の構成例では、合流部３５内に、エアは通過し、現像剤の通過を遮断する部材４４を設けたものである。このエアは通過し、現像剤の通過を遮断する部材４４としては、一般的なエアフィルタや、現像剤の粒径より小さい樹脂又は金属製のメッシュからなるフィルタでも良い。この遮断部材（フィルタ）により、現像剤はエアポンプ側に進入しないため、エアポンプ内に現像剤が進入し、エアポンプを破損させることがない。 As shown in FIG. 6, when the developer conveyed by the screw 71 is merged with air at the merging portion 35 of the portion disposed substantially perpendicular to the conveyance path of the developer conveyance path 31, the apparatus stops and the air pump 60 Is stopped, the developer in the transport path of the vertical portion falls to the merge portion 35 due to its own weight, so that the developer easily enters the air pump 60 through the air supply path 31.
Therefore, in the configuration example of FIG. 8, a member 44 that passes air and blocks the passage of the developer is provided in the merging portion 35. As the member 44 through which the air passes and blocks the passage of the developer, a general air filter or a filter made of a resin or metal mesh smaller than the particle size of the developer may be used. The blocking member (filter) prevents the developer from entering the air pump, so that the developer does not enter the air pump and damage the air pump.

［実施例３］
次に本発明に係る現像装置のさらに別の実施例について説明する。
図９は本発明のさらに別の実施例を示す現像装置の概略要部構成図である。本実施例では、図６と同様の構成の現像装置の、現像剤保持部（スクリュ搬送部）７０の上流側端部の底に、蓋７４により開閉可能な開口部（孔）７３を設けたものである。
この現像剤保持部（スクリュ搬送部）７０に設けた開口部（孔）７３は、長期にわたり現像装置が使用され、現像剤が劣化した場合に、現像剤の交換がし易いように設けたものであり、現像剤を交換する際に現像剤を排出するための開口部である。 [Example 3]
Next, still another embodiment of the developing device according to the present invention will be described.
FIG. 9 is a schematic configuration diagram of a main part of a developing device showing still another embodiment of the present invention. In the present embodiment, an opening (hole) 73 that can be opened and closed by a lid 74 is provided at the bottom of the upstream end portion of the developer holding portion (screw conveying portion) 70 of the developing device having the same configuration as in FIG. Is.
The opening (hole) 73 provided in the developer holding unit (screw conveying unit) 70 is provided so that the developer can be easily replaced when the developing device is used for a long time and the developer deteriorates. And an opening for discharging the developer when the developer is replaced.

このように、本実施例では、スクリュ搬送部７０のロータリフィーダ５０の現像剤排出部５７との合流点より上流側に、現像剤を排出する開口部（孔）７３を設けたので、メンテナンス等で現像剤を交換する際には、スクリュ搬送部７０のロータリフィーダ５０の現像剤排出部５７との合流点より上流側に設けた開口部（孔）７３の蓋７４を外して開口させ、スクリュ７１を通常と逆回転させる（現像剤を図の右方向に移動させる）ことにより、スクリュ搬送部内に保持されている現像剤を外部に排出することができ、ロータリフィーダ内部や現像剤収納部４０に残った現像剤も排出することができる。 As described above, in this embodiment, the opening (hole) 73 for discharging the developer is provided on the upstream side of the joining point with the developer discharging portion 57 of the rotary feeder 50 of the screw conveying portion 70. When the developer is exchanged, the lid 74 of the opening (hole) 73 provided on the upstream side from the junction with the developer discharging portion 57 of the rotary feeder 50 of the screw conveying portion 70 is removed and opened, and the screw is opened. The developer held in the screw conveying unit can be discharged to the outside by rotating the 71 reversely from the normal direction (the developer is moved in the right direction in the figure), and the inside of the rotary feeder or the developer storage unit 40 can be discharged. The remaining developer can also be discharged.

［実施例４］
次に本発明に係る現像装置のさらに別の実施例について説明する。
図１０は本発明のさらに別の実施例を示す現像装置の現像剤収容部、ロータリフィーダ、現像剤循環手段の概略を示す概略構成図である。
本実施例の現像装置の基本的な構成は図６と同様であるが、本実施例では、現像剤保持部（スクリュ搬送部）７０のスクリュ７１の外径、及びスクリュ経路断面（断面積）を、現像剤搬送方向下流側で小さくするように設定している。
すなわち、現像剤保持部（スクリュ搬送部）７０のスクリュ７１の現像剤搬送方向下流側（図の左側）のスクリュ部７１ａのスクリュ径（外径）は、上流側のスクリュ部のスクリュ径（外径）より小さく、現像剤搬送方向下流側（図の左側）のスクリュ経路７７の断面積も、上流側のスクリュ経路７６の断面積より小さい。したがって下流側のスクリュ部７１ａの現像剤搬送能力は、前述の式（１）から上流側のスクリュ部より少ない。よって、現像剤搬送方向上流側のスクリュ経路７６を搬送されてきた現像剤は、下流側のスクリュ部７１ａの搬送能力が低いため、一部が下流側のスクリュ経路７７に進入できずに滞留することになる。そして、この滞留する現像剤が下流側のスクリュ経路７７に充満し、エアの進入を防ぐ効果をより確実にするものである。 [Example 4]
Next, still another embodiment of the developing device according to the present invention will be described.
FIG. 10 is a schematic configuration diagram showing an outline of a developer accommodating portion, a rotary feeder, and a developer circulating means of a developing device showing still another embodiment of the present invention.
The basic configuration of the developing device of the present embodiment is the same as that shown in FIG. 6, but in this embodiment, the outer diameter of the screw 71 of the developer holding unit (screw transporting unit) 70 and the cross section (cross sectional area) of the screw path. Is set to be smaller on the downstream side in the developer conveyance direction.
That is, the screw diameter (outer diameter) of the screw portion 71a on the downstream side (left side in the drawing) of the screw 71 of the developer holding portion (screw conveying portion) 70 is the screw diameter (outside diameter) of the upstream screw portion. The cross-sectional area of the screw path 77 on the downstream side (left side in the drawing) of the developer conveyance direction is also smaller than the cross-sectional area of the upstream screw path 76. Therefore, the developer conveying capability of the downstream screw portion 71a is smaller than that of the upstream screw portion from the above-described formula (1). Accordingly, the developer that has been transported through the screw path 76 on the upstream side in the developer transport direction has a low transport capability of the downstream screw portion 71 a, and therefore a part of the developer cannot enter the downstream screw path 77 and stay there. It will be. This staying developer fills the screw path 77 on the downstream side, thereby ensuring the effect of preventing the ingress of air.

このように、本実施例の現像装置では、スクリュ搬送部７０のスクリュ７１の径、及びスクリュ経路断面（断面積）を、現像剤搬送方向下流側で小さくしたことにより、スクリュ径、経路断面を小さくした下流側の部位では搬送能力が少なくなるため、現像剤が滞留し、下流側のスクリュ経路７７に現像剤が充満してシール効果がより向上するので、より確実にエアがロータリフィーダ５０に流れ込むのを防止することができる。 As described above, in the developing device of the present embodiment, the screw diameter and path cross section are reduced by reducing the diameter of the screw 71 of the screw transport unit 70 and the screw path cross section (cross-sectional area) on the downstream side in the developer transport direction. Since the conveyance capacity is reduced at the downstream portion that has been reduced, the developer stays, the developer is filled in the downstream screw path 77, and the sealing effect is further improved, so that the air is more reliably supplied to the rotary feeder 50. Inflow can be prevented.

［実施例５］
次に以上に説明した本発明の現像装置３を装備する画像形成装置の構成例について説明する。
図１１は、本発明の一実施例を示す画像形成装置の概略構成図である。同図において画像形成装置１００は、装置本体のほぼ中央部に中間転写ベルト４と４個の１次転写ローラ５Ｙ，５Ｍ，５Ｃ，５Ｂｋとを有する中間転写ユニット６を備えている。中間転写ベルト４の下面と対向する位置には、イエロー（Ｙ）、マゼンタ（Ｍ）、シアン（Ｃ）、ブラック（Ｂｋ）の各色に対応した作像部１Ｙ，１Ｍ，１Ｃ，１Ｂｋが中間転写ベルト４の走行方向と平行して配置されている。各作像部１Ｙ，１Ｍ，１Ｃ，１Ｂｋは作像プロセスに用いられるトナーの色が異なる以外は同一構造であり、それぞれ潜像担持体としての感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋと、各感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋの周囲に配設された図示しない帯電手段、図示しない露光部、現像装置３Ｙ，３Ｍ，３Ｃ，３Ｂｋ、図示しないクリーニング手段等を有している。
なお、図１１は画像形成装置本体の上部に原稿画像の読取部（スキャナ）８０を設置したカラー複写機の構成例であるが、さらに通信機能を持たせて外部回線（電話回線、光回線）やローカルエリアネットワーク（ＬＡＮ）等と接続すれば、複写機、プリンタ、ファクシミリの機能を有するデジタルカラー複合機の構成となる。 [Example 5]
Next, a configuration example of an image forming apparatus equipped with the developing device 3 of the present invention described above will be described.
FIG. 11 is a schematic configuration diagram of an image forming apparatus showing an embodiment of the present invention. In FIG. 1, an image forming apparatus 100 includes an intermediate transfer unit 6 having an intermediate transfer belt 4 and four primary transfer rollers 5Y, 5M, 5C, and 5Bk at a substantially central portion of the apparatus main body. Image forming portions 1Y, 1M, 1C, and 1Bk corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (Bk) are intermediately transferred at positions facing the lower surface of the intermediate transfer belt 4. The belt 4 is disposed in parallel with the traveling direction of the belt 4. Each of the image forming units 1Y, 1M, 1C, and 1Bk has the same structure except that the color of the toner used in the image forming process is different. Each of the image forming units 1Y, 1M, 1C, and 1Bk has a photosensitive drum 2Y, 2M, 2C, and 2Bk as a latent image carrier. A charging unit (not shown), an exposure unit (not shown), developing devices 3Y, 3M, 3C, 3Bk, a cleaning unit (not shown), and the like disposed around the photosensitive drums 2Y, 2M, 2C, and 2Bk are provided.
FIG. 11 shows an example of the configuration of a color copying machine in which an original image reading unit (scanner) 80 is installed on the upper part of the image forming apparatus main body. However, an external line (telephone line, optical line) is provided with a communication function. Or a local area network (LAN) or the like, it becomes a configuration of a digital color multifunction peripheral having functions of a copying machine, a printer, and a facsimile.

図１１において、各作像部１Ｙ，１Ｍ，１Ｃ，１Ｂｋの感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋは図示しない駆動部によって図において時計回り方向に回転駆動され、図示しない帯電手段により表面を一様に帯電された後に、図示しない露光部から発せられたレーザ光等によって露光されることにより、装置本体の上部に設けられた画像読取部８０において読み取られた原稿画像（あるいは外部回線やＬＡＮ等を介して入力された画像情報）に基づいた静電潜像がその表面上に形成される。各感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋ形成された静電潜像は各現像装置３Ｙ，３Ｍ，３Ｃ，３Ｂｋ（図１の現像装置３の現像部１０）により現像されることにより所望のトナー像へと可視像化され、このトナー像は各感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋの表面が中間転写ベルト４を介して各１次転写ローラ５Ｙ，５Ｍ，５Ｃ，５Ｂｋとの対向部に達した際に、各１次転写ローラ５Ｙ，５Ｍ，５Ｃ，５Ｂｋの作用によって中間転写ベルト４上に順次１次転写される。 In FIG. 11, the photosensitive drums 2Y, 2M, 2C, and 2Bk of the image forming units 1Y, 1M, 1C, and 1Bk are rotationally driven in the clockwise direction in the drawing by a driving unit (not shown), and the surfaces are unified by a charging unit (not shown). After being charged in this manner, the original image read by the image reading unit 80 provided on the upper part of the apparatus body (or an external line, LAN, etc.) is exposed by a laser beam or the like emitted from an exposure unit (not shown). An electrostatic latent image is formed on the surface based on the image information input via the. The electrostatic latent images formed on the photosensitive drums 2Y, 2M, 2C, and 2Bk are developed by the developing devices 3Y, 3M, 3C, and 3Bk (the developing unit 10 of the developing device 3 in FIG. 1), thereby obtaining desired toner. The surface of each photosensitive drum 2Y, 2M, 2C, 2Bk is opposed to each primary transfer roller 5Y, 5M, 5C, 5Bk via the intermediate transfer belt 4. In this case, the primary transfer rollers 5Y, 5M, 5C, and 5Bk are sequentially primary transferred onto the intermediate transfer belt 4 by the action of the primary transfer rollers 5Y, 5M, 5C, and 5Bk.

各１次転写ローラ５Ｙ，５Ｍ，５Ｃ，５Ｂｋは、それぞれ中間転写ベルト４を各感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋとの間に挟み込んで１次転写ニップを形成しており、各１次転写ローラ５Ｙ，５Ｍ，５Ｃ，５Ｂｋにはトナーとは逆極性の転写バイアスが印加される。中間転写ベルト４が図１１の矢印方向に走行して各１次転写ローラ５Ｙ，５Ｍ，５Ｃ，５Ｂｋの１次転写ニップを順次通過することにより、各感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋ上の各色のトナー像が中間転写ベルト３上に重ねて１次転写される。１次転写後、各感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋの表面が図示しないクリーニング手段との対向位置に達すると、クリーニング手段の作用により各感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋの表面上に残存した未転写トナーが回収される。クリーニング後、各感光体ドラム２Ｙ，２Ｍ，２Ｃ，２Ｂｋの表面は図示しない除電装置により電位を初期化され、一連の作像プロセスが終了する。 Each of the primary transfer rollers 5Y, 5M, 5C, and 5Bk forms a primary transfer nip by sandwiching the intermediate transfer belt 4 with each of the photosensitive drums 2Y, 2M, 2C, and 2Bk. A transfer bias having a polarity opposite to that of the toner is applied to the transfer rollers 5Y, 5M, 5C, and 5Bk. The intermediate transfer belt 4 travels in the direction of the arrow in FIG. 11 and sequentially passes through the primary transfer nips of the primary transfer rollers 5Y, 5M, 5C, and 5Bk, so that the photosensitive drums 2Y, 2M, 2C, and 2Bk are moved upward. Are transferred onto the intermediate transfer belt 3 so as to be primarily transferred. After the primary transfer, when the surface of each photoconductive drum 2Y, 2M, 2C, 2Bk reaches a position facing a cleaning unit (not shown), the surface of each photoconductive drum 2Y, 2M, 2C, 2Bk is caused by the action of the cleaning unit. The remaining untransferred toner is collected. After cleaning, the surface of each of the photosensitive drums 2Y, 2M, 2C, and 2Bk is initialized with a potential by a static eliminator (not shown), and a series of image forming processes is completed.

装置本体２の下部には給紙部９０が配設されており、給紙部９０には記録媒体で有る複数枚の転写紙Ｐが収納されている。この転写紙Ｐは、上記の作像プロセスの開始にタイミングを合せて、給紙ローラ９１と図示しない分離部材（分離ローラ、分離パッド等）により１枚ずつ分離給送され、給送された転写紙Ｐはレジストローラ対９２で一時停止され、斜めずれを修正された後に所定のタイミングで２次転写ニップに向けて給送される。
また、上記の作像プロセスで各色のトナー像が重ねて転写された中間転写ベルト４は、２次転写ローラ９３との対向位置である２次転写ニップに到達する。そして中間転写ベルト４上に形成されたカラートナー像は、２次転写ニップ位置に搬送された転写紙Ｐ上に転写される。 A paper feeding unit 90 is disposed in the lower part of the apparatus main body 2, and a plurality of transfer papers P that are recording media are stored in the paper feeding unit 90. The transfer paper P is separated and fed one by one by a paper feed roller 91 and a separation member (not shown) (separation roller, separation pad, etc.) in synchronism with the start of the image forming process, and the transferred transfer is performed. The paper P is temporarily stopped by the registration roller pair 92, and is fed toward the secondary transfer nip at a predetermined timing after correcting the oblique shift.
In addition, the intermediate transfer belt 4 onto which the toner images of the respective colors are transferred in the image forming process reaches the secondary transfer nip that is a position facing the secondary transfer roller 93. The color toner image formed on the intermediate transfer belt 4 is transferred onto the transfer paper P conveyed to the secondary transfer nip position.

２次転写ニップ位置においてカラー画像を転写された転写紙Ｐは定着装置９４へと搬送され、定着装置９４の加熱ローラ及び加圧ローラによる熱と圧力とにより転写紙表面に転写されたカラー画像が定着される。定着を終えた転写紙Ｐは、排紙ローラ対９５により装置本体上面に形成された排紙部９６へと排出され積載される。このようにして画像形成装置における一連の画像形成プロセスが完了する。 The transfer paper P on which the color image is transferred at the secondary transfer nip position is conveyed to the fixing device 94, and the color image transferred to the transfer paper surface by the heat and pressure of the heating roller and pressure roller of the fixing device 94 is transferred. It is fixed. After the fixing, the transfer paper P is discharged and stacked by a paper discharge roller pair 95 onto a paper discharge unit 96 formed on the upper surface of the apparatus main body. In this way, a series of image forming processes in the image forming apparatus is completed.

なお、以上の実施例では、画像形成装置としてカラー複写機（またはカラー複合機）を例に挙げて説明したが、前述の本発明の現像装置３は、作像部が一つのみのモノクロ画像形成装置に適用することができることは言うまでもない。 In the above embodiment, the color copying machine (or color multifunction peripheral) is described as an example of the image forming apparatus. However, the developing device 3 of the present invention described above has a monochrome image having only one image forming unit. Needless to say, the present invention can be applied to a forming apparatus.

本発明の画像形成装置では、現像手段として前述の実施例１〜４で説明した構成の現像装置３を備えたことにより、現像剤の循環、混合、攪拌、帯電の安定化が図れるため、画質や画像濃度の安定化を図ることができる。 In the image forming apparatus of the present invention, since the developing device 3 having the structure described in the first to fourth embodiments is provided as a developing unit, the circulation, mixing, stirring, and charging of the developer can be stabilized. And stabilization of the image density can be achieved.

１Ｙ，１Ｍ，１Ｃ，１Ｂｋ：作像部
２（２Ｙ，２Ｍ，２Ｃ，２Ｂｋ）：感光体ドラム（潜像担持体）
３（３Ｙ，３Ｍ，３Ｃ，３Ｂｋ）：現像装置
４：中間転写ベルト
５Ｙ，５Ｍ，５Ｃ，５Ｂｋ：１次転写ローラ
６：中間転写ユニット
１０：現像部（現像器）
１１，１２：搬送スクリュ
１３：現像ローラ
１４：ドクタブレード
１５：ケーシング
２０：トナーカートリッジ
２１：モータ
２２：トナー補給路
３０：循環路
３１：現像剤搬送経路（循環路）
３３：空気供給路
３５：合流部
４０：現像剤収容部
４１：攪拌スクリュ
４２：撹拌羽根
４３：現像剤流入口
４５：モータ
５０：ロータリフィーダ
５１：ロータ
５２：モータ
５５：ステータ
５６：現像剤流入孔
５７：現像剤排出孔
６０：エアポンプ（空気供給源）
７０：現像剤保持部（スクリュ搬送部）
７１：スクリュ
７２：現像剤保持部（スクリュ搬送部）の搬送方向下流側の開口部
７３：現像剤保持部（スクリュ搬送部）の搬送方向上流側端部の開口部（孔）
７４：蓋
８０：画像読取部
９０：給紙部
９１：給紙ローラ
９２：レジストローラ対
９３：２次転写ローラ
９４：定着装置
９５：排紙ローラ対
９６：排紙部
１００：画像形成装置
Ｐ：転写紙 1Y, 1M, 1C, 1Bk: Image forming section 2 (2Y, 2M, 2C, 2Bk): Photosensitive drum (latent image carrier)
3 (3Y, 3M, 3C, 3Bk): developing device 4: intermediate transfer belt 5Y, 5M, 5C, 5Bk: primary transfer roller 6: intermediate transfer unit 10: developing unit (developer)
11, 12: Conveying screw 13: Developing roller 14: Doctor blade 15: Casing 20: Toner cartridge 21: Motor 22: Toner replenishing path 30: Circulating path 31: Developer conveying path (circulating path)
33: Air supply path 35: Merging section 40: Developer accommodating section 41: Stirring screw 42: Stirring blade 43: Developer inlet 45: Motor 50: Rotary feeder 51: Rotor 52: Motor 55: Stator 56: Developer inflow Hole 57: Developer discharge hole 60: Air pump (air supply source)
70: Developer holding part (screw conveying part)
71: Screw 72: Opening portion on the downstream side in the conveyance direction of the developer holding portion (screw conveyance portion) 73: Opening portion (hole) on the upstream end in the conveyance direction of the developer holding portion (screw conveyance portion)
74: lid 80: image reading unit 90: paper feeding unit 91: paper feeding roller 92: registration roller pair 93: secondary transfer roller 94: fixing device 95: paper ejection roller pair 96: paper ejection unit 100: image forming apparatus P : Transfer paper

特許第３７３４０９６号公報Japanese Patent No. 3733496 特許第３３４９２８６号公報Japanese Patent No. 3349286 特開平１１−１４３１９６号公報JP-A-11-143196 特開２００７−１９３３０１号公報JP 2007-193301 A 特開２００８−２９９２１７号公報JP 2008-299217 A 特開２００８−３５６１号公報JP 2008-3561 A 特開２００９−１０３７５１号公報JP 2009-103751 A

Claims

A developing unit that develops a latent image on the latent image carrier, a developer storage unit that is provided outside the development unit and stores a part of the developer, and the developer provided below the developer storage unit In a developing device comprising: a rotary feeder that discharges the developer in a storage unit; and a developer transport path that transfers the developer discharged from the rotary feeder to the developing unit using air.
The rotary feeder is provided in a stator having a cylindrical space inside, a developer inflow hole provided on an upper side of the stator and into which a developer from the developer storage portion flows, and provided on a lower side of the stator. A developer discharge hole for discharging the developer, and a rotatably supported rotor having a plurality of blades arranged in the space of the stator and extending radially from the shaft portion;
A developer holding portion for holding the developer is provided between the developer discharge hole of the rotary feeder and a position where the developer discharged from the developer discharge hole joins the developer transport path. A developing device.

A developing unit that develops a latent image on the latent image carrier, a developer storage unit that is provided outside the development unit and stores a part of the developer, and the developer provided below the developer storage unit In a developing device comprising: a rotary feeder that discharges the developer in a storage unit; and a developer transport path that transfers the developer discharged from the rotary feeder to the developing unit using air.
The rotary feeder is provided in a stator having a cylindrical space inside, a developer inflow hole provided on an upper side of the stator and into which a developer from the developer storage portion flows, and provided on a lower side of the stator. A developer discharge hole for discharging the developer, and a rotatably supported rotor having a plurality of blades arranged in the space of the stator and extending radially from the shaft portion;
Between the developer discharge hole of the rotary feeder and a position where the developer discharged from the developer discharge hole joins the developer transfer path, a screw transfer unit for holding and transferring the developer is provided. A developing device.

The developing device according to claim 2,
2. A developing device according to claim 1, wherein a developer conveying capacity, which is a maximum value of a theoretical value of the developer conveyed by rotation of the screw of the screw conveying unit, is set smaller than a developer discharge amount of the rotary feeder.

In the developing device according to claim 2 or 3,
The screw of the screw conveying unit is arranged substantially horizontally, and the developer conveyed by the screw merges with the air at a portion arranged substantially perpendicular to the conveying path of the developer conveying path. A developing device.

In the developing device according to any one of claims 2 to 4,
2. A developing device according to claim 1, wherein an opening for discharging the developer is provided upstream of a joining point of the screw conveying unit and the developer discharging unit of the rotary feeder.

The developing device according to claim 4 or 5,
A developing device, wherein a filter is installed at a junction between the developer and air in the developer transport path.

In the developing device according to any one of claims 2 to 6,
A developing device characterized in that the screw diameter of the screw conveying section and the screw path cross section are reduced on the downstream side in the developer conveying direction.

An image forming apparatus comprising a latent image carrier and developing means for developing and visualizing the latent image on the latent image carrier,
An image forming apparatus comprising the developing device according to claim 1 as the developing unit.