JP2010237328A

JP2010237328A - Developing device

Info

Publication number: JP2010237328A
Application number: JP2009083647A
Authority: JP
Inventors: Tomohiro Shiomi; 友洋潮見
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2009-03-30
Filing date: 2009-03-30
Publication date: 2010-10-21
Anticipated expiration: 2029-03-30
Also published as: JP5414325B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device capable of preventing a developer passing over a disc and dropping to a discharge opening side from being stagnant even after long-time continuous operation and in a high-temperature and a high-humidity environment, and properly controlling the quantity of a two-component developer discharged through a discharge opening. <P>SOLUTION: A pair of conveying screws 45, 46 set to be opposite to each other in the conveying direction of the two-component developer are disposed across a partition wall 47 both ends of which are provided with openings 47a, 47b. The conveying screw 46 conveys the two-component developer in the direction of an arrow C and the conveying screw 45 conveys it in the direction of an arrow B while stirring it, whereby the two-component developer is delivered through the openings 47a, 47b and circulated in a development container 42. A collar 51 eliminates the two-component developer which drops in the discharge opening 53 through a slit of a conveying blade of a return screw 50 to thereby stabilize the quantity of the discharged two-component developer. A projection 52 for catching the cohesion of the two-component developer to fall in the discharge opening side is disposed at the outer periphery of the collar 51. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、現像容器内の長手方向の突き当たりに配置された排出開口から古くなった二成分現像剤を少しずつ排出する現像装置、詳しくは二成分現像剤の流動性の変化に伴う排出量の変動を抑制する構造に関する。 The present invention relates to a developing device that discharges an old two-component developer little by little from a discharge opening disposed at the end of the longitudinal direction in a developing container, and more specifically, a discharge amount accompanying a change in fluidity of the two-component developer. The present invention relates to a structure that suppresses fluctuations.

隔壁を挟んで現像容器の長手方向に配置した一対の搬送スクリューを用いて、非磁性トナーに磁性キャリアを混合した二成分現像剤を攪拌しつつ搬送して循環させる現像装置が広く用いられている。 2. Description of the Related Art Developing devices that use a pair of conveying screws arranged in the longitudinal direction of a developing container across a partition wall to convey and circulate a two-component developer obtained by mixing a magnetic carrier with nonmagnetic toner while stirring are widely used. .

このような現像装置では、非磁性トナーの消費に伴って新しい非磁性トナーが供給される一方で古い磁性キャリアが現像容器内を循環し続けると、次第に非磁性トナーに対する磁性キャリアの帯電性能が低下することが知られている。このため、現像容器内の磁性キャリアについても、古いものを少しずつ排出して排出しただけ新しいものを供給して現像容器内の磁性キャリアの帯電性能を一定に維持する制御が取り入れられている。 In such a developing device, as the non-magnetic toner is consumed, new non-magnetic toner is supplied, and as the old magnetic carrier continues to circulate in the developing container, the charging performance of the magnetic carrier with respect to the non-magnetic toner gradually decreases. It is known to do. For this reason, as for the magnetic carrier in the developing container, a control is introduced to keep the charging performance of the magnetic carrier in the developing container constant by discharging the old one little by little and supplying new one.

特許文献１には、画像形成に伴って、非磁性トナーに磁性キャリアを所定割合で混合した補給用二成分現像剤を現像装置に供給して、現像容器内の古くなった磁性キャリアを少しずつ入れ替える現像装置が示される。ここでは、図２を参照して説明すると、搬送スクリュー（４６）による搬送方向の突き当たりに配置した排出開口（５３）を通じて、現像容器内を循環している二成分現像剤が少しずつ排出される。 In Patent Document 1, a two-component developer for replenishment in which a magnetic carrier is mixed with a non-magnetic toner at a predetermined ratio is supplied to a developing device along with image formation, and an old magnetic carrier in a developing container is gradually added. The developing device to be replaced is shown. Here, as will be described with reference to FIG. 2, the two-component developer circulating in the developing container is discharged little by little through the discharge opening (53) disposed at the end of the conveyance direction by the conveyance screw (46). .

搬送スクリュー（４６）は、二成分現像剤を循環させる方向に搬送して排出開口（５３）へ送り込む主スパイラル部の下流側に、回転に伴う搬送方向が主スパイラル部とは逆方向の副スパイラル部（５０）が連結されている。副スパイラル部（５０）は、主スパイラル部に搬送されて排出開口へ向かって移動する二成分現像剤の大部分を押し戻して、排出開口（５３）を通じて排出される二成分現像剤が過剰にならないようにしている。 The conveying screw (46) is a sub-spiral whose conveying direction accompanying rotation is opposite to the main spiral portion on the downstream side of the main spiral portion that conveys the two-component developer in a circulating direction and sends it to the discharge opening (53). The parts (50) are connected. The sub-spiral part (50) pushes back most of the two-component developer that is transported to the main spiral part and moves toward the discharge opening, so that the two-component developer discharged through the discharge opening (53) does not become excessive. I am doing so.

特開２００２−７２６８６号公報JP 2002-72686 A

特許文献１に示される搬送スクリューの場合、副スパイラル部の回転角度によって排出開口へ落ち込む二成分現像剤の量が変動する。副スパイラル部の末端に露出したスクリューの谷が上になる回転位置では、スクリューの谷が下になる回転位置に比較して大量の二成分現像剤が排出開口へ落ち込むからである。そして、この現象は、搬送スクリューの回転速度が高くなるとより顕著になるため、回転速度を遅い側に切り替えた際に排出量が不足したり、回転速度を速い側に切り替えた際に排出量が過剰になったりする。 In the case of the conveying screw disclosed in Patent Document 1, the amount of the two-component developer that falls into the discharge opening varies depending on the rotation angle of the sub spiral portion. This is because a large amount of the two-component developer falls into the discharge opening at the rotation position where the screw valley exposed at the end of the sub spiral portion is up compared to the rotation position where the screw valley is down. This phenomenon becomes more prominent when the rotation speed of the conveying screw is increased. Therefore, the discharge amount is insufficient when the rotation speed is switched to the slow side, or the discharge amount is decreased when the rotation speed is switched to the fast side. It becomes excessive.

そこで、図４に示すように、副スパイラル部（５０）の排出開口（５３）に対向する末端に円板部（５１）を連結してスクリューの谷を排出開口側へ露出させない構造が提案された。円板部（５１）を設けた副スパイラル部（５０）を採用することで、搬送スクリュー（４６）の回転速度を遅い側に切り替えても速い側に切り替えても期待どおりの排出量が安定して確保できることが確認された。 Therefore, as shown in FIG. 4, a structure is proposed in which a disk portion (51) is connected to the end of the auxiliary spiral portion (50) facing the discharge opening (53) so that the screw valley is not exposed to the discharge opening side. It was. By adopting the sub spiral part (50) provided with the disk part (51), the discharge amount is stabilized as expected regardless of whether the rotational speed of the conveying screw (46) is switched to the slow side or the fast side. It was confirmed that

しかし、円板部（５１）を設けた搬送スクリューを用いて、連続運転実験及び各種温度湿度での運転実験を行ったところ、長時間の連続運転後及び高温高湿環境では、排出開口を通じた二成分現像剤の排出量が大きく減少することが判明した。排出量が減少する結果、現像装置内に二成分現像剤が停滞して、帯電性能が低下して、出力画像の品質が低下してしまう。 However, when a continuous operation experiment and an operation experiment at various temperatures and humidity were performed using the conveying screw provided with the disc portion (51), it was found that the discharge opening was passed through after a long continuous operation and in a high temperature and high humidity environment. It was found that the discharge amount of the two-component developer is greatly reduced. As a result of the reduction in the discharge amount, the two-component developer stagnates in the developing device, the charging performance is lowered, and the quality of the output image is lowered.

そこで、現像容器内の二成分現像剤の流れを高速撮影したところ、二成分現像剤の流動性が低下して円板部（５１）の周囲で二成分現像剤が凝集し易くなり、二成分現像剤の排出開口側への落ち込みが不安定になっていた。円板部（５１）が無い状態ではスクリューの谷を通じてスムーズに崩落していた凝集が円板部（５１）に停滞し続け、排出開口へ向かう二成分現像剤の流れを妨げていた。 Therefore, when the flow of the two-component developer in the developing container was photographed at a high speed, the fluidity of the two-component developer was lowered, and the two-component developer was likely to aggregate around the disc portion (51). The drop of the developer toward the discharge opening was unstable. In the absence of the disc portion (51), the agglomeration that had collapsed smoothly through the screw valleys continued to stagnate in the disc portion (51), preventing the flow of the two-component developer toward the discharge opening.

本発明は、長時間の連続運転後及び高温高湿環境でも、円板部を越えた現像剤の排出開口側への落ち込みが停滞せず、排出開口を通じた二成分現像剤の排出量が適正に制御される現像装置を提供することを目的としている。 In the present invention, even after a long continuous operation and in a high-temperature and high-humidity environment, the drop of the developer beyond the disc portion to the discharge opening side does not stagnate, and the two-component developer discharge amount through the discharge opening is appropriate. An object of the present invention is to provide a developing device that is controlled by the above.

本発明の現像装置は、長手方向の一方の突き当たり面に現像剤の排出開口が配置され、現像剤を受け渡す開口部を両端に有する長手方向の隔壁で内部が仕切られた現像容器と、前記隔壁の一方の側に配置され、現像剤を前記排出開口へ向かって長手方向に搬送する主スパイラル部に、前記排出開口へ向かう現像剤の流れを逆方向に付勢する副スパイラル部を連結された第１搬送部材と、前記隔壁の他方の側に配置され、前記副スパイラル部側の前記開口部を通じて前記第１搬送部材から受け渡された現像剤を前記第１搬送部材による搬送方向と逆方向に搬送する第２搬送部材とを備えるものである。そして、長手方向で前記排出開口に重なるように前記排出開口に対向する円板部が前記副スパイラル部に連結されるとともに、前記円板部の外周に突起が配置されている。 In the developing device of the present invention, a developer discharge opening is disposed on one abutting surface in the longitudinal direction, and a developer container whose interior is partitioned by a longitudinal partition having openings at both ends for delivering the developer; A main spiral portion that is arranged on one side of the partition wall and conveys the developer in the longitudinal direction toward the discharge opening is connected to a sub spiral portion that urges the flow of the developer toward the discharge opening in the reverse direction. The first transport member and the developer disposed on the other side of the partition wall and delivered from the first transport member through the opening on the sub spiral portion side are opposite to the transport direction by the first transport member. And a second conveying member that conveys in the direction. A disk part facing the discharge opening is connected to the sub spiral part so as to overlap the discharge opening in the longitudinal direction, and a protrusion is disposed on the outer periphery of the disk part.

本発明の現像装置では、円板部と一体に回転する突起が、流動性が低下して円板部の周囲に停滞した現像剤の凝集を引っ掛けて排出開口側へ崩落させる。 In the developing device of the present invention, the protrusion that rotates integrally with the disk portion catches the aggregation of the developer that has fallen around the disk portion due to the decrease in fluidity, and collapses to the discharge opening side.

従って、長時間の連続運転後及び高温高湿環境でも、二成分現像剤の円板部を越えた排出開口への落ち込みが停滞せず、排出開口を通じた二成分現像剤の排出量が適正に制御される。 Therefore, even after a long continuous operation and in a high-temperature and high-humidity environment, the drop of the two-component developer to the discharge opening beyond the disc portion does not stagnate, and the amount of discharge of the two-component developer through the discharge opening is appropriate. Be controlled.

第１実施形態の画像形成装置の構成の説明図である。It is explanatory drawing of a structure of the image forming apparatus of 1st Embodiment. 現像装置の内部構造を説明する斜視図である。It is a perspective view explaining the internal structure of a developing device. 画像形成装置の奥側から見た現像装置の断面図である。FIG. 3 is a cross-sectional view of the developing device viewed from the back side of the image forming apparatus. 現像剤排出口の付近を拡大した断面図である。FIG. 4 is an enlarged cross-sectional view of the vicinity of a developer discharge port. 副スパイラル部を設けた搬送スクリューの斜視図である。It is a perspective view of the conveyance screw which provided the sub spiral part. 実施例１の搬送スクリューを配置した現像装置の平面図である。FIG. 3 is a plan view of a developing device in which the conveying screw of Example 1 is arranged. 突起を設けた搬送スクリューの説明図である。It is explanatory drawing of the conveyance screw which provided the processus | protrusion. 実施例３における二成分現像剤の排出メカニズムの説明図である。FIG. 10 is an explanatory diagram of a discharge mechanism of a two-component developer in Embodiment 3. 実施例３における突起の配置の説明図である。FIG. 10 is an explanatory diagram of the arrangement of protrusions in Example 3.

以下、図面を参照して本発明の実施形態を詳細に説明する。本発明は、排出開口に近い側の搬送部材の外周に突起が配置されている限りにおいて、実施形態の構成の一部または全部を、その代替的な構成で置き換えた別の実施形態でも実施できる。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention can be implemented in another embodiment in which a part or all of the configuration of the embodiment is replaced with the alternative configuration as long as the protrusion is disposed on the outer periphery of the conveying member on the side close to the discharge opening. .

従って、現像装置を共通とする種々の形態の画像形成装置で同様に実施できる。中間転写型、記録材搬送体型、タンデム型、１ドラム型、フルカラー、モノクロの区別無く実施できる。二成分現像剤を用いる現像装置のみならず、長時間の攪拌によって帯電性能が低下するような一成分現像剤を用いる現像装置でも実施できる。 Therefore, the present invention can be similarly implemented in various types of image forming apparatuses that share a developing device. It can be carried out without distinction between an intermediate transfer type, a recording material conveyance type, a tandem type, a single drum type, full color, and monochrome. Not only a developing device using a two-component developer but also a developing device using a one-component developer whose charging performance is lowered by stirring for a long time.

本実施形態では、トナー像の形成／転写に係る主要部のみを説明するが、本発明は、必要な機器、装備、筐体構造を加えて、プリンタ、各種印刷機、複写機、ＦＡＸ、複合機等、種々の用途で実施できる。 In the present embodiment, only main parts related to toner image formation / transfer will be described. However, the present invention includes a printer, various printing machines, a copier, a fax machine, a composite machine, in addition to necessary equipment, equipment, and a housing structure. It can be implemented in various applications such as a machine.

なお、特許文献１に示される画像形成装置の一般的な事項については、図示を省略して重複する説明を省略する。 In addition, about the general matter of the image forming apparatus shown by patent document 1, illustration is abbreviate | omitted and the overlapping description is abbreviate | omitted.

＜画像形成装置＞
図１は第１実施形態の画像形成装置の構成の説明図である。 <Image forming apparatus>
FIG. 1 is an explanatory diagram of a configuration of the image forming apparatus according to the first embodiment.

図１に示すように、画像形成装置１００は、中間転写ベルト１０の下向き面に沿って画像形成部Ｐａ、Ｐｂ、Ｐｃ、Ｐｄを配列したタンデム型中間転写方式のフルカラープリンタである。 As shown in FIG. 1, the image forming apparatus 100 is a tandem intermediate transfer type full-color printer in which image forming portions Pa, Pb, Pc, and Pd are arranged along the downward surface of the intermediate transfer belt 10.

画像形成部Ｐａでは、感光ドラム１ａにイエロートナー像が形成されて中間転写ベルト１０に一次転写される。画像形成部Ｐｂでは、感光ドラム１ｂにマゼンタトナー像が形成されて中間転写ベルト１０のイエロートナー像に重ねて一次転写される。画像形成部Ｐｃ、Ｐｄでは、それぞれ感光ドラム１ｃ、１ｄにシアントナー像、ブラックトナー像が形成されて同様に中間転写ベルト１０に順次重ねて一次転写される。 In the image forming portion Pa, a yellow toner image is formed on the photosensitive drum 1 a and is primarily transferred to the intermediate transfer belt 10. In the image forming unit Pb, a magenta toner image is formed on the photosensitive drum 1 b and is primarily transferred to the yellow toner image on the intermediate transfer belt 10. In the image forming portions Pc and Pd, a cyan toner image and a black toner image are formed on the photosensitive drums 1c and 1d, respectively, and are sequentially transferred to the intermediate transfer belt 10 so as to be primarily transferred.

中間転写ベルト１０に一次転写された四色のトナー像は、二次転写部Ｔ２へ搬送されて記録材Ｐへ一括二次転写される。 The four-color toner images primarily transferred to the intermediate transfer belt 10 are transported to the secondary transfer portion T2 and collectively transferred to the recording material P.

記録材Ｐの一方の面に対して画像形成を行う片面モードの場合、四色のトナー像を二次転写された記録材Ｐは、定着装置１５で加熱加圧を受けて表面にトナー像を定着された後に、排出ローラ１６を通じて上部トレイ１７へ排出される。 In the single-sided mode in which image formation is performed on one surface of the recording material P, the recording material P on which the four-color toner images are secondarily transferred is heated and pressed by the fixing device 15 to form a toner image on the surface. After fixing, the paper is discharged to the upper tray 17 through the discharge roller 16.

記録材Ｐの両方の面に対して画像形成を行う両面モードの場合、一方の面に画像が形成された記録材Ｐは、不図示の両面パスを通って表裏が反転されて二次転写部Ｔ２へ再度搬送される。表面記録と同様の画像形成プロセスで裏面記録が行われた記録材Ｐは、排出ローラ１６を通じて上部トレイ１７へ排出される。 In the double-side mode in which image formation is performed on both sides of the recording material P, the recording material P on which the image is formed on one side is reversed on the front and back through a double-sided path (not shown), and the secondary transfer unit It is conveyed again to T2. The recording material P on which the back surface recording is performed in the same image forming process as the front surface recording is discharged to the upper tray 17 through the discharge roller 16.

分離ローラ２１は、記録材カセット２０から引き出した記録材Ｐを１枚ずつに分離して、レジストローラ２２へ送り出す。レジストローラ２２は、停止状態で記録材Ｐを受け入れて待機させ、中間転写ベルト１０のトナー像にタイミングを合わせて記録材Ｐを二次転写部Ｔ２へ送り込む。 The separation roller 21 separates the recording materials P drawn from the recording material cassette 20 one by one and sends them to the registration rollers 22. The registration roller 22 receives and waits for the recording material P in a stopped state, and sends the recording material P to the secondary transfer portion T2 in time with the toner image on the intermediate transfer belt 10.

定着装置１５は、ヒータを設けた定着ローラ１５ａに加圧ローラ１５ｂを圧接して加熱ニップを形成する。記録材Ｐは、加熱ニップで挟持搬送される過程で、加熱加圧を受けてトナー像を溶融させ、フルカラー画像を表面に定着される。 The fixing device 15 presses the pressure roller 15b against the fixing roller 15a provided with a heater to form a heating nip. The recording material P is heated and pressurized in the process of being nipped and conveyed by the heating nip, melts the toner image, and fixes the full-color image on the surface.

画像形成部Ｐａ、Ｐｂ、Ｐｃ、Ｐｄは、現像装置４ａ、４ｂ、４ｃ、４ｄで用いるトナーの色がイエロー、マゼンタ、シアン、ブラックと異なる以外は、ほぼ同一に構成される。以下では、画像形成部Ｐａについて説明し、他の画像形成部Ｐｂ、Ｐｃ、Ｐｄについては、説明中の符号末尾のａを、ｂ、ｃ、ｄに読み替えて説明されるものとする。 The image forming portions Pa, Pb, Pc, and Pd are substantially the same except that the color of toner used in the developing devices 4a, 4b, 4c, and 4d is different from yellow, magenta, cyan, and black. Hereinafter, the image forming unit Pa will be described, and the other image forming units Pb, Pc, and Pd will be described by replacing “a” at the end of the reference numerals with “b”, “c”, and “d”.

画像形成部Ｐａは、感光ドラム１ａを囲んで帯電ローラ２ａ、露光装置３、現像装置４ａ、一次転写ローラ５ａ、クリーニング装置６ａを配置している。 The image forming unit Pa surrounds the photosensitive drum 1a and includes a charging roller 2a, an exposure device 3, a developing device 4a, a primary transfer roller 5a, and a cleaning device 6a.

感光ドラム１ａは、アルミニウム製シリンダの外周面に帯電極性が負極性の感光層を形成しており、切り替え可能な複数段階のプロセススピードで回転する。帯電ローラ２ａは、直流電圧に交流電圧を重畳した振動電圧を印加されて感光ドラム１ａに従動回転することにより、感光ドラム１ａの表面を一様な負極性の電位に帯電させる。 The photosensitive drum 1a has a negatively charged photosensitive layer formed on the outer peripheral surface of an aluminum cylinder, and rotates at a switchable multi-stage process speed. The charging roller 2a is applied with an oscillating voltage obtained by superimposing an AC voltage on a DC voltage and is driven to rotate by the photosensitive drum 1a, thereby charging the surface of the photosensitive drum 1a to a uniform negative potential.

露光装置３は、イエローの分解色画像を展開した走査線画像データをＯＮ−ＯＦＦ変調したレーザービームを回転ミラーで走査して、帯電した感光ドラム１ａの表面に画像の静電像を書き込む。現像装置４ａは、二成分現像剤を攪拌して帯電させ、穂立ち状態で現像スリーブ４３に担持させて、感光ドラム１ａを摺擦する。直流電圧に交流電圧を重畳した振動電圧を現像スリーブ４３に印加することで、現像スリーブ４３に対して相対的に正極性になった静電像（露光部）に負極性に帯電した非磁性トナーが移転して、静電像が反転現像される。 The exposure device 3 scans a scanning beam image data obtained by developing a yellow color separation image with a rotating mirror, and writes an electrostatic image of the image on the surface of the charged photosensitive drum 1a. The developing device 4a stirs and charges the two-component developer, carries it on the developing sleeve 43 in a stand-up state, and rubs the photosensitive drum 1a. By applying an oscillating voltage in which an alternating voltage is superimposed on a direct current voltage to the developing sleeve 43, a nonmagnetic toner charged to a negative polarity in an electrostatic image (exposed portion) having a positive polarity relative to the developing sleeve 43 The electrostatic image is reversed and developed.

一次転写ローラ５ａは、中間転写ベルト１０の内側面を押圧して、感光ドラム１ａと中間転写ベルト１０との間に一次転写部を形成する。一次転写ローラ５ａに正極性の直流電圧が印加されることにより、感光ドラム１ａに担持された負極性のトナー像が、一次転写部を通過する中間転写ベルト１０へ一次転写される。 The primary transfer roller 5 a presses the inner side surface of the intermediate transfer belt 10 to form a primary transfer portion between the photosensitive drum 1 a and the intermediate transfer belt 10. By applying a positive DC voltage to the primary transfer roller 5a, the negative toner image carried on the photosensitive drum 1a is primarily transferred to the intermediate transfer belt 10 passing through the primary transfer portion.

中間転写ベルト１０は、テンションローラ１２、駆動ローラ１１、張架ローラ１３に掛け渡して支持され、駆動ローラ１１に駆動されて矢印Ｒ２方向に回転する。二次転写ローラ１４は、接地電位に接続された張架ローラ１３によって内側面を張架された中間転写ベルト１０に当接して二次転写部Ｔ２を形成する。二次転写ローラ１４に正極性の直流電圧が印加されることで、中間転写ベルト１０に担持されたトナー像が記録材Ｐに二次転写される。 The intermediate transfer belt 10 is supported around a tension roller 12, a driving roller 11, and a stretching roller 13, and is driven by the driving roller 11 to rotate in the direction of arrow R2. The secondary transfer roller 14 abuts on the intermediate transfer belt 10 whose inner surface is stretched by the stretch roller 13 connected to the ground potential to form a secondary transfer portion T2. The toner image carried on the intermediate transfer belt 10 is secondarily transferred to the recording material P by applying a positive DC voltage to the secondary transfer roller 14.

＜現像装置＞
図２は現像装置の内部構造を説明する斜視図である。図３は画像形成装置の奥側から見た現像装置の断面図である。図４は現像剤排出口の付近を拡大した断面図である。図５は副スパイラル部を設けた搬送スクリューの斜視図である。 <Developing device>
FIG. 2 is a perspective view illustrating the internal structure of the developing device. FIG. 3 is a cross-sectional view of the developing device viewed from the back side of the image forming apparatus. FIG. 4 is an enlarged cross-sectional view of the vicinity of the developer discharge port. FIG. 5 is a perspective view of a conveying screw provided with a sub spiral portion.

図２に示すように、現像容器４２は、非磁性トナーと磁性キャリアとからなる二成分現像剤を収容しており、非磁性トナーと磁性キャリアの混合比は重量比で１：９程度である。ここで、非磁性トナーと磁性キャリアの混合比は、トナーの帯電量、キャリアの粒径、画像形成装置（１００：図１）の構成等に応じて適正に調整されているが、必ずしもこの数値には限定されない。 As shown in FIG. 2, the developing container 42 contains a two-component developer composed of a non-magnetic toner and a magnetic carrier, and the mixing ratio of the non-magnetic toner and the magnetic carrier is about 1: 9 by weight. . Here, the mixing ratio of the non-magnetic toner and the magnetic carrier is appropriately adjusted according to the charge amount of the toner, the particle size of the carrier, the configuration of the image forming apparatus (100: FIG. 1), etc. It is not limited to.

図３は、画像形成装置（１００：図１）の奥側から現像装置４ａを見た断面を示しており、紙面の奥側が二成分現像剤が排出される正面側に対応している。図３に示すように、現像装置４ａは、現像容器４２の感光ドラム１ａに対向した現像領域の部分が開口しており、開口部から一部露出するように、現像スリーブ４３が回転可能に設置されている。現像スリーブ４３の内部には、複数の固定磁極を設けたマグネット４４が非回転に配置されている。現像スリーブ４３は、非磁性材料で形成され、現像動作時には矢印Ａ方向に回転して、現像容器４２内の二成分現像剤をマグネット４４の磁力で層状に保持して現像領域に搬送する。現像スリーブ４３は、現像領域で感光ドラム１ａに非磁性トナーだけを供給して、感光ドラム１ａ上に形成されている静電像を現像する。静電像を現像した後、現像スリーブ４３上の二成分現像剤は、現像スリーブ４３の回転に従って現像容器４２内に回収される。 FIG. 3 shows a cross section when the developing device 4a is viewed from the back side of the image forming apparatus (100: FIG. 1), and the back side of the paper surface corresponds to the front side from which the two-component developer is discharged. As shown in FIG. 3, in the developing device 4a, the developing sleeve 43 is rotatably installed so that the developing region of the developing container 42 that faces the photosensitive drum 1a is open, and the developing sleeve 43 is partially exposed from the opening. Has been. Inside the developing sleeve 43, a magnet 44 provided with a plurality of fixed magnetic poles is arranged in a non-rotating manner. The developing sleeve 43 is made of a non-magnetic material, and rotates in the direction of arrow A during the developing operation to hold the two-component developer in the developing container 42 in a layered manner by the magnetic force of the magnet 44 and transport it to the developing region. The developing sleeve 43 supplies only non-magnetic toner to the photosensitive drum 1a in the developing area, and develops the electrostatic image formed on the photosensitive drum 1a. After developing the electrostatic image, the two-component developer on the developing sleeve 43 is collected in the developing container 42 as the developing sleeve 43 rotates.

現像装置４ａは、搬送スクリュー４６の回転速度が切り替えられても、現像容器４２内部の二成分現像剤を一定量に保つ現像剤自動排出機能を有する。 The developing device 4a has an automatic developer discharging function that keeps the two-component developer in the developing container 42 at a constant amount even when the rotation speed of the conveying screw 46 is switched.

図２に示すように、現像容器４２の内部の長手方向の一方の突き当たり面に過剰な現像剤を排出するための排出開口５３（つば部５１の陰になっている）が形成されている。また、現像容器４２の内部は、二成分現像剤を受け渡すための開口部４７ａ、４７ｂが両端に形成された隔壁４７で仕切られている。 As shown in FIG. 2, a discharge opening 53 (in the shade of the flange portion 51) for discharging excess developer is formed on one abutting surface in the longitudinal direction inside the developing container 42. Further, the inside of the developing container 42 is partitioned by a partition wall 47 formed at both ends with openings 47a and 47b for delivering the two-component developer.

隔壁４７を挟んで、二成分現像剤の搬送方向が逆方向に設定された一対の搬送スクリュー４５、４６が配置されている。一方の搬送スクリュー４６が矢印Ｃ方向に二成分現像剤を攪拌しつつ搬送し、他方の搬送スクリュー４５が矢印Ｂ方向に二成分現像剤を攪拌しつつ搬送することで、現像容器４２の内部を循環する。 A pair of conveying screws 45 and 46 in which the conveying direction of the two-component developer is set in the opposite direction are arranged with the partition wall 47 interposed therebetween. One conveyance screw 46 conveys the two-component developer in the direction of arrow C while stirring, and the other conveyance screw 45 conveys the two-component developer in the direction of arrow B while stirring, thereby allowing the inside of the developing container 42 to move. Circulate.

このとき、副スパイラル部側の開口部４７ａを通じて、第１搬送部材の一例である搬送スクリュー４６から第２搬送部材の一例である搬送スクリュー４５へ二成分現像剤がスムーズに受け渡される。また、副スパイラル部側の反対側に位置する開口部４７ｂを通じて、第２搬送部材の一例である搬送スクリュー４５から第１搬送部材の一例である搬送スクリュー４６へ二成分現像剤がスムーズに受け渡される。 At this time, the two-component developer is smoothly transferred from the conveying screw 46, which is an example of the first conveying member, to the conveying screw 45, which is an example of the second conveying member, through the opening 47a on the sub spiral portion side. Further, the two-component developer is smoothly transferred from the conveying screw 45, which is an example of the second conveying member, to the conveying screw 46, which is an example of the first conveying member, through the opening 47b located on the opposite side to the sub spiral portion side. It is.

搬送スクリュー４６における二成分現像剤の搬送方向の下流側には、二成分現像剤の循環経路外から循環経路内に押し戻すように二成分現像剤を搬送する返しスクリュー５０が接続されている。そして、搬送スクリュー４６の主スパイラル部（４６ｍ：図５）と返しスクリュー５０（副スパイラル部）の継ぎ目に対向する位置に、搬送スクリュー４６から搬送スクリュー４５へ二成分現像剤を受け渡すための開口部４７ａがある。 A return screw 50 that transports the two-component developer so as to push back into the circulation path from outside the circulation path of the two-component developer is connected to the downstream side of the conveyance screw 46 in the conveyance direction of the two-component developer. An opening for delivering the two-component developer from the conveying screw 46 to the conveying screw 45 at a position facing the joint between the main spiral portion (46m: FIG. 5) of the conveying screw 46 and the return screw 50 (sub-spiral portion). There is a portion 47a.

図４に示すように、返しスクリュー５０による二成分現像剤の搬送方向の上流に、循環する二成分現像剤の一部を現像容器４２の外へ排出するための排出開口５３が設けられている。搬送スクリュー４６の主スパイラル部によって排出開口５３へ向かって搬送される二成分現像剤の大部分は、返しスクリュー５０に押し戻されて排出開口５３からの排出を逃れる。そして、返しスクリュー５０に押し戻されなかった二成分現像剤が排出開口５３を通じて現像容器４２の循環経路から排出される。 As shown in FIG. 4, a discharge opening 53 for discharging a part of the circulating two-component developer to the outside of the developing container 42 is provided upstream in the conveying direction of the two-component developer by the return screw 50. . Most of the two-component developer conveyed toward the discharge opening 53 by the main spiral portion of the conveyance screw 46 is pushed back to the return screw 50 and escapes from the discharge opening 53. Then, the two-component developer that has not been pushed back to the return screw 50 is discharged from the circulation path of the developing container 42 through the discharge opening 53.

返しスクリュー５０の長さ、直径、ピッチは、現像装置４ａの構成や排出条件、現像容器４２内の二成分現像剤量、目標とする排出量に応じて適宜変更される。例えば、返しスクリュー５０の長さが長過ぎると、必要以上に二成分現像剤の排出が抑制される結果、現像容器４２内の二成分現像剤の帯電性能の低下が進行してしまう。逆に、返しスクリュー５０の長さが短か過ぎると、必要以上に二成分現像剤が排出されて現像容器４２内の二成分現像剤量が不足して現像に支障をきたす。 The length, diameter, and pitch of the return screw 50 are appropriately changed according to the configuration and discharge conditions of the developing device 4a, the two-component developer amount in the developing container 42, and the target discharge amount. For example, if the length of the return screw 50 is too long, the discharge performance of the two-component developer is suppressed more than necessary, and as a result, the charging performance of the two-component developer in the developing container 42 decreases. On the other hand, if the length of the return screw 50 is too short, the two-component developer is discharged more than necessary, and the amount of the two-component developer in the developing container 42 is insufficient, which hinders development.

図１を参照して図３に示すように、画像形成装置１００では、プロセススピードを等速＝１２０ｍｍ／ｓｅｃ、１／２速＝６０ｍｍ／ｓｅｃ、１／３速＝４０ｍｍ／ｓｅｃに切り替えて厚紙対応や高解像度対応を行っている。例えば、厚紙モードでは、トナー像を定着させる際の記録材の熱吸収量が大きくて定着装置１５では十分な加熱ができなくなるため、厚さ段階に応じてプロセススピードを１／２速又は１／３速に低下させる。また、高解像度モードでは、プロセススピードを１／２速に低下させて、副走査方向の走査線密度を２倍に増加させる。 As shown in FIG. 3 with reference to FIG. 1, in the image forming apparatus 100, the process speed is switched to constant speed = 120 mm / sec, 1/2 speed = 60 mm / sec, and 1/3 speed = 40 mm / sec. Supports high resolution. For example, in the thick paper mode, since the heat absorption amount of the recording material when fixing the toner image is large and the fixing device 15 cannot sufficiently heat, the process speed is reduced to 1/2 speed or 1 / speed depending on the thickness stage. Reduce to 3rd speed. In the high resolution mode, the process speed is reduced to 1/2 speed, and the scanning line density in the sub-scanning direction is doubled.

そして、プロセススピードの切り替えに伴って搬送スクリュー４５、４６の回転速度は、等速＝３００ｒｐｍ、１／２速＝１５０ｒｐｍ、１／３速＝１００ｒｐｍに切り替えられる。搬送スクリュー４５、４６がこのように複数の回転速度を持つ場合、搬送スクリュー４６によって搬送されて返しスクリュー５０の終端部まで到達する二成分現像剤量が変動するため、現像剤自動排出機能についても、複数の回転速度に対応させる必要がある。 The rotational speeds of the conveying screws 45 and 46 are switched to constant speed = 300 rpm, 1/2 speed = 150 rpm, and 1/3 speed = 100 rpm in accordance with the switching of the process speed. When the transport screws 45 and 46 have a plurality of rotational speeds as described above, the amount of the two-component developer that is transported by the transport screw 46 and reaches the end of the return screw 50 varies. It is necessary to correspond to a plurality of rotational speeds.

このため、返しスクリュー５０の搬送方向の最上流に、排出開口５３を覆い隠すように円板部の一例である円板状のつば部５１が設けられている。 For this reason, a disc-shaped collar portion 51, which is an example of a disc portion, is provided in the uppermost stream in the conveying direction of the return screw 50 so as to cover the discharge opening 53.

つば部５１は、搬送スクリュー４６の主スパイラル部と返しスクリュー５０との搬送能力差によって排出開口５３に向かって搬送されてきた二成分現像剤の慣性力差を低減させる。つば部５１は、返しスクリュー５０の搬送羽根の切れ目から排出開口５３へ落ち込む二成分現像剤を無くして、二成分現像剤の排出量を安定させる。つば部５１は、返しスクリュー５０の排出開口５３に対向する末端を覆い隠してスクリューの谷を排出開口５３側へ露出させない。つば部５１を設けた返しスクリューを採用することで、搬送スクリュー４６の回転速度を遅い側に切り替えても必要な排出量が確保され、搬送スクリュー４６の回転速度を速い側に切り替えても二成分現像剤の排出量が急増しない。 The collar portion 51 reduces the difference in inertial force of the two-component developer conveyed toward the discharge opening 53 due to the difference in conveyance capability between the main spiral portion of the conveyance screw 46 and the return screw 50. The collar portion 51 eliminates the two-component developer that falls into the discharge opening 53 from the break of the conveying blade of the return screw 50 and stabilizes the discharge amount of the two-component developer. The collar portion 51 covers the end of the return screw 50 facing the discharge opening 53 so as not to expose the screw valley to the discharge opening 53 side. By adopting the return screw provided with the collar portion 51, the necessary discharge amount is ensured even if the rotation speed of the conveying screw 46 is switched to the slow side, and even if the rotation speed of the conveying screw 46 is switched to the fast side, the two components Developer discharge does not increase rapidly.

排出開口５３の中心を貫通して、返しスクリュー５０に連結された排出スクリュー４９が配置されている。排出スクリュー４９は、つば部５１を乗り越えて落下してきた二成分現像剤を排出開口５３を通じて運び出し、現像剤排出口４８へ搬送して現像装置４ａ外へ排出する。 A discharge screw 49 that passes through the center of the discharge opening 53 and is connected to the return screw 50 is disposed. The discharge screw 49 transports the two-component developer that has fallen over the collar portion 51 through the discharge opening 53, conveys it to the developer discharge port 48, and discharges it to the outside of the developing device 4a.

図２を参照して図５に示すように、第１搬送部材の一例である搬送スクリュー４６は、排出開口５３へ向かう現像剤の流れを逆方向に付勢する副スパイラル部（５０）を主スパイラル部４６ｍに連結している。主スパイラル部４６ｍは、二成分現像剤の循環経路の現像剤を排出開口５３へ向かって搬送する。 As shown in FIG. 5 with reference to FIG. 2, the conveying screw 46, which is an example of a first conveying member, has a main spiral portion (50) that urges the developer flow toward the discharge opening 53 in the reverse direction. It is connected to the spiral part 46m. The main spiral portion 46m conveys the developer in the circulation path of the two-component developer toward the discharge opening 53.

＜補給用二成分現像剤の補給制御＞
図３に示すように、画像形成によって消費された非磁性トナーは、新品の磁性キャリアを一定の割合で含んだ補給用二成分現像剤として、補給機構３１により現像容器４２の搬送スクリュー４６の上流側（本体奥側）に補給される。現像装置４ａへの補給用二成分現像剤の補給は、補給機構３１のホッパーから補給スクリュー３２の回転によって行なわれ、現像容器４２上側の補給口から受け取る。補給用二成分現像剤は、補給用の非磁性トナー中に、一定の割合（重量比にして１０％程度）で磁性キャリアを含んだ二成分現像剤を使用しているが、磁性キャリアの混合比率はこれに限定されるものではない。 <Supply control of replenishment two-component developer>
As shown in FIG. 3, the non-magnetic toner consumed by the image formation is supplied upstream of the conveying screw 46 of the developing container 42 by the replenishing mechanism 31 as a replenishing two-component developer containing a new magnetic carrier at a certain ratio. It is replenished to the side (back side of main body). The supply of the two-component developer for replenishment to the developing device 4a is performed by the rotation of the replenishment screw 32 from the hopper of the replenishment mechanism 31 and is received from the replenishment port on the upper side of the developing container 42. The two-component developer for replenishment uses a two-component developer containing a magnetic carrier at a certain ratio (about 10% by weight) in the nonmagnetic toner for replenishment. The ratio is not limited to this.

補給用二成分現像剤の補給量は、補給機構３１の補給スクリュー３２の回転数によっておおよそ定められる。制御部３０は、補給スクリュー３２の回転のＯＮ／ＯＦＦ、回転速度を制御して、現像容器４２内部の二成分現像剤のトナー濃度を一定に保つように補給用二成分現像剤の補給を行う。 The replenishment amount of the replenishment two-component developer is roughly determined by the rotation speed of the replenishment screw 32 of the replenishment mechanism 31. The control unit 30 controls the ON / OFF and rotation speed of the replenishing screw 32 to replenish the replenishing two-component developer so as to keep the toner concentration of the two-component developer inside the developing container 42 constant. .

このとき、現像容器４２内の二成分現像剤の量は、画像形成にともなって次第に増加する。画像形成によって非磁性トナーは消費されるが、磁性キャリアは消費されずに現像容器４２内部に残って循環し続けるため、現像容器４２内の二成分現像剤量が増加してしまう。二成分現像剤量が増加した場合、図４に示す返しスクリュー５０およびつば部５１を現像剤が乗り越えて排出開口側へ落ち込んで、排出スクリュー４９へ受け渡されて現像剤排出口４８に搬送される。現像剤排出口４８に搬送された回収現像剤は、現像剤排出口４８から排出されて不図示の現像剤回収パイプに合流し、現像剤回収パイプを通じて不図示の回収容器にまとめて回収貯蔵される。 At this time, the amount of the two-component developer in the developing container 42 gradually increases with image formation. The non-magnetic toner is consumed by the image formation, but the magnetic carrier is not consumed but remains in the developing container 42 and continues to circulate, so that the amount of the two-component developer in the developing container 42 increases. When the amount of the two-component developer increases, the developer passes over the return screw 50 and the collar 51 shown in FIG. 4 and falls to the discharge opening side, is transferred to the discharge screw 49 and is conveyed to the developer discharge port 48. The The collected developer transported to the developer discharge port 48 is discharged from the developer discharge port 48, joins a developer recovery pipe (not shown), and is collected and stored in a recovery container (not shown) through the developer recovery pipe. The

このようにして、消費された非磁性トナーが補給用二成分現像剤によって補給される一方で、並行して、磁性キャリアが過剰になった現像容器４２内の二成分現像剤が少しずつ排出される。現像容器４２内の二成分現像剤量を一定に保つように、二成分現像剤の入れ替えが自動的に徐々に行われることで現像剤自動排出機能が実現される。 In this way, the consumed non-magnetic toner is replenished by the replenishing two-component developer, and in parallel, the two-component developer in the developing container 42 in which the magnetic carrier is excessive is discharged little by little. The The automatic developer discharge function is realized by automatically and gradually replacing the two-component developer so as to keep the two-component developer amount in the developing container 42 constant.

ところで、現像装置４ａにおいては、現像容器４２内の二成分現像剤の流動性が一定であれば、このような現像剤自動排出機能によって二成分現像剤の入れ替えが問題なく行われる。 By the way, in the developing device 4a, if the fluidity of the two-component developer in the developing container 42 is constant, the two-component developer is replaced without any problem by such a developer automatic discharge function.

しかし、出荷時の現像装置４ａ内の二成分現像剤の状態から画像形成を累積して攪拌と循環を経ることで、二成分現像剤の流動性が刻々と低下していく。二成分現像剤の流動性が低下すると、返しスクリュー１０と現像容器４２の内壁とに挟まれた空間に二成分現像剤が滞留し易くなり、望むような排出量を得ることができなくなる。出荷時の二成分現像剤(新剤)を前提とした現像剤自動排出機能が、ある程度循環攪拌を経た二成分現像剤(耐久剤)に対しては十分に機能を発揮できない可能性が出てくる。 However, the fluidity of the two-component developer is gradually reduced by accumulating image formation from the state of the two-component developer in the developing device 4a at the time of shipment and passing through stirring and circulation. When the fluidity of the two-component developer is lowered, the two-component developer tends to stay in a space sandwiched between the return screw 10 and the inner wall of the developing container 42, and a desired discharge amount cannot be obtained. There is a possibility that the developer automatic discharge function based on the two-component developer (new agent) at the time of shipment cannot fully function for the two-component developer (durable agent) that has undergone some circulation agitation. come.

また、温度湿度の変化によっても、二成分現像剤の状態が変化して流動性が変化する。常温常湿を前提とした現像剤自動排出機能が、高温高湿によって流動性が低下した二成分現像剤に対しては十分に機能を発揮できない可能性が出てくる。 In addition, even when the temperature and humidity change, the state of the two-component developer changes and the fluidity changes. There is a possibility that the developer automatic discharge function on the premise of normal temperature and humidity cannot fully function for a two-component developer whose fluidity has been lowered by high temperature and high humidity.

二成分現像剤の流動性が変化すると、搬送スクリュー４６から搬送スクリュー４５へ受け渡される二成分現像剤の一部が返しスクリュー５０と現像容器４２とに挟まれた空間を抜けて排出スクリュー４９へ達して排出されるメカニズムが十分に機能しなくなる。二成分現像剤の流動性が変化すると、搬送スクリュー４６に搬送されて返しスクリュー５０を越えてつば部５１まで到達する二成分現像剤量が減る。つば部５１を越えて排出開口５３側へ落ち込み、排出スクリュー４９によって現像剤排出口４８まで搬送される二成分現像剤量が減る。 When the fluidity of the two-component developer changes, a part of the two-component developer delivered from the conveying screw 46 to the conveying screw 45 passes through the space between the return screw 50 and the developing container 42 and is discharged to the discharge screw 49. The mechanism that reaches and discharges does not function sufficiently. When the fluidity of the two-component developer changes, the amount of the two-component developer that is conveyed to the conveying screw 46 and reaches the collar 51 beyond the return screw 50 decreases. The amount of the two-component developer that passes over the collar portion 51 and falls to the discharge opening 53 side and is conveyed to the developer discharge port 48 by the discharge screw 49 is reduced.

新しい二成分現像剤や環境が低温低湿の場合、使い古された二成分現像剤や高温多湿の場合に比較して二成分現像剤の流動性が一般的に良いとされている。このため、新しい二成分現像剤や環境が低温低湿の場合、返しスクリュー５０と現像容器４２との隙間Ｈを容易に通過し排出されていく。 When the new two-component developer and the environment are low temperature and low humidity, the fluidity of the two-component developer is generally considered to be better than that of a two-component developer that has been used and high temperature and humidity. For this reason, when the new two-component developer or the environment is low temperature and low humidity, it easily passes through the gap H between the return screw 50 and the developing container 42 and is discharged.

これに対して、使い古された二成分現像剤や高温多湿の場合、流動性の低下によって、返しスクリュー５０と現像容器４２との隙間Ｈ通過しにくくなり、隙間Ｈに滞留して二成分現像剤排出量が低下する。 On the other hand, in the case of a two-component developer that has been used up or at high temperature and high humidity, due to a decrease in fluidity, it becomes difficult to pass through the gap H between the return screw 50 and the developing container 42 and the two-component developer stays in the gap H. Emissions are reduced.

このとき、返しスクリュー５０の搬送方向下流側では、搬送スクリュー４６の搬送力を受けて、返しスクリュー５０の搬送に反して排出開口５３へ向かう流れの速度が大きいため、二成分現像剤が滞留しにくい。しかし、返しスクリュー５０の搬送方向の上流側に向うに従って排出開口５３へ向かう流れの速度が小さくなるため、二成分現像剤の流動性の低下の影響を大きく受けて滞留し易くなる。 At this time, on the downstream side in the conveyance direction of the return screw 50, the two-component developer is retained because the conveyance force of the conveyance screw 46 is received and the flow velocity toward the discharge opening 53 is large against the conveyance of the return screw 50. Hateful. However, since the speed of the flow toward the discharge opening 53 becomes smaller toward the upstream side in the conveying direction of the return screw 50, the flow rate of the two-component developer is greatly affected by the lowering of the fluidity of the two-component developer and is likely to stay.

そこで、以下の実施例では、返しスクリュー５０の最も上流位置に、二成分現像剤の凝集を引っ掛けて排出開口側へ崩落させるための突起５２を配置している。 Therefore, in the following embodiments, a protrusion 52 is provided at the most upstream position of the return screw 50 to catch the aggregation of the two-component developer and cause it to collapse to the discharge opening side.

＜実施例１＞
図６は実施例１の搬送スクリューを配置した現像装置の平面図である。図７は突起を設けた搬送スクリューの説明図である。 <Example 1>
FIG. 6 is a plan view of a developing device in which the conveying screw according to the first exemplary embodiment is arranged. FIG. 7 is an explanatory view of a conveying screw provided with a protrusion.

図６に示すように、実施例１では、円板部（５１）の外周に突起５２が配置されている。第１搬送部材（４６）は、循環経路の現像剤を排出開口５３へ向かって搬送する主スパイラル部に、排出開口５３へ向かう現像剤の流れを逆方向に付勢する副スパイラル部（５０）を連結して構成される。円板部（５１）は、副スパイラル部（５０）の開口部側（４７ａ）に接続されたつば部５１である。返しスクリュー５０とつば部５１とは同一直径である。 As shown in FIG. 6, in Example 1, the protrusion 52 is arrange | positioned on the outer periphery of the disc part (51). The first conveying member (46) is a main spiral portion that conveys the developer in the circulation path toward the discharge opening 53, and a sub spiral portion (50) that urges the developer flow toward the discharge opening 53 in the reverse direction. Concatenated. The disc part (51) is a collar part 51 connected to the opening part side (47a) of the sub spiral part (50). The return screw 50 and the collar portion 51 have the same diameter.

図３に示すように、つば部５１の外周面上に突起５２を設けることにより、搬送スクリュー４６の回転に伴って、返しスクリュー５０と現像容器４２の隙間Ｈに滞留した二成分現像剤が突起５２が掻き落し、通過させ易くする。 As shown in FIG. 3, by providing the protrusion 52 on the outer peripheral surface of the flange portion 51, the two-component developer staying in the gap H between the return screw 50 and the developing container 42 is protruded as the conveying screw 46 rotates. 52 is scraped off to facilitate passage.

二成分現像剤の使用環境差や使い古し状態などによる流動性の変化に対して、二成分現像剤の排出量の変化を減少させることができる。二成分現像剤の新品／末期、使用環境差における流動性の差に関係なく、つば部５１を乗り越えて排出スクリュー４９に到達する二成分現像剤量が安定して、現像剤排出口４８からの排出量の変化を抑えることができる。 The change in the discharge amount of the two-component developer can be reduced with respect to the change in the fluidity due to the difference in use environment of the two-component developer or the worn-out state. Regardless of the difference in flowability between the new / late stage of the two-component developer and the usage environment, the amount of the two-component developer that reaches the discharge screw 49 over the collar portion 51 is stabilized, and is discharged from the developer discharge port 48. Changes in emissions can be suppressed.

ここで、突起５２を設ける代わりに返しスクリュー径５０を拡大させると、返しスクリュー５０と現像容器４２の隙間に、より強固に押し固められた二成分現像剤が滞留する結果となった。これにより、二成分現像剤が排出開口５３へ向う流れは逆に妨害されてしまう。 Here, when the return screw diameter 50 was enlarged instead of providing the protrusions 52, the two-component developer that was more firmly pressed and solidified was retained in the gap between the return screw 50 and the developing container 42. As a result, the flow of the two-component developer toward the discharge opening 53 is obstructed.

突起５２にすることで、常に返しスクリュー５０の回転によって現像容器４２と返しスクリュー５０の隙間Ｈに滞留した二成分現像剤を掻き落し、滞留した二成分現像剤がつば部５１を乗り越える二成分現像剤の流れを妨害することを軽減できる。 By forming the protrusion 52, the two-component developer staying in the gap H between the developing container 42 and the return screw 50 is always scraped off by the rotation of the return screw 50, and the two-component developer staying over the collar portion 51 is scraped off. Interfering with the flow of the agent can be reduced.

突起５２の位置は、二成分現像剤が最も滞留し易い返しスクリュー５０のトナー搬送方向の上流部に設けることが望ましい。 The position of the protrusion 52 is desirably provided in the upstream portion of the return screw 50 in the toner conveyance direction in which the two-component developer is most likely to stay.

突起５２の形状は、滞留した二成分現像剤をより多く掻き落すことができるように、現像容器４２との隙間Ｈをできるだけ埋めるような高さにすることが望ましい。 It is desirable that the shape of the protrusion 52 be set so as to fill the gap H with the developing container 42 as much as possible so that a larger amount of the retained two-component developer can be scraped off.

以上説明したように、実施例１では、現像容器４２、搬送スクリュー４５、４６、隔壁４７等には変更を加えることなく、二成分現像剤にとって様々な使用環境、使い古し状態においても二成分現像剤量の排出量を安定させることができる。所定比率で磁性キャリアが混合された補給用二成分現像剤を補給する一方で所定量の二成分現像剤を排出し続けて現像容器４２内の二成分現像剤量を一定に保つ現像剤自動排出機能を、多様にわたる使用環境や二成分現像剤の劣化状態に対応させ得る。 As described above, in the first embodiment, the two-component developer is used in various usage environments and worn-out conditions for the two-component developer without changing the developing container 42, the conveying screws 45 and 46, the partition wall 47, and the like. The amount of discharge can be stabilized. Automatic developer discharge that keeps a predetermined amount of two-component developer discharged while maintaining a constant amount of two-component developer in the developing container 42 while supplying a two-component developer for replenishment mixed with a magnetic carrier at a predetermined ratio The function can correspond to various usage environments and deterioration states of the two-component developer.

＜実施例２＞
実施例１では、円板状のつば部５１の外周面上に突起５２を設けている。これに対して、実施例２では、つば部５１が無いため、返しスクリュー５０の搬送方向の上流側外周面に突起を配置している。実施例１においての現像装置４ａは、複数のプロセススピードに対応して複数の現像剤攪拌速度を持つためつば部５１を設けている。しかし、現像剤攪拌速度が変化しない実施形態、又は速度変化が小さい実施形態ではつば部５１は不必要となる場合がある。その場合においては、突起５２は返しスクリュー５０の搬送方向最上流より１ピッチ以内に設けることが望ましい。 <Example 2>
In the first embodiment, the protrusion 52 is provided on the outer peripheral surface of the disc-shaped collar portion 51. On the other hand, in Example 2, since there is no collar part 51, the protrusion is arrange | positioned in the upstream outer peripheral surface of the conveyance direction of the return screw 50. FIG. The developing device 4a in the first embodiment is provided with a collar portion 51 in order to have a plurality of developer stirring speeds corresponding to a plurality of process speeds. However, in the embodiment where the developer stirring speed does not change or in the embodiment where the speed change is small, the collar portion 51 may be unnecessary. In that case, it is desirable to provide the protrusions 52 within one pitch from the most upstream flow in the conveying direction of the return screw 50.

＜実施例３＞
図８は実施例３における二成分現像剤の排出メカニズムの説明図である。図９は実施例３における突起の配置の説明図である。 <Example 3>
FIG. 8 is an explanatory diagram of the discharge mechanism of the two-component developer in the third embodiment. FIG. 9 is an explanatory diagram of the arrangement of protrusions in the third embodiment.

図８に示すように、搬送スクリュー４６の回転に伴って二成分現像剤が最も活発に移動するのは領域Ｇ１、Ｇ２である。返しスクリュー５０が紙面の手前側へ二成分現像剤を搬送するため、領域Ｇ１、Ｇ２の返しスクリュー５０に近い領域では紙面の手前側、すなわち排出開口５３から遠ざかる方向の流れが形成される。一方、領域Ｇ１、Ｇ２の隔壁４７及び現像容器４２に近い外側の部分では紙面の奥側、すなわち排出開口５３に向かう流れが形成される。 As shown in FIG. 8, it is in the regions G1 and G2 that the two-component developer moves most actively as the conveying screw 46 rotates. Since the return screw 50 conveys the two-component developer to the front side of the paper surface, a flow in a direction away from the front side of the paper surface, that is, the discharge opening 53 is formed in the region near the return screw 50 in the regions G1 and G2. On the other hand, a flow toward the back side of the paper surface, that is, toward the discharge opening 53 is formed in the outer portion close to the partition wall 47 and the developing container 42 in the regions G1 and G2.

従って、領域Ｇ１、Ｇ２の隔壁４７及び現像容器４２に近い外側の部分を流れて減速し、つば部５１で反転して返しスクリュー５０に近い側を紙面の手前側へ引き返す過程で、一部の二成分現像剤（太線の矢印）がつば部５１を越えて排出開口５３側へ落下する。落下した二成分現像剤は、排出スクリュー４９に接触することで、排出開口５３を通じて現像容器４２外へ排出される。 Accordingly, in the process of flowing and decelerating through the outer portion close to the partition wall 47 and the developing container 42 in the regions G1 and G2, and reversing at the flange portion 51 and returning the side closer to the return screw 50 to the front side of the paper surface, The two-component developer (thick arrow) falls over the flange portion 51 to the discharge opening 53 side. The dropped two-component developer contacts the discharge screw 49 and is discharged out of the developing container 42 through the discharge opening 53.

これにより、二成分現像剤の供給量と排出量とをバランスさせて、返しスクリュー５０の一部が二成分現像剤の界面から飛び出した定常レベルに、現像容器４２内の二成分現像剤量が保持されている。仮に、現像容器４２内の二成分現像剤量が上の破線で示す過剰レベルになると、破線の矢印で示すように、つば部５１を越えて大量の二成分現像剤が排出開口５３側へ落下するようになる。これにより、排出量が増えて現像容器４２内の二成分現像剤量が下の破線で示す通常レベルに誘導される。逆に、現像容器４２内の二成分現像剤量が通常レベルよりも低くなると、領域Ｇ１、Ｇ２からつば部５１を越えて排出開口５３側へ落下する二成分現像剤量が極端に細るため、排出量が減って現像容器４２内の二成分現像剤量が通常レベルに誘導される。 As a result, the supply amount and discharge amount of the two-component developer are balanced, and the two-component developer amount in the developing container 42 is at a steady level where a part of the return screw 50 protrudes from the interface of the two-component developer. Is retained. If the amount of the two-component developer in the developing container 42 reaches an excessive level indicated by the broken line above, a large amount of the two-component developer falls to the discharge opening 53 side beyond the collar portion 51 as indicated by the broken line arrow. To come. As a result, the discharge amount increases and the two-component developer amount in the developing container 42 is guided to the normal level indicated by the broken line below. Conversely, when the amount of the two-component developer in the developing container 42 becomes lower than the normal level, the amount of the two-component developer that falls from the regions G1 and G2 over the collar portion 51 to the discharge opening 53 side becomes extremely thin. The discharged amount is reduced and the two-component developer amount in the developing container 42 is induced to the normal level.

ところが、二成分現像剤の流動性が低下していると、つば部５１で反転する際に凝集して排出開口５３側へ十分に落下することができなくなる。つば部５１に付着した状態で返しスクリュー５０と一体に回転し続ける二成分現像剤が増えて、つば部５１が実質的に厚くなった状態になる。つば部５１で停滞した二成分現像剤が後続の排出開口５３側へ向かう二成分現像剤の流れを妨げ、つば部５１への接近を妨げて排出開口５３側へ落下しにくくさせる。 However, when the fluidity of the two-component developer is lowered, the two-component developer is agglomerated when reversed at the collar portion 51 and cannot be sufficiently dropped to the discharge opening 53 side. The two-component developer that continues to rotate integrally with the return screw 50 in a state of adhering to the collar portion 51 increases, and the collar portion 51 becomes substantially thick. The two-component developer stagnated at the collar portion 51 prevents the flow of the two-component developer toward the subsequent discharge opening 53 side, prevents the access to the collar portion 51 and makes it difficult to fall to the discharge opening 53 side.

このとき、実施例３では、つば部５１の回転に伴って突起５２が領域Ｇ１、Ｇ２の凝集の根本を攪拌して、軸方向の圧力が小さくても凝集を排出開口５３側へ崩落し易くする。 At this time, in Example 3, the protrusion 52 stirs the root of the aggregation of the regions G1 and G2 as the collar portion 51 rotates, and the aggregation tends to collapse to the discharge opening 53 side even if the axial pressure is small. To do.

図９に示すように、実施例３では、突起５２は、つば部５１の排出開口５３に対する対向面から返しスクリュー５０側へ少し後退した位置に配置される。二成分現像剤の凝集に埋もれた状態で凝集と相対移動することで、凝集を引っ掛けて移動させる効果が高まるからである。 As shown in FIG. 9, in the third embodiment, the protrusion 52 is disposed at a position slightly retracted from the surface facing the discharge opening 53 of the collar portion 51 toward the return screw 50. This is because by moving relative to the aggregation while being buried in the aggregation of the two-component developer, the effect of catching and moving the aggregation is enhanced.

そのため、実施例３では、突起は、副スパイラル部にはみ出して円板部に近接する外周に配置される。 Therefore, in Example 3, the protrusions are disposed on the outer periphery that protrudes from the sub-spiral part and is close to the disk part.

なお、突起は、副スパイラル部の峰に沿って複数配置してもよい。しかし、円板部の周囲の凝集を崩す効果は、円板部に近い突起のほうが大きい。 A plurality of protrusions may be arranged along the peak of the sub spiral portion. However, the projections close to the disk part have a greater effect of breaking the aggregation around the disk part.

また、突起は、円板部の外周に沿って放射状に複数配置してもよい。例えば、円板部をスプライン形状に形成して、円板部の外周全体に突起を配置してもよい。しかし、突起は、凝集のアンカーとなって凝集が排出開口側へ移動するのを妨げるため、搬送方向から見た断面積を小さくして、少数設けることが効果的である。 A plurality of protrusions may be arranged radially along the outer periphery of the disk portion. For example, the disc portion may be formed in a spline shape, and the protrusions may be disposed on the entire outer periphery of the disc portion. However, since the protrusions serve as anchors for aggregation and prevent the aggregation from moving toward the discharge opening, it is effective to provide a small number of projections with a reduced cross-sectional area as viewed from the conveying direction.

また、つば部は、外周が円周面であればよく、実施例１〜３で説明した平板な板形状のみならず、円錐面、球面等の回転面を排出開口に対向させる外観でもよい。 Moreover, the collar part should just be a circumferential surface, and not only the flat plate shape demonstrated in Examples 1-3, but the external appearance which makes rotation surfaces, such as a conical surface and a spherical surface, oppose to a discharge opening may be sufficient as it.

＜実施例４＞
図２に示すように、実施例１、２では、現像スリーブ４３から遠い側の搬送スクリュー４６に副スパイラルを設けて二成分現像剤の排出量を制御していた。これに対して実施例４では、現像スリーブ４３に近い側の搬送スクリュー４５の下流側に副スパイラルを設けて二成分現像剤の排出量を制御する。すなわち、現像スリーブ４３で非磁性トナーが消費された直後の二成分現像剤を、搬送スクリュー４５の下流側の突き当たりに設けた排出開口から排出させる。 <Example 4>
As shown in FIG. 2, in the first and second embodiments, the auxiliary screw is provided in the conveyance screw 46 on the side far from the developing sleeve 43 to control the discharge amount of the two-component developer. On the other hand, in the fourth embodiment, a sub spiral is provided on the downstream side of the conveying screw 45 near the developing sleeve 43 to control the discharge amount of the two-component developer. That is, the two-component developer immediately after the non-magnetic toner is consumed by the developing sleeve 43 is discharged from the discharge opening provided at the end of the downstream side of the conveying screw 45.

１ａ、１ｂ、１ｃ、１ｄ感光ドラム
２ａ、２ｂ、２ｃ、２ｄ帯電ローラ
３露光装置
４ａ、４ｂ、４ｃ、４ｄ現像装置
５ａ、５ｂ、５ｃ、５ｄ一次転写ローラ
１０中間転写ベルト
１４二次転写ローラ
１５定着装置
４２現像容器
４３現像スリーブ（現像剤担持体）
４５搬送スクリュー（第２搬送部材）
４６搬送スクリュー（第１搬送部材）
４７隔壁
４７ａ、４７ｂ開口部
４８現像剤排出口
４９排出スクリュー
５０返しスクリュー（副スパイラル部）
５１つば部（円板部、円板）
５２突起
５３排出開口 1a, 1b, 1c, 1d Photosensitive drums 2a, 2b, 2c, 2d Charging roller 3 Exposure devices 4a, 4b, 4c, 4d Developing devices 5a, 5b, 5c, 5d Primary transfer roller 10 Intermediate transfer belt 14 Secondary transfer roller 15 Fixing device 42 Developer container 43 Developer sleeve (developer carrier)
45 Conveying screw (second conveying member)
46 Conveying screw (first conveying member)
47 Separator 47a, 47b Opening 48 Developer discharge port 49 Discharge screw 50 Return screw (sub spiral part)
51 collar (disc part, disc)
52 Projection 53 Discharge opening

Claims

長手方向の一方の突き当たり面に現像剤の排出開口が配置され、現像剤を受け渡す開口部を両端に有する長手方向の隔壁で内部が仕切られた現像容器と、
前記隔壁の一方の側に配置され、現像剤を前記排出開口へ向かって長手方向に搬送する主スパイラル部に、前記排出開口へ向かう現像剤の流れを逆方向に付勢する副スパイラル部を連結された第１搬送部材と、
前記隔壁の他方の側に配置され、前記副スパイラル部側の前記開口部を通じて前記第１搬送部材から受け渡された現像剤を前記第１搬送部材による搬送方向と逆方向に搬送する第２搬送部材と、を備える現像装置において、
長手方向で前記排出開口に重なるように前記排出開口に対向する円板部が前記副スパイラル部に連結されるとともに、前記円板部の外周に突起が配置されていることを特徴とする現像装置。 A developer container in which a developer discharge opening is disposed on one abutting surface in the longitudinal direction, and the interior is partitioned by a longitudinal partition having openings at both ends for delivering the developer;
Connected to the main spiral part that is arranged on one side of the partition wall and conveys the developer in the longitudinal direction toward the discharge opening, and a sub spiral part that urges the developer flow toward the discharge opening in the reverse direction A first conveying member,
Second transport that is disposed on the other side of the partition wall and transports the developer transferred from the first transport member through the opening on the sub spiral portion side in a direction opposite to the transport direction by the first transport member. A developing device comprising: a member;
A developing device characterized in that a disk portion facing the discharge opening is connected to the sub spiral portion so as to overlap the discharge opening in the longitudinal direction, and a protrusion is disposed on the outer periphery of the disk portion. .

前記副スパイラル部と前記円板部とは同一直径であることを特徴とする請求項１記載の現像装置。 The developing device according to claim 1, wherein the sub spiral portion and the disc portion have the same diameter.

前記突起は、前記円板部の前記排出開口に対する対向面から前記副スパイラル部側へ後退した位置に配置されることを特徴とする請求項２記載の現像装置。 The developing device according to claim 2, wherein the protrusion is disposed at a position retracted from the surface of the disc portion facing the discharge opening toward the sub spiral portion.

前記副スパイラル部の前記円板部に近接する外周に突起を配置したことを特徴とする請求項２又は３記載の現像装置。 The developing device according to claim 2, wherein a protrusion is disposed on an outer periphery of the sub spiral portion adjacent to the disk portion.

長手方向の一方の突き当たり面に現像剤の排出開口が配置され、現像剤を受け渡す開口部を両端に有する長手方向の隔壁で内部が仕切られた現像容器と、
前記隔壁の一方の側に配置され、現像剤を前記排出開口へ向かって長手方向に搬送する主スパイラル部に、前記排出開口へ向かう現像剤の流れを逆方向に付勢する副スパイラル部を連結された第１搬送部材と、
前記隔壁の他方の側に配置され、前記副スパイラル部側の前記開口部を通じて前記第１搬送部材から受け渡された現像剤を前記第１搬送部材による搬送方向と逆方向に搬送する第２搬送部材と、を備える現像装置において、
前記副スパイラル部の前記排出開口に近接する外周に突起が配置されていることを特徴とする現像装置。 A developer container in which a developer discharge opening is disposed on one abutting surface in the longitudinal direction, and the interior is partitioned by a longitudinal partition having openings at both ends for delivering the developer;
Connected to the main spiral part that is arranged on one side of the partition wall and conveys the developer in the longitudinal direction toward the discharge opening, and a sub spiral part that urges the developer flow toward the discharge opening in the reverse direction A first conveying member,
Second transport that is disposed on the other side of the partition wall and transports the developer transferred from the first transport member through the opening on the sub spiral portion side in a direction opposite to the transport direction by the first transport member. A developing device comprising: a member;
A developing device, wherein a protrusion is disposed on an outer periphery of the sub spiral portion adjacent to the discharge opening.