JP2003195638A - Developing device and image forming apparatus provided with it - Google Patents

Developing device and image forming apparatus provided with it

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Publication number
JP2003195638A
JP2003195638A JP2001398377A JP2001398377A JP2003195638A JP 2003195638 A JP2003195638 A JP 2003195638A JP 2001398377 A JP2001398377 A JP 2001398377A JP 2001398377 A JP2001398377 A JP 2001398377A JP 2003195638 A JP2003195638 A JP 2003195638A
Authority
JP
Japan
Prior art keywords
developer
chamber
developing
developing device
image
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP2001398377A
Other languages
Japanese (ja)
Inventor
Kouta Arimoto
孝太 有元
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Canon Inc
Original Assignee
Canon Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Canon Inc filed Critical Canon Inc
Priority to JP2001398377A priority Critical patent/JP2003195638A/en
Publication of JP2003195638A publication Critical patent/JP2003195638A/en
Pending legal-status Critical Current

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  • Magnetic Brush Developing In Electrophotography (AREA)
  • Dry Development In Electrophotography (AREA)
  • Color Electrophotography (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device by which a developer level height is maintained at a specified height while possessing a high maintainability and also an image forming apparatus provided with the developing device. <P>SOLUTION: A developer carrier 3 to feed developer to an image carrier is freely rotatably provided at the position of a developer storing part 2 to store the developer and replenished with the developer from a developer replenishing part 5 at which it is opposed to the image carrier, and also the developer carrier 3 is supplied with the developer stored in the developer storing part 2 while stirring by stirring/feeding members 2a and 2b provided at the developer storing part 2. Then, surplus developer out of the developer stored in the developer storing part 2 is discharged by a developer discharge mechanism so that the developer level height h1 becomes a height sufficient to cover the specified amount of the stirring/feeding member 2a. <P>COPYRIGHT: (C)2003,JPO

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【発明の属する技術分野】本発明は、現像装置及びこれ
を備えた画像形成装置に関し、特に現像剤収納部に収納
された現像剤の高さ制御に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus equipped with the same, and more particularly to controlling the height of a developer contained in a developer container.

【０００２】[0002]

【従来の技術】従来の複写機、プリンタ、ファクシミリ
等の画像形成装置においては、例えば像担持体上に静電
潜像を形成し、この静電潜像を現像装置により現像して
可視像化した後、この可視像を転写材に転写して転写材
上に画像を形成するようにしたものがある。2. Description of the Related Art In a conventional image forming apparatus such as a copying machine, a printer or a facsimile, an electrostatic latent image is formed on an image carrier, and the electrostatic latent image is developed by a developing device to form a visible image. Then, there is one in which this visible image is transferred to a transfer material to form an image on the transfer material.

【０００３】ところで、このような現像装置としては、
磁性キャリアと非磁気トナーとを混合し、現像剤として
使用する２成分現像方式が広く利用されている。ここ
で、この２成分現像方式は現在提案されている他の現像
方式と比較して画質の安定性、装置の耐久性等の長所を
備えているが、長期の耐久による現像剤の劣化、特にキ
ャリアの劣化が不可避であったため、装置の長期使用に
伴い現像剤交換という煩雑な作業を行う必要があった。By the way, as such a developing device,
A two-component developing method in which a magnetic carrier and a non-magnetic toner are mixed and used as a developer is widely used. Here, this two-component developing method has advantages such as image quality stability and device durability as compared with other currently proposed developing methods, but deterioration of the developer due to long-term durability, especially, Since the deterioration of the carrier was unavoidable, it was necessary to perform a complicated work of replacing the developer as the apparatus was used for a long time.

【０００４】そこで、この問題に対する解決策として現
像剤劣化の低減、或いは現像剤交換作業のメンテナンス
性向上を図る手法が従来より提案及び実用化されてい
る。次に、このような現像剤劣化の低減及び現像剤交換
作業のメンテナンス性向上についての手法について説明
する。Therefore, as a solution to this problem, a method for reducing the deterioration of the developer or improving the maintainability of the developer replacement work has been proposed and put into practical use. Next, a method for reducing such developer deterioration and improving the maintainability of the developer replacement work will be described.

【０００５】１．現像剤劣化の低減 現像剤の劣化は現像剤層厚規制部近傍の現像スリーブと
現像容器間における圧縮作用が主要因であり、この圧縮
作用を低減するためには、現像剤層厚規制極（以下、カ
ット極という）の、現像剤を現像スリーブに引きつける
力（Ｆｒ；現像スリーブに垂直な方向に働く磁気吸引
力）を弱めることが有効である。1. Reduction of developer deterioration The main reason for the deterioration of the developer is the compression action between the developing sleeve and the developing container near the developer layer thickness control portion.To reduce this compression action, the developer layer thickness control pole ( Hereinafter, it is effective to weaken the force (Fr; magnetic attraction force acting in the direction perpendicular to the developing sleeve) that attracts the developer to the developing sleeve (hereinafter referred to as the cut pole).

【０００６】このため、例えば、図１５に示すように現
像スリーブ１１３の反発磁極の一つをカット極として用
いる構成をとるようにする。ここで、このような構成を
取った場合、カット極を形成する各々の磁極の磁力線が
現像スリーブ面に対してほぼ垂直に出るため、カット極
からの磁力線が隣接磁極に回り込みづらくなり、現像ス
リーブ１１３からドクターブレード１２２に出るような
磁力分布となるため、現像剤を現像スリーブ１１３に引
きつける力が弱くなる。この結果、現像スリーブ１１３
と現像容器１１２間における現像剤への圧縮作用が弱ま
り、現像剤劣化が大幅に低減される。Therefore, for example, as shown in FIG. 15, one of the repulsive magnetic poles of the developing sleeve 113 is used as a cut pole. Here, when such a configuration is adopted, since the magnetic force lines of the magnetic poles forming the cut poles are substantially perpendicular to the developing sleeve surface, the magnetic force lines from the cut poles are hard to wrap around to the adjacent magnetic poles, and the developing sleeve Since the magnetic force distribution is such that the developer comes out from the doctor blade 122, the force of attracting the developer to the developing sleeve 113 becomes weak. As a result, the developing sleeve 113
The compressive action on the developer between the developing container 112 and the developing container 112 is weakened, and the deterioration of the developer is significantly reduced.

【０００７】２．現像剤交換作業のメンテナンス性向上 このための手法としては、例えば図１６に示す特開平６
−３２４５６５号公報のもののように、感光体ドラム１
１１と対向する現像位置Ｓにおける現像動作によって消
費した分のトナーを含む現像剤を現像装置１１３Ｙ，１
１３Ｍ，１１３Ｃ，１１３Ｋ内に補給し、現像装置内の
過剰な現像剤を回転体１１３の回転運動による重力作用
方向の変化を利用して不図示の現像剤カートリッジ内に
排出する構成がある。2. Improvement of maintainability of developer replacement work As a method for this, for example, Japanese Unexamined Patent Publication No. Hei 6 (1994) -56 shown in FIG.
Photoreceptor drum 1 such as that of Japanese Patent No. 324565
11, the developer containing the toner consumed by the developing operation at the developing position S facing the developing device S
13M, 113C, and 113K are replenished, and excess developer in the developing device is discharged into a developer cartridge (not shown) by utilizing the change in the direction of gravitational force caused by the rotational movement of the rotating body 113.

【０００８】そして、このように回転体特有の動きを利
用して現像剤の回収を行なうように構成した場合には、
構造がシンプルとなり、この結果、装置の大型化やコス
トの高騰を引き起こすことなく、現像剤全体としての特
性を安定させ、且つ、現像剤カートリッジの交換作業の
みが現像剤交換作業となるため、メンテナンス性が大幅
に向上させることができる。When the developer is collected by utilizing the movement peculiar to the rotating body as described above,
The structure is simple, and as a result, the characteristics of the developer as a whole are stabilized without causing an increase in the size and cost of the device, and only the developer cartridge replacement work is the developer replacement work. Sex can be greatly improved.

【０００９】[0009]

【発明が解決しようとする課題】ところが、このような
従来の画像形成装置において、例えば図１５のように反
発磁極の一つの極をカット極として用いる構成の場合、
黒ベタ画像にスクリューピッチ状の濃度ムラ（以下、ス
クリューピッチムラという）が発生することがあった。
ここで、このスクリューピッチムラは、例えば現像スリ
ーブ上の現像剤コートムラ（以下、Ｍ／Ｓムラという）
により発生する。However, in such a conventional image forming apparatus, when one pole of the repulsive magnetic pole is used as the cut pole as shown in FIG. 15, for example,
Occurrence of screw pitch-like density unevenness (hereinafter referred to as screw pitch unevenness) may occur in a black solid image.
Here, this screw pitch unevenness is, for example, developer coating unevenness on the developing sleeve (hereinafter referred to as M / S unevenness).
Caused by.

【００１０】次に、このＭ／Ｓムラに起因するスクリュ
ーピッチムラの発生原理について説明する。Next, the principle of generation of screw pitch unevenness due to this M / S unevenness will be described.

【００１１】例えば、図１５に示した構成ではカット極
Ｎ１に磁気的に吸引された現像剤の近傍にスクリュー１
２１が位置するため、現像スリーブ１１３に近い側の現
像剤収容室（以下、現像室という）１１２Ａに収容され
る現像剤の剤面高さｈ１が所定高さより低い場合、スク
リュー１２１の回転により、カット極に溜められた現像
剤に対する圧縮ムラが生じ、その結果、現像スリーブ１
１３上にスクリューピッチ状のＭ／Ｓムラができる。For example, in the configuration shown in FIG. 15, the screw 1 is provided near the developer magnetically attracted to the cut pole N1.
Since 21 is located, when the developer surface height h1 of the developer accommodated in the developer accommodating chamber (hereinafter, referred to as a developing chamber) 112A near the developing sleeve 113 is lower than a predetermined height, the screw 121 rotates, Uneven compression occurs with respect to the developer accumulated in the cut pole, and as a result, the developing sleeve 1
A screw pitch-like M / S unevenness is formed on 13.

【００１２】そして、このように現像スリーブ１１３上
にＭ／Ｓムラが生じた状態で感光体ドラム上に黒ベタ画
像を現像すると、コート量が多い部分で、スクリューピ
ッチ状に高濃度となるスクリューピッチムラが生じる。When a black solid image is developed on the photosensitive drum in the state where M / S unevenness is generated on the developing sleeve 113 as described above, a screw having a high density in a screw pitch form in a portion having a large coating amount. Pitch unevenness occurs.

【００１３】ところで、このスクリューピッチムラは高
湿環境下及び長期にわたる画像形成後に発生する頻度が
高い。ここで、高湿環境下においては磁性キャリア及び
トナーの表面抵抗値が低いため、磁性キャリアの帯電量
が小さくなり、長期にわたる画像形成後においてはキャ
リア表面上にトナーが固着する所謂トナースペントや外
添剤付着のため、キャリアのトナーへの帯電能力が低下
し、磁性キャリア自身の帯電量も小さくなる。By the way, this screw pitch unevenness frequently occurs in a high humidity environment and after image formation for a long period of time. Here, since the surface resistance values of the magnetic carrier and the toner are low in a high humidity environment, the charge amount of the magnetic carrier becomes small, and so-called toner spent or external toner in which toner adheres to the carrier surface after long-term image formation. Due to the attachment of the additive, the chargeability of the carrier to the toner is reduced, and the charge amount of the magnetic carrier itself is also reduced.

【００１４】そして、このようにキャリアの帯電量が小
さい場合、キャリア間の静電気的反発力が弱くなるた
め、二成分現像剤全体としてのかさ密度が高くなり、現
像容器内における現像剤面高さが下降する。When the charge amount of the carrier is small as described above, the electrostatic repulsive force between the carriers becomes weak, so that the bulk density of the two-component developer as a whole becomes high, and the surface height of the developer in the developing container becomes high. Goes down.

【００１５】従って、現像室２Ａの現像剤面高さｈ１が
所定高さ以下になりやすくなり、これに伴い上記のカッ
ト極Ｎ１に溜められた現像剤に対する圧縮ムラが著しく
大きくなるため、現像スリーブ１１３上にスクリューピ
ッチ状のＭ／Ｓムラが生じやすく、スクリューピッチム
ラが発生する頻度が高くなる。なお、このスクリューピ
ッチムラは現像室内の現像剤面高さｈ１がスクリュー１
２１のスパイラルのスパイラル状の搬送部材１２１ａの
高さ以下となった場合に、特に発生し易い。Therefore, the height h1 of the developer surface in the developing chamber 2A is likely to be less than a predetermined height, and along with this, the unevenness of compression of the developer accumulated in the cut pole N1 is significantly increased. Screw pitch-like M / S unevenness is likely to occur on 113, and the frequency of screw pitch unevenness increases. Note that this screw pitch unevenness is caused when the developer surface height h1 in the developing chamber is the screw 1
Especially when the height is less than the height of the spiral-shaped transport member 121a of 21 spirals.

【００１６】一方、現像室１１２Ａの現像剤面高さｈ１
がスクリュー１２１の搬送部材１２１ａの高さより大幅
に高くなると、現像剤の搬送不良及び攪拌不良が発生
し、さらに高くなると現像スリーブ１１３と現像容器１
１２の間から現像剤が漏出するという問題を引き起こす
ことがあった。On the other hand, the developer surface height h1 of the developing chamber 112A
Becomes significantly higher than the height of the conveying member 121a of the screw 121, developer conveyance failure and stirring failure occur, and when it becomes higher, the developing sleeve 113 and the developing container 1
There was a problem that the developer leaked out from between 12.

【００１７】つまり、現像スリーブ１１３の反発磁極の
一つをカット極として用いる場合、現像室１１２Ａの現
像剤面高さｈ１をスクリューピッチムラが発生する高さ
より高く、且つ、現像剤の漏出及び現像剤の攪拌・搬送
不良が発生する高さより低い所定の高さに維持すること
が必要である。That is, when one of the repelling magnetic poles of the developing sleeve 113 is used as a cut pole, the developer surface height h1 of the developing chamber 112A is higher than the height at which the screw pitch unevenness occurs, and the developer leaks and develops. It is necessary to maintain a predetermined height, which is lower than the height at which the stirring / conveying failure of the agent occurs.

【００１８】そこで、本発明は、このような現状に鑑み
てなされたものであり、高メンテナンス性を有しつつ、
現像剤面高さを所定の高さに保つことのできる現像装置
及びこれを備えた画像形成装置を提供することを目的と
するものである。Therefore, the present invention has been made in view of the above situation, and has high maintainability and
An object of the present invention is to provide a developing device capable of maintaining the height of the developer surface at a predetermined height, and an image forming apparatus including the developing device.

【００１９】[0019]

【課題を解決するための手段】本発明は、トナーとキャ
リアを含む現像剤を補給する現像剤補給部と、現像剤を
収納すると共に前記現像剤補給部から現像剤が補給され
る現像剤収納部と、前記現像剤収納部内の現像剤を担持
して像担持体に形成された潜像を現像する現像部へ搬送
する現像剤担持体と、前記現像剤担持体内に固定配置さ
れる磁界発生手段と、を有し、前記現像剤収納部は、前
記現像剤担持体を収容する第１室と、前記第１室との間
で現像剤の循環を行う第２室と、を備える現像装置にお
いて、前記第１及び第２室内にそれぞれ設けられ、現像
剤を攪拌搬送する第１及び第２の攪拌搬送部材と、前記
現像剤収納部内の現像剤のうち余剰現像剤を前記現像剤
収納部外へ排出する現像剤排出機構と、を有し、前記磁
界発生手段のうちの隣接した同極性の磁極の一つを現像
層厚を規制する現像剤層厚規制極とし、前記現像剤排出
機構は、前記第１室の現像剤の剤面高さが前記第１の攪
拌搬送部材を所定量だけ覆うような高さとなるように前
記余剰現像剤を排出することを特徴とするものである。SUMMARY OF THE INVENTION According to the present invention, there is provided a developer replenishing section for replenishing a developer containing a toner and a carrier, and a developer accommodating section for accommodating the developer and supplying the developer from the developer replenishing section. Section, a developer carrier that carries the developer in the developer accommodating section and conveys the latent image formed on the image carrier to a developing section, and a magnetic field that is fixedly arranged in the developer carrier. And a second chamber that circulates the developer between the first chamber and the first chamber. In the first and second chambers, respectively, first and second stirring / conveying members for stirring and conveying the developer, and excess developer out of the developer in the developer accommodating portion are stored in the developer accommodating portion. And a developer discharging mechanism for discharging to the outside. One of the adjacent magnetic poles of the same polarity is used as a developer layer thickness regulating pole for regulating the developing layer thickness, and the developer discharging mechanism is such that the developer surface height of the developer in the first chamber is the first agitating conveyance. The surplus developer is discharged so that the height of the member covers a predetermined amount.

【００２０】また本発明は、前記現像剤排出機構を前記
第１室内に設けたことを特徴とするものである。The present invention is also characterized in that the developer discharging mechanism is provided in the first chamber.

【００２１】また本発明は、それぞれスパイラル状の搬
送部材を有し前記現像剤収納部の第１及び第２室に配設
された前記第１及び第２の攪拌搬送部材により現像剤を
前記第２室から前記第１室に循環させると共に、前記第
１室に配設される前記第１の攪拌搬送部材の搬送部材の
間隔Ｄａと前記第２室に配設される前記第１の攪拌搬送
部材の搬送部材の間隔ＤｂとがＤａ＜Ｄｂの関係を満た
し、且つ前記現像剤排出機構を前記第１室の現像剤循環
方向下流端部近傍に設けたことを特徴とするものであ
る。According to the present invention, the developer is conveyed by the first and second agitating and conveying members provided in the first and second chambers of the developer accommodating portion, each having a spiral conveying member. While circulating from two chambers to the first chamber, the distance Da between the conveying members of the first stirring and conveying member arranged in the first chamber and the first stirring and conveying unit arranged in the second chamber. The distance Db between the member conveying members satisfies Da <Db, and the developer discharge mechanism is provided near the downstream end of the first chamber in the developer circulation direction.

【００２２】また本発明は、前記現像剤排出機構は、前
記第１の攪拌搬送部材に設けられ、前記現像剤循環方向
とは逆方向に現像剤を搬送する構成のスパイラル状の返
し部材と、前記第１室の現像剤循環方向下流に隔設さ
れ、前記余剰現像剤を収納する余剰現像剤収納部と、前
記第１室の上部に設けられ、該第１室と前記余剰現像剤
収納部とを連通する連通通路とを備え、前記スパイラル
状の返し部材と前記攪拌搬送部材の搬送部材との搬送方
向の違いにより前記余剰現像剤を前記連通通路の位置ま
で上昇させた後、前記余剰現像剤収納部に向わせるよう
にしたことを特徴とするものである。According to the present invention, the developer discharging mechanism is provided on the first stirring / conveying member, and has a spiral-shaped return member configured to convey the developer in a direction opposite to the developer circulating direction, A surplus developer accommodating portion that is provided downstream of the first chamber in the developer circulation direction and that accommodates the surplus developer, and a first chamber and the surplus developer accommodating portion that are provided above the first chamber. And a communication passage that communicates with each other, and after the excess developer is raised to the position of the communication passage due to the difference in the conveyance direction between the spiral return member and the conveyance member of the stirring conveyance member, the excess development is performed. It is characterized in that it is made to face the agent storage section.

【００２３】また本発明は、前記余剰現像剤収納部に前
記余剰現像剤を回収する回収容器を着脱自在に設けると
共に、前記第１室の攪拌搬送部材を前記余剰現像剤収納
部に延出させ、該攪拌搬送部材の延出部分に前記余剰現
像剤収納部に収納された余剰現像剤を前記回収容器に搬
送する搬送手段を設けたことを特徴とするものである。Further, according to the present invention, a recovery container for recovering the excess developer is detachably provided in the excess developer accommodating portion, and the stirring and conveying member of the first chamber is extended to the excess developer accommodating portion. A transport means for transporting the excess developer stored in the excess developer storage portion to the recovery container is provided at the extending portion of the stirring and transporting member.

【００２４】また本発明は、現像装置と、前記現像装置
と対を成す１つの像担持体とを有する画像形成部を備
え、前記一対の像担持体と現像装置とにより単色のトナ
ー画像を形成する画像形成装置において、前記現像装置
は上記のいずれかに記載のものであることを特徴とする
ものである。The present invention further comprises an image forming section having a developing device and one image bearing member paired with the developing device, and a monochromatic toner image is formed by the pair of image bearing members and the developing device. In the image forming apparatus described above, the developing device is one of those described above.

【００２５】また本発明は、複数の現像装置と、前記現
像装置と対を成す複数の像担持体とを有する画像形成部
を備え、前記複数対の像担持体と現像装置とにより有彩
色のトナー画像を形成する画像形成装置において、前記
現像装置は上記のいずれかに記載のものであることを特
徴とするものである。The present invention further comprises an image forming section having a plurality of developing devices and a plurality of image bearing members paired with the developing devices, wherein the plurality of pairs of image bearing members and the developing devices are chromatic. An image forming apparatus for forming a toner image is characterized in that the developing device is one of those described above.

【００２６】また本発明は、像担持体上に形成された静
電潜像をトナー及びキャリアを含む現像剤で現像する複
数の現像装置と、前記複数の現像装置を保持して共通の
現像位置へある現像装置を選択的に回転移動させる回転
体とを備えた画像形成装置において、前記現像装置は、
現像剤を補給する現像剤補給部と、現像剤を収納すると
共に前記現像剤補給部から現像剤が補給される現像剤収
納部と、前記現像剤収納部内の現像剤を前記像担持体に
担持搬送する現像剤担持体と、前記現像剤収納部内の現
像剤を前記現像剤担持体に攪拌搬送する攪拌搬送部材
と、前記現像剤収納部に収納された現像剤のうちの余剰
現像剤を前記現像剤収納部外へ排出する現像剤排出機構
と、を備え、前記現像剤排出機構により、現像剤の剤面
高さが前記攪拌搬送部材を所定量だけ覆うような高さと
なるように前記余剰現像剤を排出することを特徴とする
ものである。Further, according to the present invention, a plurality of developing devices for developing the electrostatic latent image formed on the image bearing member with a developer containing toner and carrier, and a common developing position for holding the plurality of developing devices. In an image forming apparatus including a rotating body that selectively rotates a developing device, the developing device is
A developer replenishing section for replenishing the developer, a developer accommodating section for accommodating the developer and replenishing the developer from the developer replenishing section, and a developer in the developer accommodating section for carrying the developer on the image carrier. The developer carrier to be conveyed, the stirring and conveying member for stirring and conveying the developer in the developer accommodating portion to the developer carrier, and the surplus developer of the developers accommodated in the developer accommodating portion are described above. And a developer discharging mechanism for discharging the developer to the outside of the developer accommodating portion, wherein the developer discharging mechanism allows the developer surface height of the developer to be a height that covers the stirring and conveying member by a predetermined amount. It is characterized in that the developer is discharged.

【００２７】また本発明は、前記現像剤収納部を前記現
像剤担持体に沿って区画して該現像剤担持体に近い第１
室と、該現像剤担持体から遠い第２室とを形成し、前記
現像剤排出機構を前記現像剤収納部の第１室に設けたこ
とを特徴とするものである。According to the present invention, the developer accommodating portion is divided along the developer carrying member so as to be close to the developer carrying member.
A chamber and a second chamber remote from the developer carrying member are formed, and the developer discharging mechanism is provided in the first chamber of the developer accommodating portion.

【００２８】また本発明は、前記現像剤収納部の第１及
び第２室にそれぞれスパイラル状の搬送部材を有する前
記攪拌搬送部材を配設して現像剤を前記第２室から前記
第１室に循環させると共に、前記第１室に配設される攪
拌搬送部材の搬送部材の間隔Ｄａと前記第２室に配設さ
れる攪拌搬送部材の搬送部材の間隔ＤｂとがＤａ＜Ｄｂ
の関係を満たし、且つ前記現像剤排出機構を前記第１室
の上方に設けたことを特徴とするものである。Further, according to the present invention, the agitating / conveying member having a spiral conveying member is disposed in each of the first and second chambers of the developer accommodating portion to transfer the developer from the second chamber to the first chamber. And the distance Da between the conveying members of the stirring and conveying member arranged in the first chamber and the distance Db between the conveying members of the stirring and conveying member arranged in the second chamber are Da <Db.
And the developer discharging mechanism is provided above the first chamber.

【００２９】また本発明は、前記現像剤排出機構は、前
記第１室の攪拌搬送部材に設けられ、前記現像剤循環方
向とは逆方向に現像剤を搬送する構成のスパイラル状の
返し部材と、前記第１室の現像剤循環方向の下流側上部
に設けられ、前記現像装置が現像位置にあるとき前記現
像剤収納部の余剰現像剤を貯溜する現像剤排出口と、前
記現像剤排出口と前記現像剤補給部とを連通する連通通
路とを備え、前記スパイラル状の返し部材と前記攪拌搬
送部材の搬送部材との搬送方向の違いにより前記余剰現
像剤を前記連通通路の位置まで上昇させて前記現像剤排
出口に貯留させた後、前記現像動作終了後の前記回転体
の回転運動による重力方向の変化により、前記現像剤排
出口内の余剰現像剤を前記連通通路を経て前記現像剤補
給部に収容することを特徴とするものである。According to the present invention, the developer discharging mechanism is provided in the agitating / conveying member in the first chamber, and has a spiral-shaped returning member configured to convey the developer in a direction opposite to the developer circulating direction. A developer outlet provided in an upper portion of the first chamber on the downstream side in the developer circulation direction, for storing the excess developer in the developer accommodating portion when the developing device is at the developing position; and the developer outlet. And a communication passage communicating with the developer replenishing section, and the surplus developer is raised to the position of the communication passage due to the difference in the conveying direction between the spiral return member and the conveying member of the stirring and conveying member. Stored in the developer discharge port, the excess developer in the developer discharge port is replenished through the communication passage due to a change in the direction of gravity due to the rotational movement of the rotating body after the developing operation is completed. Can be housed in The one in which the features.

【００３０】また本発明は、前記現像剤補給部は、隔壁
により区画された前記補給現像剤を収容する補給現像剤
収納室及び前記現像装置内の余剰現像剤を収容する排出
現像剤収納室を有していることを特徴とするものであ
る。According to the present invention, the developer replenishing section includes a replenishment developer storage chamber for storing the replenishment developer and a discharge developer storage chamber for storing excess developer in the developing device, which are partitioned by a partition wall. It is characterized by having.

【００３１】[0031]

【発明の実施の形態】以下、本発明の実施の形態につい
て図面を用いて詳細に説明する。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

【００３２】図１は、本発明の第１の実施の形態に係る
画像形成装置の概略構成を示す図である。FIG. 1 is a view showing the schematic arrangement of an image forming apparatus according to the first embodiment of the present invention.

【００３３】同図において、２８は像担持体である感光
体ドラム、２１は帯電器、１は現像装置、２２は露光手
段である。そして、記録紙２７に画像を形成する際は、
まず帯電器２１によって帯電された感光体ドラム２８表
面を露光手段２２によって露光することで感光体ドラム
２８上に静電潜像を形成し、この静電潜像を現像装置１
によって現像することで感光体ドラム２８上にトナー像
を形成する。In the figure, 28 is a photosensitive drum which is an image bearing member, 21 is a charger, 1 is a developing device, and 22 is exposure means. When forming an image on the recording paper 27,
First, the surface of the photoconductor drum 28 charged by the charger 21 is exposed by the exposure means 22 to form an electrostatic latent image on the photoconductor drum 28, and this electrostatic latent image is developed.
By developing with, a toner image is formed on the photosensitive drum 28.

【００３４】次に、このトナー像を、転写ベルト２４に
よって搬送される記録紙２７に、転写帯電器２３による
転写バイアスにより転写した後、このトナー像が転写さ
れた記録紙２７を定着器２５に搬送し、この定着器２５
において加圧／加熱することにより、記録紙上に永久画
像を形成する。なお、トナー像転写後、感光体ドラム２
８上に残った残トナーはクリーナー２６により除去さ
れ、次の画像形成に備えるようにする。Next, this toner image is transferred onto the recording paper 27 conveyed by the transfer belt 24 by the transfer bias by the transfer charger 23, and then the recording paper 27 onto which the toner image is transferred is transferred to the fixing device 25. This fixing device 25
A permanent image is formed on the recording paper by applying pressure / heating at. After the toner image is transferred, the photosensitive drum 2
The residual toner remaining on 8 is removed by the cleaner 26 so as to be ready for the next image formation.

【００３５】ここで、図２は現像装置１を長手方向手前
側から見た図、図３は現像装置１を上方から見た図であ
る。2 is a view of the developing device 1 as seen from the front side in the longitudinal direction, and FIG. 3 is a view of the developing device 1 as seen from above.

【００３６】なお、本実施の形態において、現像装置１
には、非磁性トナ−と磁性キャリアとからなる２成分現
像剤が収容されており、初期状態の現像剤中のトナー濃
度は７％である。ここで、この値はトナーの帯電量、キ
ャリア粒径、画像形成装置の構成等で適正に調整される
べきものであって、必ずしもこの数値に限られるもので
はない。Incidentally, in the present embodiment, the developing device 1
Contains a two-component developer composed of a non-magnetic toner and a magnetic carrier, and the toner concentration in the developer in the initial state is 7%. Here, this value should be properly adjusted depending on the charge amount of the toner, the particle size of the carrier, the configuration of the image forming apparatus, and the like, and is not necessarily limited to this value.

【００３７】現像装置１は、図２に示すように感光体ド
ラム２８に対向した位置に形成された開口部２ｄに一部
露出するようにして現像スリーブ３が回転可能に配置さ
れている。ここで、この感光体ドラム２８に現像剤を搬
送する現像剤担持体である現像スリーブ３は磁界発生手
段である固定のマグネット４を内包すると共に非磁性材
料で構成され、現像動作時には矢印方向に回転するよう
になっている。In the developing device 1, as shown in FIG. 2, the developing sleeve 3 is rotatably arranged so as to be partially exposed in an opening 2d formed at a position facing the photosensitive drum 28. Here, the developing sleeve 3 which is a developer carrying member that conveys the developer to the photosensitive drum 28 includes a fixed magnet 4 which is a magnetic field generating means and is made of a non-magnetic material. It is designed to rotate.

【００３８】また、この現像スリーブ３は、固定のマグ
ネット４のうち隣接した同極性の磁極の一つを現像層厚
を規制する現像剤層厚規制極とすると共に、現像スリー
ブ３と所定間隙をもって配置される磁性体からなるドク
ターブレード１３によって現像容器２内の２成分現像剤
を層状に保持しながら現像領域に担持搬送するものであ
り、この現像スリーブ３によって感光体ドラム２８と対
向する現像領域に２成分現像剤を供給することにより、
感光体ドラム２８に形成されている静電潜像を現像する
ようになっている。なお、このように静電潜像を現像し
た後の現像剤は、現像スリーブ３の回転にしたがって搬
送され、現像剤収納部である現像容器２内に回収され
る。In the developing sleeve 3, one of the adjacent magnetic poles of the same polarity among the fixed magnets 4 serves as a developer layer thickness regulating pole for regulating the developing layer thickness, and has a predetermined gap with the developing sleeve 3. The two-component developer in the developing container 2 is held and conveyed to the developing area by the doctor blade 13 made of a magnetic material and held in a layered manner. The developing sleeve 3 opposes the photosensitive drum 28 to the developing area. By supplying a two-component developer to
The electrostatic latent image formed on the photoconductor drum 28 is developed. The developer after the electrostatic latent image has been developed in this manner is conveyed according to the rotation of the developing sleeve 3 and is collected in the developer container 2 which is a developer accommodating portion.

【００３９】一方、この現像容器２は、現像スリーブ３
に沿って区画された現像スリーブ３に近い第１室である
現像剤収容室（以下、現像室という）２Ａ、現像スリー
ブ３から遠い第２室である現像剤収容室（以下、攪拌室
という）２Ｂを備えている。また、現像室２Ａには攪拌
搬送部材である第１現像剤循環スクリュー２ａが、また
攪拌室２Ｂには攪拌搬送部材である第２現像剤循環スク
リュー２ｂが設けられており、これら２つの現像剤循環
スクリュー２ａ，２ｂにより現像容器２内の現像剤は図
３に示す現像剤循環経路２ｃを循環して混合攪拌され
る。On the other hand, the developing container 2 includes a developing sleeve 3
A developer accommodating chamber (hereinafter referred to as a developing chamber) 2A which is a first chamber near the developing sleeve 3 and a developer accommodating chamber (hereinafter referred to as a stirring chamber) which is a second chamber distant from the developing sleeve 3. It has 2B. Further, the developing chamber 2A is provided with a first developer circulating screw 2a which is a stirring and conveying member, and the stirring chamber 2B is provided with a second developer circulating screw 2b which is a stirring and conveying member. The developer in the developing container 2 is circulated through the developer circulation path 2c shown in FIG. 3 and mixed and stirred by the circulation screws 2a and 2b.

【００４０】なお、本実施の形態において、現像剤循環
の方向は図３に示すように攪拌室２Ｂ側（第２現像剤循
環スクリュー側）では手前側から奥側に向かう方向、現
像室２Ａ側（第１現像剤循環スクリュー側）では奥側か
ら手前側に向かう方向である。In this embodiment, as shown in FIG. 3, the developer circulation direction is from the front side to the back side on the stirring chamber 2B side (second developer circulation screw side), and on the developing chamber 2A side. On the (first developer circulation screw side), the direction is from the back side to the front side.

【００４１】ところで、現像装置１の下流側の感光体ド
ラム２８近傍には図１に示すようにパッチ検知センサ１
１が設置されている。そして、このパッチ検知センサ１
１により、不図示の制御部は感光体ドラム２８上に現像
されたパッチ画像の濃度を検知し、そのパッチ画像濃度
を一定に維持するように現像容器中の２成分現像剤のト
ナー濃度を制御するようにしている。By the way, in the vicinity of the photosensitive drum 28 on the downstream side of the developing device 1, as shown in FIG.
1 is installed. And this patch detection sensor 1
1, the control unit (not shown) detects the density of the patch image developed on the photosensitive drum 28, and controls the toner density of the two-component developer in the developing container so as to maintain the patch image density constant. I am trying to do it.

【００４２】なお、トナー濃度の制御方法は、この方法
に限ったものではなく、例えば現像剤中の磁性キャリア
の透磁率からトナー濃度を検知する方式（インダクタン
ス方式）等でも良く、現像剤のトナー濃度を精度よく検
出可能であれば、如何なる方法でもよい。The method of controlling the toner concentration is not limited to this method. For example, a method of detecting the toner concentration from the magnetic permeability of the magnetic carrier in the developer (inductance method) may be used. Any method may be used as long as the concentration can be accurately detected.

【００４３】一方、図２において、５は画像形成装置本
体に脱着可能に設けられた現像剤補給部である現像剤カ
ートリッジであり、パッチ検知センサ１１が検知したパ
ッチ画像濃度に応じて、この現像剤カートリッジ５に収
納された補給用現像剤を現像容器２に補給するようにし
ている。On the other hand, in FIG. 2, reference numeral 5 denotes a developer cartridge which is a developer replenishing portion detachably provided in the main body of the image forming apparatus, and which develops in accordance with the patch image density detected by the patch detection sensor 11. The replenishment developer stored in the developer cartridge 5 is replenished to the developing container 2.

【００４４】ここで、この現像剤カートリッジ５は図４
に示すように略円筒形状を有しており、この現像剤カー
トリッジ５を画像形成装置に装着する際は、まず装置手
前側から現像剤カートリッジ５を挿入し、次に手前側の
把手５ａを右側にひねることで現像剤カートリッジ５を
回転させるようにしている。これにより、現像剤供給口
６が開口し、現像容器２内への現像剤の補給が可能にな
る。The developer cartridge 5 is shown in FIG.
The developer cartridge 5 has a substantially cylindrical shape as shown in FIG. 2, and when the developer cartridge 5 is mounted on the image forming apparatus, first the developer cartridge 5 is inserted from the front side of the apparatus, and then the front grip 5a is placed on the right side. The developer cartridge 5 is rotated by twisting. As a result, the developer supply port 6 is opened, and the developer can be replenished into the developing container 2.

【００４５】また、現像剤カートリッジ５を画像形成装
置から離脱する際は、把手５ａを左側にひねるようにし
ている。これにより、現像剤供給口６が閉じられ、内包
する粉体が外部に漏れることなく現像剤カートリッジ５
を引き抜くことができる。When the developer cartridge 5 is detached from the image forming apparatus, the handle 5a is twisted to the left. As a result, the developer supply port 6 is closed, and the powder contained therein is prevented from leaking outside to the developer cartridge 5.
Can be pulled out.

【００４６】なお、この現像剤カートリッジ５の補給現
像剤収納室１６の内部には、補給される現像剤を攪拌す
るための攪拌部材７が内蔵されている。ここで、この攪
拌部材７は樹脂フィルム等をらせん状にしたものを剛体
の軸で回転駆動するようにしたものであり、この攪拌部
材７を適宜回転させることで、補給現像剤収納室内の現
像剤を攪拌し、また現像剤の補給を補助することができ
るようになっている。A stirring member 7 for stirring the supplied developer is built in the supply developer storage chamber 16 of the developer cartridge 5. Here, the stirring member 7 is a spiral-shaped resin film or the like which is rotationally driven by a rigid shaft. By appropriately rotating the stirring member 7, the development in the replenishment developer accommodating chamber is performed. The developer can be agitated and the replenishment of the developer can be assisted.

【００４７】即ち、画像形成によって消費された分のト
ナーを含有する分の現像剤を現像容器２内に補給する
際、攪拌部材７が回転すると、現像剤は攪拌部材７の回
転力と重力によって現像剤供給口６を通過して現像剤カ
ートリッジ５から図２に示す現像容器２に配設された補
給スクリュー８へと搬送され、この後、この補給スクリ
ュー８の回転に従い現像容器２内に補給されるようにな
っている。That is, when the stirring member 7 rotates when the developer containing the toner consumed by the image formation is replenished in the developing container 2, the developer is rotated by the rotating force of the stirring member 7 and gravity. It passes through the developer supply port 6 and is conveyed from the developer cartridge 5 to the replenishing screw 8 arranged in the developing container 2 shown in FIG. 2, and then replenished in the developing container 2 according to the rotation of the replenishing screw 8. It is supposed to be done.

【００４８】ところで、本実施の形態において、このよ
うにして現像剤カートリッジ５から現像装置１に補給さ
れる補給現像剤のトナー及びキャリアの混合比は重量比
で９：１程度であるが、特にこの数値に限定されるもの
ではない。即ち、現像容器２内の２成分現像剤の比に対
してトナー量が圧倒的に多く、体積比を考えればトナー
中にキャリアが微量混合されていれば良い。By the way, in the present embodiment, the mixing ratio of the toner and the carrier of the replenishment developer replenished to the developing device 1 from the developer cartridge 5 in this way is about 9: 1 by weight. It is not limited to this value. That is, the toner amount is overwhelmingly large with respect to the ratio of the two-component developer in the developing container 2, and considering the volume ratio, it is sufficient that a small amount of carrier is mixed in the toner.

【００４９】この結果、画像形成によって消費されたト
ナーを補う際には、微量のキャリアも徐々に補給されて
いくことになる。なお、補給される現像剤のキャリアの
比が多くなれば同じ量のトナー補給でキャリアの入れ替
わり量が多くなり、現像装置１内の２成分現像剤はフレ
ッシュな状態に近づくが、その分キャリアの消費量が多
くなり、ランニングコストの高騰を招く。このためそれ
ぞれの装置において適当な混合比を別途定めるのが好ま
しい。As a result, when supplementing the toner consumed by image formation, a small amount of carrier is gradually replenished. It should be noted that if the carrier ratio of the replenished developer increases, the replacement amount of the carrier increases with the same amount of toner replenishment, and the two-component developer in the developing device 1 approaches a fresh state. The amount of consumption increases and the running cost rises. Therefore, it is preferable to separately determine an appropriate mixing ratio in each device.

【００５０】また、トナー（及びキャリア）の補給量は
補給スクリュー８の回転数によっておおよそ定められる
が、この回転数は図示しないトナー補給量制御手段によ
って定められる。The toner (and carrier) replenishment amount is roughly determined by the number of revolutions of the replenishing screw 8. This number of revolutions is determined by a toner replenishment amount control means (not shown).

【００５１】次に、本実施の形態にて用いられる２成分
現像剤について説明する。Next, the two-component developer used in this embodiment will be described.

【００５２】トナーは、結着樹脂、着色剤、そして必要
に応じてその他の添加剤を含む着色樹脂粒子と、コロイ
ダルシリカ微粉末のような外添剤が外添されている着色
粒子とを有している。なお、本実施の形態では、トナー
は負帯電性のポリエステル系樹脂であり、体積平均粒径
は５μｍ以上８μｍ以下が好ましいことから、７．０μ
ｍとした。The toner has colored resin particles containing a binder resin, a colorant, and optionally other additives, and colored particles externally added with an external additive such as colloidal silica fine powder. is doing. In the present embodiment, the toner is a negatively chargeable polyester-based resin, and the volume average particle diameter is preferably 5 μm or more and 8 μm or less.
m.

【００５３】又、キャリアは、例えば表面酸化或は未酸
化の鉄、ニッケル、コバルト、マンガン、クロム、希土
類等の金属及びそれらの合金、或は酸化物フェライト等
が好適に使用化能であり、これらの磁性粒子の製造法は
特に制限されない。そして、キャリアは、重量平均粒径
が２０〜５０μｍ、好ましくは３０〜４０μｍであり、
抵抗率が１０7Ωｃｍ以上、好ましくは１０８Ωｃｍ以
上である。本実施の形態では、１０８Ωｃｍのものを用
いた。As the carrier, for example, surface-oxidized or non-oxidized metals such as iron, nickel, cobalt, manganese, chromium and rare earths and their alloys, or oxide ferrites are preferably usable. The method for producing these magnetic particles is not particularly limited. The carrier has a weight average particle diameter of 20 to 50 μm, preferably 30 to 40 μm,
The resistivity is 10 7 Ωcm or more, preferably 10 8 Ωcm or more. In the present embodiment, the one having 10 8 Ωcm is used.

【００５４】なお、本実施の形態にて用いられるトナー
について、体積平均粒径は以下に示す装置及び方法にて
測定した。The volume average particle diameter of the toner used in this embodiment was measured by the following apparatus and method.

【００５５】測定装置としては、コールターカウンタＴ
Ａ−II型（コールター社製）、個数平均分布、体積平均
分布を出力するためのインターフェース（日科機製）及
びＣＸ−Ｉパーソナルコンピュータ（キヤノン製）を使
用し、電界水溶液として、一級塩化ナトリウムを用いて
調製した１％ＮａＣｌ水溶液を使用した。As a measuring device, a Coulter counter T
A-II type (manufactured by Coulter), an interface (manufactured by Nikkaki) for outputting a number average distribution and a volume average distribution, and a CX-I personal computer (manufactured by Canon) were used. A 1% NaCl aqueous solution prepared with was used.

【００５６】測定方法は以下に示す通りである。即ち、
上記電界水溶液１００〜１５０ｍｌ中に分散剤として界
面活性剤、好ましくはアルキルベンゼンスルホン酸塩を
０．１ｍｌ加え、測定試料を０．５〜５０ｍｇ加える。The measuring method is as follows. That is,
To 100 to 150 ml of the electric field aqueous solution, 0.1 ml of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant, and 0.5 to 50 mg of a measurement sample is added.

【００５７】試料を懸濁した電界水溶液は超音波分散器
で約１〜３分間分散処理を行ない、上記のコールターカ
ウンタＴＡ−II型により、アパーチャーとして１００μ
ｍアパーチャーを用いて２〜４０μｍの粒子の粒度分布
を測定して体積平均分布を求める。こうして求めた体積
平均分布より、体積平均粒径を得る。The electric field aqueous solution in which the sample is suspended is subjected to a dispersion treatment by an ultrasonic disperser for about 1 to 3 minutes, and 100 μm as an aperture by the Coulter Counter TA-II type.
The volume average distribution is determined by measuring the particle size distribution of particles of 2 to 40 μm using the m aperture. The volume average particle size is obtained from the volume average distribution thus obtained.

【００５８】又、本実施の形態にて用いられるキャリア
の抵抗率は、測定電極面積４ｃｍ、電極間間隔０．４ｃ
ｍのサンドイッチタイプのセルを用い、片方の電極に１
ｋｇの重量の加圧下で、両電極間の印加電圧Ｅ（Ｖ／ｃ
ｍ）を印加して、回路に流れた電流から、キャリアの抵
抗率を得る方法によって測定した。The resistivity of the carrier used in this embodiment is as follows: measurement electrode area: 4 cm, electrode spacing: 0.4 c
m sandwich type cell, 1 for one electrode
The applied voltage E (V / c
m) was applied and the resistivity of the carrier was measured from the current flowing in the circuit.

【００５９】ところで、後述するように現像剤カートリ
ッジ５から現像剤を補給する際、必要以上に現像剤が補
給される場合がある。そして、このように必要以上に現
像剤が補給されると、現像剤面が高くなり、現像剤の搬
送及び攪拌が不十分になる。By the way, as will be described later, when replenishing the developer from the developer cartridge 5, the developer may be replenished more than necessary. Then, when the developer is replenished more than necessary in this way, the developer surface becomes high, and the conveyance and stirring of the developer become insufficient.

【００６０】そこで、このように必要以上に現像剤が補
給された場合には、余剰の現像剤を現像容器２から排出
する必要がある。次に、このように余剰の現像剤を現像
容器２から排出する現像剤排出機構について説明する。Therefore, when the developer is replenished more than necessary in this way, it is necessary to discharge the excess developer from the developing container 2. Next, the developer discharging mechanism for discharging the excessive developer from the developing container 2 in this way will be described.

【００６１】本実施の形態において、この現像剤排出機
構は、図５及び既述した図３に示すように、現像室２Ａ
の第１現像剤循環スクリュー２ａの手前側端部に設けた
現像剤循環方向とは逆方向に現像剤を搬送する構成のス
パイラル状の返し部材３１と、余剰現像剤を回収するた
めの余剰現像剤収納部である余剰現像剤回収室２Ｃと、
返し部材３１の２ｍｍ上方に設けられ、現像室２Ａと余
剰現像剤回収室２Ｃとを連通する連通通路３４ａと、余
剰現像剤回収室２Ｃの底面に形成された現像剤排出口１
１と、第１現像剤循環スクリュー２ａの余剰現像剤回収
室延出部分に設けられ、余剰現像剤を現像剤排出口１１
に搬送する搬送部材であるスパイラル形状の余剰現像剤
搬送部材３２と、現像剤排出口１１から排出された余剰
現像剤を収納する現像剤回収容器３３とを備えている。In the present embodiment, this developer discharging mechanism is provided in the developing chamber 2A as shown in FIG. 5 and already described FIG.
Of the first developer circulation screw 2a, the spiral-shaped return member 31 configured to convey the developer in the direction opposite to the developer circulation direction, and the excess development for collecting the excess developer. An excess developer recovery chamber 2C which is an agent storage section,
A communication passage 34a that is provided 2 mm above the return member 31 and connects the developing chamber 2A and the excess developer recovery chamber 2C, and the developer discharge port 1 formed on the bottom surface of the excess developer recovery chamber 2C.
1 and a portion of the first developer circulation screw 2a that extends to the excess developer recovery chamber to remove excess developer from the developer discharge port 11
A spiral-shaped excess developer transport member 32 that is a transport member that transports the excess developer and a developer recovery container 33 that stores the excess developer discharged from the developer discharge port 11 are provided.

【００６２】なお、現像剤循環経路２ｃ内の第１現像剤
循環スクリュー２ａの周面上のスパイラル状の搬送部材
２ａ１と返し部材３１の直径とは等しく、本実施の形態
では１８ｍｍとしている。さらに、本実施の形態の現像
装置１では、図３に示す第１現像剤循環スクリュー２ａ
のスパイラル状の搬送部材間隔Ｄａを１８ｍｍ、第２現
像剤循環スクリュー２ｂのスパイラル状の搬送部材間隔
Ｄｂを２０ｍｍとしている。また、同図において、２０
はスクリュー２ａ，２ｂを支持する支持部材である。The diameters of the spiral carrying member 2a1 and the return member 31 on the peripheral surface of the first developer circulating screw 2a in the developer circulating path 2c are equal, and in the present embodiment, they are 18 mm. Further, in the developing device 1 of the present embodiment, the first developer circulating screw 2a shown in FIG.
The distance Da between the spiral conveying members is 18 mm, and the distance Db between the spiral conveying members of the second developer circulating screw 2b is 20 mm. In addition, in FIG.
Is a support member that supports the screws 2a and 2b.

【００６３】ここで、このように搬送部材間隔が異なる
場合、即ちＤａ＜Ｄｂの関係が満たされている場合、現
像室２Ａにおける現像剤搬送能力が攪拌室２Ｂにおける
現像剤搬送能力よりも劣るため、現像室２Ａにおける現
像剤面高さは、現像室２Ａと攪拌室２Ｂとを連通する不
図示の連通口が設けられている奥側が手前側に比べ若干
高くなる。また、現像室手前側端部では返し部材３１に
より現像剤は滞留気味となるため現像剤面が高くなる。Here, when the distances between the conveying members are different, that is, when the relationship of Da <Db is satisfied, the developer conveying capacity in the developing chamber 2A is inferior to that in the stirring chamber 2B. The height of the developer surface in the developing chamber 2A is slightly higher on the back side than the front side where a communication port (not shown) that connects the developing chamber 2A and the stirring chamber 2B is provided. Further, at the front end of the developing chamber, the developer tends to stay due to the return member 31, so that the developer surface becomes high.

【００６４】この結果、連通通路３４ａの入り口を返し
部材３１の１ｍｍ以上、上方に配設すると、第１現像剤
循環スクリュー２ａは搬送部材２ａ１の全域（最も現像
剤面が低い点Ｐも）が二成分現像剤で覆われるようにな
る。しかし、この連通通路３４ａの入り口を返し部材３
１の３ｍｍ以上高い位置に配設すると、現像室手前の現
像剤面が搬送部材２ａ１よりも３ｍｍ程度高くなり、現
像剤の搬送及び攪拌が不十分になる。As a result, when the entrance of the communication passage 34a is arranged 1 mm or more above the return member 31, the first developer circulation screw 2a covers the entire area of the conveying member 2a1 (even the point P having the lowest developer surface). It comes to be covered with a two-component developer. However, the return member 3 is connected to the entrance of the communication passage 34a.
If it is disposed at a position higher than 3 by 3 mm or more, the developer surface in front of the developing chamber will be higher than the conveying member 2a1 by about 3 mm, and the conveying and stirring of the developer will be insufficient.

【００６５】従って、現像装置１における現像室２Ａの
現像剤面の高さは第１現像剤循環スクリュー２ａの搬送
部材２ａ１よりも所定量高い、即ち第１現像剤循環スク
リュー２ａの搬送部材２ａ１よりも３ｍｍを超えない高
さ範囲とすることが必要である。このため、本実施の形
態においては、連通通路３４ａの入り口を返し部材３１
（又は搬送部材２ａ１）の高さよりも略２ｍｍ上方に配
設するようにしている。Therefore, the height of the developer surface of the developing chamber 2A in the developing device 1 is higher than the conveying member 2a1 of the first developer circulating screw 2a by a predetermined amount, that is, the conveying member 2a1 of the first developer circulating screw 2a. It is necessary to set the height range not to exceed 3 mm. Therefore, in the present embodiment, the return member 31 is provided at the entrance of the communication passage 34a.
(Or, it is arranged approximately 2 mm above the height of the transport member 2a1).

【００６６】なお、本実施の形態では、連通通路３４ａ
の入り口を現像室２Ａにおいて最も現像剤面が低い点Ｐ
近傍に設けて現像剤面高さを規制するようにしているの
で、現像室２Ａにおける現像剤面の低下をより効果的に
防止することができる。In the present embodiment, the communication passage 34a
At the entrance P of the developer chamber 2A where the developer surface is the lowest
Since it is provided in the vicinity to regulate the height of the developer surface, it is possible to more effectively prevent the deterioration of the developer surface in the developing chamber 2A.

【００６７】さらに、本実施の形態の現像装置１では現
像室２Ａと余剰現像剤回収室２Ｃとの間にシール部材１
９を設けて現像剤の漏出を防止している。このため、現
像装置１外への現像剤の排出は連通通路３４ａを介して
のみ行われるようになり、現像室２Ａの現像剤面を高い
精度で所定高さに維持することができる。Further, in the developing device 1 of the present embodiment, the seal member 1 is provided between the developing chamber 2A and the surplus developer collecting chamber 2C.
9 is provided to prevent the developer from leaking. Therefore, the developer is discharged to the outside of the developing device 1 only through the communication passage 34a, and the developer surface of the developing chamber 2A can be maintained at a predetermined height with high accuracy.

【００６８】なお、本実施の形態においては連通通路３
４ａの入り口の位置を上記のように定めたが、現像容器
２の構成、現像剤、第１現像剤循環スクリュー２ａ及び
第２現像剤循環スクリュー２ｂの構成により適宜決定す
ればよい。In this embodiment, the communication passage 3
Although the position of the inlet of 4a is determined as described above, it may be appropriately determined depending on the configuration of the developing container 2, the developer, the configurations of the first developer circulation screw 2a and the second developer circulation screw 2b.

【００６９】ところで、現像装置１が現像動作を行なう
際には、画像形成で消費した分のトナーを含む２成分現
像剤が現像剤カートリッジ５より補給されるが、その
際、重量比で１０％程度のキャリアも補給されるので、
現像装置１内の現像剤量が増加し現像剤面が高くなる。By the way, when the developing device 1 performs the developing operation, the two-component developer containing the toner consumed by the image formation is replenished from the developer cartridge 5, and at that time, the weight ratio is 10%. Since a certain level of carrier is also replenished,
The amount of developer in the developing device 1 increases, and the developer surface becomes higher.

【００７０】そして、このように現像剤面が高くなる
と、やがて第１現像剤循環スクリュー２ａの返し部材３
１と搬送部材２ａ１との搬送方向の違いにより図５に示
すように返し部材３１近傍の現像剤面高さが連通通路３
４ａの入り口より高くなり、この結果、余剰の現像剤ｔ
は連通通路３４ａから余剰現像剤回収室２Ｃに入り込ん
だ後、余剰現像剤搬送経路３４に落下し、さらに余剰現
像剤搬送部材３２により現像剤排出口１１方向へ搬送さ
れる。Then, when the developer surface becomes high in this way, the return member 3 of the first developer circulation screw 2a will eventually appear.
1 and the conveying member 2a1 differ in the conveying direction, the developer surface height in the vicinity of the return member 31 becomes the communication passage 3 as shown in FIG.
4a, which is higher than the entrance of 4a, resulting in excess developer t
After entering the excess developer recovery chamber 2C from the communication passage 34a, drops into the excess developer transport path 34, and is transported toward the developer discharge port 11 by the excess developer transport member 32.

【００７１】ここで、この現像剤排出口１１は現像装置
１の略下方向に着脱自在に装着された現像剤回収容器３
３と、この現像剤回収容器３３に設けられた現像剤回収
口１０を介して連結されており、これにより現像剤排出
口１１へ搬送された余剰現像剤ｔは自重により現像剤回
収口１０から現像剤回収容器３３内に回収される。Here, the developer discharge port 11 is detachably mounted in a substantially downward direction of the developing device 1 and is a developer recovery container 3
3 and the developer recovery port 10 provided in the developer recovery container 33, whereby the excess developer t conveyed to the developer discharge port 11 is discharged from the developer recovery port 10 by its own weight. It is recovered in the developer recovery container 33.

【００７２】このように、本実施の形態において、現像
剤排出機構は、第１現像剤循環スクリュー２ａの周面上
に設けた返し部材３１により余剰現像剤回収室２Ｃに余
剰現像剤ｔを送り込んだ後、この余剰現像剤ｔを余剰現
像剤搬送部材３２により現像剤回収容器３２に排出する
構成であるため、余剰現像剤ｔを排出するための余分な
部材を必要としないシンプルな構成となり、現像装置１
のコスト高騰を防ぐことができる。As described above, in the present embodiment, the developer discharging mechanism sends the excess developer t into the excess developer recovery chamber 2C by the return member 31 provided on the peripheral surface of the first developer circulation screw 2a. After that, since the surplus developer t is discharged to the developer recovery container 32 by the surplus developer transport member 32, a simple structure that does not require an extra member for discharging the surplus developer t is obtained. Developing device 1
It is possible to prevent soaring costs.

【００７３】図６は長期にわたる画像形成において現像
装置１に収容されるトナーの帯電量の推移である。な
お、同図において、（ａ）は本実施の形態のおけるトナ
ー帯電量の推移を示すものであり、（ｂ）、（ｃ）は比
較例としてキャリアの補給及び現像剤の排出を行なわな
い現像装置と、図７に示すような反発磁極の以外の極を
カット極とする現像装置におけるトナー帯電量の推移を
示すものである。FIG. 6 shows the transition of the charge amount of the toner contained in the developing device 1 in the image formation for a long time. In the figure, (a) shows the transition of the toner charge amount in the present embodiment, and (b) and (c) show comparative examples in which the carrier is not replenished and the developer is not discharged. 8A and 8B show changes in the toner charge amount in the apparatus and the developing apparatus in which the poles other than the repulsive magnetic poles as shown in FIG. 7 are cut poles.

【００７４】また、同図中の点線は画像濃度アップや画
像白地部へのトナーかぶり、トナー飛散による画像形成
装置内汚染等の問題が発生するトナー１ｇ当たりの帯電
量の境界値（−１０μＣ／ｇ）であり、この値よりも帯
電量が低下すると、上記問題が発生する。Further, the dotted line in the figure shows the boundary value of the charge amount per 1 g of toner (-10 μC / toner) which causes problems such as an increase in image density, toner fogging on the white background of the image, and contamination of the image forming apparatus due to toner scattering. g), and if the charge amount is lower than this value, the above problem occurs.

【００７５】ここで、キャリアの補給及び現像剤の排出
を行なわない現像装置の場合、（ｂ）のように画像形成
枚数に従って現像剤が劣化するため、トナーの帯電量が
−１０μＣより低下し、画像濃度アップや画像白地部へ
のトナーかぶり、トナー飛散による画像形成装置内汚染
等の問題が発生した。Here, in the case of the developing device which does not replenish the carrier and discharge the developer, the developer deteriorates according to the number of images formed as shown in (b), so that the charge amount of the toner falls below -10 μC. Problems such as increased image density, fogging of toner on the white background of the image, and contamination of the inside of the image forming apparatus due to toner scattering have occurred.

【００７６】また、反発磁極以外の極をカット極とする
現像装置の場合、カット極が現像剤を現像スリーブ３に
引きつける力が著しく大きいため、現像スリーブ３と現
像容器２間における現像剤の圧縮作用が大きくなり、現
像剤が激しく劣化する。そのため、キャリアの補給及び
現像剤の排出を行っても、（ｃ）のように、帯電量が−
１０μＣより低下するので、画像濃度アップや画像白地
部へのトナーかぶり、トナー飛散による画像形成装置内
汚染等の問題が発生した。Further, in the case of a developing device in which a pole other than the repulsive magnetic pole is a cut pole, the cut pole has a remarkably large force to attract the developer to the developing sleeve 3, so that the developer is compressed between the developing sleeve 3 and the developing container 2. The action becomes large, and the developer is severely deteriorated. Therefore, even if the carrier is replenished and the developer is discharged, the charge amount is − as shown in (c).
Since it is lower than 10 μC, problems such as an increase in image density, toner fogging on a white background portion of the image, and contamination in the image forming apparatus due to toner scattering occur.

【００７７】なお、この場合、現像剤カートリッジ５内
に収容される２成分現像剤中のキャリア重量比を２０％
程度とすれば、帯電量が−１０μＣ以下にならず、画像
濃度アップや画像白地部へのトナーかぶり、トナー飛散
による画像形成装置内汚染等の問題が発生することはな
いが、キャリアの消費量が増加するため、ランニングコ
ストの高騰を招く。In this case, the carrier weight ratio in the two-component developer accommodated in the developer cartridge 5 is 20%.
As far as the degree is concerned, the charge amount does not become -10 μC or less, and there is no problem such as image density increase, toner fogging on the white background of the image, and contamination in the image forming apparatus due to toner scattering. Therefore, the running cost rises.

【００７８】一方、本実施の形態の現像装置の場合、反
発極の一方をカット極とする構成であるため、カット極
が現像剤を現像スリーブ３に引きつける力が弱く、現像
スリーブ３と現像容器２間における現像剤の圧縮作用が
小さいので、現像剤の劣化は軽微であり、且つ、キャリ
アの補給及び劣化したキャリアを含む余剰現像剤の排出
を行っているため、トナー帯電量が境界値を下回ること
がなく、上記問題が発生することはない。On the other hand, in the case of the developing device of the present embodiment, since one of the repelling poles is the cut pole, the cut pole has a weak force for attracting the developer to the developing sleeve 3, and the developing sleeve 3 and the developing container. Since the compression effect of the developer between the two is small, the deterioration of the developer is slight, and since the replenishment of the carrier and the discharge of the excess developer including the deteriorated carrier are performed, the toner charge amount reaches the boundary value. It does not fall below the range, and the above problem does not occur.

【００７９】さらに、現像剤回収容器３２は、現像装置
１に着脱自在に装着されているので、現像剤を交換する
場合は、この現像剤回収容器３２の交換作業のみが現像
剤交換作業となるため、メンテナンス性が大幅に向上す
る。Further, since the developer recovery container 32 is detachably attached to the developing device 1, when replacing the developer, only the replacement work of the developer recovery container 32 is the developer replacement work. Therefore, maintainability is significantly improved.

【００８０】また、上記のように現像剤排出機構を構成
することにより、現像室２Ａに収容される現像剤の現像
剤面高さが所定高さに常に維持されるため、現像剤の攪
拌不良及び搬送不良、現像剤の漏出による画像形成装置
内の汚染が起こることはない。さらに、第１現像剤循環
スクリュー２ａの搬送部材全域が常に二成分現像剤に覆
われている状態となり、また第１現像剤循環スクリュー
２ａの回転によるカット極に溜められた現像剤に対する
圧縮ムラが非常に軽微であるため、現像スリーブ３上に
スクリューピッチ状のＭ／Ｓムラが生じることはなく、
黒ベタ画像においてスクリューピッチムラが発生するこ
ともない。Further, by constructing the developer discharging mechanism as described above, the developer surface height of the developer accommodated in the developing chamber 2A is always maintained at a predetermined height, so that the developer is not stirred well. In addition, there is no possibility of contamination in the image forming apparatus due to poor conveyance or developer leakage. Further, the entire area of the conveying member of the first developer circulating screw 2a is always covered with the two-component developer, and the rotation of the first developer circulating screw 2a causes unevenness in compression of the developer accumulated in the cut pole. Since it is extremely small, screw pitch-like M / S unevenness does not occur on the developing sleeve 3,
Screw pitch unevenness does not occur in a black solid image.

【００８１】また、キャリアの帯電量が小さくなる高湿
環境下における長期にわたる画像形成後であっても、第
１現像剤循環スクリュー２ａの搬送部材全域が常に二成
分現像剤に覆われている状態であるため黒ベタ画像にお
いてスクリューピッチムラが発生することもない。Further, even after the image formation for a long time in a high humidity environment in which the charge amount of the carrier is small, the entire conveying member of the first developer circulating screw 2a is always covered with the two-component developer. Therefore, the screw pitch unevenness does not occur in the black solid image.

【００８２】以上説明したように、本実施の形態によれ
ば現像剤の長寿命化及び現像剤の交換が不要であるとい
う高メンテナンス性を有しつつ、図２に示す現像室２Ａ
に収容する現像剤面ｈ１を所定高さに維持することによ
り、画質を損なうことのない画像形成装置を簡易な構成
で提供することができる。As described above, according to the present embodiment, the developing chamber 2A shown in FIG. 2 is provided while maintaining the long life of the developer and the high maintainability that the replacement of the developer is unnecessary.
By maintaining the developer surface h1 housed in the container at a predetermined height, it is possible to provide an image forming apparatus with a simple structure that does not impair the image quality.

【００８３】次に、本発明の第２の実施の形態について
説明する。Next, a second embodiment of the present invention will be described.

【００８４】図８は本実施の形態に係る画像形成装置の
概略構成を説明する図である。なお、同図において、図
１と同一符号は、同一又は相当部分を示しており、また
本実施の形態における現像装置１（１Ｙ，１Ｍ，１Ｃ，
１Ｋ）は既述した第１の実施の形態の現像装置と同様の
構成である。FIG. 8 is a view for explaining the schematic arrangement of the image forming apparatus according to this embodiment. In the figure, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions, and the developing device 1 (1Y, 1M, 1C,
1K) has the same configuration as that of the developing device according to the first embodiment described above.

【００８５】ここで、この画像形成装置は、同図に示す
ように各色のトナー像を形成するためのＹステーショ
ン、Ｍステーション、Ｃステーション、Ｋステーション
が横方向に配置されたタンデム方式のものである。Here, this image forming apparatus is of a tandem type in which Y stations, M stations, C stations, and K stations for forming toner images of respective colors are laterally arranged as shown in FIG. is there.

【００８６】そして、このような画像形成装置におい
て、記録紙２７に画像を形成する場合は、まず各ステー
ションの感光体ドラム２８（２８Ｙ，２８Ｍ，２８Ｃ，
２８Ｋ）上に、第１の実施の形態での説明と同様にして
イエロー、マゼンタ、シアン、ブラックの各色のトナー
像を形成し、この後、各色トナー像を、各ステーション
の転写帯電器２３（２３Ｙ，２３Ｍ，２３Ｃ，２３Ｋ）
によって記録紙２７上に順次重ねて転写する。When forming an image on the recording paper 27 in such an image forming apparatus, first, the photosensitive drums 28 (28Y, 28M, 28C,
28K), toner images of respective colors of yellow, magenta, cyan, and black are formed on the image forming device in the same manner as described in the first embodiment. 23Y, 23M, 23C, 23K)
Are sequentially superposed and transferred onto the recording paper 27.

【００８７】次に、このように各色トナー像が転写され
た記録紙２７を転写ベルト２４から剥離し、この後、こ
のトナー像が転写された記録紙２７を定着器２５に搬送
し、この定着器２５において加圧／加熱することによ
り、記録紙上に永久画像を形成する。なお、各ステーシ
ョンにおいて、転写後に感光体ドラム２８上に残った残
トナーはクリーナー２６（２６Ｙ，２６Ｍ，２６Ｃ，２
６Ｋ）により除去され、次の画像形成に備える。Next, the recording paper 27 on which the toner images of the respective colors have been transferred in this way is separated from the transfer belt 24, and thereafter, the recording paper 27 on which the toner images have been transferred is conveyed to the fixing device 25, and this fixing is performed. By applying pressure / heating in the container 25, a permanent image is formed on the recording paper. At each station, the residual toner remaining on the photosensitive drum 28 after the transfer is cleaned by the cleaner 26 (26Y, 26M, 26C, 2).
6K) to prepare for the next image formation.

【００８８】ここで、本実施の形態の画像形成装置にお
いて長期にわたる画像形成を行なった場合の、トナー帯
電量推移は既述した図６と同様である。つまり、現像装
置１内に収容される現像剤は画像形成枚数に従って劣化
するが、劣化したキャリアを含む余剰現像剤を排出しな
がら、新しいキャリアを含む現像剤を補給するので、同
図の（ａ）のようにトナー帯電量が−１０μＣ／ｇより
低下することがなく、画像濃度アップや画像白地部への
トナーかぶり、トナー飛散による画像形成装置内汚染等
の問題が発生することはない。さらに、現像剤回収容器
３２の交換作業のみが現像剤交換作業となるため、メン
テナンス性が大幅に向上する。Here, the toner charge amount transition when the image formation is performed for a long time in the image forming apparatus of the present embodiment is the same as that in FIG. 6 described above. That is, although the developer accommodated in the developing device 1 deteriorates according to the number of image formed sheets, the developer including the new carrier is replenished while the surplus developer including the deteriorated carrier is discharged. The toner charge amount does not fall below −10 μC / g as in the case of 1), and problems such as image density increase, toner fogging on a white background portion of the image, and contamination of the image forming apparatus due to toner scattering do not occur. Furthermore, since only the replacement work of the developer recovery container 32 is the developer replacement work, the maintainability is greatly improved.

【００８９】また、本画像形成装置では、既述した第１
実施の形態で説明した現像装置１を用いているので、黒
ベタ画像におけるスクリューピッチムラに対する効果も
第１の実施の形態と同様である。つまり、現像室全域に
おける現像剤面高さが所定高さに常に維持されるため、
現像剤の攪拌不良及び搬送不良、現像剤の漏出による画
像形成装置内の汚染が起こることはない。Further, in the present image forming apparatus, the above-mentioned first
Since the developing device 1 described in the embodiment is used, the effect on the screw pitch unevenness in the solid black image is the same as that in the first embodiment. That is, since the developer surface height in the entire developing chamber is always maintained at the predetermined height,
Contamination in the image forming apparatus does not occur due to poor stirring and conveyance of the developer and leakage of the developer.

【００９０】さらに、第１現像剤循環スクリュー２ａの
搬送部材全域が常に二成分現像剤に覆われている状態と
なり、また第１現像剤循環スクリュー２ａの回転による
カット極に溜められた現像剤に対する圧縮ムラが非常に
軽微であるため、現像スリーブ３上にスクリューピッチ
状のＭ／Ｓムラが生じることはなく、黒ベタ画像におい
てスクリューピッチムラが発生することはない。Further, the entire area of the conveying member of the first developer circulating screw 2a is always covered with the two-component developer, and the developer accumulated in the cut pole by the rotation of the first developer circulating screw 2a is Since the compression unevenness is very slight, the screw pitch-like M / S unevenness does not occur on the developing sleeve 3, and the screw pitch unevenness does not occur in the black solid image.

【００９１】また、キャリアの帯電量が小さくなる高湿
環境下における長期にわたる画像形成後であっても、第
１現像剤循環スクリュー２ａの搬送部材全域が常に二成
分現像剤に覆われている状態であるため黒ベタ画像にお
いてスクリューピッチムラが発生することはない。Further, even after the image formation for a long time in a high humidity environment where the charge amount of the carrier becomes small, the entire conveying member of the first developer circulating screw 2a is always covered with the two-component developer. Therefore, the screw pitch unevenness does not occur in the black solid image.

【００９２】以上説明したように、本実施の形態によれ
ば現像剤の長寿命化及び現像剤の交換が不要であるとい
う高メンテナンス性を有しつつ、現像室２Ａに収容する
現像剤面高さを所定高さに維持することにより、画質を
損なうことのない画像形成装置を簡易な構成で提供する
ことができる。As described above, according to the present embodiment, the developer surface height accommodated in the developing chamber 2A is high while maintaining the long life of the developer and the need for replacement of the developer. By maintaining the height at a predetermined height, it is possible to provide an image forming apparatus with a simple structure that does not impair image quality.

【００９３】次に、本発明の第３の実施の形態について
説明する。Next, a third embodiment of the present invention will be described.

【００９４】図９は本実施の形態に係る画像形成装置の
概略構成を示す図であり、本画像形成装置は回転現像方
式の現像装置を備えている。なお、同図において、図１
と同一符号は、同一又は相当部分を示している。FIG. 9 is a view showing the schematic arrangement of the image forming apparatus according to this embodiment. This image forming apparatus is equipped with a rotary developing type developing device. In addition, in FIG.
The same reference numerals as in FIG.

【００９５】同図において、１８はブラック用現像装置
１Ｋ、イエロー用現像装置１Ｙ、マゼンタ用現像装置１
Ｍ、シアン用現像装置１Ｃを保持すると共にこれら各現
像装置を順次現像位置に回転移動させる回転体であり、
この回転体１８の回転軸１８ａは図示しないモータによ
り自在に回転可能である。In the figure, 18 is a developing device 1K for black, a developing device 1Y for yellow, and a developing device 1 for magenta.
M is a rotating body for holding the cyan developing device 1C and rotating and moving each of these developing devices in sequence to a developing position.
The rotating shaft 18a of the rotating body 18 can be freely rotated by a motor (not shown).

【００９６】そして、例えば感光体ドラム２８上にブラ
ックのトナー像を形成する時は、感光体ドラム２８と近
接する現像位置Ｐ１でブラック用現像装置１Ｋにより現
像を行い、同様にイエローのトナー像を形成する時は、
回転体１８を９０°回転して現像位置Ｐ１にイエロー用
現像装置１Ｙを配置させ、現像を行なう。また、マゼン
タ、シアンのトナー像形成も同様にして行なうようにし
ている。Then, for example, when a black toner image is formed on the photosensitive drum 28, development is performed by the black developing device 1K at the developing position P1 which is close to the photosensitive drum 28, and a yellow toner image is similarly formed. When forming,
The rotating body 18 is rotated by 90 °, the yellow developing device 1Y is arranged at the developing position P1, and development is performed. Further, magenta and cyan toner images are similarly formed.

【００９７】次に、フルカラーの画像形成を行なう場合
の画像形成装置全体の動作について説明する。Next, the operation of the entire image forming apparatus when forming a full-color image will be described.

【００９８】まず、一次帯電器２１によって帯電された
感光体ドラム２８表面を露光手段２２によって露光する
ことで感光体ドラム２８上に静電潜像を形成する。次
に、この静電潜像をブラック用現像装置１Ｋにより現像
して感光体ドラム２８上にブラックのトナー像を形成
し、この後、このブラックのトナー像を第１転写帯電器
２３ａによる第１転写バイアスによって中間転写ベルト
２４ａ上に一次転写する。First, the surface of the photosensitive drum 28 charged by the primary charger 21 is exposed by the exposing means 22 to form an electrostatic latent image on the photosensitive drum 28. Next, this electrostatic latent image is developed by the black developing device 1K to form a black toner image on the photoconductor drum 28, and then this black toner image is first transferred by the first transfer charger 23a. Primary transfer is performed on the intermediate transfer belt 24a by the transfer bias.

【００９９】次に、回転体１８を９０°回転させてイエ
ロー現像装置１Ｙを現像位置Ｐ１に配置し、このイエロ
ー現像装置１Ｙにより静電潜像を現像して感光体ドラム
２８上にイエローのトナー像を形成する。そして、この
トナー像を第１転写帯電器２３ａによる第１転写バイア
スによって中間転写ベルト２４ａ上に既に転写されてい
るブラックのトナー像上に一次転写し、重ね合わせる。Next, the rotator 18 is rotated 90 ° to dispose the yellow developing device 1Y at the developing position P1, the electrostatic latent image is developed by the yellow developing device 1Y, and the yellow toner is transferred onto the photosensitive drum 28. Form an image. Then, this toner image is primarily transferred onto the black toner image already transferred onto the intermediate transfer belt 24a by the first transfer bias by the first transfer charger 23a, and is superposed.

【０１００】さらに、この後、この動作をマゼンタ用現
像装置１Ｍ、シアン用現像装置１Ｃにおいても順次行な
い、中間転写ベルト２４ａ上に既に転写されているブラ
ック及びイエローのトナー像上にマゼンタ及びシアンを
重ね合わせて所望のフルカラー画像を形成する。Further, thereafter, this operation is also sequentially performed in the magenta developing device 1M and the cyan developing device 1C, and magenta and cyan are transferred onto the black and yellow toner images already transferred onto the intermediate transfer belt 24a. Overlay to form the desired full color image.

【０１０１】次に、第２転写帯電器２３ｂによる第２転
写バイアスにより、中間転写ベルト２４ａ上のフルカラ
ー画像を一括して転写紙搬送ベルト２９上の記録紙２７
上に二次転写する。そして、このようにフルカラー画像
が一括転写された記録紙２７を転写紙搬送ベルト２９か
ら剥離した後、定着装置２５に搬送し、この定着装置２
５によってフルカラー画像を加圧／加熱することによ
り、記録紙２７上に永久画像を形成する。Next, the full-color images on the intermediate transfer belt 24a are collectively recorded by the second transfer bias by the second transfer charger 23b on the recording paper 27 on the transfer paper transport belt 29.
Secondary transfer on top. Then, after the recording paper 27 to which the full-color image has been collectively transferred in this way is separated from the transfer paper carrying belt 29, it is carried to the fixing device 25, and the fixing device 2
A permanent image is formed on the recording paper 27 by pressing / heating the full-color image by the method 5.

【０１０２】なお、一次転写後に感光体ドラム２８上に
残ったトナーは第１クリーナ２６ａにより除去され、さ
らに二次転写後に中間転写ベルト２４ａ上に残ったトナ
ーは第２クリーナ２６ｂにより除去され、次の画像形成
に備える。The toner remaining on the photosensitive drum 28 after the primary transfer is removed by the first cleaner 26a, and the toner remaining on the intermediate transfer belt 24a after the secondary transfer is removed by the second cleaner 26b. Prepare for image formation.

【０１０３】一方、単色の画像形成を行なう場合は、所
望のトナーを収容する現像装置１により感光体ドラム２
８上に形成されたトナー像を、中間転写ベルト２４ａ上
に一次転写した後、すぐに記録紙２７上に二次転写す
る。そして、この後、トナー像が転写された記録紙２７
を転写紙搬送ベルト２９から剥離して定着装置２５に搬
送し、この定着装置２５によってトナー像を加圧／加熱
することにより、記録紙２７上に永久画像を形成する。On the other hand, when a monochromatic image is formed, the photoconductor drum 2 is moved by the developing device 1 containing the desired toner.
After the primary transfer of the toner image formed on the intermediate transfer belt 24a to the intermediate transfer belt 24a, the secondary transfer to the recording paper 27 is immediately performed. Then, after this, the recording paper 27 on which the toner image is transferred
Is separated from the transfer paper conveyance belt 29 and conveyed to the fixing device 25, and the fixing device 25 pressurizes / heats the toner image to form a permanent image on the recording paper 27.

【０１０４】ところで、このような構成の画像形成装置
の各現像装置１は、それぞれ現像剤カートリッジ５Ａを
備えている。ここで、本実施の形態において、この現像
剤カートリッジ５Ａの内部は図１０に示すように隔壁１
５によって現像装置１に補給する補給現像剤を収容する
と共に現像剤供給口６を有する補給現像剤収納室１６
と、現像装置１から排出された排出現像剤を収容すると
共に現像剤回収口１０を有する排出現像剤収納室１７と
に二分されている。By the way, each developing device 1 of the image forming apparatus having such a structure is provided with a developer cartridge 5A. Here, in the present embodiment, the inside of the developer cartridge 5A has a partition wall 1 as shown in FIG.
A replenishment developer accommodating chamber 16 for accommodating replenishment developer to be replenished to the developing device 1 by 5 and having a developer supply port 6.
And a discharged developer storage chamber 17 that stores the discharged developer discharged from the developing device 1 and that has the developer recovery port 10.

【０１０５】なお、同図において、把手５ａに近い方が
排出現像剤収納室１７、遠い方が補給現像剤収納室１６
である。また、この補給現像剤のトナー及びキャリアの
混合比は重量比で９：１程度であるが、特にこの数値に
限定されるものではなく、それぞれの装置において適当
な混合比を別途定めるのが好ましい。In the figure, the discharged developer storage chamber 17 is closer to the handle 5a, and the replenishment developer storage chamber 16 is farther from the handle 5a.
Is. The mixing ratio of the toner and carrier of the replenishment developer is about 9: 1 by weight, but the mixing ratio is not particularly limited to this value, and it is preferable to separately determine an appropriate mixing ratio in each device. .

【０１０６】さらに、現像剤カートリッジ内には、補給
現像剤を現像剤供給口６方向へ、排出現像剤を現像剤回
収口１０と反対方向へ搬送するための搬送部材７が内蔵
されている。ここで、この攪拌部材７は、樹脂フィルム
等を螺旋状にしたものを剛体の軸で回転駆動するように
したもので、適宜回転することで現像剤カートリッジ５
内の現像剤を搬送するようになっている。Further, in the developer cartridge, a carrying member 7 for carrying the replenished developer in the direction of the developer supply port 6 and the discharged developer in the direction opposite to the developer recovery port 10 is built in. Here, the agitating member 7 is made by spirally rotating a resin film or the like so as to be rotationally driven by a rigid shaft, and by appropriately rotating the developer cartridge 5
The developer inside is conveyed.

【０１０７】なお、この現像剤カートリッジ５Ａを装着
する際は、まず回転体１８に手前側から現像剤カートリ
ッジ５Ａを挿入し、次に手前側の把手５ａを右側にひね
ることで現像剤カートリッジ５Ａを回転させるようにし
ている。これにより、現像剤供給口６及び現像剤回収口
１０が開口する。また、現像剤カートリッジ５Ａを画像
形成装置から離脱する際は、把手５ａを左側にひねるよ
うにしている。これにより、現像剤供給口６及び現像剤
回収口１０が閉じられ、内包する粉体が外部に漏れるこ
となく現像剤カートリッジ５を引き抜くことができる。When the developer cartridge 5A is mounted, first the developer cartridge 5A is inserted into the rotating body 18 from the front side, and then the front grip 5a is twisted to the right side so that the developer cartridge 5A is mounted. I try to rotate it. As a result, the developer supply port 6 and the developer recovery port 10 are opened. Further, when the developer cartridge 5A is detached from the image forming apparatus, the handle 5a is twisted to the left. As a result, the developer supply port 6 and the developer recovery port 10 are closed, and the developer cartridge 5 can be pulled out without the powder contained therein leaking to the outside.

【０１０８】一方、本実施の形態においても、必要以上
に現像剤が補給された場合には、余剰の現像剤を現像容
器２から排出する必要がある。次に、このように余剰の
現像剤を現像容器２から排出する現像剤排出機構につい
て図１１及び図１２を用いて説明する。なお、図１１は
現像装置１を長手方向手前側から見た図、図１２は現像
装置１の要部側面断面図である。また、図１１及び図１
２において、既述した図２及び図５と同一符号は、同一
又は相当部分を示している。On the other hand, also in the present embodiment, when the developer is replenished more than necessary, it is necessary to discharge the excess developer from the developing container 2. Next, the developer discharging mechanism for discharging the excessive developer from the developing container 2 in this way will be described with reference to FIGS. 11 and 12. Note that FIG. 11 is a view of the developing device 1 as viewed from the front side in the longitudinal direction, and FIG. 12 is a side cross-sectional view of the main parts of the developing device 1. Also, FIG. 11 and FIG.
2, the same reference numerals as those in FIGS. 2 and 5 described above indicate the same or corresponding portions.

【０１０９】本実施の形態に係る現像剤排出機構は、現
像剤循環経路２ｃの現像室手前側端部の返し部材３１
と、この返し部材３１と略２ｍｍの間隔をもって現像剤
循環方向下流側上部に設けられた現像剤排出口１１と、
連通通路である余剰現像剤搬送通路１２から成り、現像
剤排出口１１と現像剤カートリッジ５Ａの現像剤回収口
１０とは余剰現像剤搬送通路１２により通じる構成であ
る。なお、本実施の形態の現像装置１は現像剤排出機構
以外の構成は既述した第１の実施の形態の現像装置と同
様である。The developer discharging mechanism according to the present embodiment has a return member 31 at the front end of the developing chamber of the developer circulation path 2c.
And a developer discharge port 11 provided at an upper portion on the downstream side in the developer circulation direction with a space of approximately 2 mm from the return member 31.
It comprises a surplus developer transport passage 12 which is a communication passage, and the developer discharge port 11 and the developer recovery port 10 of the developer cartridge 5A are communicated by the surplus developer transport passage 12. The developing device 1 of the present embodiment is the same as the developing device of the first embodiment described above except for the developer discharging mechanism.

【０１１０】つまり、第１現像剤循環スクリュー２ａの
搬送部材間隔Ｄａを１８ｍｍ、第２現像剤循環スクリュ
ー２ｂの搬送部材間隔Ｄｂを２０ｍｍとして現像室２Ａ
における現像剤面高さを奥側が手前側に比べ若干高く
し、また現像室手前側端部では返し部材３１により現像
剤が滞留気味となるようにして現像剤面を高くしてい
る。That is, the distance Da between the conveying members of the first developer circulating screw 2a is 18 mm, and the distance Db between the conveying members of the second developer circulating screw 2b is 20 mm.
The height of the developer surface is slightly higher on the back side than on the front side, and at the end on the front side of the developing chamber, the developer surface is raised by the return member 31 so that the developer tends to stay.

【０１１１】そして、このように構成した場合、現像剤
排出口１１を返し部材３１の１ｍｍ以上上方に配設する
と、第１現像剤循環スクリュー２ａは搬送部材２ａ１の
全域（最も現像剤面が低い点Ｐも）が二成分現像剤で覆
われるようになる。しかし、現像剤排出口１１を返し部
材３１の３ｍｍ以上高い位置に配設すると、現像室奥側
の現像剤面が搬送部材よりも３ｍｍ程度高くなり、現像
剤の搬送及び攪拌が不十分になる。In such a structure, if the developer discharge port 11 is arranged at least 1 mm above the return member 31, the first developer circulation screw 2a will cover the entire area of the conveying member 2a1 (the developer surface is the lowest). The point P as well) is covered with the two-component developer. However, when the developer discharge port 11 is arranged at a position higher than the return member 31 by 3 mm or more, the developer surface on the inner side of the developing chamber is about 3 mm higher than the conveying member, and the conveying and stirring of the developer become insufficient. .

【０１１２】従って、本実施の形態の場合も、現像装置
１における現像室２Ａの現像剤面の高さは第１現像剤循
環スクリュー２ａの搬送部材２ａ１よりも所定量高い、
即ち第１現像剤循環スクリュー２ａの搬送部材２ａ１よ
りも３ｍｍを超えない高さ範囲とすることが必要であ
る。このため、本実施の形態においては、連通通路３４
ａの入り口を返し部材３１（又は搬送部材２ａ１）の高
さよりも略２ｍｍ上方に配設するようにしている。Therefore, also in the case of the present embodiment, the height of the developer surface of the developing chamber 2A in the developing device 1 is higher than the conveying member 2a1 of the first developer circulating screw 2a by a predetermined amount.
That is, it is necessary to set the height range of the first developer circulation screw 2a so as not to exceed 3 mm from the conveying member 2a1. Therefore, in the present embodiment, the communication passage 34
The entrance a is arranged approximately 2 mm above the height of the return member 31 (or the transport member 2a1).

【０１１３】また、本実施の形態では、現像剤排出口１
１を現像室２Ａにおいて最も現像剤面が低い点Ｐ近傍に
設けて現像剤面高さを規制しているため、現像室２Ａに
おける現像剤面の低下をより効果的に防止することがで
きる。なお、本実施の形態においては現像剤排出口１１
の位置を上記のように定めたが、現像容器の構成、現像
剤、第１現像剤循環スクリュー及び第２現像剤循環スク
リューの構成により適宜決定すればよい。Further, in the present embodiment, the developer discharge port 1
1 is provided in the vicinity of the point P where the developer surface is the lowest in the developing chamber 2A to regulate the height of the developer surface, so that the deterioration of the developer surface in the developing chamber 2A can be prevented more effectively. In this embodiment, the developer discharge port 11
Although the position is defined as described above, it may be appropriately determined depending on the configuration of the developing container, the developer, the configurations of the first developer circulation screw and the second developer circulation screw.

【０１１４】次に、現像装置１内の余剰現像剤の排出及
び回収方法をブラック用現像装置１Ｋを例として図１３
及び図１４を用いて説明する。なお、イエロー用現像装
置１Ｙ、マゼンタ用現像装置１Ｍ、シアン用現像装置１
Ｃの余剰現像剤の排出及び回収方法もブラック用現像装
置１Ｋと同様である。Next, the method for discharging and collecting the excess developer in the developing device 1 will be described with reference to the black developing device 1K as an example.
And FIG. 14 will be described. Incidentally, the yellow developing device 1Y, the magenta developing device 1M, and the cyan developing device 1
The method of discharging and collecting the excessive developer of C is the same as that of the black developing device 1K.

【０１１５】ブラック用現像装置１Ｋが現像位置Ｐ１に
おいて現像動作を行なう際には、画像形成で消費した分
のトナーを含む２成分現像剤がブラック用現像剤カート
リッジ５Ｋより補給されるが、その際、重量比で１０％
程度のキャリアも補給されるので、ブラック用現像装置
１Ｋ内の現像剤量が増加し、現像剤面が高くなる。When the black developing device 1K performs the developing operation at the developing position P1, the two-component developer containing the toner consumed by the image formation is replenished from the black developer cartridge 5K. , 10% by weight
Since a certain amount of carrier is also replenished, the amount of developer in the black developing device 1K increases, and the developer surface becomes higher.

【０１１６】ここで、このように現像剤面が高くなる
と、現像剤排出口１１は第１現像剤循環スクリュー２ａ
より略１ｍｍ上方に配設されているので、第１現像剤循
環スクリュー２ａより略１ｍｍ上方の余剰現像剤ｔは、
図１３の（ａ）に示すように現像剤排出口内に回収され
る。Here, when the developer surface becomes higher in this way, the developer discharge port 11 is connected to the first developer circulation screw 2a.
Since it is disposed approximately 1 mm above, the excess developer t approximately 1 mm above the first developer circulation screw 2a is
As shown in FIG. 13A, the toner is collected in the developer discharge port.

【０１１７】一方、ブラック用現像装置１Ｋの現像動作
が終了すると、次色のイエロー用現像装置１Ｙによる現
像動作に備えて、回転体１８は略９０°回転し、ブラッ
ク用現像装置１Ｋは、既述した図９に示すＰ２の位置に
移動する。このとき、現像剤排出口１１近傍の余剰現像
剤は回転体１８の回転動作による重力作用方向の変化に
より、図１３の（ｂ）に示すように現像剤搬送通路１２
に搬送される。On the other hand, when the developing operation of the black developing device 1K is completed, the rotary member 18 is rotated by about 90 ° in preparation for the developing operation of the next color yellow developing device 1Y, and the black developing device 1K is already in operation. It moves to the position of P2 shown in FIG. 9 described above. At this time, the excess developer in the vicinity of the developer discharge port 11 changes in the direction of gravitational force due to the rotating operation of the rotating body 18, and as shown in FIG.
Be transported to.

【０１１８】次に、イエロー用現像装置１Ｙの現像動作
が終了すると、次色のシアン用現像装置１Ｃによる現像
動作に備えて、回転体１８は略９０°回転し、これに伴
いブラック用現像装置１Ｋは、既述した図９に示すＰ３
の位置に移動する。この時、現像剤搬送通路１２の余剰
現像剤ｔは自重により、図１４の（ａ）に示すように現
像剤搬送通路１２に沿ってブラック用現像剤カートリッ
ジ５Ｋの現像剤回収口１０から排出現像剤収納室１７に
収容される。Next, when the developing operation of the yellow developing device 1Y is completed, the rotator 18 rotates about 90 ° in preparation for the developing operation of the cyan developing device 1C for the next color, and the black developing device accordingly. 1K corresponds to P3 shown in FIG. 9 described above.
Move to position. At this time, due to its own weight, the excess developer t in the developer transport passage 12 is discharged and developed from the developer recovery port 10 of the black developer cartridge 5K along the developer transport passage 12 as shown in FIG. It is stored in the agent storage chamber 17.

【０１１９】次に、このように現像剤搬送通路１２の余
剰現像剤が排出現像剤収納室１７に収容された後、ブラ
ック用現像装置１Ｋは既述した図９に示すＰ４の位置に
移動する。そして、この位置に移動した際、図１４の
（ｂ）に示すように余剰現像剤は全て排出され、ブラッ
ク用現像装置１Ｋは次の現像及びトナー補給に備える。Next, after the surplus developer in the developer transport passage 12 is stored in the discharged developer storage chamber 17, the black developing device 1K moves to the position P4 shown in FIG. 9 described above. . Then, when it moves to this position, as shown in FIG. 14B, all the excess developer is discharged, and the black developing device 1K prepares for the next development and toner replenishment.

【０１２０】なお、本実施の形態の画像形成装置におい
て長期にわたる画像形成を行なった場合の、トナー帯電
量推移は既述した図６で示した第１の実施の形態の場合
と同様である。つまり、現像装置１内に収容される現像
剤は画像形成枚数に従って劣化するが、劣化したキャリ
アを含む現像剤を排出しながら、新しいキャリアを含む
現像剤を補給するので、図６（ａ）のようにトナー帯電
量が−１０μＣ／ｇより低下することがなく、画像濃度
アップや画像白地部へのトナーかぶり、トナー飛散によ
る画像形成装置内汚染等の問題が発生することはない。The toner charge amount transition when the image forming apparatus of the present embodiment forms an image for a long time is the same as that of the first embodiment shown in FIG. 6 described above. That is, although the developer accommodated in the developing device 1 deteriorates according to the number of images formed, the developer containing the deteriorated carrier is discharged and the developer containing the new carrier is replenished. As described above, the toner charge amount does not fall below −10 μC / g, and there is no problem such as image density increase, toner fogging on a white background portion of the image, and contamination of the image forming apparatus due to toner scattering.

【０１２１】さらに、現像剤カートリッジ５Ａの交換作
業のみが現像剤交換作業となるため、メンテナンス性が
大幅に向上している。また、上記のように本発明におけ
る画像形成装置では、現像室に収容される現像剤の現像
剤面高さが所定高さに常に維持されるため、攪拌不良及
び搬送不良、現像剤の漏出による画像形成装置内の汚染
が起こることはない。Further, since only the replacement work of the developer cartridge 5A is the developer replacement work, the maintainability is greatly improved. Further, as described above, in the image forming apparatus of the present invention, the developer surface height of the developer accommodated in the developing chamber is always maintained at a predetermined height, so that agitation failure, conveyance failure, and developer leakage may occur. No contamination of the image forming device occurs.

【０１２２】さらに、第１現像剤循環スクリュー２ａの
搬送部材全域が常に二成分現像剤に覆われている状態と
なり、また第１現像剤循環スクリュー２ａの回転による
カット極に溜められた現像剤に対する圧縮ムラが非常に
軽微であるため、現像スリーブ３上にスクリューピッチ
状のＭ／Ｓムラが生じることはなく、黒ベタ画像におい
てスクリューピッチムラが発生することはない。Further, the entire area of the conveying member of the first developer circulating screw 2a is always covered with the two-component developer, and the developer accumulated at the cut pole due to the rotation of the first developer circulating screw 2a is Since the compression unevenness is very slight, the screw pitch-like M / S unevenness does not occur on the developing sleeve 3, and the screw pitch unevenness does not occur in the black solid image.

【０１２３】また、キャリアの帯電量が小さくなる高湿
環境下における長期にわたる画像形成後であっても、第
１現像剤循環スクリュー２ａの搬送部材全域が常に二成
分現像剤に覆われている状態であるため黒ベタ画像にお
いてスクリューピッチムラが発生することはない。Further, even after the image formation for a long period of time in a high humidity environment where the charge amount of the carrier is small, the entire conveying member of the first developer circulating screw 2a is always covered with the two-component developer. Therefore, the screw pitch unevenness does not occur in the black solid image.

【０１２４】以上説明したように、本実施の形態によっ
て、現像剤の長寿命化及び現像剤の交換が不要であると
いう高メンテナンス性を有しつつ、現像室に収容する現
像剤面高さを所定高さに維持することにより、画質を損
なうことのない画像形成装置を簡易な構成で実現し提供
することができる。As described above, according to the present embodiment, the developer surface height accommodated in the developing chamber can be increased while maintaining the long life of the developer and the need for replacement of the developer. By maintaining the height at a predetermined level, it is possible to realize and provide an image forming apparatus with a simple structure that does not impair image quality.

【０１２５】なお、これまでは第１〜第３の実施の形態
によって本発明の画像形成装置を説明したが、本発明
は、これら各実施の形態で用いた現像装置、現像剤及び
画像形成装置の構成に限ったものではなく、本発明の提
案に従ってさまざまな構成をとることが可能であること
は言うまでもない。Although the image forming apparatus of the present invention has been described with reference to the first to third embodiments, the present invention is not limited to the developing device, the developer and the image forming apparatus used in each of these embodiments. It is needless to say that the present invention is not limited to the above configuration, and various configurations can be taken according to the proposal of the present invention.

【０１２６】[0126]

【発明の効果】以上説明したように本発明によれば、現
像剤収納部に収納された現像剤のうちの余剰現像剤を現
像剤排出機構によって現像剤の剤面高さが攪拌搬送部材
を所定量だけ覆う高さとなるように排出することによ
り、高メンテナンス性を有しつつ、現像剤面高さを所定
の高さに保つことができる。さらに、このように現像剤
面高さを所定の高さに保つことにより、画質を損なうこ
とのない画像形成装置を簡易な構成で提供することがで
きる。As described above, according to the present invention, the surplus developer of the developer stored in the developer storage portion is removed by the developer discharging mechanism so that the developer surface height of the developer is agitated and conveyed. By discharging the developer so that the height of the developer covers a predetermined amount, it is possible to maintain the developer surface height at a predetermined height while maintaining high maintainability. Furthermore, by maintaining the developer surface height at a predetermined height in this way, it is possible to provide an image forming apparatus that does not impair image quality with a simple configuration.

【図面の簡単な説明】[Brief description of drawings]

【図１】本発明の第１の実施の形態に係る画像形成装置
の概略構成を示す図。FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus according to a first embodiment of the present invention.

【図２】上記画像形成装置の現像装置を長手方向手前側
から見た図。FIG. 2 is a diagram of the developing device of the image forming apparatus as viewed from the front side in the longitudinal direction.

【図３】上記現像装置を上方から見た図。FIG. 3 is a view of the developing device seen from above.

【図４】上記現像装置に着脱自在に装着された現像剤カ
ートリッジの一部断面概略斜視図。FIG. 4 is a partial cross-sectional schematic perspective view of a developer cartridge detachably attached to the developing device.

【図５】上記現像装置に設けられた現像剤排出機構を説
明する図。FIG. 5 is a diagram illustrating a developer discharging mechanism provided in the developing device.

【図６】上記現像装置に収容されるトナーの長期にわた
る画像形成中における帯電量の変化を説明する図。FIG. 6 is a diagram illustrating a change in a charge amount of a toner contained in the developing device during image formation for a long period of time.

【図７】上記現像装置の比較例を説明する図。FIG. 7 illustrates a comparative example of the developing device.

【図８】本発明の第２の実施の形態に係る画像形成装置
の概略構成を示す図。FIG. 8 is a diagram showing a schematic configuration of an image forming apparatus according to a second embodiment of the invention.

【図９】本発明の第３の実施の形態に係る画像形成装置
の概略構成を示す図。FIG. 9 is a diagram showing a schematic configuration of an image forming apparatus according to a third embodiment of the invention.

【図１０】上記画像形成装置の現像装置に着脱自在に装
着された現像剤カートリッジの一部断面概略斜視図。FIG. 10 is a partial cross-sectional schematic perspective view of a developer cartridge detachably attached to the developing device of the image forming apparatus.

【図１１】上記現像装置を長手方向手前側から見た図。FIG. 11 is a diagram of the developing device viewed from the front side in the longitudinal direction.

【図１２】上記現像装置に設けられた現像剤排出機構を
説明する図。FIG. 12 is a diagram illustrating a developer discharging mechanism provided in the developing device.

【図１３】上記現像装置の現像剤排出方法を説明する第
１の図。FIG. 13 is a first diagram illustrating a developer discharging method of the developing device.

【図１４】上記現像装置の現像剤排出方法を説明する第
２の図。FIG. 14 is a second diagram illustrating a developer discharging method of the developing device.

【図１５】従来の画像形成装置の現像装置を説明する
図。FIG. 15 is a diagram illustrating a developing device of a conventional image forming apparatus.

【図１６】従来の他の画像形成装置の現像装置を説明す
る図。FIG. 16 is a diagram illustrating a developing device of another conventional image forming apparatus.

【符号の説明】[Explanation of symbols]

１ 現像装置 ２ 現像容器 ２Ａ 現像室 ２Ｂ 攪拌室 ２Ｃ 余剰現像剤回収室 ２ａ 第１現像剤循環スクリュー ２ａ１ 搬送部材 ２ｂ 第２現像剤循環スクリュー ２ｃ 現像剤循環経路 ３ 現像スリーブ ５，５Ａ 現像剤カートリッジ ６ 現像剤供給口 ９ 現像剤補給口 １０ 現像剤回収口 １１ 現像剤排出口 １２ 余剰現像剤搬送通路 １６ 補給現像剤収納室 １７ 排出現像剤収納室 １８ 回転体 ２７ 記録紙 ２８ 感光体ドラム ３１ 返し部材 ３２ 余剰現像剤搬送部材 ３３ 現像剤回収容器 1 Development device 2 Development container 2A development room 2B stirring chamber 2C surplus developer recovery room 2a First developer circulation screw 2a1 transport member 2b Second developer circulation screw 2c Developer circulation path 3 Development sleeve 5,5A developer cartridge 6 Developer supply port 9 Developer supply port 10 Developer collection port 11 Developer outlet 12 Excess developer transport passage 16 Replenishment developer storage room 17 Discharged developer storage room 18 rotator 27 Recording paper 28 Photosensitive drum 31 Return member 32 Excess developer transport member 33 developer collection container

フロントページの続き Ｆターム(参考） 2H030 AB02 BB02 BB22 BB24 BB42 BB43 BB63 2H031 AA06 AB02 AC02 AC08 AC19 AC20 AC30 AD01 AD11 AE01 BA05 BA09 BB01 FA01 2H077 AA01 AB02 AB14 AB15 AB18 AC02 AC16 AD06 AD13 AD16 AD23 AD31 AE06 BA08 CA02 CA19 EA03 GA03 GA13 Continued front page    F term (reference) 2H030 AB02 BB02 BB22 BB24 BB42                       BB43 BB63                 2H031 AA06 AB02 AC02 AC08 AC19                       AC20 AC30 AD01 AD11 AE01                       BA05 BA09 BB01 FA01                 2H077 AA01 AB02 AB14 AB15 AB18                       AC02 AC16 AD06 AD13 AD16                       AD23 AD31 AE06 BA08 CA02                       CA19 EA03 GA03 GA13

Claims (12)

【特許請求の範囲】[Claims] 【請求項１】 トナーとキャリアを含む現像剤を補給す
る現像剤補給部と、現像剤を収納すると共に前記現像剤
補給部から現像剤が補給される現像剤収納部と、前記現
像剤収納部内の現像剤を担持して像担持体に形成された
潜像を現像する現像部へ搬送する現像剤担持体と、前記
現像剤担持体内に固定配置される磁界発生手段と、を有
し、前記現像剤収納部は、前記現像剤担持体を収容する
第１室と、前記第１室との間で現像剤の循環を行う第２
室と、を備える現像装置において、 前記第１及び第２室内にそれぞれ設けられ、現像剤を攪
拌搬送する第１及び第２の攪拌搬送部材と、 前記現像剤収納部内の現像剤のうち余剰現像剤を前記現
像剤収納部外へ排出する現像剤排出機構と、 を有し、 前記磁界発生手段のうちの隣接した同極性の磁極の一つ
を現像層厚を規制する現像剤層厚規制極とし、 前記現像剤排出機構は、前記第１室の現像剤の剤面高さ
が前記第１の攪拌搬送部材を所定量だけ覆うような高さ
となるように前記余剰現像剤を排出することを特徴とす
る現像装置。1. A developer replenishing section for replenishing a developer containing a toner and a carrier, a developer accommodating section for accommodating the developer and replenishing the developer from the developer replenishing section, and an inside of the developer accommodating section. And a magnetic field generating means fixedly arranged in the developer carrying body, the developer carrying body carrying the developer and carrying the latent image formed on the image carrying body to a developing unit for developing the latent image. The developer accommodating portion is configured to circulate the developer between a first chamber accommodating the developer carrier and the first chamber.
A first chamber and a second stirring / conveying member which are respectively provided in the first and second chambers and stir and convey the developer; and a surplus development of the developer in the developer accommodating portion. A developer discharging mechanism for discharging the developer to the outside of the developer accommodating portion, and a developer layer thickness regulating pole for regulating the developing layer thickness of one of the adjacent magnetic poles of the same polarity of the magnetic field generating means. The developer discharging mechanism discharges the excess developer so that the developer surface height of the developer in the first chamber is such that the developer stirring mechanism covers the first stirring and conveying member by a predetermined amount. Characteristic developing device. 【請求項２】 前記現像剤排出機構を前記第１室内に設
けたことを特徴とする請求項１記載の現像装置。2. The developing device according to claim 1, wherein the developer discharging mechanism is provided in the first chamber. 【請求項３】 それぞれスパイラル状の搬送部材を有し
前記現像剤収納部の第１及び第２室に配設された前記第
１及び第２の攪拌搬送部材により現像剤を前記第２室か
ら前記第１室に循環させると共に、前記第１室に配設さ
れる前記第１の攪拌搬送部材の搬送部材の間隔Ｄａと前
記第２室に配設される前記第１の攪拌搬送部材の搬送部
材の間隔ＤｂとがＤａ＜Ｄｂの関係を満たし、且つ前記
現像剤排出機構を前記第１室の現像剤循環方向下流端部
近傍に設けたことを特徴とする請求項２記載の現像装
置。3. The developer is discharged from the second chamber by the first and second agitating and transporting members, each of which has a spiral transport member and is arranged in the first and second chambers of the developer accommodating portion. While being circulated in the first chamber, the distance Da between the conveying members of the first stirring and conveying member arranged in the first chamber and the conveyance of the first stirring and conveying member arranged in the second chamber. 3. The developing device according to claim 2, wherein the distance Db between the members satisfies a relationship of Da <Db, and the developer discharging mechanism is provided near the downstream end of the first chamber in the developer circulation direction. 【請求項４】 前記現像剤排出機構は、前記第１の攪拌
搬送部材に設けられ、前記現像剤循環方向とは逆方向に
現像剤を搬送する構成のスパイラル状の返し部材と、前
記第１室の現像剤循環方向下流に隔設され、前記余剰現
像剤を収納する余剰現像剤収納部と、前記第１室の上部
に設けられ、該第１室と前記余剰現像剤収納部とを連通
する連通通路とを備え、前記スパイラル状の返し部材と
前記攪拌搬送部材の搬送部材との搬送方向の違いにより
前記余剰現像剤を前記連通通路の位置まで上昇させた
後、前記余剰現像剤収納部に向わせるようにしたことを
特徴とする請求項２又は３記載の現像装置。4. The developer discharging mechanism is provided on the first stirring and conveying member, and has a spiral-shaped return member configured to convey the developer in a direction opposite to the developer circulating direction; A surplus developer accommodating portion, which is located downstream of the chamber in the developer circulation direction and accommodates the surplus developer, is provided above the first chamber, and the first chamber communicates with the surplus developer accommodating portion. And a communication path for connecting the spiral-shaped return member and the conveying member of the agitating and conveying member, the surplus developer is raised to the position of the communication passage, and then the surplus developer accommodating portion 4. The developing device according to claim 2, wherein the developing device is directed to the developing device. 【請求項５】 前記余剰現像剤収納部に前記余剰現像剤
を回収する回収容器を着脱自在に設けると共に、前記第
１室の攪拌搬送部材を前記余剰現像剤収納部に延出さ
せ、該攪拌搬送部材の延出部分に前記余剰現像剤収納部
に収納された余剰現像剤を前記回収容器に搬送する搬送
手段を設けたことを特徴とする請求項４記載の現像装
置。5. A recovery container for recovering the excess developer is detachably provided in the excess developer accommodating portion, and the agitating / conveying member of the first chamber is extended to the excess developer accommodating portion for agitating. 5. The developing device according to claim 4, wherein the extension portion of the transport member is provided with a transport unit that transports the excess developer stored in the excess developer storage unit to the recovery container. 【請求項６】 現像装置と、前記現像装置と対を成す１
つの像担持体とを有する画像形成部を備え、前記一対の
像担持体と現像装置とにより単色のトナー画像を形成す
る画像形成装置において、 前記現像装置は前記請求項１乃至５のいずれか１項に記
載のものであることを特徴とする画像形成装置。6. A developing device, and 1 forming a pair with the developing device.
An image forming apparatus having an image forming unit having one image carrier, wherein the pair of image carriers and a developing device form a monochromatic toner image, wherein the developing device is any one of claims 1 to 5. An image forming apparatus according to item 1. 【請求項７】 複数の現像装置と、前記現像装置と対を
成す複数の像担持体とを有する画像形成部を備え、前記
複数対の像担持体と現像装置とにより有彩色のトナー画
像を形成する画像形成装置において、 前記現像装置は前記請求項１乃至５のいずれか１項に記
載のものであることを特徴とする画像形成装置。7. An image forming section having a plurality of developing devices and a plurality of image bearing members forming a pair with the developing devices, wherein a chromatic toner image is formed by the plurality of pairs of image bearing members and the developing devices. An image forming apparatus for forming an image, wherein the developing device is the one according to any one of claims 1 to 5. 【請求項８】 像担持体上に形成された静電潜像をトナ
ー及びキャリアを含む現像剤で現像する複数の現像装置
と、前記複数の現像装置を保持して共通の現像位置へあ
る現像装置を選択的に回転移動させる回転体とを備えた
画像形成装置において、 前記現像装置は、現像剤を補給する現像剤補給部と、現
像剤を収納すると共に前記現像剤補給部から現像剤が補
給される現像剤収納部と、前記現像剤収納部内の現像剤
を前記像担持体に担持搬送する現像剤担持体と、前記現
像剤収納部内の現像剤を前記現像剤担持体に攪拌搬送す
る攪拌搬送部材と、前記現像剤収納部に収納された現像
剤のうちの余剰現像剤を前記現像剤収納部外へ排出する
現像剤排出機構と、を備え、前記現像剤排出機構によ
り、現像剤の剤面高さが前記攪拌搬送部材を所定量だけ
覆うような高さとなるように前記余剰現像剤を排出する
ことを特徴とする画像形成装置。8. A plurality of developing devices for developing an electrostatic latent image formed on an image bearing member with a developer containing a toner and a carrier, and a developing device which holds the plurality of developing devices and is in a common developing position. In an image forming apparatus provided with a rotating body for selectively rotating and moving the apparatus, the developing device stores a developer replenishing section for replenishing the developer, and stores the developer and stores the developer from the developer replenishing section. A developer storage portion to be replenished, a developer carrier for carrying and transporting the developer in the developer storage portion to the image carrier, and a developer in the developer storage portion for stirring and transporting to the developer carrier. A stirring and transporting member; and a developer discharging mechanism for discharging a surplus developer of the developer stored in the developer storing section to the outside of the developer storing section. The material surface height of the agitating and conveying member is a predetermined amount. Image forming apparatus characterized by discharging the surplus developer to have a height such only cover. 【請求項９】 前記現像剤収納部を前記現像剤担持体に
沿って区画して該現像剤担持体に近い第１室と、該現像
剤担持体から遠い第２室とを形成し、前記現像剤排出機
構を前記現像剤収納部の第１室に設けたことを特徴とす
る請求項８記載の画像形成装置。9. The developer accommodating portion is partitioned along the developer carrying body to form a first chamber close to the developer carrying body and a second chamber far from the developer carrying body, The image forming apparatus according to claim 8, wherein a developer discharging mechanism is provided in the first chamber of the developer accommodating portion. 【請求項１０】 前記現像剤収納部の第１及び第２室に
それぞれスパイラル状の搬送部材を有する前記攪拌搬送
部材を配設して現像剤を前記第２室から前記第１室に循
環させると共に、前記第１室に配設される攪拌搬送部材
の搬送部材の間隔Ｄａと前記第２室に配設される攪拌搬
送部材の搬送部材の間隔ＤｂとがＤａ＜Ｄｂの関係を満
たし、且つ前記現像剤排出機構を前記第１室の上方に設
けたことを特徴とする請求項９記載の画像形成装置。10. The developer is circulated from the second chamber to the first chamber by disposing the agitating and transporting member having a spiral transporting member in each of the first and second chambers of the developer accommodating portion. At the same time, the distance Da between the conveying members of the stirring and conveying member arranged in the first chamber and the distance Db between the conveying members of the stirring and conveying member arranged in the second chamber satisfy the relation of Da <Db, and The image forming apparatus according to claim 9, wherein the developer discharging mechanism is provided above the first chamber. 【請求項１１】 前記現像剤排出機構は、前記第１室の
攪拌搬送部材に設けられ、前記現像剤循環方向とは逆方
向に現像剤を搬送する構成のスパイラル状の返し部材
と、前記第１室の現像剤循環方向の下流側上部に設けら
れ、前記現像装置が現像位置にあるとき前記現像剤収納
部の余剰現像剤を貯溜する現像剤排出口と、前記現像剤
排出口と前記現像剤補給部とを連通する連通通路とを備
え、前記スパイラル状の返し部材と前記攪拌搬送部材の
搬送部材との搬送方向の違いにより前記余剰現像剤を前
記連通通路の位置まで上昇させて前記現像剤排出口に貯
留させた後、前記現像動作終了後の前記回転体の回転運
動による重力方向の変化により、前記現像剤排出口内の
余剰現像剤を前記連通通路を経て前記現像剤補給部に収
容することを特徴とする請求項８乃至１０のいずれか１
項に記載の画像形成装置。11. The developer discharging mechanism is provided on a stirring and conveying member of the first chamber, and has a spiral-shaped return member configured to convey the developer in a direction opposite to the developer circulating direction; A developer discharge port for storing excess developer in the developer accommodating portion, the developer discharge port being provided at an upper portion on the downstream side in the developer circulation direction in one chamber, and the developing device being at a developing position. A developing device for raising the surplus developer to the position of the communication passage due to a difference in conveyance direction between the spiral return member and the conveying member of the stirring and conveying member. After being stored in the developer discharge port, the excess developer in the developer discharge port is accommodated in the developer supply unit via the communication passage due to a change in the direction of gravity due to the rotational movement of the rotating body after the completion of the developing operation. Characterized by 11. Any one of claims 8 to 10
The image forming apparatus according to item. 【請求項１２】 前記現像剤補給部は、隔壁により区画
された前記補給現像剤を収容する補給現像剤収納室及び
前記現像装置内の余剰現像剤を収容する排出現像剤収納
室を有していることを特徴とする請求項８乃至１１のい
ずれか１項に記載の画像形成装置。12. The developer replenishing section has a replenishment developer storage chamber for storing the replenishment developer partitioned by a partition wall and a discharge developer storage chamber for storing excess developer in the developing device. The image forming apparatus according to claim 8, further comprising:
JP2001398377A 2001-12-27 2001-12-27 Developing device and image forming apparatus provided with it Pending JP2003195638A (en)

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