JP5637433B2 - Developing device and image forming apparatus - Google Patents

Developing device and image forming apparatus Download PDF

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JP5637433B2
JP5637433B2 JP2010205905A JP2010205905A JP5637433B2 JP 5637433 B2 JP5637433 B2 JP 5637433B2 JP 2010205905 A JP2010205905 A JP 2010205905A JP 2010205905 A JP2010205905 A JP 2010205905A JP 5637433 B2 JP5637433 B2 JP 5637433B2
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developing device
conveyance path
supply
toner
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知也 大村
知也 大村
松本　純一
純一 松本
詫間　康夫
康夫 詫間
菊地　裕
裕 菊地
菜摘 松江
菜摘 松江
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Ricoh Co Ltd
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Description

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

この種の現像装置は、一般に、現像剤担持体の回転軸方向に沿って延在する供給搬送路中を搬送される二成分現像剤（以下、単に「現像剤」という。）を、現像剤担持体の表面に担持させ、現像剤担持体の表面移動により潜像担持体との対向部である現像領域へ供給する。現像領域では、潜像担持体上に形成された潜像を現像してトナー画像として可視化する。現像領域で現像に使用されトナーが消費された現像剤は、現像剤担持体表面上から回収され、補給されるトナーと混合・撹拌され、再び現像に用いられる。
また、このような現像装置では、供給搬送路の搬送方向下流端に到達した現像剤を供給搬送路の搬送方向上流端に搬送する循環搬送路を有する。供給搬送路と循環搬送路とは仕切り部材によって仕切られており、この仕切り部材は搬送方向両端部が開口部となっている。そして、一方の搬送路に下流側端部に到達した現像剤はこの開口部を介して他方の搬送路に受け渡され、現像装置内を現像剤が循環する。 In this type of developing device, generally, a two-component developer (hereinafter simply referred to as “developer”) conveyed in a supply conveyance path extending along the rotation axis direction of the developer carrying member is used as a developer. The toner is carried on the surface of the carrier, and is supplied to the developing region which is a portion facing the latent image carrier by moving the surface of the developer carrier. In the development area, the latent image formed on the latent image carrier is developed and visualized as a toner image. The developer used for development in the development region and consuming the toner is collected from the surface of the developer carrying member, mixed and stirred with the replenished toner, and used again for development.
Further, such a developing device has a circulation conveyance path for conveying the developer that has reached the downstream end in the conveyance direction of the supply conveyance path to the upstream end in the conveyance direction of the supply conveyance path. The supply conveyance path and the circulation conveyance path are partitioned by a partition member, and both ends of the partition member in the transport direction are openings. Then, the developer that has reached the downstream end on one transport path is transferred to the other transport path via this opening, and the developer circulates in the developing device.

このような二成分現像剤を用いる現像装置では、安定したトナー画像を得るために、現像剤中のトナー濃度やトナーの帯電量を一定の範囲に維持することが求められる。現像剤中のトナー濃度は現像で消費したトナー量に応じたトナー量が補給されることにより調整される。トナーの帯電量は、キャリアとトナーとの混合時の摩擦帯電により付与され、十分に混合されることで所望の範囲の帯電量となる。また、現像装置内全体での現像剤中のトナー濃度が所定の範囲内であっても、トナー濃度分布にバラツキがあるとトナー画像の濃度にバラツキが生じるおそれがある。   In a developing device using such a two-component developer, in order to obtain a stable toner image, it is required to maintain the toner concentration in the developer and the charge amount of the toner within a certain range. The toner concentration in the developer is adjusted by replenishing the toner amount corresponding to the toner amount consumed in the development. The charge amount of the toner is applied by frictional charging at the time of mixing the carrier and the toner, and the charge amount in a desired range is obtained by sufficiently mixing. Even if the toner density in the developer in the entire developing device is within a predetermined range, if the toner density distribution varies, the density of the toner image may vary.

供給搬送路と循環搬送路とを備える現像装置としては、供給搬送路から現像スリーブに供給された現像剤が、潜像担持体である感光体と現像スリーブとの対向部である現像領域を通過した後、供給搬送路に受け渡されるものがある。このような現像装置では、供給搬送路の搬送方向下流側端部に到達した現像剤に対して、現像で消費したトナー量に応じたトナー量が補給される。そして、循環搬送路を搬送される間に供給搬送路を通過した現像剤と補給されたトナーとが混合・撹拌され、補給されたトナーの帯電がなされる。
しかしながら、現像領域を通過した現像剤は感光体上の潜像にトナーを供給してトナー濃度が低下した状態であるので、現像領域を通過した現像剤が供給搬送路に戻る現像装置では供給搬送路の搬送方向下流側ほど現像剤中のトナー濃度が低下する。特に高印字率の画像では現像領域を通過する前の現像剤に対して現像領域を通過した後の現像剤のトナー濃度の低下が大きくなる。これにより、供給搬送路の搬送方向下流側のトナー濃度低下が大きくなって、供給搬送路内の上流側の領域と下流側の領域との間で現像剤中のトナー濃度に偏差が生じて、画像濃度にバラツキが発生し、画像品質が低下する問題が生じる。 As a developing device including a supply conveyance path and a circulation conveyance path, the developer supplied from the supply conveyance path to the developing sleeve passes through a development region which is a facing portion between the photosensitive member as the latent image carrier and the development sleeve. After that, there is something that is delivered to the supply conveyance path. In such a developing device, the amount of toner corresponding to the amount of toner consumed in development is supplied to the developer that has reached the downstream end of the supply conveyance path in the conveyance direction. Then, the developer passing through the supply conveyance path and the replenished toner are mixed and stirred while being conveyed through the circulation conveyance path, and the replenished toner is charged.
However, since the developer that has passed through the development area is in a state in which the toner density is reduced by supplying toner to the latent image on the photoreceptor, the developer that has passed through the development area returns to the supply conveyance path and is supplied and conveyed. The toner concentration in the developer decreases toward the downstream side in the conveyance direction of the path. In particular, in an image with a high printing rate, a decrease in the toner density of the developer after passing through the development region is larger than that before passing through the development region. As a result, a decrease in the toner concentration downstream in the conveyance direction of the supply conveyance path is increased, and a deviation occurs in the toner concentration in the developer between the upstream area and the downstream area in the supply conveyance path, There is a problem in that the image density varies and the image quality deteriorates.

供給搬送路内の上流側の領域と下流側の領域とのように、現像剤が循環する方向についての位置が異なる領域間のトナー濃度の偏差は、現像領域でのトナーの消費に起因するものに限るものではない。トナー補給を行うタイミングによってトナーの補給量が異なる場合、補給量が多いタイミングでトナーの補給位置を通過した現像剤と、補給量が少ないタイミングでトナーの補給位置を通過した現像剤との間では、トナー濃度に偏差が生じる。そして、このトナー濃度の偏差が、現像剤が循環する方向についての位置が異なる領域間のトナー濃度の偏差となる。
現像剤を搬送する間に現像剤を撹拌する構成では、トナー濃度が高い領域の現像剤もトナー濃度が低い領域の現像剤も供給搬送路と循環搬送路との間を同じように循環されるため、循環方向の位置が異なる領域間のトナー濃度の偏差を抑制することは困難であった。 Deviation in toner density between areas with different positions in the direction in which the developer circulates, such as upstream and downstream areas in the supply conveyance path, is caused by toner consumption in the development area. It is not limited to. When the toner replenishment amount varies depending on the timing of toner replenishment, between the developer that has passed the toner replenishment position when the replenishment amount is large and the developer that has passed the toner replenishment position when the replenishment amount is small Deviation occurs in the toner density. The deviation of the toner density becomes the deviation of the toner density between the regions having different positions in the direction in which the developer circulates.
In the configuration in which the developer is agitated while the developer is conveyed, the developer in the high toner density region and the developer in the low toner concentration region are circulated in the same manner between the supply conveyance path and the circulation conveyance path. For this reason, it is difficult to suppress a deviation in toner density between regions having different positions in the circulation direction.

特許文献１には、現像領域を通過した現像剤を供給搬送路で回収する構成で、搬送方向の両端部以外の仕切り部材の一部に供給搬送路と循環搬送路とを連通する連通口を設けた構成が記載されている。このような現像装置では、供給搬送路における連通口よりも搬送方向上流側でトナー濃度が低下した現像剤の一部が連通口を介して循環搬送路側に移動する。さらに、トナー補給がされた後にトナーが消費されず、トナー濃度の高い状態の循環搬送路内の現像剤が連通口を介して供給搬送路側に移動する。   Patent Document 1 discloses a configuration in which the developer that has passed through the development region is collected by a supply conveyance path, and a communication port that connects the supply conveyance path and the circulation conveyance path to a part of a partition member other than both ends in the conveyance direction. The provided configuration is described. In such a developing device, a part of the developer whose toner density has decreased on the upstream side in the conveyance direction with respect to the communication port in the supply conveyance path moves to the circulation conveyance path side through the communication port. Further, after the toner is replenished, the toner is not consumed, and the developer in the circulation conveyance path having a high toner concentration moves to the supply conveyance path side through the communication port.

連通口を備えない構成では、２つの搬送路の間を循環する流れが固定されるため、上述したように循環方向の位置が異なる領域間のトナー濃度の偏差を抑制することは困難である。これに対して、特許文献１の現像装置のように、２つの搬送路を連通する連通口を設けることで、一方の搬送路の端部に到達した現像剤が他方の搬送路に受け渡されて循環する流れのほかに、搬送途中に連通口を通過して他方の搬送路に移動する現像剤の流れが生じる。このように、一方の搬送路におけるある領域内の現像剤が連通口より他方の搬送路に移動すると、現像剤の移動元の領域と移動先の領域との間のトナー濃度の差は軽減する。これは、次の理由による。
すなわち、移動元の領域内の現像剤よりも移動先の領域の現像剤の方がトナー濃度が高い場合は、トナー濃度の低い現像剤が連通口より移動してくることで、移動先の現像剤のトナー濃度が下がり、移動元の現像剤のトナー濃度に近づく。同様に、移動元の現像剤よりも移動先の現像剤の方がトナー濃度が低い場合は、トナー濃度の高い現像剤が連通口より移動してくることで、移動先の現像剤のトナー濃度が上昇し、移動元の現像剤のトナー濃度に近づく。これにより、現像剤の移動元の領域と移動先の領域との間のトナー濃度の差を軽減することが出来る。そして、このような連通口を介した現像剤の受け渡しが連続的に繰り返されることで、現像装置内での循環方向の位置が異なる領域間のトナー濃度の偏差を抑制することができる。
また、特許文献１の現像装置では、連通口を設けた位置の供給搬送路と循環搬送路との現像剤のトナー濃度の差を軽減することで、連通口を設けない構成と比較して供給搬送路内の下流側の現像剤のトナー濃度が高くなる。これにより、供給搬送路内の上流側の領域と下流側の領域との間で現像剤中のトナー濃度に偏差が生じることを抑制することができる。 In a configuration that does not include a communication port, the flow that circulates between the two conveyance paths is fixed, and as described above, it is difficult to suppress the deviation in toner density between regions that have different positions in the circulation direction. On the other hand, like the developing device of Patent Document 1, by providing a communication port that communicates two transport paths, the developer that has reached the end of one transport path is transferred to the other transport path. In addition to the flow that circulates, the flow of the developer that passes through the communication port during the conveyance and moves to the other conveyance path is generated. As described above, when the developer in a certain area in one conveyance path moves from the communication port to the other conveyance path, the difference in toner density between the movement source area and the movement destination area is reduced. . This is due to the following reason.
In other words, when the developer in the destination area has a higher toner concentration than the developer in the source area, the developer having a low toner density moves from the communication port, so that the destination developer is developed. The toner concentration of the agent decreases and approaches the toner concentration of the developer at the movement source. Similarly, when the toner density of the destination developer is lower than that of the source developer, the developer having a higher toner density moves from the communication port so that the toner density of the destination developer is increased. Rises and approaches the toner concentration of the developer at the movement source. As a result, the difference in toner density between the movement source area and the movement destination area of the developer can be reduced. Then, the developer transfer via the communication port is continuously repeated, so that a deviation in toner density between regions having different positions in the circulation direction in the developing device can be suppressed.
Further, in the developing device disclosed in Patent Document 1, supply is made in comparison with a configuration in which a communication port is not provided by reducing a difference in developer toner concentration between a supply conveyance path and a circulation conveyance path at a position where the communication port is provided. The toner density of the developer on the downstream side in the conveyance path is increased. Thereby, it is possible to suppress a deviation in the toner density in the developer between the upstream area and the downstream area in the supply conveyance path.

しかしながら、特許文献１の現像装置のように、循環搬送路の搬送方向の途中に設けられた連通口から現像剤を供給搬送路に受け渡す構成では、帯電不足のトナーを含んだ現像剤が現像に用いられるおそれがある。これは、以下の理由による。
すなわち連通口を備えない従来の現像装置では、循環搬送路を搬送される間に供給搬送路を通過した現像剤と補給されたトナーとが混合・撹拌され、補給されたトナーの帯電がなされる。一方、循環搬送路の搬送方向の途中に設けられた連通口から現像剤が供給搬送路に受け渡されると、補給されたトナーと現像剤とが混合・撹拌される機会が減少し、帯電不足のトナーを含んだ現像剤が供給搬送路に受け渡される。その結果、帯電不足のトナーを含んだ現像剤が現像に用いられるおそれが生じる。帯電不足のトナーを含んだ現像剤が現像に用いられると、トナー飛散や地汚れなどの不具合が生じるおそれがある。 However, in a configuration in which the developer is transferred to the supply conveyance path from a communication port provided in the middle of the conveyance direction of the circulation conveyance path, as in the developing device of Patent Document 1, the developer containing insufficiently charged toner is developed. There is a risk of being used. This is due to the following reason.
That is, in a conventional developing device that does not have a communication port, the developer that has passed through the supply conveyance path and the replenished toner are mixed and stirred while being conveyed through the circulation conveyance path, and the replenished toner is charged. . On the other hand, if the developer is transferred to the supply conveyance path from the communication port provided in the middle of the conveyance direction of the circulation conveyance path, the chance that the replenished toner and the developer are mixed and stirred is reduced, and charging is insufficient. The developer containing the toner is transferred to the supply conveyance path. As a result, there is a risk that a developer containing toner that is insufficiently charged is used for development. When a developer containing insufficiently charged toner is used for development, problems such as toner scattering and background contamination may occur.

本発明は以上の問題点に鑑みなされたものであり、その目的は、現像装置内での循環方向の位置が異なる領域間のトナー濃度の偏差を抑制しつつ、帯電不足のトナーを含んだ現像剤が現像に用いられることを防止できる現像装置、及びこの現像装置を備えた画像形成装置を提供することである。   The present invention has been made in view of the above problems, and an object of the present invention is to develop a toner containing insufficiently charged toner while suppressing a deviation in toner density between regions having different positions in the circulation direction in the developing device. It is an object of the present invention to provide a developing device that can prevent an agent from being used for development, and an image forming apparatus including the developing device.

上記目的を達成するために、請求項１の発明は、トナー及び磁性キャリアからなる二成分の現像剤を表面に担持して潜像担持体との対向部である現像領域に搬送する現像剤担持体と、該現像剤担持体の表面に供給する現像剤を収容する現像剤収容部内の現像剤に対して一方向に向かう搬送力を付与する第一搬送部材と、該現像剤収容部内の現像剤に対して該第一搬送部材とは逆方向に向かう搬送力を付与する第二搬送部材と、該現像剤収容部内の現像剤に新たなトナーを補給するトナー補給口とを有し、該第一搬送部材によって現像剤が搬送力を付与される領域である第一搬送路における搬送方向下流側端部に到達した現像剤が該第二搬送部材によって現像剤が搬送力を付与される領域である第二搬送路に受け渡され、該第二搬送路における搬送方向下流側端部に到達した現像剤が該第一搬送路に受け渡されることで該現像剤収容部内を現像剤が循環し、該第一搬送路と該第二搬送路とにおける搬送方向の両端部以外に、該第一搬送路と該第二搬送路とを連通し、現像剤が通過可能な連通部を備える現像装置において、上記第一搬送路と上記第二搬送路とは水平方向に並んで設けられており、上記第一搬送路における搬送方向下流側端部に到達した現像剤と新たに補給されたトナーとを混合・撹拌し、上記第二搬送路に受け渡す撹拌手段を有すると共に、上記撹拌手段によって現像剤を撹拌する領域である撹拌部内の現像剤の剤面の高さ方向の位置が、該撹拌部から上記第二搬送路へ現像剤を受け渡す部分の上端の位置よりも上方となることを特徴とするものである。
また、請求項２の発明は、請求項１の現像装置において、上記第一搬送路及び上記第二搬送路では、上記第一搬送部材及び上記第二搬送部材が上記現像剤担持体の軸線方向に沿って現像剤を搬送することを特徴とするものである。
また、請求項３の発明は、請求項２の現像装置において、上記第一搬送路は、上記第一搬送部材が供給搬送部材として現像剤を搬送しながら上記現像剤担持体に現像剤を供給する供給搬送路であり、上記第二搬送路は、上記第二搬送部材が循環搬送部材として該供給搬送路の搬送方向下流側端部に到達した現像剤を該現像剤担持体の軸線方向に沿って該供給搬送部材とは逆方向に搬送する循環搬送路であって、該供給搬送路から該現像剤担持体の表面上に供給され、上記現像領域を通過した後の該現像剤担持体の表面上に残留する現像剤は、該供給搬送路内に回収されることを特徴とするものである。
また、請求項４の発明は、請求項３の現像装置において、上記供給搬送路と上記循環搬送路とを空間的に仕切る仕切り板を備え、上記連通部は該仕切り板に設けられた開口部であることを特徴とするものである。
また、請求項５の発明は、請求項４の現像装置において、上記開口部は、上記現像剤担持体の軸線方向に複数個配置されていることを特徴とするものである。
また、請求項６の発明は、請求項５の現像装置において、上記開口部の個数が該供給搬送路の搬送方向下流側ほど多いことを特徴とするものである。
また、請求項７の発明は、請求項４乃至６のいずれか１項に記載の現像装置において、上記開口部の開口面積が該供給搬送路の搬送方向下流側ほど広いことを特徴とするものである。
また、請求項８の発明は、請求項３乃至７のいずれか１項に記載の現像装置において、上記供給搬送部材は回転軸に螺旋状の羽部を設けたスクリュ部材からなる供給スクリュであり、該供給スクリュは上記供給搬送路内の現像剤を上記循環搬送路側に受け渡すことを促進する方向に回転することを特徴とするものである。
また、請求項９の発明は、請求項１乃至８のいずれか１項に記載の現像装置において、上記撹拌手段によって現像剤を撹拌する領域である撹拌部から上記第二搬送路へ現像剤を受け渡す部分の上部を仕切り、上記第二搬送路中の現像剤の嵩高さを調節する上部仕切り部材を備えることを特徴とするものである。
また、請求項１０の発明は、請求項１乃至９のいずれか１項に記載の現像装置において、上記第一搬送部材と上記第二搬送部材とは、回転軸に螺旋状の羽部を設けたスクリュ部材であり、該スクリュ部材が回転することにより該回転軸に直交する方向への現像剤の移動を促し、上記第一搬送路と上記第二搬送路との一方の搬送路から他方の搬送路への現像剤の受け渡しを促す受け渡し部材を該スクリュ部材の上記連通部と対向する位置に有することを特徴とするものである。
また、請求項１１の発明は、請求項１乃至１０のいずれか１項に記載の現像装置において、水平方向で、且つ、上記現像剤担持体の軸線方向に直交にする方向である幅方向について、上記撹拌手段によって現像剤を撹拌する領域である撹拌部の幅方向の長さは、上記第一搬送路または上記第二搬送路の一方の搬送路の幅方向の長さよりも大きく、該第一搬送路、該第二搬送路及び現像剤担持体を含む現像部の幅方向の長さよりも小さいことを特徴とするものである。
また、請求項１２の発明は、請求項１乃至１１のいずれか１項に記載の現像装置において、上記第一搬送路から上記撹拌手段によって現像剤を撹拌する領域である撹拌部に受け渡される現像剤の量である撹拌部流入量と、該撹拌部から上記第二搬送路に受け渡される現像剤の量である撹拌部排出量と、該撹拌部に補給されるトナーの量である補給トナー量とが、「撹拌部排出量＝撹拌部流入量＋補給トナー量」の関係にあることを特徴とするものである。
また、請求項１３の発明は、請求項１乃至１２のいずれか１項に記載の現像装置において、上記トナー補給口を上記撹拌手段によって現像剤を撹拌する領域である撹拌部の上部に設けたことを特徴とするものである。
また、請求項１４の発明は、請求項１乃至１３のいずれか１項に記載の現像装置において、上記撹拌手段は回転運動によって下方から上方に現像剤を持ち上げながら撹拌を行う撹拌部材を備えることを特徴とするものである。
また、請求項１５の発明は、請求項１乃至１４のいずれか１項に記載の現像装置において、上記撹拌手段は回転運動によって上記第二搬送路内の現像剤の搬送方向に現像剤を押し動かす撹拌部材を備えることを特徴とするものである。
また、請求項１６の発明は、潜像を担持する潜像担持体と、該潜像担持体に潜像を形成する潜像形成手段と、該潜像担持体上の潜像を現像する現像手段とを有する画像形成装置において、上記現像手段として、請求項１乃至１５のいずれか１項に記載の現像装置を用いたことを特徴とするものである。 In order to achieve the above object, the invention according to claim 1 is a developer carrier for carrying a two-component developer comprising a toner and a magnetic carrier on the surface and transporting the developer to a development area opposite to the latent image carrier. A first conveying member that applies a conveying force in one direction to the developer in the developer accommodating portion that accommodates the developer supplied to the surface of the developer carrying member, and the development in the developer accommodating portion A second conveying member for applying a conveying force to the agent in a direction opposite to the first conveying member, and a toner replenishing port for supplying new toner to the developer in the developer containing portion, Region where the developer reaches the downstream end in the conveyance direction in the first conveyance path, where the developer is given conveyance force by the first conveyance member. Is transferred to the second transport path, and in the second transport path The developer that has reached the downstream end in the feeding direction is transferred to the first transport path so that the developer circulates in the developer accommodating section, and the transport direction in the first transport path and the second transport path In addition to the both end portions of the developing device, the developing device includes a communicating portion that allows the developer to pass through the first conveying path and the second conveying path, and the first conveying path and the second conveying path are horizontal. Stirring means provided side by side in the direction for mixing and stirring the developer that has reached the downstream end in the transport direction in the first transport path and the newly replenished toner, and delivering them to the second transport path And the position in the height direction of the developer surface of the developer in the stirring portion, which is a region where the developer is stirred by the stirring means, is the upper end of the portion that delivers the developer from the stirring portion to the second transport path It is characterized by being above the position of .
According to a second aspect of the present invention, in the developing device according to the first aspect, in the first transport path and the second transport path, the first transport member and the second transport member are in the axial direction of the developer carrier. The developer is conveyed along the line.
According to a third aspect of the present invention, in the developing device according to the second aspect, the first conveying path supplies the developer to the developer carrier while the first conveying member conveys the developer as a supply conveying member. The second conveying path is configured such that the developer that has reached the downstream end in the conveying direction of the supply conveying path as the circulation conveying member is disposed in the axial direction of the developer carrier. And a developer carrying body after being fed from the supply carrying path onto the surface of the developer carrying member and passing through the developing region. The developer remaining on the surface of the toner is collected in the supply conveyance path.
According to a fourth aspect of the present invention, there is provided the developing device according to the third aspect, further comprising a partition plate that spatially partitions the supply transport path and the circulation transport path, wherein the communication portion is an opening provided in the partition plate. It is characterized by being.
According to a fifth aspect of the present invention, in the developing device according to the fourth aspect, a plurality of the openings are arranged in the axial direction of the developer carrier.
According to a sixth aspect of the present invention, in the developing device according to the fifth aspect, the number of the openings is larger on the downstream side in the transport direction of the supply transport path.
The invention according to claim 7 is the developing device according to any one of claims 4 to 6, wherein the opening area of the opening is wider toward the downstream side in the transport direction of the supply transport path. It is.
The invention of claim 8 is the developing device according to any one of claims 3 to 7, wherein the supply conveying member is a supply screw comprising a screw member provided with a spiral wing on a rotating shaft. The supply screw rotates in a direction that facilitates the transfer of the developer in the supply conveyance path to the circulation conveyance path side .
Also, the invention of claim 9, wherein the developing device according to any one of claims 1 to 8, the developer from the stirring unit is an area for agitating the developer by said agitating means the the second transport path An upper partition member is provided for partitioning an upper portion of the transfer portion and adjusting the bulk of the developer in the second transport path.
The invention of claim 10, in the developing device according to any one of claims 1 to 9, said a first conveying member and the second conveying member, a helical blade portion provided on the rotary shaft A screw member that urges the developer to move in a direction perpendicular to the rotation axis by rotating the screw member, and from one transport path of the first transport path and the second transport path to the other. A delivery member that prompts delivery of the developer to the conveyance path is provided at a position facing the communication portion of the screw member.
The invention according to claim 11 is the developing apparatus according to any one of claims 1 to 10 , wherein the width direction is a direction that is in a horizontal direction and orthogonal to the axial direction of the developer carrier. The width in the width direction of the stirring unit, which is a region where the developer is stirred by the stirring means, is greater than the length in the width direction of one of the first transport path or the second transport path, It is characterized in that it is smaller than the length in the width direction of the developing portion including one transport path, the second transport path and the developer carrier .
Also, the invention of claim 12, in the developing device according to any one of claims 1 to 11, transferred to the stirring section is an area for agitating the developer by said agitating means from said first conveying passage The amount of developer that is supplied, the amount of developer that is transferred from the stirring unit to the second transport path, and the amount of developer that is discharged from the stirring unit, and the amount of toner that is replenished to the stirring unit. The replenishment toner amount is characterized in that “stirring portion discharge amount = stirring portion inflow amount + replenishment toner amount”.
According to a thirteenth aspect of the present invention, in the developing device according to any one of the first to twelfth aspects, the toner replenishing port is provided at an upper portion of a stirring portion which is a region where the developer is stirred by the stirring means. It is characterized by this .
Also, the invention of claim 14, in the developing device according to any one of claims 1 to 13, said stirring means comprises a stirring member for stirring while lifting the developer from below upwards by the rotational movement It is characterized by this.
Further, the invention of claim 15 is the developing device according to any one of claims 1 to 14 , wherein the stirring means pushes the developer in the transport direction of the developer in the second transport path by a rotational motion. A moving stirring member is provided.
According to a sixteenth aspect of the present invention, there is provided a latent image carrier for carrying a latent image, latent image forming means for forming a latent image on the latent image carrier, and development for developing the latent image on the latent image carrier. In the image forming apparatus having the above-described means, the developing device according to any one of claims 1 to 15 is used as the developing means.

本発明においては、第一搬送路と第二搬送路との間を現像剤が循環する構成で、第一搬送路と第二搬送路とにおける搬送方向の両端部以外に、第一搬送路と第二搬送路とを連通し、現像剤が通過可能な連通部を備える。よって、上記特許文献１と同様に、現像装置内での循環方向の位置が異なる領域間のトナー濃度の偏差を抑制することができる。さらに、撹拌手段は、第一搬送路における搬送方向下流側端部に到達した現像剤と新たに補給されたトナーとを混合・撹拌し、第二搬送路に受け渡す。このため、新たに補給されたトナーは撹拌手段によって現像剤と混合・撹拌された後に、第一搬送路と第二搬送路とからなる現像剤の循環経路に受け渡される。よって、第一搬送路または第二搬送路から現像剤担持体に供給される現像剤が帯電不足のトナーを含んだ現像剤となることを防止し、帯電不足のトナーを含んだ現像剤が現像に用いられることを防止できる。   In the present invention, the developer circulates between the first conveyance path and the second conveyance path, and in addition to both ends of the conveyance direction in the first conveyance path and the second conveyance path, A communication portion is provided that communicates with the second conveyance path and allows the developer to pass therethrough. Therefore, similarly to the above-described Patent Document 1, it is possible to suppress a deviation in toner density between regions having different positions in the circulation direction in the developing device. Further, the agitation unit mixes and agitates the developer that has reached the downstream end portion in the conveyance direction in the first conveyance path and the newly supplied toner, and delivers them to the second conveyance path. For this reason, the newly replenished toner is mixed and stirred with the developer by the stirring means, and then transferred to the developer circulation path composed of the first transport path and the second transport path. Therefore, the developer supplied to the developer carrying member from the first conveyance path or the second conveyance path is prevented from becoming a developer containing an undercharged toner, and the developer containing an undercharged toner is developed. Can be prevented.

本発明によれば、現像装置内での循環方向の位置が異なる領域間のトナー濃度の偏差を抑制しつつ、帯電不足のトナーを含んだ現像剤が現像に用いられることを防止できるという優れた効果がある。   According to the present invention, it is possible to prevent a developer containing insufficiently charged toner from being used for development while suppressing a deviation in toner density between regions having different circulation direction positions in the developing device. effective.

実施例１の現像装置を上方から見た概略断面図。FIG. 2 is a schematic cross-sectional view of the developing device of Example 1 as viewed from above. 本実施形態の複写機の概略構成図。1 is a schematic configuration diagram of a copier according to an embodiment. 図１中のＦ−Ｆ断面における現像装置及び感光体の断面説明図。FIG. 2 is a cross-sectional explanatory view of the developing device and the photoconductor in the FF section in FIG. 図１中のＧ−Ｇ断面における現像装置の断面説明図。Cross-sectional explanatory drawing of the image development apparatus in the GG cross section in FIG. 図１中のＨ−Ｈ断面における現像装置の断面説明図。Sectional explanatory drawing of the image development apparatus in the HH cross section in FIG. 撹拌部材の斜視説明図。The perspective explanatory drawing of a stirring member. 搬送路開口部の一例の説明図、（ａ）は、搬送路開口部を設けた位置における軸線方向に直交する断面における現像装置の断面図、（ｂ）は、（ａ）中のＮ−Ｎ断面の搬送路開口部近傍の説明図。Explanatory drawing of an example of a conveyance path opening part, (a) is sectional drawing of the image development apparatus in the cross section orthogonal to the axial direction in the position which provided the conveyance path opening part, (b) is NN in (a). Explanatory drawing of the conveyance path opening part vicinity of a cross section. 搬送路開口部の他の例の説明図。Explanatory drawing of the other example of a conveyance path opening part. 実施例１の現像装置を上方から見た概略断面図。FIG. 2 is a schematic cross-sectional view of the developing device of Example 1 as viewed from above. 実施例３の現像装置の説明図、（ａ）は、上方から見た概略断面図、（ｂ）は、（ａ）中のＧ−Ｇ断面における現像装置の断面説明図。Explanatory drawing of the image development apparatus of Example 3, (a) is a schematic sectional drawing seen from upper direction, (b) is sectional explanatory drawing of the image development apparatus in the GG cross section in (a). 実施例４の現像装置を上方から見た概略断面図。FIG. 10 is a schematic cross-sectional view of the developing device of Example 4 as viewed from above. 実施例１及び従来例の現像装置のトナー濃度変動を比較したグラフ。6 is a graph comparing toner density fluctuations of the developing devices of Example 1 and a conventional example. 参考構成例の現像装置の軸線方向に直交する断面の概略断面図。FIG. 3 is a schematic cross-sectional view of a cross section orthogonal to the axial direction of the developing device of the reference configuration example . 従来例の現像装置を上方から見た概略断面図。FIG. 10 is a schematic cross-sectional view of a conventional developing device as viewed from above.

以下、本発明を画像形成装置としての複写機（以下、複写機５００という）に適用した実施形態について説明する。
図２は、複写機５００の概略構成図である。複写機５００は、画像形成装置の本体部としてのプリンタ部１００の上部に、書き込みユニット１１８、画像読取部１０６及び原稿自動搬送装置（以下、ＡＤＦ１０１という）を備える。 Hereinafter, an embodiment in which the present invention is applied to a copying machine (hereinafter referred to as a copying machine 500) as an image forming apparatus will be described.
FIG. 2 is a schematic configuration diagram of the copying machine 500. The copier 500 includes a writing unit 118, an image reading unit 106, and an automatic document feeder (hereinafter referred to as ADF 101) on the upper part of a printer unit 100 as a main body of the image forming apparatus.

以下、複写機５００における複写機機能の動作について説明する。
ＡＤＦ１０１の原稿台１０２に画像面が上となる状態で原稿束が載置され、図示しない操作部上のスタートキーが押下されると、最上位の原稿が原稿給送ローラ１０３、給送ベルト１０４によってコンタクトガラス１０５上の所定位置に給送される。コンタクトガラス１０５上の原稿は、画像読取部１０６によって画像情報が読み取られた後に給送ベルト１０４によって搬送され、排出ローラ１０７によって排紙台１０８上に排出される。原稿台１０２からコンタクトガラス１０５への原稿の給送が終了した後、原稿検知センサ１０９によって原稿台１０２上に次の原稿が存在することが検知された場合には、上述と同様にこの原稿がコンタクトガラス１０５上に給送される。 Hereinafter, the operation of the copier function in the copier 500 will be described.
When a document bundle is placed on the document table 102 of the ADF 101 with the image surface facing upward, and a start key on an operation unit (not shown) is pressed, the uppermost document is the document feeding roller 103 and the feeding belt 104. Is fed to a predetermined position on the contact glass 105. The document on the contact glass 105 is conveyed by the feeding belt 104 after the image information is read by the image reading unit 106, and is discharged onto the paper discharge tray 108 by the discharge roller 107. After the document feed from the document table 102 to the contact glass 105 is completed, when the document detection sensor 109 detects that the next document exists on the document table 102, the document is read in the same manner as described above. It is fed onto the contact glass 105.

画像読取部１０６は、コンタクトガラス１０５上の原稿を２個のランプ１２８で照射しながら原稿の画像情報を副走査方向にライン走査する。そして、その反射光を画像データとして第一ミラー１２９、第二ミラー１３０及び第三ミラー１３１により所定の方向に反射させ、画像を縮小結像させるレンズユニット１３２を介してＣＣＤ１３３に送り、画像データの読み込みを行う。
画像読取部１０６によって読み込まれた画像データは、図示しない画像処理手段を介してレーザ発光装置１３４、ｆθレンズ１３５、反射ミラー１３６等を有する書き込みユニット１１８に送られる。そして、書き込みユニット１１８のレーザ発光装置１３４が原稿画像に対応したレーザ光を発することでよって感光体１１７上に原稿画像に対応した静電潜像が形成される。 The image reading unit 106 performs line scanning on the image information of the document in the sub-scanning direction while irradiating the document on the contact glass 105 with the two lamps 128. Then, the reflected light is reflected as image data in a predetermined direction by the first mirror 129, the second mirror 130, and the third mirror 131, and sent to the CCD 133 via the lens unit 132 for reducing and forming an image. Read.
The image data read by the image reading unit 106 is sent to a writing unit 118 having a laser light emitting device 134, an fθ lens 135, a reflecting mirror 136, and the like via an image processing unit (not shown). Then, the laser light emitting device 134 of the writing unit 118 emits laser light corresponding to the document image, whereby an electrostatic latent image corresponding to the document image is formed on the photosensitive member 117.

プリンタ部１００の内部には、感光体１１７、現像装置１０、定着部１２１、排紙ユニット１２２、第一〜第三給紙装置１１０，１１１，１１２、縦搬送ユニット１１６等が配設されている。感光体１１７は、図示しない帯電器により一様に帯電された後に書き込みユニット１１８からのレーザ光によって露光されて静電潜像が形成され、この静電潜像は現像装置１０により現像されて感光体１１７の表面上にトナー像が形成される。   Inside the printer unit 100, a photoconductor 117, a developing device 10, a fixing unit 121, a paper discharge unit 122, first to third paper supply devices 110, 111, 112, a vertical conveyance unit 116, and the like are disposed. . The photosensitive member 117 is uniformly charged by a charger (not shown) and then exposed to a laser beam from the writing unit 118 to form an electrostatic latent image. The electrostatic latent image is developed by the developing device 10 and is photosensitive. A toner image is formed on the surface of the body 117.

第一〜第三給紙装置１１０，１１１，１１２はそれぞれ記録媒体である転写紙が積載された第一〜第三給紙カセット１１３，１１４，１１５を備えている。そして、上述したトナー像の形成動作と並行して、第一〜第三給紙装置１１０，１１１，１１２のうちの選択された一つの給紙装置がその給紙カセット内に積載された転写紙の最上部の一枚を縦搬送ユニット１１６に給送する。給送された転写紙は、縦搬送ユニット１１６によって感光体１１７と転写ベルト１２０とが当接する位置まで搬送される。   The first to third sheet feeding devices 110, 111, and 112 include first to third sheet feeding cassettes 113, 114, and 115 on which transfer sheets as recording media are loaded, respectively. In parallel with the above-described toner image forming operation, the transfer paper in which one selected paper feeding device among the first to third paper feeding devices 110, 111, and 112 is loaded in the paper feeding cassette. Is fed to the vertical conveyance unit 116. The fed transfer paper is conveyed by the vertical conveyance unit 116 to a position where the photoconductor 117 and the transfer belt 120 are in contact with each other.

感光体１１７の下方には転写ベルト１２０が配設されている。転写ベルト１２０は記録媒体である転写紙の搬送手段及び転写手段を兼ねており、転写ローラ１２０ａと張架ローラ１２０ｂとによって張架されている。図示しない電源から転写ローラ１２０ａに転写バイアスが印加され、転写ベルト１２０が縦搬送ユニット１１６からの転写紙を感光体１１７と等速で搬送しつつ感光体１１７上のトナー像を転写紙に転写させる。
感光体１１７と転写ローラ１２０ａとの対向部を通過した転写紙は転写ベルト１２０によって定着部１２１へと搬送される。転写紙に転写されたトナー像は定着部１２１において転写紙上に定着され、画像を定着された転写紙は排紙ユニット１２２を介して排紙トレイ１２３上に排出される。感光体１１７はトナー像転写後に図示しないクリーニング手段によってクリーニングされ、次の画像形成に備えられる。 A transfer belt 120 is disposed below the photoconductor 117. The transfer belt 120 also serves as a transfer means and transfer means for transfer paper that is a recording medium, and is stretched by a transfer roller 120a and a tension roller 120b. A transfer bias is applied to the transfer roller 120a from a power source (not shown), and the transfer belt 120 transfers the toner image on the photoconductor 117 onto the transfer paper while conveying the transfer paper from the vertical conveyance unit 116 at the same speed as the photoconductor 117. .
The transfer paper that has passed through the facing portion between the photoconductor 117 and the transfer roller 120 a is conveyed to the fixing unit 121 by the transfer belt 120. The toner image transferred to the transfer paper is fixed on the transfer paper in the fixing unit 121, and the transfer paper on which the image is fixed is discharged onto the paper discharge tray 123 via the paper discharge unit 122. The photoreceptor 117 is cleaned by a cleaning unit (not shown) after the toner image is transferred, and is prepared for the next image formation.

排紙ユニット１２２の下方には、反転ユニット１２５が配置されており、反転ユニット１２５は、排紙ユニット１２２内に設けられた不図示の分岐手段によって分岐された転写紙が図２中の矢印Ａで示すように搬送ローラ対１２４によって送り込まれる。
図２中の矢印Ｂで示すように反転ユニット１２５内に進入した転写紙は、反転ユニット１２５によって図２中の矢印Ｃ方向に搬送される。反転ユニット１２５と排紙ユニット１２２との間には、反転した転写紙を図２中の矢印Ｄで示すように再び排紙ユニット１２２側に戻す排紙搬送路１２７を有する。反転ユニット１２５で反転した転写紙を、排紙搬送路１２７を介して排紙することで、画像が形成された面を下にして転写紙を排紙トレイ１２３上に排出することができる。 A reversing unit 125 is disposed below the paper discharge unit 122. The reversing unit 125 is formed by transferring the transfer paper branched by a branching unit (not shown) provided in the paper discharge unit 122 to an arrow A in FIG. As shown in FIG.
The transfer paper that has entered the reversing unit 125 as indicated by arrow B in FIG. 2 is conveyed by the reversing unit 125 in the direction of arrow C in FIG. Between the reversing unit 125 and the paper discharge unit 122, there is a paper discharge conveyance path 127 for returning the reversed transfer paper to the paper discharge unit 122 side again as indicated by an arrow D in FIG. By transferring the transfer paper reversed by the reversing unit 125 through the paper discharge conveyance path 127, the transfer paper can be discharged onto the paper discharge tray 123 with the image-formed side down.

また、反転ユニット１２５の下方には反転ユニット１２５で反転した転写紙を再び縦搬送ユニット１１６側に搬送する両面画像形成搬送路１２６が配設されている。転写紙の両面に画像を形成するときには、反転ユニット１２５によって図２中の矢印Ｃ方向に搬送された転写紙が図２中の矢印Ｅで示すように両面画像形成搬送路１２６へ搬送される。そして、転写紙が縦搬送ユニット１１６に受け渡されることで、画像が形成された面を下にした状態で感光体１１７と転写ローラ１２０ａとの対向部に転写紙が供給される。これにより、転写紙の画像が形成されていない面が感光体１１７と対向し、トナー像が転写されることで転写紙の両面に画像を形成して排紙トレイ１２３上に排出することができる。   Further, below the reversing unit 125, a double-sided image forming conveyance path 126 for conveying the transfer sheet reversed by the reversing unit 125 to the vertical conveyance unit 116 side is disposed. When images are formed on both sides of the transfer paper, the transfer paper conveyed in the direction of arrow C in FIG. 2 by the reversing unit 125 is conveyed to the double-sided image forming conveyance path 126 as indicated by arrow E in FIG. Then, the transfer paper is delivered to the vertical conveyance unit 116, whereby the transfer paper is supplied to the facing portion between the photoconductor 117 and the transfer roller 120a with the surface on which the image is formed facing down. As a result, the surface of the transfer paper on which the image is not formed faces the photoconductor 117, and the toner image is transferred, so that an image can be formed on both sides of the transfer paper and discharged onto the paper discharge tray 123. .

複写機５００において、プリンタ機能によって画像を形成するときには、画像処理手段からの画像データの代わりに外部からの画像データが書き込みユニット１１８に入力され、画像形成手段によって転写紙上に画像が形成される。ファクシミリ機能時には画像読取部１０６からの画像データが図示しないファクシミリ送受信部により相手に送信され、相手からの画像データがファクシミリ送受信部で受信されて画像処理手段からの画像データに代えて書き込みユニット１１８に入力されることにより、画像形成手段が作動して転写紙上に画像が形成される。
上述した構成では、画像形成装置として複合機を用いた例を示したが、本発明が適用可能な画像形成装置はこれに限られず、プリンタ、ファクシミリ、プロッタ等の他の画像形成装置にも本発明は適用可能である。 When an image is formed by the printer function in the copying machine 500, image data from the outside is input to the writing unit 118 instead of image data from the image processing means, and an image is formed on the transfer paper by the image forming means. During the facsimile function, the image data from the image reading unit 106 is transmitted to the other party by a facsimile transmission / reception unit (not shown), and the image data from the other party is received by the facsimile transmission / reception unit. As a result of the input, the image forming means operates to form an image on the transfer paper.
In the above-described configuration, an example in which a multifunction peripheral is used as an image forming apparatus has been described. However, the image forming apparatus to which the present invention can be applied is not limited to this, and the present invention is also applied to other image forming apparatuses such as a printer, a facsimile, and a plotter. The invention is applicable.

〔実施例１〕
次に、本発明を適用した現像装置１０の一つ目の実施例（以下、実施例１と呼ぶ）について説明する。
図１は、実施例１の現像装置１０を上方から見た概略断面図である。
図３は、図１中のＦ−Ｆ断面における現像装置１０及び感光体１１７の断面説明図、図４は、図１中のＧ−Ｇ断面における現像装置１０の断面説明図、図５は、図１中のＨ−Ｈ断面における現像装置１０の断面説明図である。
現像装置１０は、装置の外形を形成し、現像剤を収容するケーシング１０ａを備え、図１中の矢印Ｉ（Ｉ１〜Ｉ６）は、現像装置１０のケーシング１０ａ内での現像剤の流れを示している。 [Example 1]
Next, a first embodiment of the developing device 10 to which the present invention is applied (hereinafter referred to as Embodiment 1) will be described.
FIG. 1 is a schematic cross-sectional view of the developing device 10 of Example 1 as viewed from above.
3 is a cross-sectional explanatory view of the developing device 10 and the photoconductor 117 in the FF cross section in FIG. 1, FIG. 4 is a cross-sectional explanatory view of the developing device 10 in the GG cross section in FIG. 1, and FIG. FIG. 2 is a cross-sectional explanatory view of the developing device 10 in the HH cross section in FIG. 1.
The developing device 10 includes a casing 10a that forms the outer shape of the device and accommodates the developer, and arrows I (I 1 to I 6 ) in FIG. 1 indicate the flow of the developer in the casing 10a of the developing device 10. Is shown.

現像装置１０の特徴部は、供給回収スクリュ２１と循環スクリュ２２との間に配置された仕切り板２４の端部以外の箇所に搬送路開口部２６を備え、さらに、二つのスクリュ部材とは別に二成分現像剤を撹拌する撹拌部１１を備える点である。以下、搬送路開口部２６と撹拌部１１とを備える現像装置１０について詳細を説明する。   The characteristic part of the developing device 10 includes a transport path opening 26 at a location other than the end of the partition plate 24 disposed between the supply and recovery screw 21 and the circulation screw 22, and is separate from the two screw members. It is a point provided with the stirring part 11 which stirs a two-component developer. Hereinafter, the details of the developing device 10 including the conveyance path opening 26 and the stirring unit 11 will be described.

現像装置１０は、トナーとキャリアとからなる二成分現像剤を用いて現像する二成分現像装置である。現像装置１０は、ケーシング１０ａ内に収容する現像剤を表面に担持し、回転することで感光体１１７との対向部まで現像剤を搬送し、感光体１１７の表面上の静電潜像にトナーを付与して現像する現像ローラ２０を備える。また、現像装置１０は、ケーシング１０ａ内に収容する現像剤を現像ローラ２０の回転軸の軸方向に沿って搬送する二つの搬送スクリュとして、供給回収スクリュ２１及び循環スクリュ２２を備える。供給回収スクリュ２１及び循環スクリュ２２は、回転軸に螺旋状の羽部を設けたスクリュ形状であり、回転することにより現像剤を軸方向に搬送する。   The developing device 10 is a two-component developing device that develops using a two-component developer composed of toner and carrier. The developing device 10 carries the developer accommodated in the casing 10a on the surface and rotates the developer to a portion facing the photoconductor 117 to rotate the electrostatic latent image on the surface of the photoconductor 117 with toner. And a developing roller 20 for developing the toner. Further, the developing device 10 includes a supply and recovery screw 21 and a circulation screw 22 as two conveying screws that convey the developer accommodated in the casing 10 a along the axial direction of the rotation shaft of the developing roller 20. The supply / recovery screw 21 and the circulation screw 22 have a screw shape in which a spiral blade is provided on a rotation shaft, and convey the developer in the axial direction by rotating.

現像装置１０のケーシング１０ａ内は、供給回収スクリュ２１が現像剤に搬送力を付与する供給回収搬送路５１と、が現像剤に搬送力を付与する循環搬送路５２とが、仕切り板２４によって仕切られている。現像剤は、供給回収スクリュ２１によって図１中の矢印Ｉ３及びＩ４で示すように図１中の左側から右側に搬送され、循環スクリュ２２によって図１中の矢印Ｉ１及びＩ２で示すように図１中の右側から左側に現像剤が搬送される。
また、現像装置１０は、供給回収スクリュ２１の搬送方向下流側端部であり、循環スクリュ２２の搬送方向上流側端部となる図１中の右側端部は、仕切り板２４が開口となっており、撹拌部材２７が配置され、撹拌部１１を構成する。
さらに、仕切り板２４は、供給回収スクリュ２１の搬送方向上流側端部であり、循環スクリュ２２の搬送方向下流側端部である図１中の左側端部も開口となっており、端部開口部２５を形成する。 In the casing 10 a of the developing device 10, a supply / recovery conveyance path 51 where the supply / recovery screw 21 applies a conveyance force to the developer and a circulation conveyance path 52 where the supply / recovery screw 21 applies a conveyance force to the developer are partitioned by a partition plate 24. It has been. The developer is conveyed from the left side to the right side in FIG. 1 as indicated by arrows I 3 and I 4 in FIG. 1 by the supply and recovery screw 21, and indicated by arrows I 1 and I 2 in FIG. Thus, the developer is conveyed from the right side to the left side in FIG.
Further, the developing device 10 is a downstream end portion in the transport direction of the supply / recovery screw 21, and a partition plate 24 is open at a right end portion in FIG. 1 that is an upstream end portion in the transport direction of the circulation screw 22. The stirring member 27 is arranged to constitute the stirring unit 11.
Further, the partition plate 24 is an upstream end portion in the transport direction of the supply and recovery screw 21, and a left end portion in FIG. 1 that is a downstream end portion in the transport direction of the circulation screw 22 is also open, and an end portion opening is performed. A portion 25 is formed.

供給回収スクリュ２１に搬送される供給回収搬送路５１内の現像剤の一部が現像ローラ２０内に配置された不図示の磁石の磁力によって図３で示すように現像ローラ２０の表面に吸い上げられ、吸着されることで、現像ローラ２０の表面に供給され、担持される。そして、現像ローラ２０が図２中の矢印Ｊ方向に回転することによる表面移動によって現像ローラ２０の表面とドクタブレード２２５の先端とが対向する位置を通過し、ドクタブレード２２５によって均一な厚さに均される。
ドクタブレード２２５によって均一な厚さに均された現像剤は、感光体１１７との対向部に到達し、感光体１１７に接することで感光体１１７上の静電潜像をトナーで現像してトナー像を形成する。 A part of the developer in the supply / recovery conveyance path 51 conveyed to the supply / recovery screw 21 is sucked up to the surface of the developing roller 20 by the magnetic force of a magnet (not shown) arranged in the developing roller 20 as shown in FIG. By being adsorbed, it is supplied and carried on the surface of the developing roller 20. 2 passes through a position where the surface of the developing roller 20 and the tip of the doctor blade 225 face each other due to the surface movement caused by the rotation of the developing roller 20 in the direction of arrow J in FIG. Leveled.
The developer leveled to a uniform thickness by the doctor blade 225 reaches a portion facing the photoconductor 117 and contacts the photoconductor 117 to develop the electrostatic latent image on the photoconductor 117 with toner. Form an image.

感光体１１７との対向部を通過した現像ローラ２０の表面上の現像剤は、現像ローラ２０内の磁石の磁力によって現像ローラ２０の表面から離脱し、供給回収スクリュ２１に搬送される現像剤と混合する。供給回収スクリュ２１に搬送され、供給回収スクリュ２１の搬送方向下流側端部に到達した現像剤は、撹拌部１１を通過し、循環搬送路５２へと受け渡される。   The developer on the surface of the developing roller 20 that has passed the portion facing the photoconductor 117 is separated from the surface of the developing roller 20 by the magnetic force of the magnet in the developing roller 20, and the developer conveyed to the supply and recovery screw 21. Mix. The developer that has been transported to the supply / recovery screw 21 and has reached the downstream end of the supply / recovery screw 21 in the transport direction passes through the stirring unit 11 and is delivered to the circulation transport path 52.

図４に示すように、撹拌部１１の上部のケーシング１０ａには、トナー補給口２３が設けられている。そして、現像によって消費されたトナー量に応じた量のトナーが、不図示のトナー補給装置によって、トナー補給口２３から撹拌部１１内に補給される。
トナー補給口２３から撹拌部１１内に補給されたトナーは、供給回収スクリュ２１の搬送方向下流側端部まで到達して撹拌部１１を通過する現像剤とともに、撹拌部材２７によって撹拌され混合される。
撹拌部１１で混合され、循環搬送路５２に受け渡された現像剤は、循環スクリュ２２が回転することによって図１中の矢印Ｉ１及びＩ２で示すように図１中の右側から左側へ搬送される。循環スクリュ２２の搬送方向下流側端部に到達した現像剤は、端部開口部２５を通過し、供給回収搬送路５１へと受け渡される。端部開口部２５を通過した供給回収搬送路５１内の現像剤は、上記同様に、その一部が現像ローラ２０の表面に供給されて現像に使用されながら、供給回収スクリュ２１の搬送方向下流側へ（図１中の左側から右側へ）と搬送される。 As shown in FIG. 4, a toner replenishing port 23 is provided in the upper casing 10 a of the agitation unit 11. Then, an amount of toner corresponding to the amount of toner consumed by development is replenished into the agitation unit 11 from the toner replenishing port 23 by a toner replenishing device (not shown).
The toner replenished from the toner replenishing port 23 into the stirring unit 11 is stirred and mixed by the stirring member 27 together with the developer that reaches the downstream end of the supply and recovery screw 21 in the transport direction and passes through the stirring unit 11. .
The developer mixed in the agitation unit 11 and delivered to the circulation conveyance path 52 moves from the right side to the left side in FIG. 1 as indicated by arrows I 1 and I 2 in FIG. 1 as the circulation screw 22 rotates. Be transported. The developer that has reached the downstream end of the circulating screw 22 in the transport direction passes through the end opening 25 and is delivered to the supply / recovery transport path 51. Similarly to the above, the developer in the supply / recovery conveyance path 51 that has passed through the end opening 25 is supplied to the surface of the developing roller 20 and used for development, while the supply / recovery screw 21 is downstream in the conveyance direction. It is conveyed to the side (from the left side to the right side in FIG. 1).

実施例１の現像装置１０は、軸方向（図１中の左右方向）における仕切り板２４の端部以外の箇所に搬送路開口部２６が設けられている。端部開口部２５や撹拌部１１で現像剤が受け渡されるのと同様に、搬送路開口部２６においても、供給回収搬送路５１と循環搬送路５２との間で現像剤の受け渡しが生じる。また、搬送路開口部２６では、図１中の矢印Ｉ５で示すように、供給回収搬送路５１から循環搬送路５２への受け渡しとともに、Ｉ６で示すように循環搬送路５２側から供給回収搬送路５１側への受け渡しも生じる。
これにより、図１４に示す従来例と比較して、実施例１の現像装置１０のケーシング１０ａ内での現像剤の流れが複数に増えていることが分かる。 In the developing device 10 according to the first exemplary embodiment, a conveyance path opening 26 is provided at a location other than the end of the partition plate 24 in the axial direction (left-right direction in FIG. 1). In the same way as the developer is transferred at the end opening 25 and the stirring unit 11, the developer is also transferred between the supply / recovery transfer path 51 and the circulation transfer path 52 in the transfer path opening 26. Further, the conveying path opening 26, as indicated by the arrow I 5 in FIG. 1, the transfer from the supply collection conveyance path 51 to the circular path 52, supply and recovery from the circulation path 52 side as indicated by an I 6 Delivery to the conveyance path 51 side also occurs.
As a result, it can be seen that the flow of developer in the casing 10a of the developing device 10 of Example 1 is increased to a plurality as compared with the conventional example shown in FIG.

図１４に示す従来例の現像装置１０は、二成分現像剤を用いて現像を行う２軸搬送タイプの現像装置である。現像剤担持体である現像ローラ２０への現像剤供給及び回収用の現像剤搬送部材である供給回収スクリュ２１及び供給回収搬送路５１と、トナー補給後の搬送撹拌用の現像剤搬送部材である循環スクリュ２２及び循環搬送路５２とを備える。このように、従来例の現像装置１０は、二つの現像剤搬送部材及び、二つの搬送路で構成され、これらが現像ローラ２０の下方に略水平方向に配置されている構成である。   A conventional developing device 10 shown in FIG. 14 is a biaxial transport type developing device that performs development using a two-component developer. A developer collecting member 21 for supplying and collecting developer to the developing roller 20 that is a developer carrying member, a supply / recovery conveying path 51 that is a developer conveying member, and a developer conveying member for conveying and stirring after toner replenishment. A circulation screw 22 and a circulation conveyance path 52 are provided. As described above, the developing device 10 of the conventional example is configured by the two developer transport members and the two transport paths, and these are disposed in a substantially horizontal direction below the developing roller 20.

図１４に示す従来例の現像装置１０では、供給回収搬送路５１内の現像剤は供給回収スクリュ２１によって搬送方向下流側へ搬送され、供給回収スクリュ２１の搬送方向下流側端部に到達した現像剤が循環搬送路５２における循環スクリュ２２の搬送方向上流側端部に受け渡される。そして、循環搬送路５２内の現像剤は循環スクリュ２２によって搬送方向下流側へ搬送され、循環スクリュ２２の搬送方向下流側端部に到達した現像剤が供給回収搬送路５１における供給回収スクリュ２１の搬送方向上流側端部に受け渡される。すなわち従来例の現像装置１０内での現像剤の流れでは、「Ｉ１→Ｉ２→Ｉ３→Ｉ４→Ｉ１・・・」というような流れであり、すべての現像剤が一つの流れに沿って搬送される。
このため、従来例では、供給回収搬送路５１にある現像剤は、供給回収スクリュ２１による搬送中に、その一部が現像ローラ２０に吸着され、現像に使用され、再び供給回収搬送路５１へと回収される。そして、新たなトナーの供給が成されないまま、再びその一部が現像ローラ２０へ吸着、現像、回収という一連の動作が繰り返される。このため、供給回収搬送路５１内の現像剤は供給回収スクリュ２１の搬送方向下流側ほどトナー濃度が低くなるという問題が発生する。 In the developing device 10 of the conventional example shown in FIG. 14, the developer in the supply / recovery conveyance path 51 is conveyed to the downstream side in the conveyance direction by the supply / recovery screw 21 and reaches the downstream end in the conveyance direction of the supply / recovery screw 21. The agent is delivered to the upstream end portion in the conveyance direction of the circulation screw 22 in the circulation conveyance path 52. The developer in the circulation conveyance path 52 is conveyed to the downstream side in the conveyance direction by the circulation screw 22, and the developer that has reached the downstream end in the conveyance direction of the circulation screw 22 is supplied to the supply / recovery screw 21 in the supply / recovery conveyance path 51. Delivered to the upstream end in the transport direction. That is, the flow of the developer in the conventional developing apparatus 10 is a flow such as “I 1 → I 2 → I 3 → I 4 → I 1 ...”, And all the developer flows in one flow. It is conveyed along.
Therefore, in the conventional example, a part of the developer in the supply / recovery conveyance path 51 is adsorbed by the developing roller 20 during the conveyance by the supply / recovery screw 21 and is used for development, and then again to the supply / recovery conveyance path 51. And recovered. Then, a series of operations such as adsorption, development, and collection of a part of the toner onto the developing roller 20 is repeated again without supplying new toner. For this reason, the developer in the supply / recovery conveyance path 51 has a problem that the toner concentration decreases toward the downstream side of the supply / recovery screw 21 in the conveyance direction.

一方、実施例１の現像装置１０では、供給回収搬送路５１内で搬送路開口部２６の位置に到達した現像剤の一部が図１中の矢印Ｉ５で示すように循環搬送路５２へ移動する流れが生じる。さらに、循環搬送路５２内で搬送路開口部２６の位置に到達した現像剤の一部が図１中の矢印Ｉ６で示すように供給回収搬送路５１へ移動する流れも生じる。このように、実施例１の現像装置１０では、現像剤の流れが複数存在する。
そして、搬送路開口部２６では、現像に使用されてトナー濃度が低下した供給回収搬送路５１内の現像剤の一部が循環搬送路５２へと受け渡される。さらに、搬送路開口部２６では、トナー補給後にトナーが消費されておらず、トナー濃度の高い状態の循環搬送路５２内の現像剤が供給回収搬送路５１内へと受け渡される。
このため、従来例で生じるおそれがあった供給回収搬送路５１内での供給回収スクリュ２１の搬送方向上流側と搬送方向下流側とでの著しいトナー濃度偏差を抑制することが可能である。よって、現像ローラ２０に供給される現像剤の現像ローラ２０の軸方向についてのトナー濃度偏差を抑制することができ、現像される画像の濃度ムラの発生を抑制することができる。 On the other hand, in the developing apparatus 10 of Embodiment 1, part of the developer that has reached the position of the conveying path opening 26 in the supply collection conveyance path 51 to the circulation path 52 as indicated by the arrow I 5 in FIG. 1 A moving flow occurs. Furthermore, also occurs stream part of the developer that has reached the position of the conveying path opening 26 in the circulation within the transport path 52 is moved to the supply collection conveyance path 51 as indicated by the arrow I 6 in FIG. Thus, in the developing device 10 of Example 1, there are a plurality of developer flows.
In the conveyance path opening 26, a part of the developer in the supply / recovery conveyance path 51 that has been used for development and has a reduced toner density is transferred to the circulation conveyance path 52. Further, in the conveyance path opening portion 26, the toner in the circulation conveyance path 52 in a state where the toner density is high is delivered to the supply / recovery conveyance path 51 without toner consumption after toner replenishment.
For this reason, it is possible to suppress a significant toner density deviation between the upstream side in the transport direction and the downstream side in the transport direction of the supply / recovery screw 21 that may occur in the conventional example. Therefore, the toner density deviation of the developer supplied to the developing roller 20 in the axial direction of the developing roller 20 can be suppressed, and the occurrence of uneven density in the developed image can be suppressed.

また、搬送路開口部２６での現像剤の受け渡しの量が不十分であると、トナー濃度偏差抑制の効果が減少してしまう。実施例１の現像装置１０では、図１に示すように、供給回収スクリュ２１及び循環スクリュ２２の搬送路開口部２６と対向する位置の回転軸に、第一パドル部材２８ａ及び第二パドル部材２８ｂをそれぞれ設けている。パドル部材２８のような現像剤受け渡し部材を設けることにより、搬送路開口部２６での現像剤の受け渡しの効率が向上し、トナー濃度偏差をより効果的に抑制することが可能である。   Further, if the amount of developer delivered at the conveyance path opening 26 is insufficient, the effect of suppressing the toner density deviation is reduced. In the developing device 10 according to the first embodiment, as illustrated in FIG. 1, the first paddle member 28 a and the second paddle member 28 b are disposed on the rotation shafts at positions facing the conveyance path openings 26 of the supply and recovery screw 21 and the circulation screw 22. Are provided. By providing the developer delivery member such as the paddle member 28, the efficiency of the developer delivery at the transport path opening 26 can be improved, and the toner density deviation can be more effectively suppressed.

図１４に示す従来例のように、搬送スクリュとは別に撹拌部材を備えない二軸搬送スクリュタイプの現像装置１０に、搬送路開口部２６のみを単に設けてしまうと次のような不具合が生じるおそれがある。
従来例の現像装置１０では、トナー補給口２３から補給されたトナーは循環搬送路５２内を循環スクリュ２２によって搬送方向上流側端部から下流側端部に搬送されている間にキャリアを含む現像剤と混合・撹拌される。これにより、新たに補給されたトナーが現像剤内に分散し、帯電する。その後、端部開口部２５から供給回収搬送路５１に受け渡され、現像に用いられる。このような構成に搬送路開口部２６のみを単に設けてしまうと、トナー補給口２３でトナーを補給された現像剤が循環スクリュ２２によって循環搬送路５２内を搬送路開口部２６まで搬送される距離が短くなる。このため、搬送路開口部２６で供給回収搬送路５１に受け渡される現像剤については、循環スクリュ２２によって搬送されている間の混合・撹拌のみでは補給されたトナーを現像剤中に十分に分散することができなくなる。補給されたトナーが十分に分散されていない現像剤が供給回収搬送路５１に受け渡されると、トナー飛散などの問題を生じてしまう。また、現像剤中に十分に分散されなかったトナーは帯電量が不足した弱帯電トナーとなり易く、弱帯電トナーを含む現像剤を現像ローラ２０に供給し現像に用いると、画像濃度ムラを発生してしまう恐れもある。 As in the conventional example shown in FIG. 14, if only the transport path opening 26 is provided in the developing device 10 of the biaxial transport screw type that does not include the stirring member separately from the transport screw, the following problems occur. There is a fear.
In the developing device 10 of the conventional example, the toner replenished from the toner replenishing port 23 is developed including the carrier while being conveyed in the circulation conveyance path 52 by the circulation screw 22 from the upstream end in the conveyance direction to the downstream end. It is mixed and stirred with the agent. As a result, newly supplied toner is dispersed in the developer and charged. Thereafter, the ink is transferred from the end opening 25 to the supply / recovery conveyance path 51 and used for development. If only the transport path opening 26 is provided in such a configuration, the developer replenished with toner at the toner replenishing port 23 is transported through the circulation transport path 52 to the transport path opening 26 by the circulation screw 22. The distance becomes shorter. For this reason, with respect to the developer delivered to the supply / recovery conveyance path 51 through the conveyance path opening 26, the replenished toner is sufficiently dispersed in the developer only by mixing and stirring while being conveyed by the circulation screw 22. Can not do. If the developer in which the replenished toner is not sufficiently dispersed is transferred to the supply / recovery conveyance path 51, problems such as toner scattering may occur. In addition, toner that is not sufficiently dispersed in the developer tends to be weakly charged toner with insufficient charge amount, and when the developer containing weakly charged toner is supplied to the developing roller 20 and used for development, image density unevenness occurs. There is also a risk.

一方、実施例１の現像装置１０では、２つの搬送スクリュとは別に設けられた撹拌部材２７を備え、撹拌部材２７で十分に混合・撹拌された現像剤が循環搬送路５２へと送られる。このため、現像剤にトナーが補給された後、循環スクリュ２２によって循環搬送路５２内を搬送路開口部２６まで搬送される距離が短くても、補給されたトナーが十分に分散した現像剤を供給回収搬送路５１に受け渡すことができる。よって、補給されたトナーが十分に分散されていない現像剤が供給回収スクリュ２１側に受け渡されることに起因する問題の発生を抑制できる。   On the other hand, the developing device 10 according to the first exemplary embodiment includes the stirring member 27 provided separately from the two transport screws, and the developer sufficiently mixed and stirred by the stirring member 27 is sent to the circulation transport path 52. Therefore, after the toner is replenished to the developer, the developer in which the replenished toner is sufficiently dispersed can be obtained even if the distance transported by the circulation screw 22 through the circulation conveyance path 52 to the conveyance path opening 26 is short. It can be delivered to the supply / recovery conveyance path 51. Therefore, it is possible to suppress the occurrence of a problem caused by the transfer of the developer in which the replenished toner is not sufficiently dispersed to the supply and recovery screw 21 side.

次に、撹拌部１１について詳細を説明する。撹拌部１１には、図４中のΔｈで示すように、供給回収搬送路５１や循環搬送路５２内の現像剤の剤面よりも撹拌部１１内の現像剤の剤面が高くなっている。このような現像剤の剤面の関係となるように、供給回収搬送路５１及び循環搬送路５２と撹拌部１１との間に上部仕切り部材２９が設けられている。そして、撹拌部１１から循環搬送路５２に現像剤を受け渡す部分の上端を形成する上部仕切り部材２９の下端よりも、撹拌部１１内の現像剤の剤面が高くなるように、現像装置１０内の現像剤の量が調節されている。
また、現像装置１０では、供給回収スクリュ２１及び循環スクリュ２２の回転数と、上部仕切り部材２９の下端の高さとの設定により、以下の関係が保たれている。
「供給回収スクリュ２１によって搬送力が付与される領域から撹拌部１１に流入する流入量［ｇ／ｓｅｃ］」＋「トナー補給口２３からのトナー補給量［ｇ／ｓｅｃ］」＝「循環スクリュ２２によって搬送力が付与される領域へ撹拌部１１から排出される排出量［ｇ／ｓｅｃ］」
この関係が保たれるように、設定されることで撹拌部１１内の現像剤量はほぼ一定に調整されている。 Next, the details of the stirring unit 11 will be described. In the stirring unit 11, the developer surface in the stirring unit 11 is higher than the developer surface in the supply / recovery conveyance path 51 and the circulation conveyance path 52, as indicated by Δh in FIG. 4. . An upper partition member 29 is provided between the supply / recovery conveyance path 51, the circulation conveyance path 52, and the agitation unit 11 so as to have such a developer surface relationship. Then, the developing device 10 is configured such that the developer surface in the stirring unit 11 is higher than the lower end of the upper partition member 29 that forms the upper end of the portion that delivers the developer from the stirring unit 11 to the circulation conveyance path 52. The amount of developer inside is adjusted.
Further, in the developing device 10, the following relationship is maintained by setting the rotational speeds of the supply and recovery screw 21 and the circulation screw 22 and the height of the lower end of the upper partition member 29.
“Inflow amount [g / sec] flowing into the stirring unit 11 from the region where the conveying force is applied by the supply / recovery screw 21” + “toner replenishment amount [g / sec] from the toner replenishing port 23” = “circulation screw 22” The discharge amount [g / sec] discharged from the stirring unit 11 to the region where the conveying force is applied by “
By setting so that this relationship is maintained, the amount of developer in the stirring unit 11 is adjusted to be substantially constant.

撹拌部１１内の現像剤量が略一定に調節され、その剤面が上部仕切り部材２９の下端よりも高いため、供給回収搬送路５１や循環搬送路５２と撹拌部１１との間の現像剤の出入り口は現像剤によってパッキングされた状態となっている。このため、トナー補給口２３から撹拌部１１内の現像剤の上部に補給されたトナーは、現像剤と混合した状態となって初めて現像剤とともに撹拌部１１から循環搬送路５２に受け渡される。よって、トナー補給口２３から補給されたトナーが、現像剤と未混合のまま循環搬送路５２へと流れ込むことを防止できる。   Since the amount of developer in the agitation unit 11 is adjusted to be substantially constant, and the surface of the developer is higher than the lower end of the upper partition member 29, the developer between the supply / recovery conveyance path 51 and the circulation conveyance path 52 and the agitation unit 11 is used. The doorway is packed with a developer. For this reason, the toner replenished from the toner replenishing port 23 to the upper part of the developer in the stirring unit 11 is transferred from the stirring unit 11 to the circulation conveyance path 52 together with the developer only after being mixed with the developer. Therefore, the toner replenished from the toner replenishing port 23 can be prevented from flowing into the circulation conveyance path 52 without being mixed with the developer.

また、図４及び図５に示すように、撹拌部１１内に設けられた撹拌部材２７は、撹拌軸２７ａに複数枚の撹拌羽板２７ｂが固定された部材である。図６は、撹拌部１１に設けられた撹拌部材２７の斜視説明図である。
撹拌部１１では不図示の駆動部から回転駆動が伝達され撹拌軸２７ａが回転運動することで、トナー補給口２３から撹拌部１１内の現像剤の上部に補給されたトナーは現像剤中に混合される。図６に示すように、撹拌部材２７には撹拌軸２７ａの周りに垂直方向から角度を持った撹拌羽板２７ｂが設けられている。詳しくは、一枚の撹拌羽板２７ｂの上端部に対して下端部の方が回転方向下流側となるように、撹拌軸２７ａに固定している。このような形状により、撹拌軸２７ａが図中矢印Ｋ方向に回転することによって、撹拌部１１内の現像剤を下方から上方に持ち上げながら撹拌する。そして、持ち上げられた現像剤が重力によって落下中に他の現像剤と混合することで、高い撹拌性を持たせている。これにより、トナー補給口２３から補給されたトナーを現像剤中に素早く、且つ、均一に分散するとともに、撹拌羽板２７ｂによるせん断によってトナー帯電量も十分に立ち上げることができる。 4 and 5, the stirring member 27 provided in the stirring unit 11 is a member in which a plurality of stirring blades 27b are fixed to a stirring shaft 27a. FIG. 6 is a perspective explanatory view of the stirring member 27 provided in the stirring unit 11.
In the agitation unit 11, rotational driving is transmitted from a drive unit (not shown) and the agitation shaft 27 a rotates, so that the toner replenished from the toner replenishment port 23 to the upper part of the developer in the agitation unit 11 is mixed into the developer. Is done. As shown in FIG. 6, the stirring member 27 is provided with a stirring blade 27b having an angle from the vertical direction around the stirring shaft 27a. In detail, it fixes to the stirring shaft 27a so that the lower end part may become the downstream of a rotation direction with respect to the upper end part of the stirring blade board 27b of 1 sheet. With such a shape, the stirring shaft 27a rotates in the direction of the arrow K in the figure, whereby the developer in the stirring unit 11 is stirred while being lifted upward from below. The lifted developer is mixed with another developer while dropping due to gravity, thereby providing high agitation. As a result, the toner replenished from the toner replenishing port 23 can be quickly and uniformly dispersed in the developer, and the toner charge amount can be sufficiently increased by shearing by the stirring blades 27b.

また、図１に示すように、撹拌部材２７が図中の矢印Ｋ方向に回転することで、供給回収搬送路５１内を供給回収スクリュ２１によって搬送されてきた現像剤を撹拌羽板２７ｂが撹拌部１１内に引き込むように作用する。また、循環搬送路５２側では、矢印Ｋ方向に回転する撹拌部材２７の撹拌羽板２７ｂが撹拌部１１内の現像剤を循環搬送路５２に送り出すように作用する。このように、供給回収搬送路５１から撹拌部１１への現像剤の引き込みと、撹拌部１１から循環搬送路５２への現像剤の送り出しとを促進させる向きに撹拌部材２７が回転することで、現像剤にストレスを掛けることなる良好な現像剤循環性も持たせている。   Further, as shown in FIG. 1, the stirring blade 27b stirs the developer transported by the supply / recovery screw 21 in the supply / recovery transport path 51 as the stirring member 27 rotates in the direction of arrow K in the figure. It acts to be pulled into the portion 11. On the circulation conveyance path 52 side, the stirring blades 27 b of the stirring member 27 rotating in the direction of arrow K act to send the developer in the stirring unit 11 to the circulation conveyance path 52. Thus, the stirring member 27 rotates in a direction that promotes the drawing of the developer from the supply / recovery conveyance path 51 to the stirring unit 11 and the feeding of the developer from the stirring unit 11 to the circulation conveyance path 52, It also has a good developer circulation property that puts stress on the developer.

ここで、水平面における現像ローラ２０の回転軸の軸方向と直交する方向を現像装置１０の幅方向とすると、図５に示すように、撹拌部１１の幅方向の長さＬ２は、供給回収搬送路５１及び循環搬送路５２を形成する現像剤搬送部と現像ローラ２０との幅方向の長さＬ１に収まるサイズとなっている。このため、現像装置１０が幅方向へサイズアップすることなく、高い撹拌性を得られる。
また、本実施形態では実施例１の現像装置１０を適用する画像形成装置である複写機５００は、図２に示すように現像装置１０や感光体１１７を一つずつ備えるモノクロの画像形成装置である。実施例１の現像装置１０は、モノクロの画像形成装置に限らずカラーの画像形成装置にも適用可能である。そして、通常、カラーの画像形成装置では、複数の現像装置１０（シアン、マゼンタ、イエロー、ブラックなど）が設けられており、それらを水平方向に並べて配置するため、幅方向のサイズアップは画像形成装置として大幅なサイズアップになってしまう。これに対して、実施例１の現像装置１０は、撹拌部１１を設けた構成であっても幅方向のサイズアップを抑制できるため、カラーの画像形成装置に適用したときに、大幅なサイズアップとなることを防止できる。 Here, if the direction orthogonal to the axial direction of the rotation axis of the developing roller 20 in the horizontal plane is the width direction of the developing device 10, the length L2 in the width direction of the stirring unit 11 is as shown in FIG. The size fits within the length L1 in the width direction between the developer transport unit and the developing roller 20 that form the path 51 and the circulation transport path 52. For this reason, high agitation can be obtained without the developing device 10 increasing in size in the width direction.
In this embodiment, the copying machine 500, which is an image forming apparatus to which the developing device 10 of the first embodiment is applied, is a monochrome image forming apparatus including the developing device 10 and the photosensitive member 117 as shown in FIG. is there. The developing device 10 according to the first exemplary embodiment is applicable not only to a monochrome image forming apparatus but also to a color image forming apparatus. In general, a color image forming apparatus is provided with a plurality of developing devices 10 (cyan, magenta, yellow, black, etc.), which are arranged side by side in the horizontal direction. The size of the device will increase significantly. On the other hand, since the developing device 10 of Example 1 can suppress the size increase in the width direction even when the stirring unit 11 is provided, the size can be significantly increased when applied to a color image forming apparatus. Can be prevented.

次に、搬送路開口部２６の形状について説明する。
搬送路開口部２６としては、対応する部分の仕切り板２４を除去したもの、仕切り板２４に四角形や他の形状の開口部を設けたものなど、現像剤が通過可能であればよく、その形状は特に限定されるものではない。
図７は、搬送路開口部２６の一例の説明図である。図７（ａ）は、搬送路開口部２６を設けた位置における現像ローラ２０の軸線方向に直交する断面における現像装置１０の断面図である。また、図７（ｂ）は、現像装置１０における図７（ａ）中のＮ−Ｎ断面の搬送路開口部２６近傍の説明図である。
図７に示す例では、搬送路開口部２６を上下二つの穴によって形成する。そして、現像ローラ２０が図７（ａ）における反時計回り方向に回転する構成で、供給回収スクリュ２１及び循環スクリュ２２の回転方向が、図７（ａ）における反時計回り方向となるように設定している。 Next, the shape of the conveyance path opening 26 will be described.
The conveyance path opening 26 may be any shape as long as the developer can pass through, for example, a part obtained by removing the corresponding partition plate 24 or a part provided with a square or other shape opening in the partition plate 24. Is not particularly limited.
FIG. 7 is an explanatory diagram of an example of the conveyance path opening 26. FIG. 7A is a cross-sectional view of the developing device 10 in a cross section orthogonal to the axial direction of the developing roller 20 at a position where the conveyance path opening 26 is provided. FIG. 7B is an explanatory view of the developing device 10 in the vicinity of the conveyance path opening 26 in the NN cross section in FIG. 7A.
In the example shown in FIG. 7, the conveyance path opening 26 is formed by two upper and lower holes. Then, the developing roller 20 is configured to rotate in the counterclockwise direction in FIG. 7A, and the rotation directions of the supply and recovery screw 21 and the circulation screw 22 are set to be in the counterclockwise direction in FIG. 7A. doing.

図７に示す現像装置１０では、現像ローラ２０に汲み上げられた現像剤は、現像ローラ２０の上部を通過して、感光体１１７との対向部である現像領域に到達し現像に用いられる。現像領域を通過した現像剤は、現像ローラ２０の下部を通過して供給回収スクリュ２１と対向する位置に戻り、現像ローラ２０から離間し、供給回収搬送路５１内に戻る。このため、供給回収搬送路５１内における供給回収スクリュ２１の下方の図７（ａ）中のαで示す領域が、現像に用いられてトナー濃度が低下した現像剤が多く存在する領域となる。このため、供給回収搬送路５１内でも供給回収スクリュ２１の下方の現像剤が相対的にトナー濃度が低い状態となっている。
このような状態となる現像装置１０において、現像装置１０の供給回収スクリュ２１は、図７に示すように、回転軸を挟んで現像ローラ２０側の羽部は、回転によって回転軸の下方を通過し、回転軸を挟んで仕切り板２４側に移動する。このように供給回収スクリュ２１が回転することによって、領域αに存在するトナー濃度が低い現像剤は羽部に押されて回転軸の下方を通過して、さらに、回転軸を挟んで仕切り板２４側に押されることで、搬送路開口部２６の下方の穴から循環搬送路５２に押し出される。また、循環搬送路５２では、回転軸を挟んで仕切り板２４とは反対側の羽部は、回転によって回転軸の上方を通過し、回転軸を挟んで仕切り板２４側に移動する。このように循環スクリュ２２が回転することによって、搬送路開口部２６の上方の穴からはトナー補給された循環搬送路５２内の現像剤が供給回収搬送路５１へと受け渡される。 In the developing device 10 shown in FIG. 7, the developer pumped up by the developing roller 20 passes through the upper part of the developing roller 20, reaches the developing region that is a portion facing the photoreceptor 117, and is used for development. The developer that has passed through the developing region passes through the lower part of the developing roller 20, returns to a position facing the supply / recovery screw 21, moves away from the developing roller 20, and returns to the supply / recovery conveyance path 51. For this reason, the area indicated by α in FIG. 7A below the supply / recovery screw 21 in the supply / recovery conveyance path 51 is an area where a large amount of the developer used for development and having a reduced toner density exists. For this reason, even in the supply / recovery conveyance path 51, the developer below the supply / recovery screw 21 has a relatively low toner concentration.
In the developing device 10 in such a state, as shown in FIG. 7, the supply / recovery screw 21 of the developing device 10 has the wing portion on the developing roller 20 side of the rotating shaft passing under the rotating shaft by rotation. And it moves to the partition plate 24 side across the rotating shaft. As the supply / recovery screw 21 rotates in this manner, the low-concentration developer present in the region α is pushed by the blades and passes below the rotation shaft, and further, the partition plate 24 sandwiching the rotation shaft. By being pushed to the side, it is pushed out from the hole below the conveyance path opening 26 to the circulation conveyance path 52. Further, in the circulation conveyance path 52, the wing part on the opposite side of the partition plate 24 across the rotation shaft passes above the rotation shaft by rotation and moves to the partition plate 24 side across the rotation shaft. By rotating the circulation screw 22 in this way, the developer in the circulation conveyance path 52 supplied with toner is delivered to the supply / recovery conveyance path 51 from the hole above the conveyance path opening 26.

なお、図７に示す現像装置１０のように、搬送路開口部２６を上下二つの穴によって形成する構成で、ドクタブレード２２５が現像ローラ２０の下方に配置された構成では、現像ローラ２０と２つの搬送スクリュとの回転方向を図７の構成とは逆方向とすることが望ましい。すなわち、ドクタブレード２２５が現像ローラ２０の下方に配置された構成では、供給回収スクリュ２１と対向する位置を通過した現像ローラ２０の表面がドクタブレード２２５との対向部に向かうように、現像ローラ２０は図７の構成とは逆方向に回転する。このように回転する現像ローラ２０に担持され、現像領域を通過した現像剤は現像ローラ２０の上部を通過して供給回収搬送路５１に戻される。このため、供給回収搬送路５１内における供給回収スクリュ２１の上方の領域が、現像に用いられてトナー濃度が低下した現像剤が多く存在する領域となる。このとき、供給回収スクリュ２１の回転方向を図７とは逆方向とすることにより、供給回収スクリュ２１の上方の領域に存在するトナー濃度が低い現像剤は羽部に押されて回転軸の上方を通過して、さらに、回転軸を挟んで仕切り板２４側に押されることで、搬送路開口部２６の上方の穴から循環搬送路５２に押し出される。また、循環搬送路５２では、回転軸を挟んで仕切り板２４とは反対側の羽部は、回転によって回転軸の下方を通過し、回転軸を挟んで仕切り板２４側に移動する。このように循環スクリュ２２が回転することによって、搬送路開口部２６の下方の穴からはトナー補給された循環搬送路５２内の現像剤が供給回収搬送路５１へと受け渡される。
すなわち、何れの構成においても、供給回収スクリュ２１及び循環スクリュ２２は現像ローラ２０と回転方向が同方向となる構成が望ましい。 In the configuration in which the conveyance path opening 26 is formed by two upper and lower holes as in the developing device 10 shown in FIG. 7 and the doctor blade 225 is disposed below the developing roller 20, the developing rollers 20 and 2 are provided. It is desirable that the direction of rotation with the two conveying screws be opposite to the configuration of FIG. In other words, in the configuration in which the doctor blade 225 is disposed below the developing roller 20, the developing roller 20 so that the surface of the developing roller 20 that has passed through the position facing the supply / recovery screw 21 faces the portion facing the doctor blade 225. Rotates in the opposite direction to the configuration of FIG. The developer carried on the developing roller 20 rotating in this way and having passed through the developing region passes through the upper portion of the developing roller 20 and is returned to the supply / recovery conveyance path 51. For this reason, the area above the supply / recovery screw 21 in the supply / recovery conveyance path 51 is an area where there is a large amount of developer used for development and having a reduced toner concentration. At this time, the rotation direction of the supply / recovery screw 21 is opposite to that shown in FIG. 7, so that the low-concentration developer present in the region above the supply / recovery screw 21 is pushed by the wings and above the rotation shaft. And is further pushed to the partition plate 24 side with the rotation shaft interposed therebetween, thereby being pushed out from the hole above the conveyance path opening 26 to the circulation conveyance path 52. In the circulation conveyance path 52, the wing portion on the opposite side of the partition plate 24 across the rotation shaft passes under the rotation shaft by rotation and moves toward the partition plate 24 across the rotation shaft. By rotating the circulation screw 22 in this way, the developer in the circulation conveyance path 52 supplied with toner is delivered to the supply / recovery conveyance path 51 from the hole below the conveyance path opening 26.
That is, in any configuration, it is desirable that the supply / recovery screw 21 and the circulating screw 22 have the same rotational direction as the developing roller 20.

図８は、搬送路開口部２６の他の例の説明図であり、図７（ｂ）と同方向から見た現像装置１０の搬送路開口部２６近傍の説明図である。
図８中の矢印Ｉは供給回収スクリュ２１による現像剤の搬送方向を示しており、図８の例は、供給回収スクリュ２１の搬送方向下流側ほど搬送路開口部２６の開口面積が大きい構成である。搬送路開口部２６を設けない構成では、供給回収搬送路５１内の現像剤は供給回収スクリュ２１の搬送方向下流側ほどトナー濃度が低くなる傾向がある。搬送路開口部２６の開口面積が大きいほど現像剤の受け渡しの頻度が高まるため、図８に示す例では、トナー濃度低下の著しい供給回収スクリュ２１の搬送方向下流側ほど、搬送路開口部２６の開口面積を大きくしている。よって、搬送路開口部２６の開口面積を大きい供給回収スクリュ２１の搬送方向下流側ほど、現像剤の受け渡しの頻度が高まる。これにより、トナー濃度が低くなる傾向となる供給回収搬送路５１の供給回収スクリュ２１の搬送方向下流側ほど、トナー補給された現像剤が循環搬送路５２から供給回収搬送路５１へと受け渡され、よりトナー濃度偏差を抑制できる構成となる。 FIG. 8 is an explanatory diagram of another example of the transport path opening 26, and is an explanatory view of the vicinity of the transport path opening 26 of the developing device 10 as viewed from the same direction as FIG. 7B.
An arrow I in FIG. 8 indicates the developer conveyance direction by the supply / recovery screw 21, and the example of FIG. 8 has a configuration in which the opening area of the conveyance path opening 26 is larger toward the downstream side of the supply / recovery screw 21 in the conveyance direction. is there. In the configuration in which the conveyance path opening 26 is not provided, the developer concentration in the supply / recovery conveyance path 51 tends to be lower toward the downstream side in the conveyance direction of the supply / recovery screw 21. The larger the opening area of the conveyance path opening 26 is, the more frequently the developer is delivered. Therefore, in the example shown in FIG. The opening area is increased. Therefore, the frequency of developer delivery increases as the supply recovery screw 21 has a larger opening area on the downstream side in the conveyance direction. As a result, the toner replenished developer is transferred from the circulation conveyance path 52 to the supply / recovery conveyance path 51 toward the downstream side of the supply / recovery screw 21 in the conveyance direction of the supply / recovery conveyance path 51 where the toner concentration tends to decrease. Thus, the toner density deviation can be further suppressed.

〔実施例２〕
次に、本発明を適用した現像装置１０の二つ目の実施例（以下、実施例２と呼ぶ）について説明する。
図９は、実施例２の現像装置１０を上方から見た概略断面図である。
実施例２の現像装置１０は、仕切り板２４の複数箇所の搬送路開口部２６を設けた点で図１に示す実施例１の現像装置１０と相違し、他の点は共通する。このため、実施例１と共通する点についての説明は省略し、相違点についてのみ説明する。 [Example 2]
Next, a second embodiment (hereinafter referred to as a second embodiment) of the developing device 10 to which the present invention is applied will be described.
FIG. 9 is a schematic cross-sectional view of the developing device 10 of Example 2 as viewed from above.
The developing device 10 of the second embodiment is different from the developing device 10 of the first embodiment shown in FIG. 1 in that a plurality of conveyance path openings 26 of the partition plate 24 are provided, and the other points are common. For this reason, the description of the points common to the first embodiment is omitted, and only the differences are described.

実施例２の現像装置１０では、仕切り板２４に複数の搬送路開口部２６が設けられているため、実施例１の現像装置１０よりも、供給回収搬送路５１と循環搬送路５２との間で、より頻繁に現像剤の受け渡しが起こる。これにより、供給回収搬送路５１における供給回収スクリュ２１の搬送方向上流側と下流側とのトナー濃度偏差をさらに低減することが可能となる。
また、実施例２の現像装置１０では、図９に示すように、供給回収スクリュ２１の搬送方向下流側に形成された搬送路開口部２６ほど開口面積が大きくなっている。さらに、供給回収スクリュ２１の搬送方向下流側ほど、隣り合う搬送路開口部２６同士の間隔が狭く、搬送路開口部２６の数が多くなっている。搬送路開口部２６を設けない構成では、供給回収搬送路５１内の現像剤は供給回収スクリュ２１の搬送方向下流側ほどトナー濃度が低くなる傾向がある。このため、供給回収スクリュ２１の搬送方向下流側ほど、トナー補給側なされてトナー濃度が高い状態の現像剤を、循環搬送路５２から供給回収搬送路５１に受け渡す必要がある。搬送路開口部２６の開口面積が大きいほど、また、搬送路開口部２６の数が多いほど現像剤の受け渡しの頻度が高まる。このため、実施例２の現像装置１０では、供給回収搬送路５１内での供給回収スクリュ２１の搬送方向上流側と下流側とでのトナー濃度偏差をさらに効果的に抑制することができる。 In the developing device 10 according to the second embodiment, since the plurality of transport path openings 26 are provided in the partition plate 24, the gap between the supply / recovery transport path 51 and the circulation transport path 52 is greater than that of the developing device 10 according to the first embodiment. Therefore, delivery of the developer occurs more frequently. As a result, it is possible to further reduce the toner density deviation between the upstream side and the downstream side in the conveyance direction of the supply / recovery screw 21 in the supply / recovery conveyance path 51.
Further, in the developing device 10 according to the second embodiment, as illustrated in FIG. 9, the opening area of the conveyance path opening 26 formed on the downstream side in the conveyance direction of the supply and recovery screw 21 is larger. Furthermore, the intervals between the adjacent conveyance path openings 26 are narrower toward the downstream side of the supply and recovery screw 21 in the conveyance direction, and the number of conveyance path openings 26 is increased. In the configuration in which the conveyance path opening 26 is not provided, the developer concentration in the supply / recovery conveyance path 51 tends to be lower toward the downstream side in the conveyance direction of the supply / recovery screw 21. For this reason, it is necessary to transfer the developer, which is on the toner replenishment side and has a higher toner concentration, to the supply / recovery conveyance path 51 from the circulation conveyance path 52 toward the downstream side of the supply / recovery screw 21 in the conveyance direction. The larger the opening area of the transport path opening 26 and the greater the number of transport path openings 26, the higher the frequency of developer delivery. For this reason, in the developing device 10 according to the second embodiment, the toner density deviation between the upstream side and the downstream side in the conveyance direction of the supply / recovery screw 21 in the supply / recovery conveyance path 51 can be further effectively suppressed.

〔実施例３〕
次に、本発明を適用した現像装置１０の三つ目の実施例（以下、実施例３と呼ぶ）について説明する。
図１０は、実施例３の現像装置１０の説明図である。図１０（ａ）は、実施例３の現像装置１０を上方から見た概略断面図であり、図１０（ｂ）は、図１０（ａ）中のＧ−Ｇ断面における現像装置１０の断面説明図である。
実施例３の現像装置１０は、供給回収スクリュ２１の搬送方向上流側端部、且つ、循環スクリュ２２の搬送方向下流側端部、となる位置にも撹拌部１１を設けた点で図９に示す実施例２の現像装置１０と相違し、他の点は共通する。このため、実施例２と共通する点についての説明は省略し、相違点についてのみ説明する。 Example 3
Next, a third embodiment (hereinafter referred to as a third embodiment) of the developing device 10 to which the present invention is applied will be described.
FIG. 10 is an explanatory diagram of the developing device 10 according to the third embodiment. FIG. 10A is a schematic cross-sectional view of the developing device 10 of Example 3 as viewed from above, and FIG. 10B is a cross-sectional view of the developing device 10 taken along the line GG in FIG. FIG.
The developing device 10 according to the third embodiment is illustrated in FIG. 9 in that the agitation unit 11 is also provided at the upstream end of the supply / recovery screw 21 in the transport direction and the downstream end of the circulation screw 22 in the transport direction. It differs from the developing device 10 of Example 2 shown, and the other points are common. For this reason, the description of the points common to the second embodiment is omitted, and only the differences are described.

実施例３の現像装置１０は、供給回収スクリュ２１の搬送方向上流側及び下流側の両端部に撹拌部１１が設けられている。実施例２のように、搬送路開口部２６を複数設けた構成では、供給回収搬送路５１内における供給回収スクリュ２１の搬送方向上流側と下流側とでの現像剤のトナー濃度偏差を抑制することが可能である。しかし、トナー補給口２３が設けられた箇所に近いほどトナー濃度が高く、離れるに従いトナー濃度低下していくという傾向が若干見られる。
これに対して、実施例３の現像装置１０は、供給回収スクリュ２１の搬送方向の両端部に撹拌部１１及びトナー補給口２３をそれぞれ設けている。このため、トナー補給口２３からの距離によって生じるトナー濃度偏差を抑制することができる。また、搬送路開口部２６が複数箇所設けられているために、供給回収搬送路５１と循環搬送路５２との間での現像剤の受け渡しが非常に頻繁に生じ、現像ローラ２０の軸方向についてトナー濃度の均一な現像剤を現像ローラ２０に供給することが可能となる。 In the developing device 10 according to the third exemplary embodiment, the stirring units 11 are provided at both ends on the upstream side and the downstream side in the conveyance direction of the supply and recovery screw 21. In the configuration in which a plurality of transport path openings 26 are provided as in the second embodiment, a deviation in developer toner concentration between the upstream and downstream sides in the transport direction of the supply / recovery screw 21 in the supply / recovery transport path 51 is suppressed. It is possible. However, there is a slight tendency that the toner density is higher as it is closer to the location where the toner supply port 23 is provided, and the toner density decreases as the distance from the position increases.
On the other hand, the developing device 10 according to the third exemplary embodiment is provided with the stirring unit 11 and the toner supply port 23 at both ends of the supply and recovery screw 21 in the transport direction. For this reason, the toner density deviation caused by the distance from the toner supply port 23 can be suppressed. In addition, since a plurality of conveyance path openings 26 are provided, the developer is frequently transferred between the supply / recovery conveyance path 51 and the circulation conveyance path 52, and the axial direction of the developing roller 20. A developer having a uniform toner density can be supplied to the developing roller 20.

〔実施例４〕
次に、本発明を適用した現像装置１０の四つ目の実施例（以下、実施例４と呼ぶ）について説明する。
図１１は、実施例４の現像装置１０を上方から見た概略断面図である。
実施例４の現像装置１０は、図１０に示す実施例３の現像装置１０から仕切り板２４を完全になくした構成であり、他の点は実施例３と共通する。
仕切り板２４をなくしたことで、現像装置１０のケーシング１０ａ内の軸方向の全域が、供給回収搬送路５１と循環搬送路５２とを連通し、現像剤が通過可能な連通部となっている。これにより、供給回収搬送路５１と循環搬送路５２との間での現像剤の受け渡しがさらに頻繁になり、より良好なトナー濃度均一性を得ることが可能である。 Example 4
Next, a fourth embodiment (hereinafter referred to as a fourth embodiment) of the developing device 10 to which the present invention is applied will be described.
FIG. 11 is a schematic cross-sectional view of the developing device 10 of Example 4 as viewed from above.
The developing device 10 of the fourth embodiment has a configuration in which the partition plate 24 is completely eliminated from the developing device 10 of the third embodiment shown in FIG. 10, and the other points are common to the third embodiment.
By eliminating the partition plate 24, the entire axial area in the casing 10 a of the developing device 10 communicates with the supply / recovery conveyance path 51 and the circulation conveyance path 52, thereby providing a communication portion through which the developer can pass. . As a result, the developer is more frequently transferred between the supply / recovery conveyance path 51 and the circulation conveyance path 52, and better toner density uniformity can be obtained.

図１２は、図１に示す実施例１の現像装置１０と図１４に示す従来例の現像装置１０とで、トナー濃度変動を比較したシミュレーションの結果を示すグラフである。図１２（ａ）は、上流側及び下流側のそれぞれのトナー濃度変動を示すグラフであり、図１２（ｂ）は、上流側と下流側とのトナー濃度の偏差の変動を示すグラフである。図１２（ａ）中の「上流」及び「下流」は、図１及び図１４における現像ローラ２０上の位置ａ及び位置ｂにおいて、全面ベタ画像出力時の時間に対するトナー濃度変動を求めている。   FIG. 12 is a graph showing the results of a simulation comparing toner density fluctuations in the developing device 10 of Example 1 shown in FIG. 1 and the conventional developing device 10 shown in FIG. FIG. 12A is a graph showing variations in toner density on the upstream side and downstream side, and FIG. 12B is a graph showing variation in deviation in toner density between the upstream side and downstream side. In FIG. 12A, “upstream” and “downstream” indicate the change in toner density with respect to time when a full-color solid image is output at positions a and b on the developing roller 20 in FIGS.

従来例の現像装置１０は、上流側と下流側とのトナー濃度偏差が大きいだけでなく、トナー消費、補給による変動（時間に対する変動）も大きい。これは、従来例のように、搬送スクリュのみの撹拌では、現像ローラ２０の長手方向のトナー濃度を均一にするのが困難となるためである。
一方、実施例１では、上流側と下流側とのトナー濃度偏差が低減されており、さらにトナー消費、補給による変動が非常に小さくなっていることがわかる。これは、実施例１の現像装置１０では、撹拌部１１で搬送スクリュによって搬送力が付与される領域に対してより多くの量の現像剤が存在し、その現像剤中に補給トナーを均一に分散させることが可能であるためである。
また、図１２（ｂ）は、現像ローラ２０上のトナー濃度偏差ΔＴＣ（上流側のトナー濃度−下流側のトナー濃度）の経時の変動を示している。従来例では現像ローラ２０上でのトナー濃度偏差ΔＴＣが経時で１［ｗｔ％］以上変動が生じている。一方、実施例１では、トナー濃度偏差ΔＴＣが約０．３［ｗｔ％］で略安定に推移しており、従来例に比べてトナー濃度偏差ΔＴＣの値が非常に安定していることがわかる。また、図９に示す実施例２の現像装置１０のように、複数の搬送路開口部２６を設けることにより、より安定した濃度変動を達成することも可能である。 In the developing device 10 of the conventional example, not only the toner density deviation between the upstream side and the downstream side is large, but also the variation due to toner consumption and replenishment (variation with respect to time) is large. This is because, as in the conventional example, it is difficult to make the toner density in the longitudinal direction of the developing roller 20 uniform by stirring only with the conveying screw.
On the other hand, in Example 1, the toner density deviation between the upstream side and the downstream side is reduced, and it can be seen that the fluctuation due to toner consumption and replenishment is very small. This is because, in the developing device 10 of Example 1, a larger amount of developer is present in the region where the conveying force is applied by the conveying screw in the agitating unit 11, and the replenishment toner is uniformly distributed in the developer. This is because they can be dispersed.
FIG. 12B shows the change over time of the toner density deviation ΔTC (upstream toner density−downstream toner density) on the developing roller 20. In the conventional example, the toner density deviation ΔTC on the developing roller 20 fluctuates by 1 [wt%] or more over time. On the other hand, in Example 1, the toner density deviation ΔTC is substantially stable at about 0.3 [wt%], and it can be seen that the value of the toner density deviation ΔTC is very stable compared to the conventional example. . Further, by providing a plurality of transport path openings 26 as in the developing device 10 of Example 2 shown in FIG. 9, it is possible to achieve more stable density fluctuations.

〔参考構成例〕
次に、現像装置１０の参考構成例について説明する。
図１３は、参考構成例の現像装置１０の現像ローラ２０の軸方向に直交する断面の概略断面図である。図１３中の矢印は、現像装置１０内の現像剤の流れを示している。
上述した実施例１〜４の現像装置は、ケーシング１０ａ内の現像剤を供給搬送路及び回収搬送路に配置されたスクリュ部材によって現像ローラ２０の回転軸方向に沿って搬送する構成である。
二つの搬送路で現像剤を逆方向に搬送し、二つの搬送路の間に連通部を設ける構成としては、現像剤担持体の回転軸方向に沿って現像剤を搬送する構成に限るものだはない。図１３に示すように、二つの現像剤の搬送路を上下に配置し、現像剤担持体の回転軸方向に直交する方向に現像剤を搬送する構成で、二つの搬送路の間に連通部を設けても良い。
以下、図１３に示す参考構成例の現像装置１０について説明する。 [ Reference configuration example ]
Next, a description will be given in Reference example configuration of the current image device 10.
FIG. 13 is a schematic cross-sectional view of a cross section orthogonal to the axial direction of the developing roller 20 of the developing device 10 of the reference configuration example . The arrows in FIG. 13 indicate the flow of the developer in the developing device 10.
The developing devices of Embodiments 1 to 4 described above have a configuration in which the developer in the casing 10a is transported along the rotation axis direction of the developing roller 20 by the screw members disposed in the supply transport path and the recovery transport path.
The configuration in which the developer is transported in the opposite direction on the two transport paths and the communication portion is provided between the two transport paths is limited to the configuration in which the developer is transported along the rotation axis direction of the developer carrier. There is no. As shown in FIG. 13, the two developer transport paths are arranged one above the other so that the developer is transported in a direction perpendicular to the rotation axis direction of the developer carrier, and the communication section is provided between the two transport paths. May be provided.
Hereinafter, the developing device 10 of the reference configuration example shown in FIG. 13 will be described.

参考構成例の現像装置１０は、現像剤担持体である現像ローラ２０と、現像ローラ２０の表面に供給する現像剤を収容する現像剤収容部であるケーシング１０ａとを備える。さらに、ケーシング１０ａ内の現像剤に対して一方向に向かう搬送力を付与する第一搬送部材である回収パドル６２と、ケーシング１０ａ内の現像剤に対して回収パドル６２とは逆方向に向かう搬送力を付与する第二搬送部材である供給パドル６１とを有する。また、ケーシング１０ａにはケーシング１０ａ内の現像剤に新たなトナーを補給するトナー補給口２３が形成されている。
また、回収パドル６２によって現像剤が搬送力を付与される領域である第一搬送路としての回収搬送路４２における搬送方向下流側端部に到達した現像剤は、撹拌部１１を介して供給パドル６１によって現像剤が搬送力を付与される領域である第二搬送路としての供給搬送路４１に受け渡される。そして、供給搬送路４１における搬送方向下流側端部に到達した現像剤が、現像ローラ２０に供給され、さらに、回収搬送路４２に受け渡されることでケーシング１０ａ内を現像剤が循環する。また、供給搬送路４１と回収搬送路４２とは仕切り板２４によって仕切られている。
参考構成例の現像装置１０は、回収搬送路４２と供給搬送路４１とにおける搬送方向の両端部以外の仕切り板２４に、回収搬送路４２と供給搬送路４１とを連通し、現像剤が通過可能な連通部である搬送路開口部２６を備える。さらに、回収搬送路４２における搬送方向下流側端部に到達した現像剤とトナー補給口２３から新たに補給されたトナーとを混合・撹拌し、供給搬送路４１に受け渡す撹拌手段である撹拌部材２７を有する。 The developing device 10 of the reference configuration example includes a developing roller 20 that is a developer carrying member, and a casing 10a that is a developer accommodating portion that accommodates the developer supplied to the surface of the developing roller 20. Further, the recovery paddle 62, which is a first conveyance member that applies a conveyance force in one direction to the developer in the casing 10a, and the conveyance in the direction opposite to the recovery paddle 62 with respect to the developer in the casing 10a. And a supply paddle 61 that is a second conveying member that applies force. The casing 10a has a toner supply port 23 for supplying new toner to the developer in the casing 10a.
Further, the developer that has reached the downstream end in the transport direction in the recovery transport path 42 as the first transport path, which is a region to which the developer is transported by the recovery paddle 62, is supplied through the agitation unit 11. 61, the developer is delivered to a supply conveyance path 41 as a second conveyance path, which is an area to which the conveyance force is applied. Then, the developer that has reached the downstream end in the conveyance direction in the supply conveyance path 41 is supplied to the developing roller 20 and further transferred to the collection conveyance path 42, whereby the developer circulates in the casing 10a. Further, the supply conveyance path 41 and the collection conveyance path 42 are partitioned by a partition plate 24.
In the developing device 10 of the reference configuration example , the recovery conveyance path 42 and the supply conveyance path 41 are communicated with the partition plates 24 other than both ends of the collection conveyance path 42 and the supply conveyance path 41 in the conveyance direction, and the developer passes. The conveyance path opening 26 which is a possible communication part is provided. Further, the developer that has reached the downstream end in the conveyance direction in the collection conveyance path 42 and the newly replenished toner from the toner replenishment port 23 are mixed and agitated, and the agitation member is an agitation unit that delivers to the supply conveyance path 41. 27.

参考構成例の現像装置１０では、各搬送路（４１、４２）にパドル（６１、６２）をそれぞれ複数設けることにより、図１３中の矢印方向に現像剤が循環している。供給パドル６１、回収パドル６２及びパドル形状の撹拌部材２７は、それぞれ、現像ローラ２０の長手方向に沿って、図１３中の紙面手前−奥方向に延在する形状である。同様に、トナー補給口２３も図１３中の紙面手前−奥方向に延在するように形成され、この長手方向に延在するトナー補給口２３から長手方向に沿ってトナーが補給される。
このようにして、長手方向の濃度偏差を抑制するとともに、パドル状の撹拌部材２７の回転運動により現像剤を撹拌し、トナー濃度およびトナー帯電量を均一にしている。撹拌部材２７は撹拌羽板２７ｂの一部に羽開口部３０が複数設けられている。そして、撹拌羽板２７ｂが撹拌軸２７ａを中心に回転することにより、現像剤が持ち上げられ、一部の現像剤が撹拌羽板２７ｂの羽開口部３０から落ちることで、撹拌部１１内の現像剤の分散性を高めている。 In the developing device 10 of the reference configuration example, a plurality of paddles (61, 62) are provided in each transport path (41, 42), whereby the developer circulates in the direction of the arrow in FIG. The supply paddle 61, the recovery paddle 62, and the paddle-shaped stirring member 27 each have a shape extending along the longitudinal direction of the developing roller 20 in the front-to-back direction in FIG. Similarly, the toner replenishing port 23 is also formed so as to extend in the front-back direction in FIG. 13, and the toner is replenished along the longitudinal direction from the toner replenishing port 23 extending in the longitudinal direction.
In this way, the density deviation in the longitudinal direction is suppressed, and the developer is stirred by the rotational movement of the paddle-shaped stirring member 27, so that the toner density and the toner charge amount are made uniform. The stirring member 27 is provided with a plurality of blade openings 30 in a part of the stirring blade plate 27b. Then, the developer is lifted by rotating the stirring blade 27b around the stirring shaft 27a, and a part of the developer falls from the blade opening 30 of the stirring blade 27b, so that the development in the stirring unit 11 is performed. Increases the dispersibility of the agent.

供給パドル６１の下方の仕切り板２４には、現像剤の搬送方向における複数箇所に搬送路開口部２６が設けられている。この搬送路開口部２６も、トナー補給口２３と同様に図１３中の紙面手前−奥方向に延在するように形成されている。
参考構成例の現像装置１０では、供給搬送路４１内の現像剤の一部が搬送路開口部２６から落下し、回収搬送路４２へと受け渡される。これにより、供給搬送路４１と回収搬送路４２との間のトナー濃度は軽減する。
また、参考構成例の現像装置１０では、供給搬送路４１から現像ローラ２０を介して回収搬送路４２に到達し、さらに、撹拌部１１を介して供給搬送路４１に戻る現像剤の循環の流れが生じている。トナーの補給タイミング等によって、周期的なトナー濃度変動が生じると、現像剤の循環に沿ってトナー濃度変動は伝播する。このため、供給搬送路４１内の現像剤に周期的なトナー濃度変動が生じた場合、同じ周期のトナー濃度変動が回収搬送路４２内の現像剤にも伝達し、それが、再び供給搬送路４１に伝達する。 The partition plate 24 below the supply paddle 61 is provided with transport path openings 26 at a plurality of locations in the developer transport direction. Similarly to the toner supply port 23, the conveyance path opening 26 is also formed so as to extend in the front-back direction in FIG.
In the developing device 10 of the reference configuration example , a part of the developer in the supply conveyance path 41 falls from the conveyance path opening 26 and is delivered to the collection conveyance path 42. Thereby, the toner density between the supply conveyance path 41 and the collection conveyance path 42 is reduced.
Further, in the developing device 10 of the reference configuration example, the developer circulation flow that reaches the recovery conveyance path 42 from the supply conveyance path 41 via the developing roller 20 and returns to the supply conveyance path 41 via the agitation unit 11. Has occurred. When periodic toner density fluctuations occur due to toner replenishment timing or the like, the toner density fluctuations propagate along the developer circulation. For this reason, when a periodic toner density fluctuation occurs in the developer in the supply conveyance path 41, the toner density fluctuation of the same period is also transmitted to the developer in the recovery conveyance path 42, which again becomes the supply conveyance path. 41.

ここで、搬送路開口部２６を供給搬送路４１から回収搬送路４２に現像剤が受け渡されることで、回収搬送路４２内の現像剤の周期的なトナー濃度変動の振幅を抑制することが出来る。これは、以下の理由による。
例えば、周期的に変動する現像剤のトナー濃度の最大値が８［％］、最小値が６［％］であるとする。搬送路開口部２６を挟んで対向する供給搬送路４１内の位置と回収搬送路４２内の位置とで、トナー濃度変動の位相が同じ場合、回収搬送路４２内のトナー濃度が８［％］の現像剤が存在するタイミングで搬送路開口部２６を介して、供給搬送路４１からトナー濃度が８［％］の現像剤が受け渡される。同様に、回収搬送路４２内のトナー濃度が６［％］の現像剤が存在するタイミングで搬送路開口部２６を介して、供給搬送路４１からトナー濃度が６［％］の現像剤が受け渡される。このような場合、回収搬送路４２内では現像剤の量が増加するのみで、現像剤のトナー濃度変動の振幅は変動しない。
一方、搬送路開口部２６を挟んで対向する供給搬送路４１内の位置と回収搬送路４２内の位置とで、トナー濃度変動の位相が異なる場合、回収搬送路４２内のトナー濃度が８［％］の現像剤が存在するタイミングで搬送路開口部２６を介して、供給搬送路４１からトナー濃度が８［％］よりも低い現像剤が受け渡される。同様に、回収搬送路４２内のトナー濃度が６［％］の現像剤が存在するタイミングで搬送路開口部２６を介して、供給搬送路４１からトナー濃度が６［％］よりも高い現像剤が受け渡される。このような場合、回収搬送路４２内では現像剤の量が増加するとともに、現像剤のトナー濃度変動の振幅は小さくなる。 Here, the developer is transferred from the supply conveyance path 41 to the collection conveyance path 42 through the conveyance path opening 26, thereby suppressing the amplitude of the periodic toner density fluctuation of the developer in the collection conveyance path 42. I can do it. This is due to the following reason.
For example, it is assumed that the maximum value of the toner density of the developer that varies periodically is 8 [%] and the minimum value is 6 [%]. When the toner density fluctuation phase is the same in the position in the supply conveyance path 41 and the position in the collection conveyance path 42 facing each other across the conveyance path opening 26, the toner concentration in the collection conveyance path 42 is 8 [%]. The developer having a toner concentration of 8% is delivered from the supply conveyance path 41 through the conveyance path opening 26 at the timing when the developer exists. Similarly, a developer having a toner concentration of 6 [%] is received from the supply conveyance path 41 via the conveyance path opening 26 at a timing when the developer having a toner concentration of 6 [%] in the collection conveyance path 42 exists. Passed. In such a case, only the amount of the developer increases in the recovery conveyance path 42, and the amplitude of the toner density variation of the developer does not vary.
On the other hand, when the phase of the toner density variation differs between the position in the supply conveyance path 41 and the position in the collection conveyance path 42 facing each other across the conveyance path opening 26, the toner concentration in the collection conveyance path 42 is 8 [ %] Developer is delivered from the supply conveyance path 41 via the conveyance path opening 26 at a timing when the developer concentration is lower than 8 [%]. Similarly, a developer having a toner concentration higher than 6 [%] from the supply conveyance path 41 via the conveyance path opening 26 at the timing when the developer having a toner concentration of 6 [%] in the collection conveyance path 42 exists. Is passed. In such a case, the amount of the developer increases in the collection conveyance path 42, and the amplitude of the toner density fluctuation of the developer decreases.

そして、搬送路開口部２６を挟んで対向する供給搬送路４１内の位置と回収搬送路４２内の位置とで、トナー濃度変動の位相を同じとすることは困難である。さらに、参考構成例の現像装置１０では、現像剤の搬送方向における四箇所に搬送路開口部２６を設けており、すべての搬送路開口部２６において、供給搬送路４１内と回収搬送路４２内との間でトナー濃度変動の位相を同じとすることはさらに困難である。よって、参考構成例の現像装置１０では、搬送路開口部２６を備えない構成に比べて回収搬送路４２内の現像剤の周期的なトナー濃度変動の振幅を抑制することが出来る。
回収搬送路４２内で周期的なトナー濃度変動の振幅を抑制された現像剤が供給搬送路４１に受け渡されることで、供給搬送路４１内の現像剤の周期的なトナー濃度変動の振幅を抑制することができる。
これにより、現像ローラ２０に受け渡される現像剤の周期的なトナー濃度変動の振幅も抑制することができ、作像における副走査方向（紙搬送方向）の画像濃度変動を抑制することが可能である。 Further, it is difficult to make the phase of the toner density variation the same in the position in the supply conveyance path 41 and the position in the collection conveyance path 42 that are opposed to each other with the conveyance path opening 26 interposed therebetween. Furthermore, in the developing device 10 of the reference configuration example , the conveyance path openings 26 are provided at four locations in the developer conveyance direction, and the supply conveyance path 41 and the recovery conveyance path 42 are all in the conveyance path openings 26. It is even more difficult to make the phase of toner density fluctuations the same. Therefore, in the developing device 10 of the reference configuration example , it is possible to suppress the amplitude of the periodic toner density fluctuation of the developer in the collection transport path 42 as compared with the configuration in which the transport path opening 26 is not provided.
The developer in which the amplitude of the periodic toner density fluctuation in the collection conveyance path 42 is suppressed is delivered to the supply conveyance path 41, so that the periodic toner density fluctuation amplitude of the developer in the supply conveyance path 41 is reduced. Can be suppressed.
Thereby, the amplitude of the periodic toner density fluctuation of the developer delivered to the developing roller 20 can also be suppressed, and the image density fluctuation in the sub-scanning direction (paper transport direction) in image formation can be suppressed. is there.

以上、実施例１〜実施例４の現像装置１０は、現像ローラ２０、供給回収スクリュ２１、循環スクリュ２２及びトナー補給口２３を備える。現像ローラ２０は、トナー及び磁性キャリアからなる二成分の現像剤を表面に担持して潜像担持体である感光体１１７との対向部である現像領域に搬送する現像剤担持体である。供給回収スクリュ２１は、現像ローラ２０の表面に供給する現像剤を収容する現像剤収容部であるケーシング１０ａ内の現像剤に対して一方向に向かう搬送力を付与する第一搬送部材である。循環スクリュ２２は、ケーシング１０ａ内の現像剤に対して供給回収スクリュ２１とは逆方向に向かう搬送力を付与する第二搬送部材である。トナー補給口２３はケーシング１０ａ内の現像剤に新たなトナーを補給する補給口である。供給回収スクリュ２１によって現像剤が搬送力を付与される領域である第一搬送路としての供給回収搬送路５１における搬送方向下流側端部に到達した現像剤が循環スクリュ２２によって現像剤が搬送力を付与される領域である第二搬送路としての循環搬送路５２に受け渡される。また、循環搬送路５２における搬送方向下流側端部に到達した現像剤が供給回収搬送路５１に受け渡されることでケーシング１０ａ内を現像剤が循環する。また、供給回収搬送路５１と循環搬送路５２とにおける搬送方向の両端部以外に、供給回収搬送路５１と循環搬送路５２とを連通し、現像剤が通過可能な連通部を備える。このような現像装置１０において、供給回収搬送路５１における搬送方向下流側端部に到達した現像剤と新たに補給されたトナーとを混合・撹拌し、循環搬送路５２に受け渡す撹拌手段である撹拌部材２７を有する。このような撹拌部材２７によって、新たに補給されたトナーは現像剤と混合・撹拌された後に、供給回収搬送路５１と循環搬送路５２とからなる現像剤の循環経路に受け渡される。よって、供給回収搬送路５１から現像ローラ２０に供給される現像剤が帯電不足のトナーを含んだ現像剤となることを防止し、帯電不足のトナーを含んだ現像剤が現像に用いられることを防止できる。さらに、現像装置１０は、連通部を備えることにより、上記特許文献１と同様に、現像装置１０内での循環方向の位置が異なる領域間のトナー濃度の偏差を抑制することが出来る。
このような現像装置１０によれば、装置内での循環方向の位置が異なる領域間のトナー濃度の偏差を抑制しつつ、帯電不足のトナーを含んだ現像剤が現像に用いられることを防止できる。 As described above, the developing device 10 according to the first to fourth embodiments includes the developing roller 20, the supply / recovery screw 21, the circulation screw 22, and the toner supply port 23. The developing roller 20 is a developer carrying member that carries a two-component developer composed of toner and a magnetic carrier on the surface and conveys it to a developing region that is a portion facing the photosensitive member 117 that is a latent image carrier. The supply / recovery screw 21 is a first conveying member that applies a conveying force in one direction to the developer in the casing 10 a that is a developer accommodating portion that accommodates the developer supplied to the surface of the developing roller 20. The circulation screw 22 is a second conveying member that applies a conveying force in the direction opposite to the supply and recovery screw 21 to the developer in the casing 10a. The toner supply port 23 is a supply port for supplying new toner to the developer in the casing 10a. The developer that has reached the downstream end in the conveyance direction in the supply / recovery conveyance path 51 as the first conveyance path, which is a region to which the developer is conveyed by the supply / recovery screw 21, is conveyed by the circulation screw 22. Is transferred to the circulation conveyance path 52 as the second conveyance path. Further, the developer that has reached the downstream end in the conveyance direction in the circulation conveyance path 52 is transferred to the supply / recovery conveyance path 51, whereby the developer circulates in the casing 10a. In addition to both ends of the supply / recovery conveyance path 51 and the circulation conveyance path 52 in the conveyance direction, the supply / recovery conveyance path 51 and the circulation conveyance path 52 communicate with each other, and a communication section through which the developer can pass is provided. In such a developing device 10, the developer that has reached the downstream end in the conveyance direction in the supply / recovery conveyance path 51 and the newly replenished toner are mixed and agitated, and the agitation means delivers to the circulation conveyance path 52. A stirring member 27 is provided. The newly replenished toner is mixed and stirred with the developer by the agitating member 27 and then transferred to the developer circulation path including the supply / recovery conveyance path 51 and the circulation conveyance path 52. Therefore, the developer supplied from the supply / recovery conveyance path 51 to the developing roller 20 is prevented from becoming a developer containing an undercharged toner, and the developer containing an undercharged toner is used for development. Can be prevented. Further, since the developing device 10 includes the communication unit, similarly to the above-described Patent Document 1, it is possible to suppress a deviation in toner density between regions having different positions in the circulation direction in the developing device 10.
According to the developing device 10 as described above, it is possible to prevent a developer containing insufficiently charged toner from being used for development while suppressing a deviation in toner concentration between regions having different positions in the circulation direction in the device. .

実施例１〜実施例４の現像装置１０は、供給回収搬送路５１及び循環搬送路５２では、供給回収スクリュ２１及び循環スクリュ２２が現像ローラ２０の軸線方向に沿って現像剤を搬送する。このような構成では、装置内の現像剤の軸線方向に沿って循環しており、現像装置１０内での循環方向の位置が異なる領域間のトナー濃度の偏差を抑制することで現像ローラ２０の軸線方向に沿う方向での現像剤のトナー濃度の偏差を抑制することができる。   In the developing device 10 according to the first to fourth embodiments, in the supply / recovery conveyance path 51 and the circulation conveyance path 52, the supply / recovery screw 21 and the circulation screw 22 convey the developer along the axial direction of the developing roller 20. In such a configuration, the developing roller 20 circulates along the axial direction of the developer in the apparatus, and the deviation of the toner density between the regions having different positions in the circulation direction in the developing apparatus 10 is suppressed, so that the developing roller 20 Deviation of the toner density of the developer in the direction along the axial direction can be suppressed.

実施例１〜実施例４の現像装置１０では、供給回収搬送路５１は、現像剤を搬送しながら現像ローラ２０に現像剤を供給する供給搬送部材である供給回収スクリュ２１が配置された供給搬送路であり、循環搬送路５２は、供給回収搬送路５１の搬送方向下流側端部に到達した現像剤を現像ローラ２０の軸線方向に沿って供給回収スクリュ２１とは逆方向に搬送する循環搬送部材である循環スクリュ２２が配置されている。供給回収搬送路５１から現像ローラ２０の表面上に供給され、現像領域を通過した後の現像ローラ２０の表面上に残留する現像剤は、供給回収搬送路５１内に回収される。 The developing device 10 of Example 1 to Example 4, the supply collection transport path 51, the supply of supply and recovery screw 21 as a supply conveying member for supplying the developer to the developing roller 20 while transporting the developer is disposed The circulation conveyance path 52 is a circulation that conveys the developer that has reached the downstream end in the conveyance direction of the supply / recovery conveyance path 51 in the direction opposite to the supply / recovery screw 21 along the axial direction of the developing roller 20. A circulation screw 22 as a conveying member is arranged. The developer supplied from the supply / recovery conveyance path 51 onto the surface of the developing roller 20 and remaining on the surface of the development roller 20 after passing through the development region is collected in the supply / recovery conveyance path 51.

実施例１〜４や従来例の現像装置１０のように、二軸搬送タイプの現像装置においては、現像装置１０内の現像剤は、トナー補給やトナー消費（現像）によって、空間的にトナー濃度が変動している。現像ローラ２０に現像剤を供給する供給回収搬送路５１では、現像ローラ２０においてトナー消費され、トナー濃度の低下した現像剤を回収・搬送し、再び現像ローラ２０に汲み上げている。このため、従来例の現像装置１０では、特に供給回収搬送路５１では、下流に行くに従いトナー濃度が低下して濃度の偏差が大きくなってしまう。また、トナー帯電量に関しては現像剤担持体へ供給されるまでに十分撹拌され、均一の帯電量に立ち上がっている必要がある。そこで従来は、循環スクリュ２２や供給回収スクリュ２１といった現像剤搬送部材で現像剤を拡散（均一に分散混合）させることによって、そのトナー濃度変動を小さくしてきた。スクリュ等の現像剤搬送部材での拡散能力を上げるには、スクリュの回転数を上げたり、フィンを取り付けたりする等、スクリュ形状を工夫したりできる。しかし、それにも限界があり、現像剤が現像ローラ２０に到達するまでに十分に拡散しきれず、現像ローラ２０に汲み上げられた現像剤にもトナー濃度変動が残ってしまっているのが現状である。また、スクリュ回転数の増加は、現像剤にストレスを与えるとともに、スクリュ軸受け部での発熱が大きくなるため、トナーが凝集し、画像品質に悪影響を及ぼす懸念もある。
このため、二成分現像装置では、トナーと現像剤を短時間に余計なストレスをかけることなく混合撹拌を行いうことで、トナー消費やトナー補給によって発生したトナー濃度変動を抑制し、現像領域に均一なトナー濃度とトナー帯電量を持った現像剤を連続的に供給することが求められる。 In the developing device of the biaxial conveyance type, like the developing devices 10 of Examples 1 to 4 and the conventional example, the developer in the developing device 10 is spatially toner concentration due to toner supply or toner consumption (development). Is fluctuating. In the supply / recovery conveyance path 51 for supplying the developer to the developing roller 20, the toner consumed in the developing roller 20 and the developer having a lowered toner concentration is collected and conveyed, and pumped up to the developing roller 20 again. For this reason, in the conventional developing device 10, particularly in the supply / recovery conveyance path 51, the toner density decreases and the density deviation increases as it goes downstream. In addition, the toner charge amount needs to be sufficiently agitated before being supplied to the developer carrying member and rise to a uniform charge amount. Therefore, conventionally, the toner density fluctuation is reduced by diffusing (uniformly mixing and mixing) the developer with a developer conveying member such as the circulation screw 22 and the supply and recovery screw 21. In order to increase the diffusion capability of the developer conveying member such as a screw, the screw shape can be devised by increasing the number of rotations of the screw or attaching a fin. However, there is a limit to this, and the developer is not sufficiently diffused until it reaches the developing roller 20, and the toner density fluctuation still remains in the developer pumped up to the developing roller 20. . In addition, an increase in the number of rotations of the screw gives stress to the developer, and heat generation at the screw bearing increases, so that there is a concern that toner aggregates and adversely affects image quality.
For this reason, in the two-component developing device, the toner and developer are mixed and agitated in a short time without applying excessive stress, so that the toner density fluctuation caused by toner consumption and toner replenishment can be suppressed, and the development area can be reduced. It is required to continuously supply a developer having a uniform toner concentration and toner charge amount.

上記特許文献１には、トナー濃度の均一化により、トナー濃度変動やトナー帯電量のばらつきを抑える目的で、現像剤搬送経路の途中で分岐を設け、再び合流させることで、トナー濃度変動の位相をずらす位相制御機構を有する構成が開示されている。実施例１〜４の現像装置１０とは、確かに搬送経路途中に分岐（連通部）を設ける点では似ている点がある。しかし、特許文献１では、搬送経路途中に開口を設けることにより、トナー補給場所から現像剤担持体に現像剤が汲み上がるまでの距離が短くなり、補給トナーが十分に混合されずに、トナー濃度が不均一になる、または十分なトナー帯電量が得られず、トナー飛散を招く恐れがある。これを防ぐために開口部に開閉機構を設けているが、構成が複雑化するとともに、開閉時に現像剤またはトナーが挟まれることによりストレスを受けてしまう。以上の理由から、トナー濃度の偏差やトナー帯電量のばらつきといった問題は解消できていない。また、特許文献６に関しても同様で、補給されたトナーが十分に混合される前に現像剤担持体へと供給される可能性があり、トナー濃度偏差やトナー帯電量ばらつきの問題は解消できていない。
これに対して、実施例１〜実施例４の現像装置１０は、供給回収搬送路５１と循環搬送路５２との間に連通部を備え、これらの搬送路とは別に撹拌部１１を備える。補給されたトナーは撹拌部１１で十分に混合・撹拌されるとともに、トナーの消費により生じたトナー濃度変動は連通部における現像剤の入れ替わりによって低減する。
トナーが十分に分散した現像剤を供給することで、未帯電トナーが現像ローラ２０へ汲み上がることを抑制するとともに、現像剤の供給回収搬送路５１と循環搬送路５２との間に連通部を設けることにより、低トナー濃度現像剤と高トナー濃度現像剤が交換され、スクリュ回転数を上げることなく、現像ローラ２０の軸線方向でのトナー濃度を均一に保つことが可能である。よって、現像ローラ２０の軸線方向において、均一なトナー濃度およびトナー帯電量の現像剤を安定して供給することが可能となる。
また、未帯電トナーの現像ローラ２０への汲み上げを防止することで、トナー飛散を抑制することができる。また、撹拌部材２７によって撹拌することで、搬送スクリュによる現像剤の撹拌性を高めることを目的として回転数を上げる必要がなく、搬送スクリュの回転数の低減を図ることができる。 In Patent Document 1 described above, for the purpose of suppressing toner density fluctuation and toner charge amount variation by making the toner density uniform, a branch is provided in the middle of the developer transport path and joined again, so that the phase of toner density fluctuation is achieved. A configuration having a phase control mechanism for shifting is disclosed. The developing device 10 according to the first to fourth embodiments is similar to the developing device 10 in that a branch (communication portion) is provided in the middle of the conveyance path. However, in Patent Document 1, by providing an opening in the middle of the conveyance path, the distance from the toner replenishment location to the developer pumping up to the developer carrying member is shortened, and the replenishment toner is not sufficiently mixed and the toner concentration is reduced. May become non-uniform or a sufficient toner charge amount may not be obtained, resulting in toner scattering. In order to prevent this, an opening / closing mechanism is provided in the opening. However, the structure is complicated, and the developer or toner is sandwiched during opening / closing, so that stress is applied. For these reasons, problems such as deviations in toner density and variations in toner charge amount cannot be solved. The same applies to Patent Document 6, in which the replenished toner may be supplied to the developer carrier before being sufficiently mixed, and the problems of toner density deviation and toner charge amount variation can be solved. Absent.
On the other hand, the developing device 10 according to the first to fourth embodiments includes a communication unit between the supply / recovery conveyance path 51 and the circulation conveyance path 52, and a stirring unit 11 separately from these conveyance paths. The replenished toner is sufficiently mixed and agitated in the agitation unit 11, and toner density fluctuation caused by toner consumption is reduced by replacement of the developer in the communication part.
By supplying the developer in which the toner is sufficiently dispersed, the uncharged toner is prevented from being pumped up to the developing roller 20, and a communication portion is provided between the developer supply / recovery conveyance path 51 and the circulation conveyance path 52. By providing the low toner density developer and the high toner density developer, the toner density in the axial direction of the developing roller 20 can be kept uniform without increasing the screw rotation speed. Therefore, it is possible to stably supply a developer having a uniform toner density and toner charge amount in the axial direction of the developing roller 20.
Further, the toner scattering can be suppressed by preventing the uncharged toner from being drawn up to the developing roller 20. Further, by stirring with the stirring member 27, there is no need to increase the rotational speed for the purpose of enhancing the stirring property of the developer by the transport screw, and the rotational speed of the transport screw can be reduced.

また、実施例１〜実施例４の現像装置１０では、現像ローラ２０に現像剤を供給する供給搬送路としての機能と、現像領域を通過した現像ローラ２０上の現像剤を回収する回収搬送路としての機能とを一つの現像剤搬送路である、第一搬送路である供給回収搬送路５１が備える。本発明の特徴部を備える現像装置の現像剤搬送路の構成としては、供給搬送路の機能と回収搬送路の機能とを第一搬送路と第二搬送路とに分けた構成であってもよい。   Further, in the developing device 10 according to the first to fourth embodiments, a function as a supply conveyance path for supplying the developer to the development roller 20 and a collection conveyance path for collecting the developer on the development roller 20 that has passed through the development region. The supply / recovery conveyance path 51, which is the first conveyance path, is a single developer conveyance path. As a configuration of the developer transport path of the developing device including the characterizing portion of the present invention, the function of the supply transport path and the function of the recovery transport path may be divided into a first transport path and a second transport path. Good.

また、実施例１〜実施例３の現像装置１０では、供給回収搬送路５１と循環搬送路５２とを空間的に仕切る仕切り板２４を備え、連通部は仕切り板２４に設けられた開口部としての搬送路開口部２６である。このような搬送路開口部２６を設けることによって、供給回収搬送路５１と循環搬送路５２との間を現像剤が移動する連通部を実現することができる。なお、実施例４のように、仕切り板２４を設けず、供給回収搬送路５１と循環搬送路５２との間の搬送方向の全域を連通部とする構成であってもよい。   Further, the developing device 10 according to the first to third embodiments includes the partition plate 24 that spatially partitions the supply / recovery transport path 51 and the circulation transport path 52, and the communication portion is an opening provided in the partition plate 24. It is the conveyance path opening part 26 of this. By providing such a conveyance path opening 26, it is possible to realize a communication section in which the developer moves between the supply / recovery conveyance path 51 and the circulation conveyance path 52. As in the fourth embodiment, the partition plate 24 may not be provided, and the entire area in the conveyance direction between the supply / recovery conveyance path 51 and the circulation conveyance path 52 may be a communication unit.

また、実施例２及び実施例３の現像装置１０は、搬送路開口部２６が現像ローラ２０の軸線方向に複数個配置されている。図９に示すように、搬送路開口部２６が現像ローラ２０の軸線方向に複数並んでいることにより、軸線方向の現像剤のトナー濃度変動の位相を変化させることができ、軸線方向の現像剤の濃度偏差を均一にすることが可能となる。   In the developing devices 10 according to the second and third embodiments, a plurality of conveyance path openings 26 are arranged in the axial direction of the developing roller 20. As shown in FIG. 9, the plurality of transport path openings 26 are arranged in the axial direction of the developing roller 20, whereby the phase of the toner density fluctuation of the developer in the axial direction can be changed, and the developer in the axial direction can be changed. It is possible to make the concentration deviation uniform.

また、実施例２及び実施例３の現像装置１０は、図９に示すように、搬送路開口部２６の個数が供給回収搬送路５１の搬送方向下流側ほど多くなっている。これにより、トナー濃度が低下し易い供給回収搬送路５１の搬送方向下流側ほど搬送路開口部２６の個数を増やすことができ、循環搬送路５２との間での現像剤の受け渡しの頻度を上げることが可能となる。   Further, in the developing devices 10 according to the second and third embodiments, as shown in FIG. 9, the number of the conveyance path openings 26 increases toward the downstream side in the conveyance direction of the supply / recovery conveyance path 51. As a result, the number of the conveyance path openings 26 can be increased toward the downstream side of the supply / recovery conveyance path 51 where the toner concentration is likely to decrease, and the frequency of developer delivery to the circulation conveyance path 52 is increased. It becomes possible.

また、実施例２及び実施例３の現像装置１０は、供給回収搬送路５１の搬送方向下流側にある搬送路開口部２６ほど開口を広くなっており、搬送路開口部２６の開口面積が供給回収搬送路５１の搬送方向下流側ほど広い構成である。現像装置１０では、現像ローラ２０に現像剤を供給する供給回収搬送路５１の搬送方向下流側ほど、トナー消費された現像剤の割合が大きく、トナー濃度が低くなってしまっている。このため、供給回収搬送路５１の搬送方向下流側ほど搬送路開口部２６の開口面積を広くし、搬送路開口部２６における現像剤の受け渡しの頻度を高めることで、よりトナー濃度を均一に保つことが可能である。
また、供給回収搬送路５１の搬送方向下流側ほど搬送路開口部２６の開口面積を広くする構成としては、図８に示すように、現像剤の搬送方向に延在するように形成された搬送路開口部２６の高さ方向の幅を供給回収搬送路５１の搬送方向下流側ほど広くする構成であってもよい。 Further, in the developing devices 10 according to the second and third embodiments, the opening is widened toward the conveyance path opening 26 on the downstream side in the conveyance direction of the supply / recovery conveyance path 51, and the opening area of the conveyance path opening 26 is supplied. The downstream side of the collection conveyance path 51 in the conveyance direction is wider. In the developing device 10, the proportion of the developer that has consumed the toner is larger and the toner density is lower toward the downstream side in the conveyance direction of the supply / recovery conveyance path 51 that supplies the developer to the development roller 20. For this reason, the toner area can be kept more uniform by increasing the opening area of the transport path opening 26 toward the downstream side in the transport direction of the supply / collection transport path 51 and increasing the frequency of developer delivery at the transport path opening 26. It is possible.
Further, as a configuration in which the opening area of the conveyance path opening 26 is increased toward the downstream side in the conveyance direction of the supply / recovery conveyance path 51, as illustrated in FIG. 8, the conveyance formed to extend in the developer conveyance direction. The width | variety of the height direction of the path opening part 26 may be the structure which becomes wide toward the conveyance direction downstream of the supply collection | recovery conveyance path 51. FIG.

また、図７に示す現像装置１０は、供給搬送部材は回転軸に螺旋状の羽部を設けたスクリュ部材からなる供給スクリュとしての供給回収スクリュ２１であり、供給回収スクリュ２１は、供給回収搬送路５１内の現像剤を循環搬送路５２側に受け渡すことを促進する方向とすて、図７（ａ）中の反時計回り方向に回転する。図７に示す現像装置１０は現像ローラ２０の上方にドクタブレード２２５が配置されており、現像領域を通過した現像ローラ２０の下方から供給回収搬送路５１に受け渡される。このため、現像ローラ２０から回収されてトナー濃度が低下された現像剤は、供給回収スクリュ２１の回転軸に対して下方の図７（ａ）中の領域αに多く存在する。このとき、供給回収スクリュ２１を図７（ａ）中の反時計回り方向に回転することにより、供給回収スクリュ２１の回転軸の下方では、供給回収スクリュ２１の羽部が図７（ａ）中の左から右に移動する。これにより、供給回収スクリュ２１の回転軸の下方の現像剤が供給回収搬送路５１内の図７（ａ）中の左から右に移動し、循環搬送路５２側への移動が促される。これにより、供給回収搬送路５１内の現像剤のうち、トナー濃度が低下した現像剤を効率的に循環搬送路５２に受け渡すことができ、供給回収搬送路５１内の現像剤について、よりトナー濃度を均一にすることが可能である。   Further, the developing device 10 shown in FIG. 7 is a supply / recovery screw 21 as a supply screw made up of a screw member having a spiral blade provided on a rotating shaft of the supply / conveyance member. As a direction for facilitating the transfer of the developer in the path 51 to the circulation conveyance path 52 side, the developer rotates counterclockwise in FIG. In the developing device 10 shown in FIG. 7, a doctor blade 225 is disposed above the developing roller 20, and is delivered to the supply / recovery conveyance path 51 from below the developing roller 20 that has passed through the developing region. Therefore, a large amount of developer collected from the developing roller 20 and having a reduced toner concentration exists in a region α in FIG. 7A below the rotation axis of the supply / recovery screw 21. At this time, by rotating the supply / recovery screw 21 counterclockwise in FIG. 7 (a), the wing portion of the supply / recovery screw 21 is located in the lower part of the rotation shaft of the supply / recovery screw 21 in FIG. 7 (a). Move from left to right. As a result, the developer below the rotation shaft of the supply / recovery screw 21 moves from the left to the right in FIG. 7A in the supply / recovery conveyance path 51, and the movement toward the circulation conveyance path 52 is urged. Thereby, among the developers in the supply / recovery conveyance path 51, the developer having a lowered toner concentration can be efficiently transferred to the circulation / conveyance path 52. It is possible to make the concentration uniform.

また、図４及び図１０（ｂ）に示すように、実施例１〜実施例４の現像装置１０は、撹拌部材２７によって現像剤を撹拌する領域である撹拌部１１内の現像剤の剤面の高さ方向の位置が、撹拌部１１から循環搬送路５２への現像剤の受け渡し部の上端となる上部仕切り部材２９の下端の位置よりも上方となっている。トナー補給口２３から補給された補給トナーは、現像剤との比重差から現像剤に浮いた状態で存在するため、上部仕切り部材２９の下端の位置よりも撹拌部１１内の現像剤の剤面を高く設定することで、現像剤に対して未混合の補給トナーが循環搬送路５２に流れ込むことを抑制することが可能である。 Further, as shown in FIG. 4 and FIG. 10 (b), the developing device 10 of Example 1 to Example 4, the developer surface of the developer in the stirring portion 11 is a region for stirring the developer by stirring member 27 The position in the height direction is higher than the position of the lower end of the upper partition member 29 serving as the upper end of the developer delivery section from the stirring section 11 to the circulation conveyance path 52. The replenished toner replenished from the toner replenishing port 23 exists in a state of floating on the developer due to the difference in specific gravity with the developer, and therefore, the developer surface of the developer in the agitation unit 11 is located more than the position of the lower end of the upper partition member 29. Is set high, it is possible to suppress the supply of unmixed replenishment toner to the developer into the circulation conveyance path 52.

また、図４及び図１０（ｂ）に示すように、実施例１〜実施例４の現像装置１０は、撹拌部１１から循環搬送路５２への現像剤の受け渡し部の上部を仕切り、循環搬送路５２中の現像剤の嵩高さを調節する上部仕切り部材２９を備える。上部仕切り部材２９を設けることで、撹拌部１１から循環搬送路５２に必要以上の現像剤が流出することを防ぎ、撹拌部１１内の現像剤量を確保するとともに、循環搬送路５２中の剤嵩を一定に維持することができる。現像剤が流出することを防ぐことで、撹拌部１１内での現像剤量を維持することができ、現像装置１０内での現像剤量のバランスの安定化を図ることができる。循環搬送路５２中の剤嵩を一定に維持することで、搬送路開口部２６における現像剤の受け渡しを良好に行うことが可能となる。特に、図７に示す現像装置１０では、循環搬送路５２内の現像剤の嵩が多すぎると、上下に配置した搬送路開口部２６の上側を使った現像剤の受け渡しが困難となるが、上部仕切り部材２９を設けることで安定した現像剤の受け渡しを行うことができる。 Further, as shown in FIG. 4 and FIG. 10 (b), the developing device 10 of Example 1 to Example 4, partition the upper portion of the transfer portion of the developer from the stirring section 11 to the circulation path 52, the circulating transport An upper partition member 29 for adjusting the bulk of the developer in the path 52 is provided. By providing the upper partition member 29, it is possible to prevent an unnecessarily large amount of developer from flowing out of the stirring unit 11 into the circulation conveyance path 52, to secure the amount of developer in the stirring unit 11, and to add the agent in the circulation conveyance path 52. The bulk can be kept constant. By preventing the developer from flowing out, the amount of developer in the stirring unit 11 can be maintained, and the balance of the amount of developer in the developing device 10 can be stabilized. By maintaining the volume of the agent in the circulation conveyance path 52 constant, it is possible to satisfactorily deliver the developer at the conveyance path opening 26. In particular, in the developing device 10 shown in FIG. 7, if the volume of the developer in the circulation conveyance path 52 is too large, it becomes difficult to deliver the developer using the upper side of the conveyance path opening 26 arranged above and below. By providing the upper partition member 29, the developer can be delivered stably.

また、実施例１の現像装置１０の供給回収スクリュ２１と循環スクリュ２２とは、回転軸に螺旋状の羽部を設けたスクリュ部材であり、このスクリュ部材が回転することにより回転軸に直交する方向への現像剤の移動を促し、供給回収搬送路５１と循環搬送路５２との一方の搬送路から他方の搬送路への現像剤の受け渡しを促す受け渡し部材である第一パドル部材２８ａ及び第二パドル部材２８ｂを各スクリュ部材の搬送路開口部２６と対向する位置に有する。
スクリュ部材のみでは主に軸方向に現像剤に力が働くため、回転軸に直交する方向に現像剤が押し動かされる力が生じ難く、搬送路開口部２６における受け渡しの効率を高めることが困難である。実施例１のように、受け渡し部材である第一パドル部材２８ａ及び第二パドル部材２８ｂを各スクリュ部材の搬送路開口部２６と対向する位置に設けることで、各搬送路内の現像剤に対して、回転軸に直交する方向に力を作用させることができる。これにより、搬送路開口部２６における現像剤の受け渡し性が向上し、トナー濃度をより安定化させることができる。 The supply / recovery screw 21 and the circulation screw 22 of the developing device 10 according to the first exemplary embodiment are screw members provided with a spiral wing portion on the rotation shaft, and are orthogonal to the rotation shaft when the screw member rotates. The first paddle member 28a and the first paddle member 28a, which are transfer members that urge the developer to move in the direction and urge the transfer of the developer from one conveyance path of the supply / recovery conveyance path 51 and the circulation conveyance path 52 to the other conveyance path. A two paddle member 28b is provided at a position facing the conveying path opening 26 of each screw member.
Since only the screw member exerts a force on the developer mainly in the axial direction, it is difficult to generate a force that pushes the developer in a direction orthogonal to the rotation axis, and it is difficult to increase the efficiency of delivery at the conveyance path opening 26. is there. As in the first embodiment, the first paddle member 28a and the second paddle member 28b, which are delivery members, are provided at positions facing the conveyance path openings 26 of the screw members, so that the developer in each conveyance path Thus, a force can be applied in a direction orthogonal to the rotation axis. As a result, the developer transferability at the conveyance path opening 26 is improved, and the toner density can be further stabilized.

現像装置１０の水平方向で、且つ、上記現像剤担持体の軸線方向に直交にする方向を幅方向（図１の上下方向、図３及び図５の左右方向、図４の紙面手前−奥方向）とする。実施例１〜実施例４の現像装置１０の撹拌部１１の幅方向の長さは、供給回収搬送路５１または循環搬送路５２の一方の搬送路の幅方向の長さよりも大きく、供給回収搬送路５１、循環搬送路５２及び現像ローラ２０を含む現像部の幅方向の長さよりも小さい。撹拌部１１の幅方向の大きさを２つの搬送路の一方の搬送路の幅よりも広くすることで、撹拌部１１内の現像剤の量を多く確保することが可能であり、撹拌性を向上することが可能である。また、撹拌部を現像部の幅以下に抑えることで、現像装置１０の幅方向の必要以上の大型化を招くことない。このような現像装置１０であれば、感光体１１７と現像装置１０とを複数個備える画像形成装置において、感光体間ピッチを広げる必要がなく、画像形成装置の小型化を図ることができる。   The horizontal direction of the developing device 10 and the direction perpendicular to the axial direction of the developer carrier are the width direction (the vertical direction in FIG. 1, the horizontal direction in FIGS. 3 and 5, the front-back direction in FIG. 4). ). The length in the width direction of the stirring unit 11 of the developing device 10 of the first to fourth embodiments is larger than the length in the width direction of one of the supply / recovery conveyance path 51 or the circulation conveyance path 52, and the supply / recovery conveyance. The length in the width direction of the developing portion including the path 51, the circulation conveyance path 52 and the developing roller 20 is smaller. By making the size in the width direction of the agitating unit 11 wider than the width of one of the two conveying paths, it is possible to secure a large amount of developer in the agitating unit 11 and to improve the agitation. It is possible to improve. In addition, by suppressing the stirring unit to be equal to or smaller than the width of the developing unit, the development apparatus 10 is not unnecessarily enlarged in the width direction. With such a developing device 10, in an image forming apparatus including a plurality of photoreceptors 117 and developing devices 10, it is not necessary to increase the pitch between the photoreceptors, and the image forming apparatus can be downsized.

また、参考構成例の現像装置１０では、第一搬送路である回収搬送路４２及び第二搬送路である供給搬送路４１では、第一搬送部材である回収パドル６２及び第二搬送部材である供給パドル６１が現像ローラ２０の軸線方向に対して直交する方向に現像剤を搬送する。また、回収搬送路４２と供給搬送路４１とを空間的に仕切る仕切り板２４を備え、連通部として仕切り板２４に設けられた開口部である搬送路開口部２６が形成されている。参考構成例の現像装置１０のように、現像剤を現像ローラ２０の軸線方向に直交する方向搬送する構成では、搬送路開口部２６を挟んで対向する供給搬送路４１内の位置と回収搬送路４２内の位置とで、周期的に変化するトナー濃度変動の位相がずれていれば、回収搬送路４２内の現像剤のトナー濃度偏差を抑制することができる。現像装置１０内では現像剤が循環しているため、回収搬送路４２内の現像剤のトナー濃度偏差を抑制することで、現像装置１０内全体でのトナー濃度偏差を抑制することができる。軸線方向に直交する方向に現像剤が循環する構成で、現像剤のトナー濃度偏差を抑制することにより、副走査方向（紙の搬送方向）の濃度を均一にすることができる。また、図１３に示すように、搬送路開口部２６を、二つの搬送部材の搬送方向に複数個配置することにより、さらに、トナー濃度偏差を抑制することができる。 Further, in the developing device 10 of the reference configuration example , the recovery conveyance path 42 that is the first conveyance path and the supply conveyance path 41 that is the second conveyance path are the recovery paddle 62 and the second conveyance member that are the first conveyance members. The supply paddle 61 conveys the developer in a direction orthogonal to the axial direction of the developing roller 20. Further, a partition plate 24 that spatially partitions the collection transport path 42 and the supply transport path 41 is provided, and a transport path opening 26 that is an opening provided in the partition plate 24 is formed as a communication portion. In the configuration in which the developer is conveyed in a direction orthogonal to the axial direction of the developing roller 20 as in the developing device 10 of the reference configuration example , the position in the supply conveyance path 41 and the collection conveyance path that are opposed to each other with the conveyance path opening 26 interposed therebetween. If the phase of the toner density fluctuation that periodically changes is shifted from the position in 42, the toner density deviation of the developer in the collection transport path 42 can be suppressed. Since the developer circulates in the developing device 10, the toner density deviation in the entire developing device 10 can be suppressed by suppressing the toner density deviation of the developer in the collection conveyance path 42. In the configuration in which the developer circulates in a direction orthogonal to the axial direction, the density in the sub-scanning direction (paper transport direction) can be made uniform by suppressing the toner density deviation of the developer. In addition, as shown in FIG. 13, by arranging a plurality of transport path openings 26 in the transport direction of the two transport members, the toner density deviation can be further suppressed.

また、実施例１〜実施例４の現像装置１０は、供給回収搬送路５１から撹拌部１１に受け渡される現像剤の量である撹拌部流入量と、撹拌部１１から循環搬送路５２に受け渡される現像剤の量である撹拌部排出量と、トナー補給口２３から撹拌部１１に補給されるトナーの量である補給トナー量とが、「撹拌部排出量＝撹拌部流入量＋補給トナー量」の関係を満たしている。
撹拌部１１へ流入する現像剤の量と撹拌部１１から排出される現像剤の量を同じにすることで、撹拌部１１内の現像剤量を確保し、撹拌部１１における現像剤の撹拌性を安定的に維持することが可能である。これにより、補給トナーを剤中に均一分散し、さらに帯電量を立ち上げることが可能となる。よって、未混合のトナーが搬送路内に流れ込むことを防止できる。 Further, the developing device 10 according to the first to fourth embodiments receives the agitation unit inflow amount that is the amount of developer delivered from the supply / recovery conveyance path 51 to the agitation unit 11 and the circulation conveyance path 52 from the agitation unit 11. The amount of developer agitated, which is delivered, and the amount of toner supplied, which is the amount of toner replenished from the toner replenishing port 23 to the agitator 11, is expressed as “Agitator discharge amount = Agitator inflow + Supply toner. Satisfies the “quantity” relationship.
By making the amount of the developer flowing into the stirring unit 11 and the amount of the developer discharged from the stirring unit 11 the same, the amount of the developer in the stirring unit 11 is secured, and the stirring property of the developer in the stirring unit 11 Can be stably maintained. As a result, the replenishment toner can be uniformly dispersed in the agent, and the charge amount can be further increased. Therefore, unmixed toner can be prevented from flowing into the conveyance path.

また、実施例１〜実施例４及び参考構成例の現像装置１０は、新たなトナーを装置内に補給するトナー補給口２３を撹拌部１１の上部に設けている。トナー補給口２３を撹拌部１１の上に設けることで、現像剤内に撹拌されたトナーのみが撹拌部１１から搬送路へ排出され、未混合トナーが搬送路中に流れ込むことを防止することができる。 Further, in the developing devices 10 of the first to fourth embodiments and the reference configuration example , a toner supply port 23 for supplying new toner into the device is provided in the upper portion of the stirring unit 11. By providing the toner replenishing port 23 on the agitation unit 11, only the toner agitated in the developer is discharged from the agitation unit 11 to the conveyance path, and unmixed toner can be prevented from flowing into the conveyance path. it can.

また、実施例３及び実施例４の現像装置１０は、撹拌部１１及び撹拌部１１の上部に設けられたトナー補給口２３を複数箇所に備える。撹拌部１１およびトナー補給口２３を複数設けることで、現像ローラ２０の軸線方向の現像剤のトナー濃度偏差を一部に設けるよりも、より均一化することが可能である。   In addition, the developing device 10 according to the third and fourth embodiments includes the agitation unit 11 and the toner supply ports 23 provided on the upper part of the agitation unit 11 at a plurality of locations. By providing a plurality of agitation units 11 and toner replenishing ports 23, it is possible to make the toner density deviation of the developer in the axial direction of the developing roller 20 more uniform than providing a part thereof.

また、実施例１〜実施例４の現像装置１０が備える撹拌部材２７は、図６に示すように、回転運動によって下方から上方に現像剤を持ち上げながら撹拌を行う撹拌部材である。撹拌部１１内の現像剤を撹拌部材２７によって持ち上げ、重力によって落下させることで、良好な混合・撹拌性を得られるとともに、未混合トナーの搬送路への流出も防ぐことができる。   Further, as shown in FIG. 6, the stirring member 27 provided in the developing device 10 of the first to fourth embodiments is a stirring member that performs stirring while lifting the developer from below to above by rotating motion. By lifting the developer in the stirring unit 11 by the stirring member 27 and dropping it by gravity, it is possible to obtain good mixing / stirring properties and to prevent the unmixed toner from flowing out to the conveyance path.

また、実施例１〜実施例４の現像装置１０が備える撹拌部材２７は、図中の矢印Ｋ方向の回転運動によって循環搬送路５２内現像剤の搬送方向に現像剤を押し動かす構成である。撹拌部材２７が現像剤に与える動きを各搬送スクリュによる搬送方向と揃えてやることで、現像剤に余計なストレスを与えず、現像剤が一部で滞留して循環のバランスが崩れることを防ぐことも可能である。   Further, the stirring member 27 provided in the developing device 10 of the first to fourth embodiments is configured to push the developer in the transport direction of the developer in the circulation transport path 52 by the rotational movement in the arrow K direction in the drawing. By aligning the movement of the agitating member 27 to the developer with the conveying direction of each conveying screw, the developer is not subjected to excessive stress, and the developer is partially retained to prevent the circulation balance from being lost. It is also possible.

また、本実施形態の複写機５００は、潜像を担持する潜像担持体である感光体１１７と、感光体１１７上の潜像を現像する現像手段とを備える画像形成装置であり、複写機５００が備える現像手段として、実施例１または実施例２の現像装置１０を用いることで、現像に用いられる現像剤のトナー濃度及びトナーの帯電性が安定し、良好な画像形成を行うことができる。 The copier 500 of the present embodiment is an image forming apparatus including a photoconductor 117 that is a latent image carrier that carries a latent image, and a developing unit that develops the latent image on the photoconductor 117. By using the developing device 10 of Example 1 or Example 2 as the developing means included in 500, the toner concentration of the developer used for the development and the chargeability of the toner are stabilized, and good image formation can be performed. .

１０ 現像装置
１０ａ ケーシング
１１ 撹拌部
２０ 現像ローラ
２１ 供給回収スクリュ
２２ 循環スクリュ
２３ トナー補給口
２４ 仕切り板
２５ 端部開口部
２６ 搬送路開口部
２７ 撹拌部材
２８ パドル部材
２９ 上部仕切り部材
３０ 羽開口部
４１ 供給搬送路
４２ 回収搬送路
５１ 供給回収搬送路
５２ 循環搬送路
６１ 供給パドル
６２ 回収パドル
１００ プリンタ部
１１７ 感光体
１１８ 書き込みユニット
１２０ 転写ベルト
１２１ 定着部
５００ 複写機 DESCRIPTION OF SYMBOLS 10 Developing apparatus 10a Casing 11 Stirring part 20 Developing roller 21 Supply / recovery screw 22 Circulating screw 23 Toner supply port 24 Partition plate 25 End opening part 26 Transport path opening part 27 Stirring member 28 Paddle member 29 Upper partition member 30 Wing opening part 41 Supply conveyance path 42 Collection conveyance path 51 Supply collection conveyance path 52 Circulation conveyance path 61 Supply paddle 62 Collection paddle 100 Printer unit 117 Photoconductor 118 Writing unit 120 Transfer belt 121 Fixing unit 500 Copying machine

特開２００７−３１６１３０号公報JP 2007-316130 A 特開２００１−２９０３６８号公報JP 2001-290368 A 特開平０４−２２１９８０号公報Japanese Patent Laid-Open No. 04-221980 特開平０６−０１９３０９号公報Japanese Patent Laid-Open No. 06-019309 特開平１１−１７４８００号公報JP-A-11-174800 特開平１１−２０２６２６号公報JP-A-11-202626

Claims (16)

トナー及び磁性キャリアからなる二成分の現像剤を表面に担持して潜像担持体との対向部である現像領域に搬送する現像剤担持体と、
該現像剤担持体の表面に供給する現像剤を収容する現像剤収容部内の現像剤に対して一方向に向かう搬送力を付与する第一搬送部材と、
該現像剤収容部内の現像剤に対して該第一搬送部材とは逆方向に向かう搬送力を付与する第二搬送部材と、
該現像剤収容部内の現像剤に新たなトナーを補給するトナー補給口とを有し、
該第一搬送部材によって現像剤が搬送力を付与される領域である第一搬送路における搬送方向下流側端部に到達した現像剤が該第二搬送部材によって現像剤が搬送力を付与される領域である第二搬送路に受け渡され、該第二搬送路における搬送方向下流側端部に到達した現像剤が該第一搬送路に受け渡されることで該現像剤収容部内を現像剤が循環し、
該第一搬送路と該第二搬送路とにおける搬送方向の両端部以外に、該第一搬送路と該第二搬送路とを連通し、現像剤が通過可能な連通部を備える現像装置において、
上記第一搬送路と上記第二搬送路とは水平方向に並んで設けられており、
上記第一搬送路における搬送方向下流側端部に到達した現像剤と新たに補給されたトナーとを混合・撹拌し、上記第二搬送路に受け渡す撹拌手段を有すると共に、
上記撹拌手段によって現像剤を撹拌する領域である撹拌部内の現像剤の剤面の高さ方向の位置が、該撹拌部から上記第二搬送路へ現像剤を受け渡す部分の上端の位置よりも上方となることを特徴とする現像装置。 A developer carrying member that carries a two-component developer comprising a toner and a magnetic carrier on the surface and conveys the developer to a developing region that is opposite to the latent image carrier;
A first conveying member that applies a conveying force in one direction to the developer in the developer accommodating portion that accommodates the developer supplied to the surface of the developer carrying member;
A second conveying member that applies a conveying force in a direction opposite to the first conveying member to the developer in the developer accommodating portion;
A toner replenishing port for replenishing new developer to the developer in the developer accommodating portion;
The developer that has reached the downstream end in the transport direction in the first transport path, which is the region where the developer is transported by the first transport member, is transported by the developer by the second transport member. The developer that has been delivered to the second conveyance path, which is an area, and has reached the downstream end in the conveyance direction of the second conveyance path is delivered to the first conveyance path, so that the developer is contained in the developer accommodating portion. Circulate and
In the developing device, in addition to both ends of the first transport path and the second transport path in the transport direction, the first transport path and the second transport path communicate with each other, and a communication section through which the developer can pass is provided. ,
The first transport path and the second transport path are provided side by side in the horizontal direction,
The developer that has reached the downstream end in the conveyance direction in the first conveyance path and the newly supplied toner are mixed and agitated, and has an agitation unit that delivers to the second conveyance path, and
The position in the height direction of the developer surface of the developer in the stirring unit, which is a region where the developer is stirred by the stirring unit, is higher than the position of the upper end of the portion that delivers the developer from the stirring unit to the second transport path. A developing device characterized by being above . 請求項１の現像装置において、
上記第一搬送路及び上記第二搬送路では、上記第一搬送部材及び上記第二搬送部材が上記現像剤担持体の軸線方向に沿って現像剤を搬送することを特徴とする現像装置。 The developing device according to claim 1.
In the first transport path and the second transport path, the first transport member and the second transport member transport the developer along the axial direction of the developer carrier. 請求項２の現像装置において、
上記第一搬送路は、上記第一搬送部材が供給搬送部材として現像剤を搬送しながら上記現像剤担持体に現像剤を供給する供給搬送路であり、
上記第二搬送路は、上記第二搬送部材が循環搬送部材として該供給搬送路の搬送方向下流側端部に到達した現像剤を該現像剤担持体の軸線方向に沿って該供給搬送部材とは逆方向に搬送する循環搬送路であって、
該供給搬送路から該現像剤担持体の表面上に供給され、上記現像領域を通過した後の該現像剤担持体の表面上に残留する現像剤は、該供給搬送路内に回収されることを特徴とする現像装置。 The developing device according to claim 2.
The first conveyance path is a supply conveyance path that supplies the developer to the developer carrier while the first conveyance member conveys the developer as a supply conveyance member.
The second transport path is configured such that the developer that has reached the downstream end in the transport direction of the supply transport path as the circulation transport member is the supply transport member along the axial direction of the developer carrier. Is a circulating transport path that transports in the opposite direction,
The developer that is supplied from the supply conveyance path onto the surface of the developer carrier and remains on the surface of the developer carrier after passing through the development region is collected in the supply conveyance path. A developing device. 請求項３の現像装置において、
上記供給搬送路と上記循環搬送路とを空間的に仕切る仕切り板を備え、上記連通部は該仕切り板に設けられた開口部であることを特徴とする現像装置。 The developing device according to claim 3.
A developing device comprising: a partition plate that spatially partitions the supply transport path and the circulation transport path, wherein the communication portion is an opening provided in the partition plate. 請求項４の現像装置において、
上記開口部は、上記現像剤担持体の軸線方向に複数個配置されていることを特徴とする現像装置。 The developing device according to claim 4.
2. A developing device according to claim 1, wherein a plurality of the openings are arranged in the axial direction of the developer carrier. 請求項５の現像装置において、
上記開口部の個数が該供給搬送路の搬送方向下流側ほど多いことを特徴とする現像装置。 The developing device according to claim 5.
The developing device according to claim 1, wherein the number of the opening portions is larger toward the downstream side in the transport direction of the supply transport path. 請求項４乃至６のいずれか１項に記載の現像装置において、
上記開口部の開口面積が該供給搬送路の搬送方向下流側ほど広いことを特徴とする現像装置。 The developing device according to any one of claims 4 to 6,
The developing device characterized in that the opening area of the opening is wider toward the downstream side in the transport direction of the supply transport path. 請求項３乃至７のいずれか１項に記載の現像装置において、
上記供給搬送部材は回転軸に螺旋状の羽部を設けたスクリュ部材からなる供給スクリュであり、
該供給スクリュは上記供給搬送路内の現像剤を上記循環搬送路側に受け渡すことを促進する方向に回転することを特徴とする現像装置。 The developing device according to any one of claims 3 to 7,
The supply conveying member is a supply screw composed of a screw member provided with a spiral wing portion on a rotating shaft,
The developing device according to claim 1, wherein the supply screw rotates in a direction that facilitates delivery of the developer in the supply conveyance path to the circulation conveyance path side . 請求項１乃至８のいずれか１項に記載の現像装置において、
上記撹拌手段によって現像剤を撹拌する領域である撹拌部から上記第二搬送路へ現像剤を受け渡す部分の上部を仕切り、上記第二搬送路中の現像剤の嵩高さを調節する上部仕切り部材を備えることを特徴とする現像装置。 The developing device according to any one of 請 Motomeko 1 to 8,
An upper partition member for partitioning an upper portion of a portion for delivering the developer from the agitating portion, which is a region where the developer is agitated by the agitating means, to the second conveying path, and adjusting the bulk of the developer in the second conveying path A developing device comprising: 請求項１乃至９のいずれか１項に記載の現像装置において、
上記第一搬送部材と上記第二搬送部材とは、回転軸に螺旋状の羽部を設けたスクリュ部材であり、該スクリュ部材が回転することにより該回転軸に直交する方向への現像剤の移動を促し、上記第一搬送路と上記第二搬送路との一方の搬送路から他方の搬送路への現像剤の受け渡しを促す受け渡し部材を該スクリュ部材の上記連通部と対向する位置に有することを特徴とする現像装置。 The developing device according to any one of claims 1 to 9 ,
The first conveying member and the second conveying member are screw members provided with a spiral wing portion on a rotating shaft, and the developer in a direction orthogonal to the rotating shaft is generated by rotating the screw member. A transfer member that urges movement and prompts transfer of the developer from one transfer path to the other transfer path of the first transfer path and the second transfer path is provided at a position facing the communication portion of the screw member. A developing device. 請求項１乃至１０のいずれか１項に記載の現像装置において、
水平方向で、且つ、上記現像剤担持体の軸線方向に直交にする方向である幅方向について、上記撹拌手段によって現像剤を撹拌する領域である撹拌部の幅方向の長さは、上記第一搬送路または上記第二搬送路の一方の搬送路の幅方向の長さよりも大きく、該第一搬送路、該第二搬送路及び現像剤担持体を含む現像部の幅方向の長さよりも小さいことを特徴とする現像装置。 In the developing device according to any one of claims 1 to 10 ,
With respect to the width direction, which is the horizontal direction and the direction perpendicular to the axial direction of the developer carrying member, the length in the width direction of the stirring unit, which is a region where the developer is stirred by the stirring means, is The length in the width direction of the transport path or one of the transport paths is smaller than the length in the width direction of the developing unit including the first transport path, the second transport path, and the developer carrier. A developing device . 請求項１乃至１１のいずれか１項に記載の現像装置において、
上記第一搬送路から上記撹拌手段によって現像剤を撹拌する領域である撹拌部に受け渡される現像剤の量である撹拌部流入量と、該撹拌部から上記第二搬送路に受け渡される現像剤の量である撹拌部排出量と、該撹拌部に補給されるトナーの量である補給トナー量とが、
「撹拌部排出量＝撹拌部流入量＋補給トナー量」
の関係にあることを特徴とする現像装置。 The developing device according to any one of 請 Motomeko 1 to 11,
The amount of developer flow that is the amount of developer that is transferred from the first transport path to the stirring section that is the area where the developer is stirred by the stirring means, and the development that is transferred from the stirring section to the second transport path The amount of the stirring portion discharged, which is the amount of the agent, and the amount of replenished toner, which is the amount of toner supplied to the stirring portion,
“Agitator discharge amount = Agitator inflow + Replenishment toner amount”
A developing device characterized by the following relationship: 請求項１乃至１２のいずれか１項に記載の現像装置において、
上記新たなトナーを装置内に補給するトナー補給口を上記撹拌手段によって現像剤を撹拌する領域である撹拌部の上部に設けたことを特徴とする現像装置。 The developing device according to any one of claims 1 to 12 ,
A developing device, wherein a toner replenishing port for replenishing the new toner into the device is provided above an agitating portion which is a region where the developer is agitated by the agitating means . 請求項１乃至１３のいずれか１項に記載の現像装置において、
上記撹拌手段は回転運動によって下方から上方に現像剤を持ち上げながら撹拌を行う撹拌部材を備えることを特徴とする現像装置。 The developing device according to any one of 請 Motomeko 1 to 13,
The developing device according to claim 1, wherein the stirring means includes a stirring member that performs stirring while lifting the developer from below to above by rotation. 請求項１乃至１４のいずれか１項に記載の現像装置において、
上記撹拌手段は回転運動によって上記第二搬送路内の現像剤の搬送方向に現像剤を押し動かす撹拌部材を備えることを特徴とする現像装置。 The developing device according to any one of claims 1 to 14 ,
The developing device, wherein the agitation unit includes an agitation member that pushes the developer in a conveyance direction of the developer in the second conveyance path by a rotational motion. 潜像を担持する潜像担持体と、
該潜像担持体に潜像を形成する潜像形成手段と、
該潜像担持体上の潜像を現像する現像手段とを有する画像形成装置において、
上記現像手段として、請求項１乃至１５のいずれか１項に記載の現像装置を用いたことを特徴とする画像形成装置。 A latent image carrier for carrying a latent image;
Latent image forming means for forming a latent image on the latent image carrier;
In an image forming apparatus having a developing means for developing a latent image on the latent image carrier,
As the developing means, the image forming apparatus characterized by using the developing apparatus according to any one of claims 1 to 15.
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