JP2011186243A

JP2011186243A - Developing device, image forming apparatus using the same and process cartridge

Info

Publication number: JP2011186243A
Application number: JP2010052272A
Authority: JP
Inventors: Yasuo Miyoshi; 康雄三好; Hiroshi Hosokawa; 浩細川; Kouko Fujiwara; 香弘藤原; Tsuneo Kudo; 経生工藤; Hiroaki Okamoto; 啓明岡本
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2010-03-09
Filing date: 2010-03-09
Publication date: 2011-09-22
Anticipated expiration: 2030-03-09
Also published as: JP5500437B2

Abstract

PROBLEM TO BE SOLVED: To provide a developing device capable of smoothly delivering developer between developer conveying members, and to provide an image forming apparatus using the same and a process cartridge. SOLUTION: The developing device includes: a developing roller 33; a supply conveyance path 36 and a collection conveyance path 37 having a supply screw 38 and a collecting screw 39 conveying the developer in an axial direction of the developing roller 33; a partition plate 35 partitioning the supply conveyance path 36 and the collection conveyance path 37; and a delivery part 40 adjoining the end on a downstream side in a developer conveying direction of each of the supply conveyance path 36 and the collection conveyance path 37 and delivering the developer to the other conveyance path, wherein the developing device circularly conveys the developer in the supply conveyance path 36 and the collection conveyance path 37. The collection screw 39 includes a paddle 41 whose conveying force for conveying the developer in a direction orthogonal to the axial direction becomes larger as advancing in the developer conveying direction. COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、トナーと磁性キャリアからなる二成分現像剤を用いた現像装置並びにこれを用いた複写機、ファクシミリ、プリンタ等の画像形成装置及びプロセスカートリッジに関するものである
に関するものである。 The present invention relates to a developing device using a two-component developer composed of toner and a magnetic carrier, and an image forming apparatus such as a copying machine, a facsimile, and a printer using the same, and a process cartridge.

従来、二成分現像装置では、図１１に示すように、現像剤を収容する現像剤収容器１００内に、現像剤担持体の軸線方向に沿って現像剤攪拌搬送部材たる２本のスクリュ１０１、１０２を並行に配置している。そして、２本のスクリュ１０１、１０２が回転して互いに逆方向に現像剤を攪拌搬送し、両端部に設けられた受け渡し部１０３で一方のスクリュ１０１から他方のスクリュ１０２へ現像剤の受け渡しを行って現像剤を循環させている。その過程で一旦現像した現像剤を回収し、供給されたトナーと混合攪拌を行っている。この混合攪拌が不十分であると、画像濃度ムラが発生するなどの異常画像が形成される。必要な攪拌性は、現像剤容量に対する相対的なトナー消費量で決まる。現像装置の小型化、高速化を図る場合には、現像剤容量に対するトナーの消費量が増加するため、より攪拌性を向上させる必要がある。 Conventionally, in the two-component developing device, as shown in FIG. 11, two screws 101 serving as developer agitating and conveying members are provided in the developer container 100 for containing the developer along the axial direction of the developer carrier. 102 are arranged in parallel. Then, the two screws 101 and 102 rotate to stir and convey the developer in opposite directions, and the developer is transferred from one screw 101 to the other screw 102 by the transfer portions 103 provided at both ends. The developer is circulated. In this process, the developer once developed is collected and mixed and agitated with the supplied toner. If this mixing and stirring is insufficient, an abnormal image such as image density unevenness is formed. The required agitation is determined by the amount of toner consumed relative to the developer volume. In order to reduce the size and increase the speed of the developing device, the amount of toner consumed with respect to the developer capacity increases, and therefore it is necessary to further improve the stirring ability.

しかしながら、従来の現像装置では、２本のスクリュ１０１、１０２間での現像剤の受け渡しが必ずしもスムーズに行われていなかった。なぜなら、各スクリュ１０１、１０２による現像剤の搬送力は、図中矢印で示すようにスクリュ１０１、１０２の軸方向に作用するものであり、受け渡し部１０３でスクリュ１０１の軸方向と直交する受け渡し方向には作用しないからである。このため、送り側のスクリュ１０１の駆動トルクを著しく大きくして現像剤を圧縮する必要があり、現像剤にストレスがかかって凝着等の劣化を起こす場合があった。特に小型化などにより現像剤容量を低減していくと、スクリュ１０１、１０２間の受け渡し部１０３を通る回数が相対的に増加するため、現像劣化などの影響が大きくなる。 However, in the conventional developing device, the delivery of the developer between the two screws 101 and 102 has not always been performed smoothly. This is because the developer conveyance force by the screws 101 and 102 acts in the axial direction of the screws 101 and 102 as indicated by the arrows in the drawing, and the delivery direction is perpendicular to the axial direction of the screw 101 at the delivery unit 103. It does not work on. For this reason, it is necessary to remarkably increase the driving torque of the screw 101 on the feeding side to compress the developer, and the developer is stressed and may cause deterioration such as adhesion. In particular, when the developer capacity is reduced by downsizing or the like, the number of times of passing through the transfer portion 103 between the screws 101 and 102 relatively increases, so that the influence of development deterioration and the like becomes large.

このような問題を改善するため、例えば、図１１に示すスクリュ１０１の端部には、本来の現像剤搬送方向とは逆方向へ現像剤を搬送するべく、スクリュの傾きが逆に形成される逆搬送部１０１ａが設けられている。これにより、逆搬送部１０１ａに隣接する壁部近傍の現像剤にかかるストレスを低減することができる。また、図１２に示す現像装置は、現像剤担持体の軸線方向に沿って２本のスクリュ１０４、１０５を平行に配置し、スクリュ１０４、１０５の下流端の軸上にそれぞれ板状のパドル１０６、１０７を設けている。このパドル１０６、１０７は、軸に直交する方向へ搬送力をもち、隣接する搬送路に受け渡し部１０８、１０９を介して現像剤を送り出すことが可能である。 In order to remedy such a problem, for example, the end of the screw 101 shown in FIG. 11 is formed with a reverse inclination of the screw so as to convey the developer in the direction opposite to the original developer conveying direction. A reverse conveyance unit 101a is provided. Thereby, it is possible to reduce the stress applied to the developer in the vicinity of the wall portion adjacent to the reverse conveying portion 101a. Further, in the developing device shown in FIG. 12, two screws 104 and 105 are arranged in parallel along the axial direction of the developer carrier, and plate-like paddles 106 are respectively arranged on the shafts at the downstream ends of the screws 104 and 105. 107 are provided. The paddles 106 and 107 have a conveyance force in a direction orthogonal to the axis, and can feed the developer to the adjacent conveyance path via the transfer units 108 and 109.

また、特許文献１では、スクリュ端部のスクリュ径を大きくし、現像剤に受け渡し方向の力を加え、円滑に現像剤を流すことにより、トルクの低下と現像剤のストレスを抑制する現像装置が提案されている。また、特許文献２では、スクリュ端部のスクリュ角度を規定することで、現像剤に受け渡し方向の力を加え、円滑に現像剤を流すことにより、現像剤を均一に帯電させるようにした現像装置が提案されている。また、特許文献３では、現像剤を受け渡す受け渡し部に、受け渡し部の中途に開口径が大きく形成される現像剤貯留部を設けた現像装置が提案されている。 Further, in Patent Document 1, there is provided a developing device that suppresses torque reduction and developer stress by enlarging a screw diameter at a screw end, applying a force in a delivery direction to the developer, and smoothly flowing the developer. Proposed. Further, in Patent Document 2, by defining the screw angle of the screw end, a developing device that applies a force in the delivery direction to the developer and smoothly flows the developer to uniformly charge the developer. Has been proposed. Patent Document 3 proposes a developing device in which a developer storage section having a large opening diameter is provided in the middle of the delivery section in the delivery section that delivers the developer.

しかしながら、図１１に示す現像装置では、例えばスクリュを上下に配置し受け渡し部１０３が長くなる構成では、スクリュから離れた領域にスクリュによる搬送力が及ばず受け渡し部１０３で現像剤が滞留してしまう。同様に、特許文献１及び２に提案される現像装置においても、スクリュ形状の改良のみでは、スクリュから離れた領域にスクリュによる搬送力が及ばず受け渡し部で現像剤が滞留してしまう。また、図１２に示す現像装置では、パドル１０６、１０７により現像剤搬送路下流端の現像剤にスクリュ１０４、１０５の軸と直交する方向へ急激に強い搬送力が付与されることになる。そのため、受け渡し部１０８、１０９の現像剤に急激に現像剤の流れを変えるような力が働いてうまく力が伝わらず、現像剤が滞留してしまう。 However, in the developing device shown in FIG. 11, for example, in a configuration in which the screw is arranged up and down and the delivery unit 103 is long, the conveying force by the screw does not reach the region away from the screw, and the developer stays in the delivery unit 103. . Similarly, in the developing devices proposed in Patent Documents 1 and 2, only by improving the screw shape, the conveying force by the screw does not reach the area away from the screw, and the developer stays at the transfer portion. In the developing device shown in FIG. 12, the paddles 106 and 107 abruptly apply a strong conveying force to the developer at the downstream end of the developer conveying path in a direction perpendicular to the axes of the screws 104 and 105. Therefore, a force that suddenly changes the flow of the developer acts on the developers in the transfer units 108 and 109, and the force is not transmitted well, and the developer stays.

また、特許文献３による提案では、受け渡し部が長い場合には現像剤へのストレスを低減させる効果が大きいが、受け渡し部が短い場合には効果が小さい。このように、複数のスクリュで現像剤を循環搬送する現像装置においては、何れの場合もスクリュ間での現像剤のより円滑な受け渡しが望まれる。 Further, in the proposal according to Patent Document 3, the effect of reducing the stress on the developer is great when the delivery part is long, but the effect is small when the delivery part is short. As described above, in the developing device that circulates and conveys the developer with a plurality of screws, in any case, smoother delivery of the developer between the screws is desired.

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、現像剤搬送部材間で現像剤の円滑な受け渡しができる現像装置並びにこれを用いた画像形成装置及びプロセスカートリッジ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 provide a developing device capable of smoothly transferring a developer between developer conveying members, and an image forming apparatus and a process cartridge using the developing device. It is.

上記課題を解決するため、請求項１の発明は、トナーと磁性キャリアとを含む二成分現像剤を表面上に担持して回転し、潜像担持体と対向する箇所で該潜像担持体の表面の潜像にトナーを供給して現像する現像剤担持体と、該現像剤担持体の軸線方向に沿って現像剤を搬送する攪拌搬送部材をそれぞれ有する複数の現像剤搬送路と、該現像剤搬送路をそれぞれに仕切る仕切部材と、該複数の現像剤搬送路のそれぞれの現像剤搬送方向下流側端部に隣接して他の現像剤搬送路に現像剤を受け渡す受け渡し部とを備え、該複数の現像剤搬送路内で現像剤を循環搬送させる現像装置において、上記複数の現像剤搬送部材のうち少なくとも一つが、現像剤搬送方向に進むにしたがって軸線方向と直交する方向に現像剤を搬送する搬送力が大きくなる搬送力増大部材を備えることを特徴とするものである。
請求項２の発明は、請求項１の現像装置において、上記現像剤搬送部材は、回転軸上に螺旋状のスクリュ部を備え、上記搬送力増大部材は、上記受け渡し部に対向する領域で上記スクリュ部の回転軌跡よりも大きい回転軌跡を描くように回転し、該現像剤搬送部材の現像剤搬送方向に進むにしたがって現像剤との接触面積が増大するパドル部を備えることを特徴とするものである。
請求項３の発明は、請求項２の現像装置において、上記現像剤搬送部材は、上記搬送力増大部材からの搬送力が作用する部位で、現像剤搬送方向に進むにしたがってスクリュ部の径が小さくなることを特徴とするものである。
請求項４の発明は、請求項１、２又は３の現像装置において、上記現像剤搬送路は、上記現像剤担持体に現像剤を供給する現像剤供給搬送路と、該現像剤担持体から現像剤を回収する現像剤回収搬送路とから構成されることを特徴とするものである。
請求項５の発明は、請求項１、２、３又は４の現像装置において、上記現像剤担持体は、少なくとも上記現像担持体に対向する現像領域に磁界を発生させるための現像磁極と、上記現像剤搬送路から現像剤を汲み上げ該現像領域へ搬送する現像前磁極と、該現像領域を通過した後の現像剤を該現像剤担持体から離脱させるための現像後磁極を備え、該現像前磁極は、該現像剤担持体の表面上での法線方向の磁束密度を４０ｍＴ以下とすることを特徴とするものである。
請求項６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備える画像形成装置において、上記現像手段として、請求項１、２、３、４又は５の現像装置を用いたことを特徴とするものである。
請求項７の発明は、潜像を担持する潜像担持体と、該潜像担持体を一様帯電せしめる帯電手段と、該潜像担持体上の潜像を現像する現像手段と、該潜像担持体に残留する転写残トナーをクリーニングするクリーニング手段とを備える画像形成装置に用いられ、該潜像担持体と、該帯電手段と、該クリーニング手段との中より選ばれる少なくとも１つと、該現像手段とが一体になって画像形成装置本体に対して着脱可能に構成されたプロセスカートリッジにおいて、上記現像手段として、請求項１、２、３、４又は５の現像装置を用いたことを特徴とするものである。
本発明においては、現像剤搬送路の現像剤には、現像剤搬送部材によって軸線方向への搬送力が付与されつつ、搬送力増大部材によって現像剤搬送部材の軸線方向と直交する方向への搬送力が現像剤搬送方向に進むにしたがって次第に大きく付与される。そのため、現像剤搬送路を搬送される現像剤は、受け渡し部近傍で徐々に受け渡し部へ押し出されることになり、受け渡し部に滞留することなく円滑にもう一方の現像剤搬送路に受け渡される。これにより、従来のように現像剤搬送路下流側端部に現像剤を圧縮させる必要がなくなり、現像剤へのストレスを低減することができる。さらに、受け渡し部で現像剤の搬送速度が勾配を持つようになり、現像剤同士の接触回数が増え、トナーの分散性の向上と帯電特性の安定化を図ることができる。 In order to solve the above-mentioned problems, the invention of claim 1 is the one in which a two-component developer containing a toner and a magnetic carrier is carried on the surface and rotated, and the latent image carrier is rotated at a position facing the latent image carrier. A developer carrying member for supplying toner to the latent image on the surface for development; a plurality of developer carrying paths each having an agitation carrying member for carrying the developer along the axial direction of the developer carrying member; A partition member that divides each of the developer transport paths, and a delivery section that delivers the developer to another developer transport path adjacent to the downstream end of each of the plurality of developer transport paths in the developer transport direction. In the developing device that circulates and conveys the developer in the plurality of developer conveying paths, at least one of the plurality of developer conveying members proceeds in the direction orthogonal to the axial direction as the developer proceeds in the developer conveying direction. Carrying that increases the transport force It is characterized in further comprising a force-increasing members.
According to a second aspect of the present invention, in the developing device according to the first aspect, the developer conveying member includes a spiral screw portion on a rotation shaft, and the conveying force increasing member is located in a region facing the delivery portion. A paddle portion that rotates so as to draw a rotation trajectory larger than the rotation trajectory of the screw portion and has a contact area with the developer that increases as the developer transport member advances in the developer transport direction is provided. It is.
According to a third aspect of the present invention, in the developing device according to the second aspect, the developer conveying member is a portion to which the conveying force from the conveying force increasing member acts, and the diameter of the screw portion increases in the developer conveying direction. It is characterized by becoming smaller.
According to a fourth aspect of the present invention, in the developing device according to the first, second, or third aspect, the developer transport path includes a developer supply transport path that supplies the developer to the developer carrier, and the developer carrier. It is composed of a developer recovery transport path for recovering the developer.
According to a fifth aspect of the present invention, in the developing device according to the first, second, third, or fourth aspect, the developer carrier has a development magnetic pole for generating a magnetic field in at least a development region facing the development carrier, and A pre-development magnetic pole that pumps up the developer from the developer conveyance path and conveys it to the development area; and a post-development magnetic pole for separating the developer after passing through the development area from the developer carrier. The magnetic pole is characterized in that the magnetic flux density in the normal direction on the surface of the developer carrying member is 40 mT or less.
According to a sixth aspect of the present invention, there is provided a latent image carrier that carries a latent image, a latent image forming unit that forms a latent image on the latent image carrier, and a developing unit that develops the latent image on the latent image carrier. In the image forming apparatus having the above, the developing device according to claim 1, 2, 3, 4 or 5 is used as the developing means.
According to a seventh aspect of the present invention, there is provided a latent image carrier that carries a latent image, a charging unit that uniformly charges the latent image carrier, a developing unit that develops the latent image on the latent image carrier, and the latent image carrier. An image forming apparatus comprising: a cleaning unit that cleans transfer residual toner remaining on the image carrier; and at least one selected from the latent image carrier, the charging unit, and the cleaning unit, In a process cartridge which is integrated with a developing unit and is detachable from the main body of the image forming apparatus, the developing device according to claim 1, 2, 3, 4 or 5 is used as the developing unit. It is what.
In the present invention, the developer in the developer transport path is given a transport force in the axial direction by the developer transport member, and transported in a direction orthogonal to the axial direction of the developer transport member by the transport force increasing member. The force is gradually increased as the developer advances in the developer conveyance direction. Therefore, the developer conveyed through the developer conveyance path is gradually pushed out to the delivery part in the vicinity of the delivery part, and is smoothly delivered to the other developer conveyance path without staying in the delivery part. This eliminates the need for compressing the developer at the downstream end of the developer conveyance path as in the prior art, and can reduce stress on the developer. Furthermore, the developer conveyance speed has a gradient at the transfer section, the number of contacts between the developers increases, and it is possible to improve the dispersibility of the toner and stabilize the charging characteristics.

本発明は、現像剤搬送部材間で現像剤の円滑な受け渡しができる現像装置並びにこれを用いた画像形成装置及びプロセスカートリッジを提供できるという優れた効果がある。 The present invention has an excellent effect that it is possible to provide a developing device capable of smoothly delivering a developer between developer conveying members, an image forming apparatus using the same, and a process cartridge.

本実施形態に係るプリンタの概略構成を説明する構成図。1 is a configuration diagram illustrating a schematic configuration of a printer according to an embodiment. 同プリンタの現像装置の概略構成を説明する構成図。FIG. 2 is a configuration diagram illustrating a schematic configuration of a developing device of the printer. 同現像装置中の現像剤の流れを説明する断面図。Sectional drawing explaining the flow of the developer in the developing device. 同現像装置のパドルの構成を示す斜視図。The perspective view which shows the structure of the paddle of the developing device. 別の実施形態に係る回収搬送路の構成を説明する斜視図。The perspective view explaining the structure of the collection conveyance path which concerns on another embodiment. 別の実施形態に係るパドルの構成を説明する模式図。The schematic diagram explaining the structure of the paddle which concerns on another embodiment. 現像ローラ内に配置される磁石の法線磁束密度分布を説明する模式図。The schematic diagram explaining the normal-line magnetic flux density distribution of the magnet arrange | positioned in a developing roller. 供給搬送路と回収搬送路の現像剤の受け渡し効率を説明する特性図。FIG. 6 is a characteristic diagram illustrating developer delivery efficiency in a supply conveyance path and a collection conveyance path. 別の実施形態に係る現像装置の構成を説明する構成図。The block diagram explaining the structure of the developing device which concerns on another embodiment. 本実施形態に係るプロセスカートリッジの構成を説明する構成図。FIG. 3 is a configuration diagram illustrating a configuration of a process cartridge according to the present embodiment. 従来の現像装置の構成を説明する断面図。Sectional drawing explaining the structure of the conventional image development apparatus. 従来の現像装置の構成を説明する構成図。The block diagram explaining the structure of the conventional image development apparatus.

以下、本発明を画像形成装置として、タンデム方式のプリンタに適用した実施形態について説明する。図１は、本実施形態に係るプリンタの概略構成を説明する構成図である。このプリンタは、図１に示すように、シアン、イエロー、マゼンタ、ブラックの各色のトナー像を形成する４つの作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋを備えている（以下添字Ｃ、Ｙ、Ｍ、Ｋはシアン、イエロー、マゼンタ、ブラックの各色をそれぞれ示す）。この作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋは、それぞれ各色のトナー像を担持する像担持体である感光体１Ｃ、１Ｙ、１Ｍ、１Ｋを備えている。これら各感光体１の周囲には、各感光体１表面を一様に帯電する帯電装置２Ｃ、２Ｙ、２Ｍ、２Ｋ、各感光体１表面に形成される静電潜像を現像する現像装置３Ｃ、３Ｙ、３Ｍ、３Ｋ、トナー像転写後の各感光体１表面をクリーニングする感光体クリーニング装置４Ｃ、４Ｙ、４Ｍ、４Ｋ等を備えている。また、上記作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋは、各感光体１の一様に帯電された表面に画像情報に応じたレーザ光を照射して静電潜像を形成する露光装置５Ｃ、５Ｙ、５Ｍ、５Ｋを備えている。なお、感光体１は、ドラム状ではなく、ベルト状であってもよい。 Hereinafter, an embodiment in which the present invention is applied to a tandem printer as an image forming apparatus will be described. FIG. 1 is a configuration diagram illustrating a schematic configuration of a printer according to the present embodiment. As shown in FIG. 1, the printer includes four image forming units 10C, 10Y, 10M, and 10K that form toner images of cyan, yellow, magenta, and black (hereinafter, subscripts C, Y, and M). , K represents cyan, yellow, magenta, and black, respectively). Each of the image forming units 10C, 10Y, 10M, and 10K includes photoreceptors 1C, 1Y, 1M, and 1K that are image carriers that carry toner images of respective colors. Around each of these photoreceptors 1 are charging devices 2C, 2Y, 2M, and 2K that uniformly charge the surface of each photoreceptor 1, and a developing device 3C that develops an electrostatic latent image formed on each photoreceptor 1 surface. 3Y, 3M, 3K, and photoconductor cleaning devices 4C, 4Y, 4M, 4K, etc. for cleaning the surface of each photoconductor 1 after the transfer of the toner image. The image forming units 10C, 10Y, 10M, and 10K are each an exposure device 5C that forms an electrostatic latent image by irradiating a uniformly charged surface of each photoreceptor 1 with laser light according to image information. 5Y, 5M, 5K. Note that the photoreceptor 1 may have a belt shape instead of a drum shape.

上記作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋの下方には、下流側張架ローラ６及び上流側張架ローラ７に掛け回されて記録紙Ｐを表面に担持して表面移動する転写搬送ベルト８を備えている。転写搬送ベルト８を挟んで各作像ユニット１０の感光体１Ｃ、１Ｙ、１Ｍ、１Ｋと対向する位置には、転写バイアスローラ９Ｃ、９Ｙ、９Ｍ、９Ｋを備えている。下流側張架ローラ６よりも転写搬送ベルト８による記録紙搬送方向下流側には、転写搬送ベルト８から分離した記録紙Ｐ上の未定着トナーを定着する定着装置１１を備えている。また、プリンタの本体上部には、定着装置１１を通過しトナー像が定着した記録紙Ｐを積載するための排紙トレイ１２を備えている。 Below the image forming units 10C, 10Y, 10M, and 10K, a transfer conveyance belt 8 is wound around the downstream tension roller 6 and the upstream tension roller 7 and carries the recording paper P on the surface and moves. It has. Transfer bias rollers 9C, 9Y, 9M, and 9K are provided at positions facing the photoconductors 1C, 1Y, 1M, and 1K of the image forming units 10 with the transfer conveyance belt 8 interposed therebetween. A fixing device 11 that fixes unfixed toner on the recording paper P separated from the transfer conveyance belt 8 is provided on the downstream side of the downstream tension roller 6 in the recording paper conveyance direction by the transfer conveyance belt 8. In addition, a discharge tray 12 for loading recording paper P that has passed through the fixing device 11 and has a toner image fixed thereon is provided at the top of the printer main body.

上記転写搬送ベルト８の下方には、記録紙Ｐを収容する複数の給紙カセット１３、１４、１５を備えている。給紙カセット１３、１４、１５と転写搬送ベルト８との間には、転写搬送ベルト８と感光体１Ｃ、１Ｙ、１Ｍ、１Ｋとが対向する転写領域に向けて各給紙カセット１３、１４、１５から記録紙Ｐを供給する給紙搬送装置１６を備えている。そして、給紙搬送装置１６の用紙搬送方向最下流側には、搬送されてきた記録紙Ｐを作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋによる作像タイミングに合わせて供給するレジストローラ対１７を備えている。 A plurality of paper feed cassettes 13, 14, 15 for storing the recording paper P are provided below the transfer conveyance belt 8. Between the paper feed cassettes 13, 14, 15 and the transfer transport belt 8, each of the paper feed cassettes 13, 14, A paper feeding / conveying device 16 for supplying recording paper P from 15 is provided. A registration roller pair 17 is provided on the most downstream side in the paper conveyance direction of the paper feeding / conveying device 16 to supply the conveyed recording paper P in accordance with the image formation timing of the image forming units 10C, 10Y, 10M, and 10K. ing.

なお、上記作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋは、図１０に示すように、感光体１と耐電装置２、現像装置３、クリーニング装置４とが一体になってプリンタ本体に対して着脱可能に構成されたプロセスカートリッジとするとよい。これにより、メンテナンス性に優れ、また後述するように小型化された現像装置３を用いることにより、プリンタ本体の小型化を図ることができる。また、上記プリンタは、図１中の左右方向において小型になるよう、転写搬送ベルト８が斜め方向に配設され、記録紙Ｐの搬送方向が斜め方向となっている。これにより、プリンタは、図１中の左右方向における筐体の幅が、Ａ３サイズの記録紙長手方向の長さよりも僅かに長い大きさとなっている。すなわち、プリンタは、内部に記録紙Ｐを収容するために最低限必要な大きさとされることで大幅に小型化されている。 As shown in FIG. 10, the image forming units 10C, 10Y, 10M, and 10K can be attached to and detached from the printer body by integrating the photosensitive member 1, the electric resistance device 2, the developing device 3, and the cleaning device 4. The process cartridge may be configured as described above. As a result, it is possible to reduce the size of the printer body by using the developing device 3 that is excellent in maintainability and is downsized as will be described later. Further, in the printer, the transfer conveyance belt 8 is disposed in an oblique direction so that the printer is small in the left-right direction in FIG. 1, and the conveyance direction of the recording paper P is an oblique direction. Thereby, the width of the housing in the left-right direction in FIG. 1 is slightly longer than the length in the longitudinal direction of the A3 size recording paper. That is, the printer is greatly reduced in size by being the minimum size required to accommodate the recording paper P therein.

上記構成のプリンタは、画像形成スタートとともに、各作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋで各色トナー像が形成される。各作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋでは、感光体１Ｃ、１Ｙ、１Ｍ、１Ｋが、図示されないメインモータにより回転駆動され、帯電装置２Ｃ、２Ｙ、２Ｍ、２Ｋによって一様帯電された後、露光装置５Ｃ、５Ｙ、５Ｍ、５Ｋより、画像を色分解した色毎の画像情報に応じて書込み光Ｌが照射され、静電潜像が形成される。感光体１Ｃ、１Ｙ、１Ｍ、１Ｋ上に形成された静電潜像は、現像装置３Ｃ、３Ｙ、３Ｍ、３Ｋにより現像され、各感光体１Ｃ、１Ｙ、１Ｍ、１Ｋの表面上に各色トナー像が形成される。一方、給紙カセット１３、１４、１５のうち選択された給紙カセットから給紙搬送装置１６により給紙搬送された記録紙Ｐは、レジストローラ１７によって作像ユニット１０Ｃ、１０Ｙ、１０Ｍ、１０Ｋによる作像タイミングに合わせて、転写搬送ベルト８の表面上に供給される。そして、転写搬送ベルト８に担持された記録紙Ｐは転写搬送ベルト８の表面移動によって各色の転写領域に搬送される。 In the printer having the above-described configuration, each color toner image is formed by the image forming units 10C, 10Y, 10M, and 10K at the start of image formation. In each of the image forming units 10C, 10Y, 10M, and 10K, the photoreceptors 1C, 1Y, 1M, and 1K are rotationally driven by a main motor (not shown) and uniformly charged by the charging devices 2C, 2Y, 2M, and 2K. From the exposure devices 5C, 5Y, 5M, and 5K, writing light L is irradiated according to image information for each color obtained by color separation of the image, and an electrostatic latent image is formed. The electrostatic latent images formed on the photoreceptors 1C, 1Y, 1M, and 1K are developed by the developing devices 3C, 3Y, 3M, and 3K, and toner images of the respective colors are formed on the surfaces of the photoreceptors 1C, 1Y, 1M, and 1K. Is formed. On the other hand, the recording paper P fed and conveyed by the paper feeding / conveying device 16 from the selected paper feeding cassette among the paper feeding cassettes 13, 14, and 15 is registered by the image forming units 10 C, 10 Y, 10 M, and 10 K by the registration rollers 17. The toner is supplied onto the surface of the transfer conveyance belt 8 in accordance with the image forming timing. Then, the recording paper P carried on the transfer conveyance belt 8 is conveyed to the transfer area of each color by the surface movement of the transfer conveyance belt 8.

各感光体１Ｃ、１Ｙ、１Ｍ、１Ｋ上に形成されたトナー像は、感光体１Ｃ、１Ｙ、１Ｍ、１Ｋと転写搬送ベルト８との対向部となる転写領域で転写バイアスローラ９Ｃ、９Ｙ、９Ｍ、９Ｋによって転写搬送ベルト８上に担持された記録紙Ｐに順次転写される。このようにしてＣ（シアン）、Ｙ（イエロー）、Ｍ（マゼンタ）、Ｋ（ブラック）の順で各感光体１Ｃ、１Ｙ、１Ｍ、１Ｋ上に形成されたトナー像が転写され、重ね合わせカラートナー像が記録紙Ｐ上に形成される。トナー像を転写された記録紙Ｐは、転写搬送ベルト８から分離され、定着装置１１に搬送され、トナー像が定着されて機外の排紙トレイ１２に排出される。一方、記録紙Ｐ上にトナー像を転写した後の感光体１Ｃ、１Ｙ、１Ｍ、１Ｋは、クリーニング装置４Ｃ、４Ｙ、４Ｍ、４Ｋによって転写残トナーの除去がなされ、必要に応じて図示しない除電ランプで除電された後、再度、帯電装置２Ｃ、２Ｙ、２Ｍ、２Ｋで一様に帯電される動作を繰り返す。 The toner images formed on the photoconductors 1C, 1Y, 1M, and 1K are transferred to transfer bias rollers 9C, 9Y, and 9M in transfer regions that are opposed to the photoconductors 1C, 1Y, 1M, and 1K and the transfer conveyance belt 8, respectively. , 9K, and sequentially transferred onto the recording paper P carried on the transfer conveyance belt 8. In this way, the toner images formed on the photoreceptors 1C, 1Y, 1M, and 1K are transferred in the order of C (cyan), Y (yellow), M (magenta), and K (black) to superimpose color. A toner image is formed on the recording paper P. The recording paper P onto which the toner image has been transferred is separated from the transfer conveyance belt 8 and conveyed to the fixing device 11 where the toner image is fixed and discharged to a discharge tray 12 outside the apparatus. On the other hand, after the toner image is transferred onto the recording paper P, the transfer residual toner is removed by the cleaning devices 4C, 4Y, 4M, and 4K, and the static elimination (not shown) is performed as necessary. After being neutralized by the lamp, the operation of being uniformly charged by the charging devices 2C, 2Y, 2M and 2K is repeated again.

次に、本発明の特徴部となる現像装置３について詳しく説明する。現像装置３Ｃ、３Ｙ、３Ｍ、３Ｋは、画像形成物質として、互いに異なる色のトナーを用いるが、それ以外は同様の構成になっている。このため、以下、添字Ｃ、Ｙ、Ｍ、Ｋを省略し、現像装置３として説明する。図２は、現像装置の概略構成を説明する構成図である。図３は、現像装置中の現像剤の流れを説明する断面図である。 Next, the developing device 3 that is a feature of the present invention will be described in detail. The developing devices 3C, 3Y, 3M, and 3K use toners of different colors as image forming materials, but have the same configuration except that. For this reason, hereinafter, the subscripts C, Y, M, and K are omitted, and the developing device 3 will be described. FIG. 2 is a configuration diagram illustrating a schematic configuration of the developing device. FIG. 3 is a cross-sectional view illustrating the flow of the developer in the developing device.

現像装置３は、図２に示すように、現像容器３２内に磁性キャリアと磁性又は非磁性のトナーとを含む二成分現像剤である現像剤３１を収容している。そして、この現像装置３の現像容器３２は、図２中時計回り方向に回転駆動する感光体１に対向する位置に開口部を有し、該開口部から現像剤担持体としての現像ローラ３３の一部を露出させている。現像ローラ３３は、感光体１の表面に形成された静電潜像にトナーを供給して現像を行う現像領域まで現像容器３２内の現像剤３１を担持して、図２中反時計回り方向に表面移動する現像剤担持体としての現像スリーブを備える。現像スリーブの内部には、現像装置３に対して固定された複数の磁石（Ｎ１、Ｎ２、Ｎ３、Ｓ１、Ｓ２）からなるマグネットローラを備えている。さらに、現像容器３２の開口部には、現像ローラ（現像スリーブ）３３上に担持された現像剤３１の層厚規制する剤規制部材３４を有している。 As shown in FIG. 2, the developing device 3 contains a developer 31 that is a two-component developer containing a magnetic carrier and magnetic or nonmagnetic toner in a developing container 32. The developing container 32 of the developing device 3 has an opening at a position facing the photoreceptor 1 that is driven to rotate in the clockwise direction in FIG. 2, and the developing roller 33 serving as a developer carrying member from the opening. Some are exposed. The developing roller 33 carries the developer 31 in the developing container 32 up to a developing region where toner is supplied to the electrostatic latent image formed on the surface of the photoreceptor 1 and development is performed, and the counterclockwise direction in FIG. And a developing sleeve as a developer carrying member that moves on the surface. Inside the developing sleeve, a magnet roller comprising a plurality of magnets (N1, N2, N3, S1, S2) fixed to the developing device 3 is provided. Further, an opening of the developing container 32 has an agent regulating member 34 that regulates the layer thickness of the developer 31 carried on the developing roller (developing sleeve) 33.

現像剤３１を収容する現像容器３２は、内壁と仕切板３５によって、供給搬送路３６と回収搬送路３７とが上下に形成されている。上方に配置される供給搬送路３６には、図中時計回り方向に回転して、現像ローラ３３の軸線方向に沿って紙面手前側に現像剤３１を搬送し、現像ローラ３３に現像剤３１を供給する攪拌搬送部材たる供給スクリュ３８を備える。下方に配置される回収搬送路３７は、現像領域通過後の現像ローラ３３上から回収された現像剤３１を供給スクリュ３８による搬送方向とは逆方向、すなわち紙面奥側に搬送する攪拌搬送部材たる回収スクリュ３９を備える。仕切板３５は、現像ローラ３３側の端部が供給スクリュ３８を囲むように立設され、現像ローラ３３側に開口部が形成されており、供給搬送路３６内の現像剤３１は該開口部から現像ローラ３３へ供給される。この開口部は、現像ローラ３３の軸線方向に延びており、現像幅に亘って現像ローラ３３へ現像剤３１が供給可能にされている。また、仕切板３５の軸方向両端部には供給搬送路３６と回収搬送路３７との間で現像剤の受け渡しを行うための受け渡し部が設けられている。 In the developing container 32 that contains the developer 31, a supply conveyance path 36 and a recovery conveyance path 37 are formed vertically by an inner wall and a partition plate 35. The supply conveyance path 36 disposed above is rotated clockwise in the drawing to convey the developer 31 toward the front side of the paper along the axial direction of the development roller 33, and the developer 31 is conveyed to the development roller 33. A supply screw 38 as a stirring and conveying member to be supplied is provided. The collection conveyance path 37 disposed below is a stirring conveyance member that conveys the developer 31 collected from the development roller 33 after passing through the development region in a direction opposite to the conveyance direction by the supply screw 38, that is, the back side of the paper surface. A recovery screw 39 is provided. The partition plate 35 is erected so that the end portion on the developing roller 33 side surrounds the supply screw 38, and an opening is formed on the developing roller 33 side. The developer 31 in the supply conveyance path 36 has the opening portion. To the developing roller 33. The opening extends in the axial direction of the developing roller 33, and the developer 31 can be supplied to the developing roller 33 over the developing width. Further, at both end portions in the axial direction of the partition plate 35, delivery portions for delivering the developer between the supply conveyance path 36 and the collection conveyance path 37 are provided.

図３に示すように、供給スクリュ３８は、図中矢印Ａ方向に現像剤を搬送すべく、回転軸３８ａ上に螺旋状の羽根部となるスクリュ部３８ｂが所定のピッチで形成され、図示しない駆動モータによって回転する駆動ギア５０と噛み合うギア５１によって回転する。また、回収スクリュ３９は、図中矢印Ｂ方向に現像剤を搬送すべく、回転軸３９ａ上に螺旋状の羽根部となるスクリュ部３９ｂが所定のピッチで形成され、図示しない駆動モータによって回転する駆動ギア５０と噛み合うギア５２によって回転する。供給スクリュ３８と回収スクリュ３９とは互いに逆方向に現像剤３１を搬送することになる。現像容器３２内の現像剤３１は、供給スクリュ３８及び回収スクリュ３９による搬送によって供給搬送路３６と回収搬送路３７との間を両端部に設けられた受け渡し部４０を通じて循環する。供給搬送路３６内で供給スクリュ３８により矢印Ａ方向に搬送され搬送方向下流端に到達した現像剤３１は、受け渡し部（図示せず）より落下し、回収搬送路３７内の搬送方向上流端に受け渡される。回収搬送路３７内で回収スクリュ３９により矢印Ｂ方向に搬送され搬送方向下流端に到達した現像剤３１は、受け渡し部４０で矢印Ｃ方向に持ち上げられ、供給搬送路３６内の供給スクリュ３８の搬送方向上流端に受け渡される。 As shown in FIG. 3, in the supply screw 38, screw portions 38b serving as spiral blade portions are formed on the rotation shaft 38a at a predetermined pitch so as to convey the developer in the direction of arrow A in the drawing, and are not shown. It rotates by the gear 51 which meshes with the drive gear 50 rotated by a drive motor. Further, the recovery screw 39 has screw portions 39b, which are spiral blades, formed on the rotation shaft 39a at a predetermined pitch so as to convey the developer in the direction of arrow B in the figure, and is rotated by a drive motor (not shown). It is rotated by a gear 52 that meshes with the drive gear 50. The supply screw 38 and the recovery screw 39 convey the developer 31 in the opposite directions. The developer 31 in the developing container 32 circulates between the supply conveyance path 36 and the collection conveyance path 37 through the transfer sections 40 provided at both ends by conveyance by the supply screw 38 and the collection screw 39. The developer 31 conveyed in the direction of the arrow A by the supply screw 38 in the supply conveyance path 36 and reaching the downstream end in the conveyance direction falls from the transfer section (not shown) and reaches the upstream end in the conveyance direction in the collection conveyance path 37. Delivered. The developer 31 that has been transported in the direction of arrow B by the recovery screw 39 in the recovery transport path 37 and has reached the downstream end in the transport direction is lifted in the direction of arrow C by the transfer section 40 and transported by the supply screw 38 in the supply transport path 36. Passed to the upstream end in the direction.

上記構成の現像装置３において、供給搬送路３６内の現像剤３１は、供給スクリュ３８によって軸線方向に搬送されつつ、現像ローラ３３上に上から落ちるようにして供給される。現像ローラ３３に供給されずに供給搬送路３６内の供給スクリュ３８の搬送方向下流端部まで搬送された現像剤３１は、受け渡し部４０から下方の回収搬送路３７へ落ちていく。現像ローラ３３に供給された現像剤３１は、現像ローラ３３の回転と、内設されたマグネットローラの汲み上げ極Ｎ１の磁力とによって、現像ローラ３３の表面に担持されつつ、剤規制部材３４との対向部を通過する。このとき、現像ローラ３３の表面に担持された現像剤３１のうち余分な現像剤３１は、剤規制部材３４との対向部を通過するときに剤規制部材３４によって掻き取られる。 In the developing device 3 configured as described above, the developer 31 in the supply conveyance path 36 is supplied so as to fall on the developing roller 33 from above while being conveyed in the axial direction by the supply screw 38. The developer 31 transported to the downstream end in the transport direction of the supply screw 38 in the supply transport path 36 without being supplied to the developing roller 33 falls from the transfer section 40 to the lower recovery transport path 37. The developer 31 supplied to the developing roller 33 is carried on the surface of the developing roller 33 by the rotation of the developing roller 33 and the magnetic force of the pumping pole N1 of the built-in magnet roller. Pass through the opposite part. At this time, of the developer 31 carried on the surface of the developing roller 33, excess developer 31 is scraped off by the agent regulating member 34 when passing through a portion facing the agent regulating member 34.

剤規制部材３４との対向部を通過した適正量の現像剤３１は、現像ローラ３３と感光体１との間の現像領域３１を通過したのち、現像ローラ３３から離れ、現像容器３２の底部へ流れて回収搬送路３７へと受け渡される。すなわち、現像ローラ３３上に担持されて現像領域に搬送され、現像領域において感光体１の表面の供給されずに現像ローラ３３上に残った現像剤３１は、現像ローラ３３の回転に伴って供給搬送路３６に回収されるのではなく、回収搬送路３７に回収される。 The appropriate amount of developer 31 that has passed through the portion facing the agent regulating member 34 passes through the developing region 31 between the developing roller 33 and the photosensitive member 1, and then leaves the developing roller 33 and moves to the bottom of the developing container 32. It flows and is delivered to the collection conveyance path 37. That is, the developer 31 that is carried on the developing roller 33 and conveyed to the developing region and remains on the developing roller 33 without being supplied to the surface of the photoreceptor 1 in the developing region is supplied as the developing roller 33 rotates. Instead of being collected in the conveyance path 36, it is collected in the collection conveyance path 37.

供給搬送路３６の下流端に到達した現像剤３１と、現像領域３１を通過して現像ローラ３３の表面から離脱した現像剤３１は、回収搬送路３７によって搬送され受け渡し部（図示せず）を通じて供給搬送路３６の上流端に受け渡される。回収搬送路３７内の現像剤３１は現像領域３１を通過してトナー濃度が低下した現像剤３１を含むため、トナーを補給する必要がある。よって、図示しないトナー濃度センサの検知結果に応じて図示しないトナー補給機構によりトナーが回収搬送路３７内に補給される。 The developer 31 that has reached the downstream end of the supply conveyance path 36 and the developer 31 that has passed through the development region 31 and separated from the surface of the developing roller 33 are conveyed by a collection conveyance path 37 and passed through a delivery section (not shown). It is delivered to the upstream end of the supply conveyance path 36. Since the developer 31 in the collection conveyance path 37 includes the developer 31 that has passed through the development region 31 and has a reduced toner concentration, it is necessary to replenish the toner. Therefore, toner is supplied into the collection conveyance path 37 by a toner supply mechanism (not shown) according to a detection result of a toner density sensor (not shown).

回収搬送路３７内では、供給搬送路３６内で搬送方向下流端に到達し受け渡し部（図示せず）を通過した現像剤３１と、トナー補給口から補給されたトナーと、現像ローラ３３表面から離脱した現像剤３１とが回収スクリュ３９によって攪拌されながら搬送される。回収搬送路３７内で搬送方向下流端部に到達した現像剤３１は、受け渡し部４０を通して持ち上げられ、供給搬送路３６内の搬送方向上流端部に受け渡される。 In the collection conveyance path 37, the developer 31 that has reached the downstream end in the conveyance direction in the supply conveyance path 36 and passed through a transfer portion (not shown), the toner replenished from the toner replenishing port, and the surface of the developing roller 33 The separated developer 31 is conveyed while being agitated by the recovery screw 39. The developer 31 that has reached the downstream end in the transport direction in the collection transport path 37 is lifted through the transfer section 40 and transferred to the upstream end in the transport direction in the supply transport path 36.

次に、回収搬送路３７の搬送方向下流端に設けられた搬送力増大部材たるパドル４１の構成について説明する。図４は、パドルの構成を示す斜視図である。図３及び図４に示すように、回収搬送路３７の搬送方向下流端側には、断面略コの字状のパドル４１が回収スクリュ３９の回転軸３９ａと同軸上の位置に軸装されている。このパドル４１は、円形板状の基端部４１ａと、基端部４１ａの外周縁上に１８０°の間隔を設けて突設された２本のパドル部４１ｂ、４１ｃを備えている。このパドル部４１ｂ、４１ｃは、現像剤搬送方向（矢印Ｂ方向）に進むにしたがって現像剤との接触面積が増えるように、幅が徐々に大きく形成されている。このように構成されるパドル４１ｂ、４１ｃは、矢印Ｂ方向に進むにしたがって、矢印Ｃ方向に現像剤を搬送する搬送力が徐々に大きくなる。なお、回収スクリュ３９とパドル４１は、一体に成形してもよいが、別々に成形したものを用いてもよい。この場合には、両者に異なる駆動源を用いることにより、回転数を個別に設置することができる。 Next, the configuration of the paddle 41 that is a conveyance force increasing member provided at the downstream end of the collection conveyance path 37 in the conveyance direction will be described. FIG. 4 is a perspective view showing the configuration of the paddle. As shown in FIGS. 3 and 4, a paddle 41 having a substantially U-shaped cross section is mounted at a position coaxial with the rotation shaft 39 a of the collection screw 39 on the downstream end side in the conveyance direction of the collection conveyance path 37. Yes. The paddle 41 includes a circular plate-like base end portion 41a and two paddle portions 41b and 41c projecting from the outer peripheral edge of the base end portion 41a with an interval of 180 °. The paddle portions 41b and 41c are formed so that the width gradually increases so that the contact area with the developer increases as the developer advances in the developer transport direction (arrow B direction). In the paddles 41b and 41c configured in this manner, the transport force for transporting the developer in the arrow C direction gradually increases as it proceeds in the arrow B direction. The recovery screw 39 and the paddle 41 may be integrally molded, but may be molded separately. In this case, the rotational speed can be individually set by using different drive sources for both.

また、上記回収搬送路３７の構成は、図３及び図４に示す構成に限定されるものではない。図５は、別の実施形態に係る回収搬送路の構成を説明する斜視図である。図５に示す回収搬送路３７では、矢印Ｂ方向に進むにしたがって回収スクリュ３９のスクリュ部３９ｂの径が小さくなり、搬送力が低減している。これによりパドル４１のパドル部４１ｂの面積の変化を大きくつけることができるため、より効率的な現像剤の受け渡しが可能となる。また、回収スクリュ３９のスクリュ径を受け渡し部４０で大きくする必要がないので、装置の小型化に有利である。 Further, the configuration of the collection conveyance path 37 is not limited to the configuration shown in FIGS. 3 and 4. FIG. 5 is a perspective view for explaining a configuration of a collection conveyance path according to another embodiment. In the collection conveyance path 37 shown in FIG. 5, the diameter of the screw portion 39b of the collection screw 39 is reduced as it proceeds in the arrow B direction, and the conveyance force is reduced. As a result, the change in the area of the paddle portion 41b of the paddle 41 can be greatly increased, so that the developer can be delivered more efficiently. Moreover, since it is not necessary to increase the screw diameter of the collection screw 39 at the transfer section 40, it is advantageous for downsizing the apparatus.

図６は、本実施形態に係るパドルの構成例を説明する模式図である。図６（ａ）に示すパドルは、円形板状の基端部４１ａの外周縁上に２本のパドル部４１ｂ、４１ｃが１８０°の間隔をあけて突設されている。そして、このパドル４１のパドル部４１ｂ、４１ｃは、現像剤と接触するパドル面が基端部の４１ａの接線方向と略平行に形成され、先端（トナー搬送方向（矢印Ｂ方向）上流側）にいくほど、現像剤と接触する面積が小さくなっている。また、図６（ｂ）に示すパドルは、円形板状の基端部４２ａの外周縁上に２本のパドル部４２ｂ、４２ｃが１８０°の間隔をあけて突設されている。そして、このパドル４２のパドル部４２ｂ、４２ｃは、現像剤と接触するパドル面が基端部４２ａの接線方向に対して斜めに傾けられ、先端（トナー搬送方向（矢印Ｂ方向）上流側）にいくほど、現像剤と接触する面積が小さくなっている。また、図６（ｃ）に示すパドル４３は、円形板状の基端部４３ａの外周縁上に３本のパドル部４３ｂ、４３ｃ、４３ｄが１２０°の間隔をあけて突設されている。そして、このパドル４３のパドル部４３ｂ、４３ｃ、４３ｄは、現像剤と接触するパドル面が基端部４２ａの接線方向に対して斜めに傾けられ、先端（トナー搬送方向（矢印Ｂ方向）上流側）にいくほど、現像剤と接触する面積が小さくなっている。図６（ｂ）（ｃ）に示すパドル４２、４３は、図６（ａ）に示すパドル４１に比べ、現像剤を外側へ押し出す力が大きくなる。 FIG. 6 is a schematic diagram illustrating a configuration example of a paddle according to the present embodiment. In the paddle shown in FIG. 6A, two paddle portions 41b and 41c are projected from the outer peripheral edge of a circular plate-like base end portion 41a with an interval of 180 °. The paddle portions 41b and 41c of the paddle 41 are formed so that the paddle surface in contact with the developer is substantially parallel to the tangential direction of the base end portion 41a, and at the tip (upstream side in the toner transport direction (arrow B direction)). The smaller the area in contact with the developer, the smaller the area. Further, in the paddle shown in FIG. 6B, two paddle portions 42b and 42c protrude from the outer peripheral edge of the circular plate-like base end portion 42a with an interval of 180 °. The paddle portions 42b and 42c of the paddle 42 are inclined with respect to the tangential direction of the base end portion 42a so that the paddle surface in contact with the developer is inclined toward the tip (upstream side in the toner transport direction (arrow B direction)). The smaller the area in contact with the developer, the smaller the area. Further, in the paddle 43 shown in FIG. 6C, three paddle portions 43b, 43c, and 43d are projected from the outer peripheral edge of the circular plate-like base end portion 43a with an interval of 120 °. The paddle portions 43b, 43c, and 43d of the paddle 43 are inclined with respect to the tangential direction of the base end portion 42a with respect to the paddle surface that contacts the developer, and upstream of the leading end (toner transport direction (arrow B direction)) ), The area in contact with the developer becomes smaller. The paddles 42 and 43 shown in FIGS. 6B and 6C have a greater force to push the developer outward than the paddles 41 shown in FIG.

このように、図２乃至図６に示した現像装置３では、供給搬送路３６から現像ローラ３３に供給され現像領域を通過してトナー濃度が低下した現像剤３１は、回収搬送路３７と対向する位置で現像ローラ３３の表面から離脱し回収搬送路３７内に回収される。また、回収搬送路３７内に回収された現像剤３１は図示しないトナー補給機構から補給されるトナーと回収搬送路３７内で攪拌され、所望のトナー濃度となった状態で供給搬送路３６に供給される。つまり、現像領域を通過してトナー濃度が低下した現像剤３１は供給搬送路３６には回収されない。よって、供給搬送路３６内での現像剤３１のトナー濃度は、供給スクリュ３８による搬送方向上流側と下流側とで変化せず安定している。 As described above, in the developing device 3 shown in FIGS. 2 to 6, the developer 31 that has been supplied to the developing roller 33 from the supply conveyance path 36 and has passed through the development region and whose toner density has decreased is opposed to the collection conveyance path 37. At this position, it is separated from the surface of the developing roller 33 and collected in the collection conveyance path 37. The developer 31 collected in the collection conveyance path 37 is agitated in the collection conveyance path 37 with toner replenished from a toner supply mechanism (not shown), and is supplied to the supply conveyance path 36 in a state where a desired toner concentration is obtained. Is done. That is, the developer 31 whose toner density has decreased after passing through the development region is not collected in the supply conveyance path 36. Therefore, the toner concentration of the developer 31 in the supply conveyance path 36 is stable without changing between the upstream side and the downstream side in the conveyance direction by the supply screw 38.

また、上記構成の回収スクリュ３９とパドル４１、４２、４３を備えた回収搬送路３７では、受け渡し部４１の現像剤に矢印Ｃ方向への搬送力を徐々に強く付加することができるため、受け渡し部４０で現像剤３１のスムーズな流れを形成することができる。その結果、従来のように回収スクリュの搬送方向下流端部で現像剤を圧縮させる必要もなくなり、現像剤へのストレスを低減することができる。また、受け渡し部４０で現像剤３１が搬送速度の勾配をもつようになり、現像剤３１同士の接触回数が増え、電荷を付与することができるため、トナーの分散性の向上と帯電特性の安定化を図ることができる。 Further, in the collection conveyance path 37 provided with the collection screw 39 and the paddles 41, 42, and 43 having the above-described configuration, the conveyance force in the direction of arrow C can be gradually and strongly applied to the developer in the transfer section 41. A smooth flow of the developer 31 can be formed in the portion 40. As a result, it is not necessary to compress the developer at the downstream end in the transport direction of the recovery screw as in the conventional case, and the stress on the developer can be reduced. In addition, since the developer 31 has a gradient in the conveyance speed at the transfer unit 40, the number of contacts between the developers 31 can be increased and a charge can be imparted, thereby improving the dispersibility of the toner and stabilizing the charging characteristics. Can be achieved.

また、本実施形態に係る現像装置３では、上述したように受け渡し部４０を通過して電荷が付与され、帯電特性が安定した現像剤３１が感光体１に供給される。そのため、受け渡し部４０での電荷の付与分だけ、剤規制部３４における電荷付与機能を低減できる。よって、剤規制部３４での磁場の大きさを下げて、現像剤にかかるストレスを低減でき、長期の使用に対しても帯電特性の安定化を図ることができる。例えば、本実施例では、図７に示すように、現像ローラ３３内に配置される磁石の法線磁束密度分布を変更している。すなわち、図７（ａ）に示すように、剤規制部３４に対向する位置の磁場が５０ｍＴを超える大きさとした比較例のものに対して、図７（ｂ）に示すように剤規制部３４に対向する位置の磁場を５０ｍＴ以下とした場合でも、経時の使用において良好なトナー帯電特性が維持されることが判明した。 Further, in the developing device 3 according to the present embodiment, as described above, the developer 31 that has passed through the transfer unit 40 to be charged and has stable charging characteristics is supplied to the photoreceptor 1. Therefore, the charge imparting function in the agent restricting unit 34 can be reduced by the amount of charge imparted by the delivery unit 40. Therefore, the magnitude | size of the magnetic field in the agent control part 34 can be lowered | hung, the stress concerning a developing agent can be reduced, and stabilization of a charging characteristic can be aimed at also for a long-term use. For example, in this embodiment, as shown in FIG. 7, the normal magnetic flux density distribution of the magnet disposed in the developing roller 33 is changed. That is, as shown in FIG. 7 (a), as compared with the comparative example in which the magnetic field at the position facing the agent restricting portion 34 exceeds 50 mT, the agent restricting portion 34 is shown in FIG. 7 (b). It was found that even when the magnetic field at the position facing the toner was 50 mT or less, good toner charging characteristics were maintained over time.

次に、本実施形態に係る現像装置の供給搬送路３６及び回収搬送路３７間における現像剤の受け渡し効率を検証した実施例及び比較例を示す。本実施例では、図２及び図５に示す現像装置（現像ローラ３３は外している）３を用いている。回収スクリュ３９のスクリュ径は１４ｍｍ、スクリュ部３９ｂは、３．５ｍｍ〜１ｍｍまで傾斜をもたしている。スクリュ部３９ｂとパドル部４１ｂ、４１ｃとの隙間は０．５ｍｍ以上とする。受け渡し部４０の開口径は２０ｍｍとする。比較例では、図２及び図１１に示す現像装置（現像ローラは外している）を用いている。これら現像装置の現像容器３２、１００に現像剤１５０ｇ投入し、１秒間攪拌後、供給搬送路及び回収搬送路における現像剤の重さを測定した。その結果を図８に示す。図８の結果から、本実施例では、回収搬送路３７における現像剤量が低下し、供給搬送路３６における現像剤量が増加し、両搬送路３６、３７間の現像剤受け渡しの効率が上がっていることがわかる。 Next, examples and comparative examples in which the developer delivery efficiency between the supply conveyance path 36 and the collection conveyance path 37 of the developing device according to the present embodiment are verified are shown. In this embodiment, the developing device 3 (with the developing roller 33 removed) 3 shown in FIGS. 2 and 5 is used. The screw diameter of the recovery screw 39 is 14 mm, and the screw part 39b is inclined from 3.5 mm to 1 mm. The clearance between the screw part 39b and the paddle parts 41b and 41c is 0.5 mm or more. The opening diameter of the delivery part 40 shall be 20 mm. In the comparative example, the developing device (developing roller is removed) shown in FIGS. 2 and 11 is used. The developer containers 32 and 100 of these developing devices were charged with 150 g of the developer, and after stirring for 1 second, the weight of the developer in the supply conveyance path and the recovery conveyance path was measured. The result is shown in FIG. From the results shown in FIG. 8, in this embodiment, the developer amount in the recovery conveyance path 37 is decreased, the developer amount in the supply conveyance path 36 is increased, and the efficiency of developer delivery between the conveyance paths 36 and 37 is increased. You can see that

なお、本実施形態では、回収搬送路３７の搬送方向下流側端部に搬送力増大部材たるパドル４１を設ける実施形態について説明したが、供給搬送路３６の搬送方向下流側端部にも同様に搬送力増大部材を設けてもよい。また、本実施形態では、供給搬送路３７が上方にあり、回収搬送路３８が下方にある現像装置の構成について説明したが、これに限定されるものではない。本発明は、供給搬送路と回収搬送路の上下関係が逆である現像装置にも適用可能である。この場合には、供給搬送路から回収搬送路へ現像剤を受け渡す受け渡し部で重力に逆らって現像剤を搬送することになるため、少なくとも供給搬送路の搬送方向下流側端部に搬送力増大部材を設けることが好ましい。また、本実施形態では、現像剤搬送路である供給搬送路３６と回収搬送路３７とが上下に配置された現像装置３の構成について説明したがこれに限定されるものではない。本発明は、図９に示すように現像剤搬送路６１、６２が水平に配置された現像装置６０においても、適用することができる。図９に示す現像装置６０においても、現像剤攪拌搬送路６１、６２の現像剤搬送方向下流端にある壁部近傍の現像剤に強いストレスが発生する点は同じであり、上述した搬送力増大部材たるパドルを設けることにより、現像剤へのストレスを低減できる。 In the present embodiment, the embodiment has been described in which the paddle 41 that is a conveyance force increasing member is provided at the downstream end portion of the collection conveyance path 37 in the conveyance direction. A conveying force increasing member may be provided. Further, in the present embodiment, the configuration of the developing device in which the supply conveyance path 37 is on the upper side and the recovery conveyance path 38 is on the lower side is described, but the present invention is not limited to this. The present invention is also applicable to a developing device in which the vertical relationship between the supply conveyance path and the collection conveyance path is reversed. In this case, since the developer is transported against the gravity at the transfer section that transfers the developer from the supply transport path to the collection transport path, the transport force is increased at least at the downstream end in the transport direction of the supply transport path. It is preferable to provide a member. In the present exemplary embodiment, the configuration of the developing device 3 in which the supply conveyance path 36 and the recovery conveyance path 37 that are developer conveyance paths are vertically arranged has been described. However, the present invention is not limited to this. The present invention can also be applied to a developing device 60 in which developer transport paths 61 and 62 are horizontally arranged as shown in FIG. The developing device 60 shown in FIG. 9 also has the same point that strong stress is generated in the developer near the wall portion at the downstream end in the developer conveying direction of the developer agitating / conveying paths 61 and 62. By providing a paddle as a member, stress on the developer can be reduced.

以上、本実施形態に係る現像装置３によれば、現像剤搬送路となる回収搬送路３７に搬送力増大部材たるパドル４１、４２、４３を備えているので、供給搬送路３６と回収搬送路３７との間の受け渡し部４０で円滑な現像剤の受け渡しができる。その結果、現像剤に対するストレスを低減でき、トナーの分散性の向上、帯電特性の安定性を図ることができる。
また、本実施形態に係る現像装置３によれば、回収搬送路３７の搬送方向下流端に、スクリュ部３９ｂの回転軌跡よりも大きい回転軌跡となり、現像剤搬送方向に進むにしたがって現像剤との接触面積が増大するパドル４１、４２、４３を備えている。そのため、受け渡し部４０の現像剤３１に対して、現像剤搬送方向（矢印Ｂ方向）に進むにしたがって大きくなる図中矢印Ｃ方向への搬送力を付与することができる。
また、本実施形態に係る現像装置３によれば、受け渡し部４０の近傍では、現像剤搬送方向（矢印Ｂ方向）に進むにしたがってスクリュ部３９ｂの径が小さくなっている。これにより、パドル４１、４２、４３の現像剤との接触面積の変化を大きくつけることができるため、より効率的に現像剤の受け渡しを行うことができる。
また、本実施形態に係る現像装置５によれば、２つの現像剤搬送部材を上下方向に配置することができるので、水平方向の幅を小さくすることができ、装置の小型化を図ることができる。
また、本実施形態に係る現像装置５によれば、良好な帯電特性が得られるので、剤規制部３４に対向する位置の磁極の磁場の大きさを小さくすることができ、現像剤へのストレスを低減することができる。
また、本実施形態に係るプリンタによれば、上述した現像装置３を搭載しているので、長期使用や装置の小型化に対しても、高品質な画像を形成することができる。
また、本実施形態に係るプロセスカートリッジによれば、上述した現像装置３を搭載しているので、長期使用や装置の小型化に対しても、高品質な画像を形成することができる。 As described above, according to the developing device 3 according to the present embodiment, the collection conveyance path 37 serving as the developer conveyance path includes the paddles 41, 42, and 43 serving as conveyance force increasing members. Smooth transfer of the developer can be performed by the transfer portion 40 between the transfer member 37 and the terminal 37. As a result, stress on the developer can be reduced, toner dispersibility can be improved, and charging characteristics can be stabilized.
Further, according to the developing device 3 according to the present embodiment, the rotation trajectory is larger than the rotation trajectory of the screw portion 39b at the downstream end in the transport direction of the collection transport path 37, and the developer and the developer move in the developer transport direction. Paddles 41, 42, and 43 with increased contact areas are provided. Therefore, it is possible to apply a transport force in the direction of arrow C in the drawing, which increases as the developer 31 moves in the developer transport direction (arrow B direction) to the developer 31 of the delivery unit 40.
Further, according to the developing device 3 according to the present embodiment, in the vicinity of the delivery unit 40, the diameter of the screw part 39b becomes smaller as the developer proceeds in the developer transport direction (arrow B direction). Thereby, since the change of the contact area with the developer of the paddles 41, 42, 43 can be greatly increased, the developer can be delivered more efficiently.
Further, according to the developing device 5 according to the present embodiment, since the two developer conveying members can be arranged in the vertical direction, the horizontal width can be reduced, and the device can be miniaturized. it can.
Further, according to the developing device 5 according to the present embodiment, good charging characteristics can be obtained, so that the magnitude of the magnetic field of the magnetic pole at the position facing the agent restricting portion 34 can be reduced, and stress on the developer can be reduced. Can be reduced.
In addition, according to the printer according to the present embodiment, since the developing device 3 described above is mounted, a high-quality image can be formed even for long-term use and downsizing of the device.
In addition, according to the process cartridge according to the present embodiment, since the developing device 3 described above is mounted, a high-quality image can be formed even for long-term use or downsizing of the device.

１感光体
３現像装置
３３現像ローラ
３４剤規制部材
３５仕切板
３６供給搬送路
３７回収搬送路
３８供給スクリュ
３９回収スクリュ
４０受け渡し部
４１、４２、４３パドル DESCRIPTION OF SYMBOLS 1 Photoconductor 3 Developing device 33 Developing roller 34 Agent control member 35 Partition plate 36 Supply conveyance path 37 Collection conveyance path 38 Supply screw 39 Collection screw 40 Delivery part 41, 42, 43 Paddle

特開平１１−２４４０４号公報Japanese Patent Laid-Open No. 11-24404 特開２００３−１０７８５９号公報Japanese Patent Laid-Open No. 2003-107859 特開２００８−１４５９６８号公報JP 2008-145968 A

Claims

A developer that rotates by supporting a two-component developer containing toner and a magnetic carrier on the surface, and supplies the toner to the latent image on the surface of the latent image carrier at a position facing the latent image carrier. A plurality of developer conveying paths each having a carrier, an agitation conveying member that conveys the developer along the axial direction of the developer carrying body, a partition member that divides the developer conveying path, and the plurality of the plurality of developer conveying paths. A developer transfer path is provided adjacent to each downstream end of the developer transport direction in the developer transport path, and a delivery section that delivers the developer to another developer transport path. The developer is circulated in the plurality of developer transport paths. In the developing device to be conveyed,
At least one of the plurality of developer transport members includes a transport force increasing member that increases a transport force for transporting the developer in a direction orthogonal to the axial direction as it proceeds in the developer transport direction. apparatus.

The developing device according to claim 1.
The developer conveying member includes a spiral screw portion on a rotation shaft,
The conveyance force increasing member rotates so as to draw a rotation trajectory larger than the rotation trajectory of the screw part in a region facing the transfer unit, and the developer and the developer increasing member move in the developer conveyance direction of the developer conveying member. A developing device comprising a paddle portion that increases the contact area of the developing device.

The developing device according to claim 2.
The developing device according to claim 1, wherein the developer conveying member is a portion where the conveying force from the conveying force increasing member acts, and the diameter of the screw portion decreases as the developer conveying direction proceeds.

The developing device according to claim 1, 2 or 3,
The developer transport path is composed of a developer supply transport path for supplying a developer to the developer carrier and a developer recovery transport path for recovering the developer from the developer carrier. Developing device.

The developing device according to claim 1, 2, 3 or 4,
The developer carrier includes a development magnetic pole for generating a magnetic field at least in a development region facing the development carrier, a pre-development magnetic pole that draws the developer from the developer conveyance path and conveys the developer to the development region, A post-development magnetic pole for separating the developer after passing through the development region from the developer carrier,
The developing device, wherein the pre-development magnetic pole has a normal magnetic flux density of 40 mT or less on the surface of the developer carrying member.

In an image forming apparatus comprising: a latent image carrier that carries a latent image; a latent image forming unit that forms a latent image on the latent image carrier; and a developing unit that develops the latent image on the latent image carrier.
An image forming apparatus using the developing device of claim 1, 2, 3, 4 or 5 as the developing means.

A latent image carrier that carries a latent image, a charging unit that uniformly charges the latent image carrier, a developing unit that develops the latent image on the latent image carrier, and a transfer that remains on the latent image carrier The image forming apparatus includes a cleaning unit that cleans residual toner, and at least one selected from the latent image carrier, the charging unit, and the cleaning unit, and the developing unit are integrated. In the process cartridge configured to be detachable from the image forming apparatus main body,
6. A process cartridge using the developing device according to claim 1, 2, 3, 4 or 5 as the developing means.