JP2007171589A

JP2007171589A - Image forming apparatus

Info

Publication number: JP2007171589A
Application number: JP2005369581A
Authority: JP
Inventors: Tomoyuki Imura; 知之井村
Original assignee: Konica Minolta Business Technologies Inc
Current assignee: Konica Minolta Business Technologies Inc
Priority date: 2005-12-22
Filing date: 2005-12-22
Publication date: 2007-07-05
Anticipated expiration: 2025-12-22
Also published as: JP4774982B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of obtaining satisfactory developability. <P>SOLUTION: The image forming apparatus includes: a developer carrier 12 that holds toner thereon; a regulating member 16 that has a potential difference Δv between the developer carrier 12 and itself while kept in contact with the developer carrier 12 at predetermined pressure n, and regulates toner, thereby forming the toner layer on the developer carrier 12; an electrode member 20 disposed opposite the developer carrier 12 so as not to be in contact with the developer carrier 12 while the toner layer is interposed between them; and an AC current generating means 22 that generates an AC electric field between the developer carrier 12 and electrode member 20. The AC electric field generating means 22 generates an AC electric field so that the electric field intensity E(V/m) of an electric field for moving the toner from the developer carrier 12 to the electrode member 20 satisfies relations expressed by the following formula: E≥(0.033×n+0.0033×Δv+2)×10<SP>-6</SP>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、画像形成装置に関するものであり、特に、規制部材を用いて現像剤担持体に現像剤の層を形成するものに関する。 The present invention relates to an image forming apparatus, and more particularly to an apparatus for forming a developer layer on a developer carrier using a regulating member.

従来、非磁性一成分現像方式の画像形成装置は、現像剤担持体に担持されている現像剤（トナー）を該現像剤担持体に圧接している規制部材を用いて規制し、該トナーの層を現像剤担持体上に形成する。このような画像形成装置として、例えば特許文献１に記載のものがある。
特開２００１−７５３５７公報 Conventionally, an image forming apparatus of a non-magnetic one-component development system regulates a developer (toner) carried on a developer carrying body using a regulating member in pressure contact with the developer carrying body, A layer is formed on the developer carrier. An example of such an image forming apparatus is disclosed in Patent Document 1.
JP 2001-75357 A

しかしながら、トナーが規制部材によって規制されることにより高い充填密度で且つ大きい付着力で現像剤担持体に担持された結果、現像剤担持体から像担持体に向かってトナーが移動し難い、すなわち、良好な現像性が得られないことがあった。特に、かぶりの発生を抑制するために、現像剤担持体と規制部材の間に一定の電位差を設けた場合、規制部材が現像剤担持体に吸着され、それによりトナーの現像剤担持体に対する付着力がより大きくなり、その結果、最終的に画像が形成される記録シートにおいて十分な画像濃度を得ることができないなどの問題、言い換えると現像剤担持体から像担持体に移動するトナー量が少ないことを原因とする問題が生じていた。 However, as a result of the toner being regulated by the regulating member and being carried on the developer carrier with a high filling density and a large adhesion force, the toner is difficult to move from the developer carrier to the image carrier. In some cases, good developability could not be obtained. In particular, when a constant potential difference is provided between the developer carrying member and the regulating member in order to suppress the occurrence of fogging, the regulating member is adsorbed on the developer carrying member, thereby attaching toner to the developer carrying member. The adhesion force becomes larger, and as a result, there is a problem that a sufficient image density cannot be obtained on the recording sheet on which an image is finally formed, in other words, the amount of toner that moves from the developer carrier to the image carrier is small. There was a problem caused by this.

そこで、本発明は、規制部材によって高い充填密度で且つ大きい付着力でトナーが現像剤担持体に担持されても、多くのトナーが現像剤担持体から像担持体に移動して良好な現像性が得られる画像形成装置を提供することを目的とする。 In view of the above, the present invention provides a good developability because a large amount of toner moves from the developer carrier to the image carrier even when the toner is carried on the developer carrier by the regulating member with a high filling density and a large adhesion force. An object of the present invention is to provide an image forming apparatus capable of obtaining the above.

上記目的を達成するために、本発明の画像形成装置は、
現像剤担持体上のトナーを規制してトナーの層を形成する画像形成装置であって、
トナーを担持する現像剤担持体と、
現像剤担持体と所定の圧力で当接しつつ該現像剤担持体との間に所定の電位差が設けられ、トナーを規制して該トナーの層を現像剤担持体上に形成する規制部材と、
トナー層を挟んで現像剤担持体と非接触で対向する電極部材と、
現像剤担持体と電極部材の間に交流電界を形成する交流電界形成手段を有し、
交流電界形成手段は、上記所定の圧力をｎ（Ｎ／ｍ）、上記所定の電位差をΔｖ（Ｖ）としたとき、
トナーを現像剤担持体から電極部材に移動させる電界の電界強度Ｅ（Ｖ／ｍ）が、数２に示す関係を満たすように交流電界を形成することを特徴とする。

In order to achieve the above object, an image forming apparatus of the present invention includes:
An image forming apparatus for forming a toner layer by regulating toner on a developer carrier,
A developer carrier for carrying toner;
A regulating member that is in contact with the developer carrying body at a given pressure and has a predetermined potential difference between the developer carrying body and regulates the toner to form a layer of the toner on the developer carrying body;
An electrode member that faces the developer carrying member in a non-contact manner across the toner layer;
An AC electric field forming means for forming an AC electric field between the developer carrier and the electrode member;
The AC electric field forming means is configured such that the predetermined pressure is n (N / m) and the predetermined potential difference is Δv (V).
An AC electric field is formed so that the electric field intensity E (V / m) of the electric field for moving the toner from the developer carrying member to the electrode member satisfies the relationship shown in Formula 2.

本発明によれば、トナーの現像剤担持体に対する付着力に対応した現像剤担持体に対する規制部材の圧力と該現像剤担持体と該規制部材の電位差とに基づく電界強度の電界により、トナーが該現像剤担持体から電極部材に静電的に移動する。また、この電界とは異なる方向の電界により、電極部材に移動したトナーは現像剤担持体に戻り、規制部材に規制された直後の付着力より小さい付着力で現像剤担持体に付着する。そのため、現像剤担持体から像担持体にトナーが移動しやすくなり、良好な現像性が得られる。 According to the present invention, the toner is caused by the electric field having an electric field strength based on the pressure of the regulating member against the developer carrying body corresponding to the adhesion force of the toner to the developer carrying body and the potential difference between the developer carrying body and the regulating member. Electrostatically moves from the developer carrying member to the electrode member. Further, due to the electric field in a direction different from the electric field, the toner moved to the electrode member returns to the developer carrying member and adheres to the developer carrying member with an adhesion force smaller than that immediately after being regulated by the regulating member. For this reason, the toner easily moves from the developer carrying member to the image carrying member, and good developability can be obtained.

図１に、本発明の一実施形態に係る画像形成装置の概略的な構成を示す。 FIG. 1 shows a schematic configuration of an image forming apparatus according to an embodiment of the present invention.

図１に符号１０で示す画像形成装置は、現像剤担持体である現像ローラ１２と、現像ローラ１２にトナーを供給する供給ローラ１４と、現像ローラ１２上のトナーを帯電しつつ該現像路ローラ１２の外周面上にトナー層を形成する規制部材である規制ブレード１６と、現像ローラ１２が担持するトナーによって現像される静電潜像を担持する像担持体である感光体１８とを有する。現像ローラ１２、供給ローラ１４、感光体１８の回転中心線それぞれは、互いに平行で図面に対して垂直方向である。 An image forming apparatus denoted by reference numeral 10 in FIG. 1 includes a developing roller 12 that is a developer carrying member, a supply roller 14 that supplies toner to the developing roller 12, and the developing path roller while charging the toner on the developing roller 12. 12 includes a regulating blade 16 that is a regulating member that forms a toner layer on the outer peripheral surface of the toner 12, and a photoconductor 18 that is an image carrier that carries an electrostatic latent image developed by toner carried by the developing roller 12. The rotation center lines of the developing roller 12, the supply roller 14, and the photosensitive member 18 are parallel to each other and perpendicular to the drawing.

また、画像形成装置１０は、現像ローラ１２との間に交流電界を形成して該現像ローラ１２に担持されているトナーの付着力を小さくするための電極部材２０を有する。また、現像ローラ１２と規制ブレード１６の間、また、現像ローラ１２と電極部材２０の間に所定の電界を形成する電界形成手段２２を有する。 Further, the image forming apparatus 10 includes an electrode member 20 for forming an alternating electric field between the developing roller 12 and reducing the adhesion force of the toner carried on the developing roller 12. Further, it has an electric field forming means 22 for forming a predetermined electric field between the developing roller 12 and the regulating blade 16 and between the developing roller 12 and the electrode member 20.

なお、本明細書において、上述以外の画像形成に必要な画像形成装置１０の構成要素は、本発明に直接関わるものでないため図示および詳細な説明を省略する。 In the present specification, the constituent elements of the image forming apparatus 10 other than those described above that are necessary for image formation are not directly related to the present invention, and thus illustration and detailed description thereof are omitted.

現像ローラ１２は、導電性ローラ軸の周りに導電性弾性層を形成した構造で、該弾性層の表面でトナーを担持するように構成されている。現像ローラ１２には、後述するように規制ブレードによって帯電されたトナーを現像ローラ１２から感光体１８に向かって静電的に移動させる、また、その逆に感光体１８から現像ローラ１２に向かって静電的に移動させる交流電界を現像ローラ１２と感光体１８の間に形成するために、電界形成手段２２によって所定の交流電圧が印加されるようにしてある。 The developing roller 12 has a structure in which a conductive elastic layer is formed around a conductive roller shaft, and is configured to carry toner on the surface of the elastic layer. As will be described later, the toner charged by the regulating blade is electrostatically moved from the developing roller 12 toward the photosensitive member 18, and conversely, from the photosensitive member 18 toward the developing roller 12. In order to form an AC electric field that moves electrostatically between the developing roller 12 and the photosensitive member 18, a predetermined AC voltage is applied by the electric field forming means 22.

供給ローラ１４はローラ軸の周りにトナーを担持するための弾性層を形成した構造で、該弾性層の表面が現像ローラ１２の外周面と当接してトナー供給領域（以下、「供給領域」と称する。）２４を形成している。供給ローラ１４は、該供給ローラ１４の回転方向に関して供給領域２２の上流側のトナー貯蔵部（図示せず）で担持したトナーを現像ローラ１２の外周面に供給する（現像ローラ１２に担持させる）ように構成されている。 The supply roller 14 has a structure in which an elastic layer for carrying toner is formed around the roller shaft. The surface of the elastic layer abuts on the outer peripheral surface of the developing roller 12 and is referred to as a toner supply area (hereinafter referred to as “supply area”). 24) is formed. The supply roller 14 supplies the toner carried by the toner storage unit (not shown) upstream of the supply region 22 with respect to the rotation direction of the supply roller 14 to the outer peripheral surface of the developing roller 12 (supported by the developing roller 12). It is configured as follows.

規制ブレード１６は、ステンレスなどの金属板であって、所定の圧力（以下、「規制圧力」と称する。）で現像ローラ１４の外周面と当接してトナー規制領域（以下、「規制領域」と称する。）２６を形成している。規制領域２６は、現像ローラ１２の回転方向に関して供給領域２４の下流側に位置する。規制ブレード１６は、供給領域２２で供給された現像ローラ１２の外周面上のトナーを帯電しつつ規制して該トナーの層を形成するように形成されている。そのために、規制ブレード１６には、電界形成手段２２によって現像ローラ１４との電位差（以下、「規制電位差」と称する。）が一定なるような電圧が印加されている。なお、規制部材は、現像ローラのトナーを帯電しつつ規制して該トナーの層が形成できるものであれば金属のブレードでなくてもよく、例えばポリエチレンなどの樹脂のローラであってもよい。 The regulation blade 16 is a metal plate such as stainless steel, and abuts against the outer peripheral surface of the developing roller 14 with a predetermined pressure (hereinafter referred to as “regulation pressure”), thereby forming a toner regulation area (hereinafter referred to as “regulation area”). 26) is formed. The restriction area 26 is located downstream of the supply area 24 with respect to the rotation direction of the developing roller 12. The regulating blade 16 is formed so as to form a toner layer by charging and regulating the toner on the outer peripheral surface of the developing roller 12 supplied in the supply region 22. For this purpose, a voltage is applied to the regulating blade 16 so that the potential difference from the developing roller 14 (hereinafter referred to as “regulated potential difference”) is constant by the electric field forming means 22. The regulating member may not be a metal blade as long as the toner layer can be formed by charging the toner of the developing roller while being charged, and may be a roller of resin such as polyethylene.

感光体１８は、その外周面が帯電チャージャなどの帯電手段（図示せず）によって帯電され、帯電部分に露光手段（図示せず）によって静電潜像が形成されるようにしてある。また、感光体１８は、現像ローラ１２に対向して静電潜像が現像される現像領域２８を形成している。現像領域２８は、現像ローラ１２の回転方向に関して規制領域２６の下流側に位置する。この現像領域２８で、現像ローラ１２の外周面のトナーが、現像ローラ１２と感光体１８の静電潜像部分の電位差により、静電的に現像ローラ１２から静電潜像部分に移動し、静電潜像を現像する。 The outer peripheral surface of the photoconductor 18 is charged by a charging means (not shown) such as a charging charger, and an electrostatic latent image is formed on the charged portion by an exposure means (not shown). Further, the photosensitive member 18 forms a developing region 28 that faces the developing roller 12 and develops the electrostatic latent image. The development area 28 is located downstream of the restriction area 26 with respect to the rotation direction of the development roller 12. In the developing area 28, the toner on the outer peripheral surface of the developing roller 12 is electrostatically moved from the developing roller 12 to the electrostatic latent image portion due to the potential difference between the developing roller 12 and the electrostatic latent image portion of the photosensitive member 18. Develop the electrostatic latent image.

電極部材２０は、規制ブレード１６により現像ローラ１２の外周面に高い充填密度で且つ大きい付着力で付着しているトナーについて、その付着力を小さくして良好な現像性を得るために機能する。言い換えると、電極部材２０は、現像ローラ１２上に押し固められた状態で担持されているトナーをほぐす役割をする。 The electrode member 20 functions to obtain a good developability by reducing the adhesion force of the toner adhered to the outer peripheral surface of the developing roller 12 with a high filling density and a large adhesion force by the regulating blade 16. In other words, the electrode member 20 serves to loosen the toner carried on the developing roller 12 in a pressed state.

具体的には、電極部材２０は、現像ローラ１２の回転方向に関して規制領域２６の下流にあるとともに、現像領域２８の上流側に位置する領域３０で、現像ローラ１２の外周面と所定の距離（ギャップ）をあけて対向している。また、電極部材２０には、現像ローラ１２との間にトナーをほぐす交流電界を形成するために、電界発生手段２２によって所定の直流電圧が印加されている。なお、電極部材２０の形状は、現像ローラ１２との間において安定した交流電界が形成されるものであれば、例えばローラであってもよいし、また、現像ローラ１２の外周面と平行な湾曲面を有する板状部材であってもよい。 Specifically, the electrode member 20 is downstream of the restriction region 26 with respect to the rotation direction of the developing roller 12 and in a region 30 located upstream of the developing region 28, the electrode member 20 is a predetermined distance from the outer peripheral surface of the developing roller 12 ( Opposing with a gap). In addition, a predetermined DC voltage is applied to the electrode member 20 by the electric field generating means 22 in order to form an AC electric field that loosens the toner between the electrode member 20 and the developing roller 12. The shape of the electrode member 20 may be, for example, a roller as long as a stable alternating electric field is formed between the electrode member 20 and the developing roller 12, and the electrode member 20 is curved parallel to the outer peripheral surface of the developing roller 12. It may be a plate-like member having a surface.

現像ローラ１２と電極部材２０の間の交流電界は、現像ローラ１２に付着しているトナーを電極部材２０に移動させる電界の電界強度Ｅ（Ｖ／ｍ）が数２の式を満たすように電界形成手段２２によって形成される。数２の式中、ｎは規制圧力（Ｎ／ｍ）であり、Δｖは規制電位差（Ｖ）である。また、現像ローラ１２と電極部材２０の間の交流電界は、最終的には、現像ローラ１２の外周面上にトナーのほとんど全てが維持される大きさの交流電界である（電極部材２０にトナーがほとんど付着しない交流電界である。）。 The AC electric field between the developing roller 12 and the electrode member 20 is such that the electric field strength E (V / m) of the electric field for moving the toner adhering to the developing roller 12 to the electrode member 20 satisfies the equation (2). It is formed by the forming means 22. In Equation 2, n is the regulation pressure (N / m), and Δv is the regulation potential difference (V). In addition, the AC electric field between the developing roller 12 and the electrode member 20 is finally an AC electric field having such a magnitude that almost all of the toner is maintained on the outer peripheral surface of the developing roller 12 (the toner on the electrode member 20). Is an AC electric field that hardly adheres.)

数２の式は、発明者が実験から導き出したものである。以下、発明者が数２の式を導出するために行った実験について説明する。 Equation 2 is derived from experiments by the inventors. Hereinafter, an experiment performed by the inventor to derive the formula 2 will be described.

実験において、図１に示す画像形成装置１０を用い、異なる規制条件（規制圧力ｎと規制電位差Δｖとがそれぞれ異なる条件）毎に、良好な現像性を得るために必要とする、トナーを現像ローラ１２から電極部材２０に移動させる電界の電界強度Ｅを求めた。また、実験は、負極性に帯電するトナーを使用した。 In the experiment, the image forming apparatus 10 shown in FIG. 1 was used, and the toner required for obtaining good developability for each different regulation condition (a condition where the regulation pressure n and the regulation potential difference Δv are different) was developed on the developing roller. The electric field strength E of the electric field moved from 12 to the electrode member 20 was determined. In the experiment, a negatively charged toner was used.

実験は、規制圧力ｎが１０、２０、３０Ｎ／ｍから選択され、また、規制電位差Δｖが５０、１００、１５０、２００、２５０、３００Ｖから選択された、１８個の規制条件の下で行った（図２参照。）。 The experiment was performed under 18 regulatory conditions where the regulated pressure n was selected from 10, 20, 30 N / m, and the regulated potential difference Δv was selected from 50, 100, 150, 200, 250, 300V. (See FIG. 2).

実験において、現像ローラ１２に印加した交流電圧は、振幅（ピーク・ツー・ピーク値）Ｖｐｐが１３２０Ｖ、振幅中心が−３２０Ｖ、デューティー（ｄｕｔｙ）値（トナーを現像ローラ１２から電極部材２０に移動させる電圧側）が３５％、周波数が２ｋＨｚ、すなわち感光体１８の外周面上で−７０Ｖの電位を有する静電潜像を現像するための現像バイアス電圧に設定した。また、電極部材２０に印加される直流電圧は、−３２０Ｖに設定した。これにより、トナーが現像ローラ１２から電極部材２０に静電的に移動する電界が形成される、該現像ローラ１２と電極部材２０の電位差を６６０Ｖとした。 In the experiment, the AC voltage applied to the developing roller 12 has an amplitude (peak-to-peak value) Vpp of 1320 V, an amplitude center of −320 V, and a duty value (moving toner from the developing roller 12 to the electrode member 20. The developing bias voltage for developing an electrostatic latent image having a potential of −70 V on the outer peripheral surface of the photoreceptor 18 is set to 35% on the voltage side) and 2 kHz in frequency. The DC voltage applied to the electrode member 20 was set to −320V. As a result, an electric field for electrostatically moving the toner from the developing roller 12 to the electrode member 20 is formed, and the potential difference between the developing roller 12 and the electrode member 20 is set to 660V.

各規制条件において、電位差が６６０Ｖである現像ローラ１２と電極部材２０のギャップを変更することにより、トナーを現像ローラ１２から電極部材２０に移動させる電界の電界強度を変更した。変更した電界強度それぞれにおいて、現像性が良好か否かを判断した。 Under each regulation condition, the electric field strength of the electric field for moving the toner from the developing roller 12 to the electrode member 20 was changed by changing the gap between the developing roller 12 and the electrode member 20 having a potential difference of 660V. Whether or not the developability was good was determined for each of the changed electric field strengths.

現像性が良好か否かの判断は、現像によって現像ローラ１２から感光体１８に移動したトナー量（現像量）に基づいて判断し、感光体１８上に６ｇ／ｍ^２のトナーが存在する場合を良好とした。 Whether the developing property is good or not is determined based on the amount of toner (development amount) transferred from the developing roller 12 to the photosensitive member 18 by the development, and when 6 g / m ² of toner exists on the photosensitive member 18. Was good.

実験の結果を示す表を図２に示す。なお、表において、電界強度の単位は、Ｖ／μｍである。 A table showing the results of the experiment is shown in FIG. In the table, the unit of electric field strength is V / μm.

発明者は、図２に示す実験結果の表に基づいて、数２の式に示す、良好な現像性を得るために必要な、トナーを現像ローラ１２から電極部材２０に移動させる電界の電界強度Ｅを導き出した。 The inventor, based on the experimental result table shown in FIG. 2, shows the electric field strength of the electric field for moving the toner from the developing roller 12 to the electrode member 20, which is necessary to obtain good developability shown in the formula (2). Derived E.

なお、トナーを現像ローラ１２から電極部材２０に移動させる電界の電界強度Ｅは、現像ローラ１２と規制ブレード１６の間の規制圧力ｎと規制電位差Δｖが適正値であることが前提である。すなわち、規制圧力ｎは、最低限トナーを現像ローラ１２に付着させる圧力であって、現像ローラ１２のスムーズな回転を妨げない圧力である。一方、規制電位差Δｖは、現像に必要な帯電量をトナーに与える電位差であって、現像ローラ１２と規制ブレード１６の間に異常放電が発生しない電位差である。例えば、実験の条件では、規制圧力ｎは１０Ｎ／ｍ以上に設定され、規制電位差Δｖは１００〜５００Ｖの範囲で設定される。 The electric field strength E of the electric field for moving the toner from the developing roller 12 to the electrode member 20 is based on the premise that the regulating pressure n and the regulating potential difference Δv between the developing roller 12 and the regulating blade 16 are appropriate values. That is, the regulation pressure n is a pressure that causes toner to adhere to the developing roller 12 at a minimum, and does not hinder the smooth rotation of the developing roller 12. On the other hand, the regulation potential difference Δv is a potential difference that gives the toner a charge amount necessary for development, and is a potential difference that does not cause an abnormal discharge between the developing roller 12 and the regulation blade 16. For example, under experimental conditions, the regulated pressure n is set to 10 N / m or more, and the regulated potential difference Δv is set in the range of 100 to 500V.

また、電界強度Ｅは、可能な限り大きい値を取り得るわけでなく（規制圧力ｎと規制電位差Δｖそれぞれの上限値で決まる値以下である）、当然ながら、現像ローラ１２と電極部材２０の間に異常放電が発生しない値であることが前提である。したがって、例えば、実験の条件では、電界強度Ｅは、数２の式を満たしつつ、１５×１０^６（Ｖ／ｍ）以下に設定される。 Further, the electric field strength E cannot take as large a value as possible (below the value determined by the upper limit values of the regulation pressure n and the regulation potential difference Δv), and of course, between the developing roller 12 and the electrode member 20. It is assumed that the value is such that no abnormal discharge occurs. Therefore, for example, under the experimental conditions, the electric field strength E is set to 15 × 10 ⁶ (V / m) or less while satisfying the expression (2).

本実施形態によれば、供給ローラ１４から現像ローラ１２に供給されたトナーは、現像ローラ１２の回転により規制領域２４に搬送される。規制領域２４において、規制圧力ｎであって規制電位差Δｖの規制条件の下、規制ブレード１６により、トナーは帯電されつつ高い充填密度で且つ大きい付着力で現像ローラ１２に付着される。言い換えると、現像ローラ１２の外周面には、トナーが押し固められた状態のトナー層が形成される。 According to the present embodiment, the toner supplied from the supply roller 14 to the developing roller 12 is conveyed to the regulation region 24 by the rotation of the developing roller 12. In the regulation region 24, the toner is attached to the developing roller 12 with a high filling density and a large adhesion force while being charged by the regulation blade 16 under the regulation condition of the regulation pressure n and the regulation potential difference Δv. In other words, a toner layer in which the toner is pressed and hardened is formed on the outer peripheral surface of the developing roller 12.

次に、トナー（トナー層）は、現像ローラ１２の回転により、規制領域を２４から電極部材２０と対向する領域３０に搬送される。そこで、押し固められた状態のトナーは、トナーを現像ローラ１２から電極部材２０に移動させる電界の電界強度Ｅが数２の式を満たす交流電界によってほぐされ、現像ローラ１２に対する付着力が弱まる。すなわち、規制ブレード１６による規制圧力と規制ブレード１６と現像ローラ１２との電位差によって機械的且つ静電的に現像ローラ１２に大きい付着力で付着していたトナーが、一旦現像ローラ１２から離され、静電的に再び現像ローラ１２に小さい付着力で付着される。 Next, the toner (toner layer) is conveyed from the restriction region 24 to the region 30 facing the electrode member 20 by the rotation of the developing roller 12. Therefore, the toner in the pressed state is loosened by an AC electric field that causes the electric field strength E to move the toner from the developing roller 12 to the electrode member 20 by the AC electric field satisfying the formula 2, and the adhesion to the developing roller 12 is weakened. That is, the toner that has mechanically and electrostatically adhered to the developing roller 12 with a large adhesion force due to the regulating pressure by the regulating blade 16 and the potential difference between the regulating blade 16 and the developing roller 12 is once separated from the developing roller 12. It electrostatically adheres again to the developing roller 12 with a small adhesion force.

続いて、付着力が小さくされたトナーは、現像領域２８で現像に使用される。このとき、現像ローラ１２に対する付着力が小さいことによって現像ローラ１２から感光体１８にトナーが移動しやすく、それにより多くのトナーが感光体１８に移動し、良好な現像性が得られる。 Subsequently, the toner having a reduced adhesive force is used for development in the development region 28. At this time, since the adhesion force to the developing roller 12 is small, the toner easily moves from the developing roller 12 to the photoconductor 18, whereby a large amount of toner moves to the photoconductor 18 and good developability is obtained.

以上、一実施形態を挙げて本発明を説明したが、本発明はこれに限定されない。 While the present invention has been described with reference to one embodiment, the present invention is not limited to this.

上述の実施形態において、現像ローラと電極部材の間の交流電界は、現像ローラに交流電圧を印加しつつ電極部材に直流電圧を印加して形成されているが、これに限定されない。例えば現像ローラと電極部材の両者に交流電圧を印加して両者の間に交流電界を形成しても良い。広義には、現像ローラから電極部材にトナーを移動させる電界の電界強度が数２の式を満たしつつ、最終的にほとんど全てのトナーが現像ローラの外周面上に存在するような交流電界が現像ローラと電極部材の間に形成されればよい。 In the above-described embodiment, the AC electric field between the developing roller and the electrode member is formed by applying a DC voltage to the electrode member while applying an AC voltage to the developing roller, but is not limited thereto. For example, an AC electric field may be formed between both the developing roller and the electrode member by applying an AC voltage. In a broad sense, an AC electric field that causes the toner to move from the developing roller to the electrode member has an electric field strength satisfying the formula (2) and that almost all of the toner is finally present on the outer peripheral surface of the developing roller. What is necessary is just to form between a roller and an electrode member.

本発明によれば、規制部材によって高い充填密度で且つ大きい付着力でトナーが現像剤担持体に担持されても、多くのトナーが現像剤担持体から像担持体に移動して良好な現像性が得られる。 According to the present invention, even when the toner is carried on the developer carrying member with a high packing density and a large adhesion force by the regulating member, a large amount of toner moves from the developer carrying member to the image carrying member, and good developability. Is obtained.

本発明に係る画像形成装置の構成を概略的に示す図である。1 is a diagram schematically showing a configuration of an image forming apparatus according to the present invention. 実験の結果の表を示す図である。It is a figure which shows the table | surface of an experimental result.

符号の説明Explanation of symbols

１２：現像剤担持体（現像ローラ）
１６：規制部材（規制ブレード）
２０：電極部材
２２：電界形成手段
12: Developer carrier (developing roller)
16: Restriction member (regulation blade)
20: Electrode member 22: Electric field forming means

Claims

現像剤担持体上のトナーを規制してトナーの層を形成する画像形成装置であって、
トナーを担持する現像剤担持体と、
現像剤担持体と所定の圧力で当接しつつ該現像剤担持体との間に所定の電位差が設けられ、トナーを規制して該トナーの層を現像剤担持体上に形成する規制部材と、
トナー層を挟んで現像剤担持体と非接触で対向する電極部材と、
現像剤担持体と電極部材の間に交流電界を形成する交流電界形成手段を有し、
交流電界形成手段は、上記所定の圧力をｎ（Ｎ／ｍ）、上記所定の電位差をΔｖ（Ｖ）としたとき、
トナーを現像剤担持体から電極部材に移動させる電界の電界強度Ｅ（Ｖ／ｍ）が、数１に示す関係を満たすように交流電界を形成することを特徴とする画像形成装置。

An image forming apparatus for forming a toner layer by regulating toner on a developer carrier,
A developer carrier for carrying toner;
A regulating member that is in contact with the developer carrying body at a given pressure and has a predetermined potential difference between the developer carrying body and regulates the toner to form a layer of the toner on the developer carrying body;
An electrode member that faces the developer carrying member in a non-contact manner across the toner layer;
An AC electric field forming means for forming an AC electric field between the developer carrier and the electrode member;
The AC electric field forming means is configured such that the predetermined pressure is n (N / m) and the predetermined potential difference is Δv (V).
An image forming apparatus, wherein an alternating electric field is formed so that an electric field intensity E (V / m) of an electric field for moving toner from a developer carrying member to an electrode member satisfies a relationship expressed by Formula 1.