JP2010204219A - Image forming apparatus - Google Patents

Image forming apparatus Download PDF

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JP2010204219A
JP2010204219A JP2009047325A JP2009047325A JP2010204219A JP 2010204219 A JP2010204219 A JP 2010204219A JP 2009047325 A JP2009047325 A JP 2009047325A JP 2009047325 A JP2009047325 A JP 2009047325A JP 2010204219 A JP2010204219 A JP 2010204219A
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image
carrier
toner
developer carrier
forming apparatus
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JP5221418B2 (en
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Ikuo Makie
郁雄 牧江
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Kyocera Document Solutions Inc
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Kyocera Mita Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for preventing the degradation of image quality by efficiently discharging deteriorated toner on the whole circumference of a developing roller in a present refresh process. <P>SOLUTION: The image forming apparatus includes an image carrier and a developer carrier arranged to face the image carrier and executes a refresh process for developing an electrostatic latent image formed on the surface of the image carrier into a toner image by rotating the image carrier and the developer carrier, to apply a developing bias, when an image is formed and for conveying toner on the developer carrier to the side of the image carrier, when the image is not formed. In the refresh process, the image carrier and the developer carrier are rotated and the circumferential speed of the developer carrier is lower than the circumferential speed of the developer carrier when the image is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、複写機、プリンタ、ファクシミリ等の画像形成装置に関し、特に非画像形成時に現像ローラ上のトナーを感光体ドラムへと搬送するリフレッシュ工程を実行可能な画像形成装置に関するものである。   The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus capable of executing a refresh process for conveying toner on a developing roller to a photosensitive drum during non-image formation.

一般に1成分現像方式の画像形成装置においては、画像形成を繰り返し行うことにより粒径の小さなトナーがトナー担持体(現像ローラ)表面に高い帯電量による鏡映力のために付着し、他のトナー粒子が現像ローラとの間で摩擦帯電することを阻害し、現像ローラ上で均一な帯電が行われないまま静電潜像担持体(感光体ドラム)まで搬送されることにより、画像濃度低下やカブリ等の画質低下を引き起こすことがある。   In general, in a one-component development type image forming apparatus, by repeating image formation, a toner having a small particle size adheres to the surface of a toner carrying member (developing roller) due to a mirror image with a high charge amount. The particles are prevented from being frictionally charged with the developing roller, and are transported to the electrostatic latent image carrier (photosensitive drum) without being uniformly charged on the developing roller. It may cause image degradation such as fogging.

このような現象は、特に画像上の原稿印字率が低い場合に、現像ローラから感光体ドラムに搬送されるトナーが少なく、トナー粒子が現像ローラ上に残りやすいために促進され、発生しやすい。   Such a phenomenon is promoted and is likely to occur particularly when the document printing rate on the image is low, because the toner transported from the developing roller to the photosensitive drum is small and the toner particles tend to remain on the developing roller.

これらの問題は、ベタ黒等の原稿印字率が高いパターンによって、現像ローラから感光体ドラム側に多量のトナーを搬送し、該トナーを記録媒体(用紙)に転写してトナーを消費することにより緩和することができる。   These problems are caused by conveying a large amount of toner from the developing roller to the photosensitive drum side by a pattern having a high original printing ratio such as solid black, and transferring the toner to a recording medium (paper) to consume the toner. Can be relaxed.

しかし、ベタ黒パターンを印字することもなく長期に亘りトナーの消費が行われないまま放置した場合には、現像ローラ表面に残留するトナーが劣化(特に外添剤の剥がれ等による帯電特性の劣化)し、画像濃度低下やカブリ等の画質低下を解消できない。   However, if the toner is not consumed for a long time without printing a solid black pattern, the toner remaining on the surface of the developing roller is deteriorated (particularly, charging characteristics are deteriorated due to peeling of an external additive). ) And image quality degradation such as image density degradation and fog cannot be solved.

こうした問題を解決すべく特許文献1では、用紙に画像形成する毎に平均印字密度を求め、該平均印字密度が所定の値を下回った場合に、感光体ドラムと現像ローラの回転を停止してバイアス電圧を印加することで、現像ローラ上のトナーを感光体ドラム側へと搬送して、劣化したトナーを吐き出し現像ローラ表面をリフレッシュしている(図5参照)。   In order to solve such a problem, Patent Document 1 obtains an average print density every time an image is formed on a sheet, and when the average print density falls below a predetermined value, the rotation of the photosensitive drum and the developing roller is stopped. By applying a bias voltage, the toner on the developing roller is conveyed to the photosensitive drum side, the deteriorated toner is discharged, and the surface of the developing roller is refreshed (see FIG. 5).

しかしながら、上記のリフレッシュ工程では、現像ローラを停止させてトナーの搬送を行っており、現像ローラ表面のトナーが感光体ドラム側へ搬送されるのは、現像ローラの感光体ドラムに近接する部分(w)においてのみである。そのため、1回のリフレッシュ工程で現像ローラ全周の劣化トナーを吐き出すことができず、画質低下を防止できないという問題や、リフレッシュ工程の実行頻度が多くなってしまい効率が悪くなる場合がある。   However, in the above refreshing process, the developing roller is stopped and the toner is transported, and the toner on the surface of the developing roller is transported to the photosensitive drum side in the portion adjacent to the photosensitive drum of the developing roller ( only in w). Therefore, there is a problem that the deteriorated toner cannot be discharged around the entire circumference of the developing roller in one refresh process, and the image quality cannot be prevented from being deteriorated.

特開2000−330379号公報JP 2000-330379 A

本発明が解決しようとする課題は、リフレッシュ工程において現像ローラ全周の劣化トナーを効率良く吐き出すことができ、画質低下を防止できる画像形成装置を提供することである。   The problem to be solved by the present invention is to provide an image forming apparatus capable of efficiently discharging the deteriorated toner around the entire circumference of the developing roller in the refresh process and preventing the image quality from being lowered.

請求項1に係る発明は、像担持体と、該像担持体に対向配置される現像剤担持体を備え、画像形成時において、前記像担持体と前記現像剤担持体を回転させて現像バイアスを印加することで前記像担持体表面に形成された静電潜像をトナー像に現像し、非画像形成時において、前記現像剤担持体上のトナーを前記像担持体側へ搬送するリフレッシュ工程を実行可能な画像形成装置であって、前記リフレッシュ工程において、前記像担持体と前記現像剤担持体が回転し、該現像剤担持体の周速度は画像形成時における該現像剤担持体の周速度より遅いことを特徴とする画像形成装置に関する。   The invention according to claim 1 includes an image carrier and a developer carrier disposed opposite to the image carrier, and at the time of image formation, the image carrier and the developer carrier are rotated to develop bias. A refreshing step of developing the electrostatic latent image formed on the surface of the image carrier to a toner image by applying a toner and transporting the toner on the developer carrier to the image carrier side during non-image formation. An executable image forming apparatus, wherein in the refreshing step, the image carrier and the developer carrier rotate, and a peripheral speed of the developer carrier is a peripheral speed of the developer carrier during image formation. The present invention relates to an image forming apparatus characterized by being slower.

請求項2に係る発明は、前記リフレッシュ工程において、前記現像剤担持体の周速度が前記像担持体の周速度より遅いことを特徴とする請求項1に記載の画像形成装置に関する。   The invention according to claim 2 relates to the image forming apparatus according to claim 1, wherein in the refreshing step, a peripheral speed of the developer carrier is lower than a peripheral speed of the image carrier.

請求項3に係る発明は、前記現像剤担持体の周速度は、前記像担持体と前記現像剤担持体とが近接する部分の幅を、前記現像剤担持体を停止させて現像バイアスを印加した時に該現像剤担持体表面に積層されたトナーが前記近接する部分において最下層まで前記像担持体側へ搬送されるのに要する時間で除することによって定められることを特徴とする請求項1又は2に記載の画像形成装置に関する。   According to a third aspect of the present invention, the peripheral speed of the developer carrying member is set such that the width of the portion where the image carrying member and the developer carrying member are close to each other, and the developing carrier is stopped to apply the developing bias. 2. The toner content is determined by dividing the toner laminated on the surface of the developer carrying member by the time required to be transported to the lowermost layer in the adjacent portion to the image carrying member side. The image forming apparatus according to 2.

請求項4に係る発明は、前記像担持体は、前記現像剤担持体に形成されたトナー層によって現像されることを特徴とする請求項1乃至3の何れかに記載の画像形成装置に関する。   The invention according to claim 4 relates to the image forming apparatus according to claim 1, wherein the image carrier is developed by a toner layer formed on the developer carrier.

請求項1に係る発明によれば、像担持体と、該像担持体に対向配置される現像剤担持体を備え、画像形成時において、像担持体と現像剤担持体を回転させて現像バイアスを印加することで像担持体表面に形成された静電潜像をトナー像に現像し、非画像形成時において、現像剤担持体上のトナーを像担持体側へ搬送するリフレッシュ工程を実行可能な画像形成装置であって、リフレッシュ工程において、像担持体と現像剤担持体が回転し、該現像剤担持体の周速度は画像形成時における該現像剤担持体の周速度より遅いことにより、現像剤担持体表面の一所から一度に多くのトナーを像担持体へ搬送できるので、現像剤担持体全周の劣化トナーを効率良く吐き出すことができ、画質低下を防止できる。   According to the first aspect of the present invention, the image bearing member and the developer bearing member disposed opposite to the image bearing member are provided, and the developing bias is generated by rotating the image bearing member and the developer bearing member during image formation. Is applied to develop an electrostatic latent image formed on the surface of the image carrier into a toner image, and during non-image formation, a refresh process can be performed in which the toner on the developer carrier is conveyed to the image carrier side. In the image forming apparatus, in the refresh process, the image carrier and the developer carrier rotate, and the peripheral speed of the developer carrier is lower than the peripheral speed of the developer carrier during image formation. Since a large amount of toner can be conveyed from one place on the surface of the developer carrier to the image carrier at once, the deteriorated toner on the entire circumference of the developer carrier can be discharged efficiently, and deterioration in image quality can be prevented.

請求項2に係る発明によれば、リフレッシュ工程において、現像剤担持体の周速度が像担持体の周速度より遅いことにより、現像剤担持体全周の劣化トナーをより効率良く吐き出すことができ、画質低下を防止できる。   According to the second aspect of the present invention, in the refresh process, the peripheral speed of the developer carrier is slower than the peripheral speed of the image carrier, so that the deteriorated toner on the entire circumference of the developer carrier can be discharged more efficiently. , Image quality can be prevented from being degraded.

請求項3に係る発明によれば、現像剤担持体の周速度は、像担持体と現像剤担持体とが近接する部分の幅を、現像剤担持体を停止させて現像バイアスを印加した時に該現像剤担持体表面に積層されたトナーが前記近接する部分において最下層まで像担持体側へ搬送されるのに要する時間で除することによって定められることにより、現像剤担持体全周の劣化トナーを1回のリフレッシュ工程で確実に吐き出すことができ、画質低下を防止できる。   According to the third aspect of the present invention, the peripheral speed of the developer carrier is the width of the portion where the image carrier and the developer carrier are close to each other, when the developer carrier is stopped and the developing bias is applied. The toner laminated on the surface of the developer carrying member is determined by dividing by the time required to be transported to the lowermost layer at the adjacent portion to the image carrying member side, whereby the deteriorated toner on the entire circumference of the developer carrying member Can be reliably discharged in one refresh step, and deterioration in image quality can be prevented.

請求項4に係る発明によれば、像担持体は、前記現像剤担持体に形成されたトナー層によって現像されることにより、現像剤担持体表面に担持されるのはトナーのみであり、リフレッシュ工程によって劣化したトナーを確実に吐き出すことができる。   According to the invention of claim 4, the image carrier is developed by the toner layer formed on the developer carrier, so that only the toner is carried on the surface of the developer carrier, and the refreshing is performed. The toner deteriorated by the process can be discharged reliably.

本発明に係る画像形成装置の内部構造を示す模式図である。1 is a schematic diagram showing an internal structure of an image forming apparatus according to the present invention. 本発明に係る画像形成装置の現像装置を示す概略断面図である。1 is a schematic cross-sectional view showing a developing device of an image forming apparatus according to the present invention. 本発明に係る画像形成装置のリフレッシュ工程を示す模式図である。It is a schematic diagram showing a refresh process of the image forming apparatus according to the present invention. 現像ローラと感光体ドラムを画像形成時と同じ速度で回転させた場合のリフレッシュ工程を示す模式図である。FIG. 6 is a schematic diagram illustrating a refresh process when a developing roller and a photosensitive drum are rotated at the same speed as when an image is formed. 従来の画像形成装置のリフレッシュ工程を示す模式図である。It is a schematic diagram showing a refresh process of a conventional image forming apparatus.

以下、本発明に係る画像形成装置の好適な実施形態について、図面を参照しつつ説明する。
図1は、本発明に係る画像形成装置の内部構造を示す模式図である。
本実施形態においては、本発明に係る画像形成装置(100)の一例として図1に示す単色の1成分現像方式の複写機を挙げているが、これに限定されるものではなく、カラー画像を形成するものや他の現像方式のものであっても良いし、プリンタやファクシミリ等、他の画像形成装置であっても良い。
DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of an image forming apparatus according to the invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing the internal structure of an image forming apparatus according to the present invention.
In this embodiment, the monochromatic one-component developing type copying machine shown in FIG. 1 is cited as an example of the image forming apparatus (100) according to the present invention, but the present invention is not limited to this. The image forming apparatus may be formed or may be of another developing system, or may be another image forming apparatus such as a printer or a facsimile.

本発明に係る画像形成装置(100)は、図1に示すように、給紙装置(101)、画像読取部(102)、画像形成部(103)、定着部(104)、及び排紙部(105)、を主要な構成とする。
給紙装置(101)より画像形成部(103)に用紙が供給され、画像読取部(102)で読み取られた画像データが画像形成部(103)にてトナー像として用紙に形成され、定着部(104)にて用紙にトナーが定着される。画像が形成された用紙は排紙部(105)へと排出される。
As shown in FIG. 1, an image forming apparatus (100) according to the present invention includes a paper feeding device (101), an image reading unit (102), an image forming unit (103), a fixing unit (104), and a paper discharge unit. (105) is the main configuration.
The paper is supplied from the paper feeding device (101) to the image forming unit (103), and the image data read by the image reading unit (102) is formed on the paper as a toner image by the image forming unit (103), and the fixing unit. At (104), the toner is fixed on the sheet. The paper on which the image is formed is discharged to the paper discharge unit (105).

画像形成部(103)は、像担持体として感光体ドラム(1)を備えており、感光体ドラム(1)の周囲には帯電装置(2)、現像装置(3)、露光装置(4)、クリーニング装置(5)等を備えている。
なお、感光体ドラム(1)は、アモルファスシリコン感光体であるが、これに限定されず、有機感光体であっても良い。
The image forming unit (103) includes a photosensitive drum (1) as an image carrier, and a charging device (2), a developing device (3), and an exposure device (4) are provided around the photosensitive drum (1). And a cleaning device (5).
The photoconductor drum (1) is an amorphous silicon photoconductor, but is not limited to this and may be an organic photoconductor.

転写ローラ(6)は感光体ドラム(1)に対向、圧接して配置されている。
また、転写ローラ(6)は、トナーの正規の帯電極性とは逆極性を示すバイアス電圧を印加する電源を備えているが図1では省略し図示していない。
The transfer roller (6) is disposed so as to face and press against the photosensitive drum (1).
The transfer roller (6) includes a power source that applies a bias voltage having a polarity opposite to the normal charging polarity of the toner, but is omitted from FIG.

この画像形成装置による画像形成動作は、従来の画像形成装置と特に変わるところはなく、感光体ドラム(1)は回転駆動されながら、帯電装置(2)によって帯電され、露光装置(4)によって露光され、現像装置(3)によって現像されることにより、感光体ドラム(1)表面にトナー像が形成される。
その後、転写ローラ(6)に前記バイアス電圧を印加することで、前記トナー像が用紙に転写される。
The image forming operation by this image forming apparatus is not particularly different from that of a conventional image forming apparatus. The photosensitive drum (1) is charged by the charging device (2) while being driven to rotate, and is exposed by the exposure device (4). Then, the toner image is formed on the surface of the photosensitive drum (1) by being developed by the developing device (3).
Thereafter, the toner image is transferred to a sheet by applying the bias voltage to the transfer roller (6).

図2は、現像装置(3)を示す概略断面図である。
現像装置(3)は、現像剤担持体として図2に示すように感光体ドラム(1)に対向して配置された現像ローラ(31)を備えており、現像ローラ(31)表面のトナーを均一に均す規制ブレード(32)、トナーを撹拌、搬送するスパイラル(33)、トナーを供給するトナータンク(34)等を備える。
FIG. 2 is a schematic sectional view showing the developing device (3).
As shown in FIG. 2, the developing device (3) includes a developing roller (31) disposed as opposed to the photosensitive drum (1) as shown in FIG. 2, and removes toner on the surface of the developing roller (31). A regulation blade (32) for uniformly leveling, a spiral (33) for stirring and conveying toner, a toner tank (34) for supplying toner, and the like are provided.

トナータンク(34)から供給されたトナーは、スパイラル(33)によって撹拌、搬送され現像ローラ(31)上に担持される。
現像ローラ(31)上に担持されたトナーは、現像ローラ(31)が回転することで規制ブレード(32)によって均一なトナー層とされ、バイアス電圧が印加されることで感光体ドラム(1)表面の静電潜像を現像して可視化し、感光体ドラム(1)表面にトナー像を形成する。
The toner supplied from the toner tank (34) is stirred and conveyed by the spiral (33) and is carried on the developing roller (31).
The toner carried on the developing roller (31) is turned into a uniform toner layer by the regulating blade (32) as the developing roller (31) rotates, and the bias voltage is applied to the photosensitive drum (1). The electrostatic latent image on the surface is developed and visualized, and a toner image is formed on the surface of the photosensitive drum (1).

この時、現像ローラ(31)は、感光体ドラム(1)より速い周速度で回転している。
画像形成のために、感光体ドラム(1)と現像ローラ(31)の近接する部分において、現像ローラ(31)から感光体ドラム(1)へ単位時間当たりにより多くのトナーを供給できるようにするためである。
At this time, the developing roller (31) rotates at a faster peripheral speed than the photosensitive drum (1).
In order to form an image, more toner can be supplied per unit time from the developing roller (31) to the photosensitive drum (1) in the vicinity of the photosensitive drum (1) and the developing roller (31). Because.

次に、画像形成装置(100)のリフレッシュ工程を説明する。
図3は、本発明の画像形成装置(100)のリフレッシュ工程を示す模式図である。
図4は、感光体ドラム(1)と現像ローラ(31)を画像形成時と同じ周速度で回転させてリフレッシュさせた場合のリフレッシュ工程を示す模式図である。
Next, a refresh process of the image forming apparatus (100) will be described.
FIG. 3 is a schematic diagram showing a refresh process of the image forming apparatus (100) of the present invention.
FIG. 4 is a schematic diagram showing a refresh process when the photosensitive drum (1) and the developing roller (31) are refreshed by rotating them at the same peripheral speed as when forming an image.

画像形成装置(100)において、リフレッシュ工程は、用紙に画像形成する毎に平均印字密度を求めて該平均印字密度が所定の値を下回った時や、画像形成処理が所定枚数終了した時等に実行される。また、リフレッシュ工程は、連続印字中の紙間に相当する非画像形成時に実行してもよい。   In the image forming apparatus (100), the refresh process is performed when an average print density is obtained every time an image is formed on a sheet and the average print density falls below a predetermined value, or when a predetermined number of image forming processes are completed. Executed. Further, the refreshing process may be executed at the time of non-image formation corresponding to the interval between sheets during continuous printing.

上記のような予め定められた条件が充足されると、現像ローラ(31)は駆動が制御され、画像形成時よりも低速で回転させられる。
感光体ドラム(1)上にはベタ画像(濃度の濃い画像)に相当する静電潜像が形成される。この静電潜像の大きさは、感光体ドラム(1)の軸方向にはほぼ最大幅で、周方向には少なくとも現像ローラ(31)1周分に相当する長さであることが好ましい。
現像ローラ(31)には、バイアス電圧が印加されることにより、現像ローラ(31)上のトナー(T)を静電潜像に搬送する。
感光体ドラム(1)に搬送されたトナー(T)は、転写されずにクリーニング装置(5)によって回収される。
When the predetermined condition as described above is satisfied, the driving of the developing roller (31) is controlled, and the developing roller (31) is rotated at a lower speed than during image formation.
An electrostatic latent image corresponding to a solid image (a dark image) is formed on the photosensitive drum (1). The size of the electrostatic latent image is preferably approximately the maximum width in the axial direction of the photosensitive drum (1) and a length corresponding to at least one rotation of the developing roller (31) in the circumferential direction.
When a bias voltage is applied to the developing roller (31), the toner (T) on the developing roller (31) is conveyed to the electrostatic latent image.
The toner (T) conveyed to the photosensitive drum (1) is collected by the cleaning device (5) without being transferred.

このように、本発明のリフレッシュ工程は、現像ローラ(31)を画像形成時よりも低速で回転させた状態で行われる。
本発明のように、現像ローラ(31)を画像形成時よりも低速で回転させた場合(図3)と、画像形成時と同じ周速度で回転させた場合(図4)とを模式図を用いて説明する。
Thus, the refreshing process of the present invention is performed in a state where the developing roller (31) is rotated at a lower speed than during image formation.
As in the present invention, the development roller (31) is rotated at a lower speed than that during image formation (FIG. 3) and the case where it is rotated at the same peripheral speed as during image formation (FIG. 4). It explains using.

本発明は、図3に示すように、現像ローラ(31)を低速で回転させるので、現像ローラ(31)と感光体ドラム(1)の対向部でのトナー(T)を感光体ドラム(1)へ搬送するための時間が増加し、現像ローラ(31)上のトナー層のうち最下層のトナー(T)まで搬送することができる。   In the present invention, as shown in FIG. 3, since the developing roller (31) is rotated at a low speed, the toner (T) at the facing portion between the developing roller (31) and the photosensitive drum (1) is transferred to the photosensitive drum (1). ) Is increased, so that the toner (T) in the lowermost layer among the toner layers on the developing roller (31) can be transported.

それに比べ、画像形成時と同じ周速度で現像ローラ(31)を回転させると、図4に示すように、現像ローラ(31)上に積層されたトナー(T)のうち、表層に位置するトナー(T)のみが感光体ドラム(1)へ搬送されて、最下層のトナー(T)まで搬送することができず、下層のトナー(T)は現像ローラ(31)上に残留してしまい、十分にリフレッシュできない。   In contrast, when the developing roller (31) is rotated at the same peripheral speed as in image formation, as shown in FIG. 4, the toner positioned on the surface layer among the toner (T) stacked on the developing roller (31). Only (T) is conveyed to the photosensitive drum (1) and cannot be conveyed to the lowermost toner (T), and the lower toner (T) remains on the developing roller (31). It cannot be fully refreshed.

より詳細に現像ローラ(31)の周速度について説明する。リフレッシュ工程における現像ローラ(31)の周速度(v)は、感光体ドラム(1)と現像ローラ(31)とが近接する部分の幅(w)を、図5に示す従来の画像形成装置のように現像ローラ(31)を停止させて現像バイアスを印加した時に現像ローラ(31)表面に積層されたトナー(T)が該近接する部分において最下層まで感光体ドラム(1)側へ搬送されるのに要する時間(トナー搬送時間(t)と称す)で除することによって定められる周速度(v)以下であることが好ましい。   The peripheral speed of the developing roller (31) will be described in more detail. The peripheral speed (v) of the developing roller (31) in the refreshing process is the width (w) of the portion where the photosensitive drum (1) and the developing roller (31) are close to each other, as in the conventional image forming apparatus shown in FIG. Thus, when the developing roller (31) is stopped and the developing bias is applied, the toner (T) stacked on the surface of the developing roller (31) is conveyed to the photosensitive drum (1) side to the lowest layer in the adjacent portion. It is preferable that the speed is equal to or less than the peripheral speed (v) determined by dividing by the time required for the transfer (referred to as toner transport time (t)).

例えば、画像形成時の感光体ドラム(1)の外径が40mm、周速度(D)が230mm/sec、現像ローラ(31)の外径が20mm、周速度(S)が414mm/secの画像形成装置において、トナー搬送時間(t)が50msec、感光体ドラム(1)と現像ローラ(31)が近接する部分の幅(w)が6mmである場合には、現像ローラ(31)の周速度(v)は、6mm/50msec=120mm/s以下であることが好ましい。   For example, an image in which the outer diameter of the photosensitive drum (1) during image formation is 40 mm, the peripheral speed (D) is 230 mm / sec, the outer diameter of the developing roller (31) is 20 mm, and the peripheral speed (S) is 414 mm / sec. In the forming apparatus, when the toner conveyance time (t) is 50 msec and the width (w) of the portion where the photosensitive drum (1) and the developing roller (31) are close to each other is 6 mm, the peripheral speed of the developing roller (31) (V) is preferably 6 mm / 50 msec = 120 mm / s or less.

周速度(v)を上記のように設定することにより、現像ローラ(31)は回転させているが、現像ローラ(31)上の1点において、近接する部分の幅(w)=6mmを通過する時間が、トナー搬送時間(t)=50msecよりも長くとることができる。そのため、現像ローラ(31)全周の劣化トナーを1回のリフレッシュ工程で確実に吐き出すことができる。   By setting the peripheral speed (v) as described above, the developing roller (31) is rotated, but at one point on the developing roller (31), the width (w) of the adjacent portion passes through 6 mm. It is possible to take a longer time than the toner transport time (t) = 50 msec. Therefore, the deteriorated toner on the entire circumference of the developing roller (31) can be reliably discharged in one refresh process.

また、現像ローラ(31)の周速度(v)は感光体ドラム(1)の周速度より遅いことが好ましい。
感光体ドラム(1)の周速度が現像ローラ(31)の周速度(v)より遅いと感光体ドラム(1)上のトナー(T)が飽和してしまい現像ローラ(31)からトナー(T)が搬送されにくくなるからである。
The peripheral speed (v) of the developing roller (31) is preferably slower than the peripheral speed of the photosensitive drum (1).
When the peripheral speed of the photosensitive drum (1) is lower than the peripheral speed (v) of the developing roller (31), the toner (T) on the photosensitive drum (1) is saturated and the toner (T) from the developing roller (31) is saturated. This is because it is difficult to convey.

上記したように、リフレッシュ工程を実行することで、現像ローラ(1)全周の劣化トナーを効率良く吐き出すことができ、画質低下を防止することができる。   As described above, by performing the refresh process, the deteriorated toner on the entire circumference of the developing roller (1) can be discharged efficiently, and the image quality can be prevented from being lowered.

なお、本実施形態では、1成分現像方式の画像形成装置としたが、現像ローラ上にトナーのみが担持される画像形成装置であれば良く、2成分現像方式を用いて現像ローラ上にトナー層を形成して現像させる方式でも良い。
上記したリフレッシュ工程によって、劣化したトナーを効率よく排出することができ、画質低下の防止に効果的である。
In this embodiment, the image forming apparatus of the one-component development method is used. However, any image forming apparatus in which only toner is carried on the developing roller may be used, and the toner layer is formed on the developing roller using the two-component development method. A method of forming and developing the film may be used.
The above-described refresh process can efficiently discharge deteriorated toner, and is effective in preventing image quality deterioration.

本発明は、複写機、プリンタ、ファクシミリ等の画像形成装置、特に非画像形成時に現像ローラ上のトナーを感光体ドラムへと搬送するリフレッシュ工程を実行可能な画像形成装置に利用されるものである。   The present invention is used in an image forming apparatus such as a copying machine, a printer, and a facsimile, and in particular, an image forming apparatus capable of executing a refresh process for conveying toner on a developing roller to a photosensitive drum during non-image formation. .

100 画像形成装置
103 画像形成部
1 感光体ドラム
3 現像装置
31 現像ローラ
w 感光体ドラムと現像ローラの近接部分の幅
T トナー
DESCRIPTION OF SYMBOLS 100 Image forming apparatus 103 Image forming part 1 Photosensitive drum 3 Developing apparatus 31 Developing roller w Width of the proximity part of photosensitive drum and developing roller

Claims (4)

像担持体と、該像担持体に対向配置される現像剤担持体を備え、
画像形成時において、前記像担持体と前記現像剤担持体を回転させて現像バイアスを印加することで前記像担持体表面に形成された静電潜像をトナー像に現像し、
非画像形成時において、前記現像剤担持体上のトナーを前記像担持体側へ搬送するリフレッシュ工程を実行可能な画像形成装置であって、
前記リフレッシュ工程において、前記像担持体と前記現像剤担持体が回転し、該現像剤担持体の周速度は画像形成時における該現像剤担持体の周速度より遅いことを特徴とする画像形成装置。
An image carrier, and a developer carrier disposed opposite to the image carrier,
At the time of image formation, the electrostatic latent image formed on the surface of the image carrier is developed into a toner image by rotating the image carrier and the developer carrier and applying a development bias.
An image forming apparatus capable of executing a refreshing process for conveying toner on the developer carrier to the image carrier side during non-image formation,
In the refresh step, the image carrier and the developer carrier rotate, and the peripheral speed of the developer carrier is lower than the peripheral speed of the developer carrier during image formation. .
前記リフレッシュ工程において、前記現像剤担持体の周速度が前記像担持体の周速度より遅いことを特徴とする請求項1に記載の画像形成装置。   The image forming apparatus according to claim 1, wherein in the refreshing step, a peripheral speed of the developer carrier is lower than a peripheral speed of the image carrier. 前記現像剤担持体の周速度は、前記像担持体と前記現像剤担持体とが近接する部分の幅を、前記現像剤担持体を停止させて現像バイアスを印加した時に該現像剤担持体表面に積層されたトナーが前記近接する部分において最下層まで前記像担持体側へ搬送されるのに要する時間で除することによって定められることを特徴とする請求項1又は2に記載の画像形成装置。   The peripheral speed of the developer carrier is such that the width of the portion where the image carrier and the developer carrier are close to each other, the surface of the developer carrier when the developer carrier is stopped and a developing bias is applied. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is determined by dividing by a time required for the toner laminated on the toner to be conveyed to the lowermost layer in the adjacent portion to the image carrier side. 前記像担持体は、前記現像剤担持体に形成されたトナー層によって現像されることを特徴とする請求項1乃至3の何れかに記載の画像形成装置。   The image forming apparatus according to claim 1, wherein the image carrier is developed by a toner layer formed on the developer carrier.
JP2009047325A 2009-02-27 2009-02-27 Image forming apparatus Expired - Fee Related JP5221418B2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018155925A (en) * 2017-03-17 2018-10-04 富士ゼロックス株式会社 Image forming apparatus, image holding body, exposure device, and developing device

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Publication number Priority date Publication date Assignee Title
JP2005043799A (en) * 2003-07-25 2005-02-17 Canon Inc Image forming apparatus
JP2005062637A (en) * 2003-08-19 2005-03-10 Fuji Xerox Co Ltd Developing device and image forming apparatus
JP2008096688A (en) * 2006-10-12 2008-04-24 Kyocera Mita Corp Image forming apparatus

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Publication number Priority date Publication date Assignee Title
JP2005043799A (en) * 2003-07-25 2005-02-17 Canon Inc Image forming apparatus
JP2005062637A (en) * 2003-08-19 2005-03-10 Fuji Xerox Co Ltd Developing device and image forming apparatus
JP2008096688A (en) * 2006-10-12 2008-04-24 Kyocera Mita Corp Image forming apparatus

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2018155925A (en) * 2017-03-17 2018-10-04 富士ゼロックス株式会社 Image forming apparatus, image holding body, exposure device, and developing device

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