JP2011008137A - Image forming apparatus - Google Patents
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- JP2011008137A JP2011008137A JP2009153285A JP2009153285A JP2011008137A JP 2011008137 A JP2011008137 A JP 2011008137A JP 2009153285 A JP2009153285 A JP 2009153285A JP 2009153285 A JP2009153285 A JP 2009153285A JP 2011008137 A JP2011008137 A JP 2011008137A
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Abstract
Description
本発明は画像形成装置に関し、複写機・ファクシミリ・プリンター及びこれらの機能を複合装備した複合機などの電子写真方式を用いた画像形成装置に関するものである。 The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus using an electrophotographic system such as a copying machine, a facsimile machine, a printer, and a multifunction machine equipped with these functions.
複写機やファクシミリ、プリンターなどの電子写真方式を用いた画像形成装置において、カラー画像を形成する場合、少なくとも１つの感光体（静電潜像担持体）の表面にトナー像を形成する工程と、このトナー像を中間転写ベルト（中間転写体）上に一次転写する工程とを、各色ごとに繰り返し行い中間転写ベルト上にカラートナー画像を形成した後、このカラートナー画像を用紙に一括して二次転写する方式が用いられている。この中間転写ベルトを用いた画像形成方式では、２次転写後に中間転写ベルト上に残る残留トナーをクリーニングブレードによって除去・回収することが多い。 In the case of forming a color image in an image forming apparatus using an electrophotographic system such as a copying machine, a facsimile machine, or a printer, a step of forming a toner image on the surface of at least one photoconductor (electrostatic latent image carrier); The process of primary transfer of the toner image onto an intermediate transfer belt (intermediate transfer member) is repeated for each color to form a color toner image on the intermediate transfer belt, and then the color toner image is collectively transferred onto a sheet. The next transfer method is used. In this image forming system using an intermediate transfer belt, residual toner remaining on the intermediate transfer belt after secondary transfer is often removed and collected by a cleaning blade.
中間転写ベルトを用いた画像形成方式では、転写中の画像への加圧力が大きいために、文字画像や細線画像において”中抜け”と呼ばれる不具合が生じることがある。そこで、この”中抜け”を防止する一つの方策として、感光体と中間転写ベルトとの相対速度に差を設けることが考えられる。 In an image forming system using an intermediate transfer belt, a large amount of pressure is applied to an image being transferred, and thus a defect called “missing” may occur in a character image or a fine line image. Therefore, as one measure for preventing the “missing”, it is conceivable to provide a difference in the relative speed between the photosensitive member and the intermediate transfer belt.
ところが、感光体と中間転写ベルトとの相対速度に差を設けると、中間転写ベルト上の残留トナーをクリーニングブレードでうまく除去できないという新たな不具合が生じる。これは次のような機構によるものと考えられる。すなわち、トナー粒子の表面からシリカなどの外添剤が脱離し感光体上に付着する。これらの外添剤はサブミクロン域の微小粒子であるため、感光体のクリーニング手段では除去できず、クリーニング手段をすり抜けて感光体の回転によって帯電領域に搬送される。そして、例えば帯電ローラなどの接触方式の帯電装置から発生した放電生成物が外添剤の表面に付着する。これによって、外添剤は感光体から中間転写ベルトへ移動しやすくなる。加えて、上記のように感光体と中間転写ベルトとの相対速度に差があると、感光体と中間転写ベルトとの間で外添剤は強く摺擦される。これが繰り返されることによって、中間転写ベルトの表面にフィルム状に外添剤が付着して（この現象を以下「フィルミング」と記す）、中間転写ベルトの表面の平滑性が失われ、クリーニングブレードで中間転写ベルト上の残留トナーをうまく除去できなくなる。 However, if there is a difference in the relative speed between the photosensitive member and the intermediate transfer belt, a new problem arises in that the residual toner on the intermediate transfer belt cannot be removed well by the cleaning blade. This is thought to be due to the following mechanism. That is, an external additive such as silica is detached from the surface of the toner particles and adheres to the photoreceptor. Since these external additives are fine particles in the sub-micron range, they cannot be removed by the cleaning means of the photoconductor, but are passed through the cleaning means and conveyed to the charged region by the rotation of the photoconductor. Then, for example, a discharge product generated from a contact-type charging device such as a charging roller adheres to the surface of the external additive. This facilitates the movement of the external additive from the photoreceptor to the intermediate transfer belt. In addition, when there is a difference in the relative speed between the photosensitive member and the intermediate transfer belt as described above, the external additive is rubbed strongly between the photosensitive member and the intermediate transfer belt. By repeating this, an external additive adheres to the surface of the intermediate transfer belt in the form of a film (this phenomenon is hereinafter referred to as “filming”), and the smoothness of the surface of the intermediate transfer belt is lost. Residual toner on the intermediate transfer belt cannot be removed successfully.
下記表１に、中間転写ベルトの回転速度と感光体の回転速度との差の割合（「＋」は中間転写ベルトの方が速く、「−」は感光体の方が速い）に対する、フィルミング及び中抜けの発生状態を示す。なお、「１層」は、ブラック、シアン、マゼンタ、イエロのトナー１層のみで形成された画像の中抜けの状態、「２層」は、レッド、グリーン、ブルー等のトナー２層で形成される画像の中抜けの状態を意味する。 Table 1 below shows filming with respect to the ratio of the difference between the rotation speed of the intermediate transfer belt and the rotation speed of the photosensitive member (“+” is faster for the intermediate transfer belt and “−” is faster for the photosensitive member). In addition, the state of occurrence of voids is shown. Note that “one layer” is an image that is formed of only one toner layer of black, cyan, magenta, and yellow, and “two layers” is formed of two toner layers such as red, green, and blue. This means that the image is missing.
表１から理解されるように、回転速度差の割合を＋０．５％以上とすると、”中抜け”は防止できるが、フィルミングは防止できない。一方、回転速度差の割合を−０．１〜＋０．１％の範囲とすると、フィルミングは防止できるが、”中抜け”は防止できない。このように、フィルミングと”中抜け”の両者を同時に防止できる回転速度差は見いだせない。 As can be seen from Table 1, when the ratio of the rotational speed difference is + 0.5% or more, “missing” can be prevented, but filming cannot be prevented. On the other hand, when the ratio of the rotational speed difference is in the range of −0.1 to + 0.1%, filming can be prevented, but “missing” cannot be prevented. Thus, a difference in rotational speed that can simultaneously prevent both filming and “missing” cannot be found.
そこで、感光体と中間転写ベルトとの相対速度に差を設けて”中抜け”を防止しながら、中間転写ベルトのフィルミングについては、研磨手段を設けて、中間転写ベルトに付着した外添剤を研磨・除去することが考えられる（例えば、特許文献１を参照）。 Therefore, for the filming of the intermediate transfer belt, a polishing means is provided to provide a difference in the relative speed between the photoconductor and the intermediate transfer belt to prevent “missing”, and the external additive adhered to the intermediate transfer belt. It is conceivable to polish and remove (see, for example, Patent Document 1).
しかしながら、中間転写ベルトに付着した外添剤を研磨するための研磨手段を新たに設けると、装置の大型化・複雑化を招くことになる。 However, if a polishing means for polishing the external additive attached to the intermediate transfer belt is newly provided, the apparatus becomes large and complicated.
本発明は、このような従来の問題に鑑みてなされたものであり、その目的は、感光体と中間転写ベルトとの相対速度に差を設けて”中抜け”を防止しながら、装置の大型化・複雑化を招くことなく、中間転写ベルトのフィルミングを抑制することにある。 The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a large-sized apparatus while preventing a “drilling” by providing a difference in relative speed between the photosensitive member and the intermediate transfer belt. It is to suppress the filming of the intermediate transfer belt without increasing the size and complexity.
本発明者は上記目的を達成するため鋭意検討を重ねた結果、感光体にトナー像を形成している間は中間転写ベルトにフィルミングが生じないという知見を得た。これは、感光体に形成されたトナー像及び非画像形成部分に付着したかぶりトナーが、感光体と中間転写ベルトとのニップ部において、いわゆるスペーサ効果を奏し、外添剤が中間転写ベルトの表面に強く摺擦されるのを防ぐためと考えられる。本発明はかかる知見に基づきなされたものであり、回転自在の静電潜像担持体と、静電潜像担持体の表面を一様に帯電させる帯電手段と、帯電された前記静電潜像担持体に静電潜像を形成する露光装置と、前記静電潜像をトナーで可視像化する現像手段とを備える作像部と、前記静電潜像担持体の表面に圧接又は離間しながら回転する中間転写体と、前記中間転写体を挟んで前記静電潜像担持体と対向する位置に配置され、前記静電潜像担持体の表面に形成されたトナー画像を前記中間転写体に転写させる一次転写手段とを有する画像形成装置であって、前記静電潜像担持体と前記中間転写体との相対速度が異なり、前記静電潜像担持体と前記中間転写体とは圧接位置と離間位置とに相対的に移動可能であり、画像形成信号が入力されると、前記静電潜像担持体に形成されたトナー画像の前記中間転写体への転写開始と略同時に、前記静電潜像担持体と前記中間転写体とを離間位置から圧接位置とし、前記静電潜像担持体から前記中間転写体へのトナー画像の転写が終了すると、当該転写終了から次のトナー画像の転写開始までの時間が、所定時間以上の場合は、前記トナー画像の転写終了と略同時に、前記静電潜像担持体と前記中間転写体とを圧接位置から離間位置にするとともに、前記現像手段を停止させる一方、前記転写終了から次のトナー画像の転写開始までの時間が、所定時間未満の場合は、前記トナー画像の転写終了後も、前記静電潜像担持体と前記中間転写体とを継続して圧接位置とするとともに、前記現像手段も継続して駆動させることを特徴とする。 As a result of intensive studies to achieve the above object, the present inventor has found that filming does not occur on the intermediate transfer belt while the toner image is formed on the photosensitive member. This is because the toner image formed on the photosensitive member and the fog toner attached to the non-image forming portion exhibit a so-called spacer effect at the nip portion between the photosensitive member and the intermediate transfer belt, and the external additive is on the surface of the intermediate transfer belt. This is considered to prevent it from being rubbed strongly. The present invention has been made based on such knowledge, and is a rotatable electrostatic latent image carrier, charging means for uniformly charging the surface of the electrostatic latent image carrier, and the charged electrostatic latent image. An image forming unit including an exposure device that forms an electrostatic latent image on a carrier, and a developing unit that visualizes the electrostatic latent image with toner, and press-contacts or separates from the surface of the electrostatic latent image carrier A toner image formed on the surface of the electrostatic latent image carrier, the intermediate transfer member rotating while being positioned at a position facing the electrostatic latent image carrier across the intermediate transfer member. An image forming apparatus having a primary transfer means for transferring to a body, wherein the electrostatic latent image carrier and the intermediate transfer member have different relative speeds, and the electrostatic latent image carrier and the intermediate transfer member are When the image forming signal is input, it can be moved relative to the pressure contact position and the separation position. At substantially the same time as the transfer of the toner image formed on the electrostatic latent image carrier to the intermediate transfer member, the electrostatic latent image carrier and the intermediate transfer member are moved from the separated position to the pressure contact position, and the electrostatic image is transferred. When the transfer of the toner image from the latent image carrier to the intermediate transfer member is completed, if the time from the end of the transfer to the start of the transfer of the next toner image is a predetermined time or more, it is substantially the same as the end of transfer of the toner image. At the same time, the electrostatic latent image carrier and the intermediate transfer member are moved away from the press contact position and the developing unit is stopped, while the time from the end of the transfer to the start of the transfer of the next toner image is predetermined. If the time is less than the time, the electrostatic latent image carrier and the intermediate transfer member are continuously brought into the press contact position even after the transfer of the toner image is completed, and the developing unit is also continuously driven. And
前記帯電手段としては、前記静電潜像担持体の表面に接触して帯電させるものが好ましい。 The charging means is preferably one that contacts and charges the surface of the electrostatic latent image carrier.
また、前記中間転写体の表面に当接し、転写せずに前記中間転写体上に残留したトナーを除去するクリーニングブレードをさらに有するのが好ましい。 In addition, it is preferable to further include a cleaning blade that contacts the surface of the intermediate transfer member and removes toner remaining on the intermediate transfer member without transferring.
なお、本明細書において、画像形成装置が複数の作像部を有する場合、「静電潜像担持体に形成されたトナー画像の中間転写体への転写開始」とは、複数の作像部のうち最初の、トナー画像の中間転写体への転写開始を意味し、「静電潜像担持体から中間転写体へのトナー画像の転写終了」とは、複数の作像部のうち最後の、トナー画像の中間転写体への転写終了を意味するものとする。 In the present specification, when the image forming apparatus has a plurality of image forming units, “starting transfer of the toner image formed on the electrostatic latent image carrier to the intermediate transfer member” means a plurality of image forming units. Means the start of the transfer of the toner image to the intermediate transfer member, and “the end of the transfer of the toner image from the electrostatic latent image carrier to the intermediate transfer member” means the last of the plurality of image forming units. It means that the transfer of the toner image to the intermediate transfer member is completed.
本発明の画像形成装置では、静電潜像担持体に形成されたトナー画像の中間転写体への転写開始と略同時に、静電潜像担持体と中間転写体とを離間位置から圧接位置とし、静電潜像担持体から中間転写体へのトナー画像の転写が終了すると、転写終了から次のトナー画像の転写開始までの時間が、所定時間以上の場合は、トナー画像の転写終了と略同時に、静電潜像担持体と前記中間転写体とを圧接位置から離間位置にするとともに、現像手段を停止する一方、転写終了から次のトナー画像の転写開始までの時間が、所定時間未満の場合は、トナー画像の転写終了後も、静電潜像担持体と中間転写体とを継続して圧接位置とするとともに、現像手段も継続して駆動させる。すなわち、少なくとも静電潜像担持体と中間転写体とが圧接している間は、現像手段を駆動させるので、中間転写体のフィルミングが効果的に抑制される。 In the image forming apparatus of the present invention, the electrostatic latent image carrier and the intermediate transfer member are moved from the separated position to the pressure contact position substantially simultaneously with the start of transfer of the toner image formed on the electrostatic latent image carrier to the intermediate transfer member. When the transfer of the toner image from the electrostatic latent image carrier to the intermediate transfer member is completed, if the time from the end of the transfer to the start of the transfer of the next toner image is equal to or longer than the predetermined time, the transfer of the toner image is abbreviated. At the same time, the electrostatic latent image carrier and the intermediate transfer member are moved away from the press contact position and the developing unit is stopped, while the time from the end of transfer to the start of transfer of the next toner image is less than a predetermined time. In this case, after the transfer of the toner image is completed, the electrostatic latent image carrier and the intermediate transfer member are continuously brought into the press contact position, and the developing unit is continuously driven. In other words, since the developing means is driven at least while the electrostatic latent image carrier and the intermediate transfer member are in pressure contact, filming of the intermediate transfer member is effectively suppressed.
以下、本発明を図に基づいてさらに詳しく説明するが、本発明はこれらの実施形態に何ら限定されるものではない。 Hereinafter, the present invention will be described in more detail with reference to the drawings. However, the present invention is not limited to these embodiments.
図１は、本発明に係る画像形成装置の一例を示す概説図である。図１の画像形成装置は、タンデム型デジタルカラープリンタ（以下、単に「プリンタ」と記すことがある）である。もちろん、プリンタのほか、さらにスキャナを有する複写機、ファクシミリ又はそれらの機能を複合的に備えた複合機等にも本発明を適用することができる。また、画像形成方式としてはタンデム方式に限定されるものではなく、他の方式、例えば、回転軸の周囲に４つの現像装置を配置し、これらを順次静電潜像担持体に対向させてフルカラー画像を作成する所謂４サイクル方式、あるいは一つの現像装置でモノクロ画像を作成するモノクロ方式であっても構わない。 FIG. 1 is a schematic diagram showing an example of an image forming apparatus according to the present invention. The image forming apparatus in FIG. 1 is a tandem digital color printer (hereinafter, simply referred to as “printer”). Of course, in addition to a printer, the present invention can also be applied to a copying machine having a scanner, a facsimile, or a multi-function machine having these functions combined. Further, the image forming method is not limited to the tandem method, and other methods, for example, four developing devices are arranged around the rotation shaft, and these are sequentially opposed to the electrostatic latent image carrier to be full color. A so-called four-cycle method of creating an image or a monochrome method of creating a monochrome image with one developing device may be used.
まず、プリンタ１の概略構成を説明する。プリンタ１は、その内部のほぼ中央部に中間転写ベルト（中間転写体）１１を備えている。中間転写ベルト１１は、ローラ１２，テンションローラ１３，ガイドローラ１４，１５の外周部に掛け渡されて反時計回りに回転駆動する。テンションローラ１３は、外側へスライド可能に取り付けられていると共に、押しバネＳによって中間転写ベルト１１の内側から外側に向かって付勢されている。これにより、中間転写ベルト１１は、常に張力がかかった状態となっている。 First, a schematic configuration of the printer 1 will be described. The printer 1 includes an intermediate transfer belt (intermediate transfer member) 11 at a substantially central portion inside thereof. The intermediate transfer belt 11 is wound around the outer periphery of the roller 12, the tension roller 13, and the guide rollers 14 and 15, and is driven to rotate counterclockwise. The tension roller 13 is slidably attached to the outside and is urged by the pressing spring S from the inside to the outside of the intermediate transfer belt 11. Thus, the intermediate transfer belt 11 is always in a tensioned state.
中間転写ベルト１１の下部水平部の下には、イエロー（Ｙ）、マゼンタ（Ｍ）、シアン（Ｃ）、ブラック（Ｂ）の各色にそれぞれ対応する４つの作像部２Ｙ，２Ｍ，２Ｃ，２Ｂ（以下、「作像部２」と総称することがある）が、中間転写ベルト１１に沿ってこの順に並んで配置されている。各作像部２は、感光体（静電潜像担持体）２１Ｙ，２１Ｍ，２１Ｃ，２１Ｂ（以下、「感光体２１」と総称することがある）をそれぞれ有している。各感光体２１の周囲には、その回転方向に沿って順に、帯電ローラ２２Ｙ，２２Ｍ，２２Ｃ，２２Ｂ（以下、「帯電ローラ２２」と総称することがある）と、プリントヘッド部２３Ｙ，２３Ｍ，２３Ｃ，２３Ｂと、現像器（現像手段）２４Ｙ，２４Ｍ，２４Ｃ，２４Ｂ（以下、「現像器２４」と総称することがある）と、クリーナ（クリーニング手段）２５Ｙ，２５Ｍ，２５Ｃ，２５Ｂとがそれぞれ配置されている。プリントヘッド部２３Ｙ，２３Ｍ，２３Ｃ，２３Ｂは、感光体の軸方向と平行な主走査方向に並べられた多数のＬＥＤから構成されている。 Below the lower horizontal portion of the intermediate transfer belt 11, four image forming portions 2Y, 2M, 2C, and 2B respectively corresponding to yellow (Y), magenta (M), cyan (C), and black (B) colors. (Hereinafter, sometimes collectively referred to as “image forming unit 2”) are arranged along the intermediate transfer belt 11 in this order. Each image forming unit 2 includes a photoreceptor (electrostatic latent image carrier) 21Y, 21M, 21C, and 21B (hereinafter may be collectively referred to as “photoreceptor 21”). Around each photosensitive member 21, charging rollers 22Y, 22M, 22C, and 22B (hereinafter sometimes collectively referred to as “charging roller 22”) and print head portions 23Y, 23M, 23C, 23B, developing units (developing units) 24Y, 24M, 24C, 24B (hereinafter may be collectively referred to as “developing unit 24”) and cleaners (cleaning units) 25Y, 25M, 25C, 25B, respectively. Has been placed. The print head portions 23Y, 23M, 23C, and 23B are composed of a large number of LEDs arranged in the main scanning direction parallel to the axial direction of the photosensitive member.
そして、中間転写ベルト１１を挟んで、各感光体２１と対向する位置には、一次転写ローラ（一次転写手段）３０Ｙ，３０Ｍ，３０Ｃ，３０Ｂ（以下、「一次転写ローラ３０」と総称することがある）が設けられている。また、中間転写ベルト１１のローラ１２で支持された部分には、二次転写ローラ１６が圧接されている。二次転写ローラ１６と中間転写ベルト１１とのニップ部が二次転写領域１７となる。この二次転写領域１７において中間転写ベルト１１上に形成されたトナー画像が、搬送されてきた用紙Ｐに転写される。 Then, primary transfer rollers (primary transfer means) 30Y, 30M, 30C, and 30B (hereinafter collectively referred to as “primary transfer roller 30”) are located at positions facing each photoconductor 21 with the intermediate transfer belt 11 interposed therebetween. There is). A secondary transfer roller 16 is pressed against a portion of the intermediate transfer belt 11 supported by the roller 12. A nip portion between the secondary transfer roller 16 and the intermediate transfer belt 11 becomes a secondary transfer region 17. The toner image formed on the intermediate transfer belt 11 in the secondary transfer region 17 is transferred to the conveyed paper P.
プリンタ１に下部には、給紙カセット９１が着脱可能に配置されている。給紙カセット９１内に積載収容された用紙Ｐは、給紙ローラ９２の回転によって最上部のものから１枚ずつ引き出されて搬送路９３に送り出される。搬送路９３は、給紙カセット９１から、タイミングローラ対９４のニップ部、二次転写領域１７、および定着ユニット９５を通って排紙トレイ９８まで延びている。給紙カセット９１から送り出された用紙Ｐは、タイミングローラ対９４に搬送され、ここで所定のタイミングで二次転写領域１７に送り出される。 A paper feed cassette 91 is detachably disposed at the bottom of the printer 1. The sheets P stacked and housed in the sheet feeding cassette 91 are pulled out one by one from the uppermost one by the rotation of the sheet feeding roller 92 and sent out to the transport path 93. The conveyance path 93 extends from the paper feed cassette 91 to the paper discharge tray 98 through the nip portion of the timing roller pair 94, the secondary transfer region 17, and the fixing unit 95. The paper P sent out from the paper feed cassette 91 is conveyed to the timing roller pair 94 and is sent out to the secondary transfer region 17 at a predetermined timing.
定着ユニット９５は、中空円筒状で、ハロゲンヒータＨを内部に備えた定着ローラ９６と、この定着ローラ９６に圧接されて従動回転する加圧ローラ９７を備える。トナー画像が二次転写された用紙Ｐが通過する、定着ローラ９６と加圧ローラ９７とのニップ部が、定着領域となる。 The fixing unit 95 has a hollow cylindrical shape, and includes a fixing roller 96 having a halogen heater H therein, and a pressure roller 97 that is pressed against the fixing roller 96 and rotates. A nip portion between the fixing roller 96 and the pressure roller 97 through which the paper P onto which the toner image has been secondarily transferred passes is a fixing region.
このような構成のプリンタ１の概略動作について説明する。まず、カラー画像を出力するフルカラーモードの場合、外部装置（例えばパソコン）からプリンタ１の画像信号処理部（不図示）に画像信号が入力されると、画像信号処理部ではこの画像信号をイエロー、シアン、マゼンタ、ブラックに色変換したデジタル画像信号を作成し、この信号をプリントヘッド用ＬＥＤドライブ回路に伝達する。このドライブ回路は、入力されたデジタル信号に基づいて、各作像部２のプリントヘッド部２３Ｙ，２３Ｍ，２３Ｃ，２３Ｂを発光させて露光を行う。この露光は、プリントヘッド部２３Ｙ，２３Ｍ，２３Ｃ，２３Ｂの順にそれぞれ時間差をもって行われる。これにより、各感光体２１の表面に各色用の静電潜像がそれぞれ形成される。 A schematic operation of the printer 1 having such a configuration will be described. First, in the full color mode for outputting a color image, when an image signal is input from an external device (for example, a personal computer) to an image signal processing unit (not shown) of the printer 1, the image signal processing unit converts the image signal to yellow, A digital image signal color-converted to cyan, magenta, and black is created, and this signal is transmitted to the LED drive circuit for the print head. This drive circuit performs exposure by causing the print head units 23Y, 23M, 23C, and 23B of each image forming unit 2 to emit light based on the input digital signal. This exposure is performed with a time difference in the order of the print head portions 23Y, 23M, 23C, and 23B. Thereby, an electrostatic latent image for each color is formed on the surface of each photoconductor 21.
各感光体２１上に形成された静電潜像は、各現像器２４の現像ローラから各色のトナーが供給されることによりそれぞれ現像されて各色のトナー画像となる。現像ローラと感光体とは通常０．０５〜１．０ｍｍ程度離間している。また現像剤としてはトナーのみからなる１成分系、トナーとキャリアとを有する２成分系のいずれであってもよい。現像方法は接触現像や非接触現像など従来公知の現像方法を用いることができる。 The electrostatic latent image formed on each photoconductor 21 is developed by supplying toner of each color from the developing roller of each developing device 24 to become a toner image of each color. The developing roller and the photoreceptor are usually separated from each other by about 0.05 to 1.0 mm. The developer may be either a one-component system composed only of toner or a two-component system having a toner and a carrier. As the development method, a conventionally known development method such as contact development or non-contact development can be used.
そして、各感光体２１上に形成された各色のトナー画像は、各一次転写ローラ３０の作用により、図中反時計回りに回転する中間転写ベルト１１上に順次一次転写されて重ね合わせられる。 The toner images of the respective colors formed on the respective photoconductors 21 are successively primary-transferred and superimposed on the intermediate transfer belt 11 that rotates counterclockwise in the drawing by the action of each primary transfer roller 30.
このようにして中間転写ベルト１１上に形成されたトナー画像は、中間転写ベルト１１の移動にしたがって二次転写領域１７に達する。この二次転写領域１７において、重ね合わされた各色トナー画像は、二次転写ローラ１６の作用により、給紙カセット９１から搬送路９３に送り出されてタイミングローラ対９４により供給された用紙Ｐに、一括して二次転写される。なお、二次転写後に中間転写ベルト１１上に残留するトナーは、クリーニングブレード１８により除去・回収される。 The toner image formed on the intermediate transfer belt 11 in this way reaches the secondary transfer region 17 as the intermediate transfer belt 11 moves. In the secondary transfer region 17, the superimposed color toner images are collectively delivered to the paper P supplied from the paper feed cassette 91 to the transport path 93 and supplied by the timing roller pair 94 by the action of the secondary transfer roller 16. Second transfer is performed. The toner remaining on the intermediate transfer belt 11 after the secondary transfer is removed and collected by the cleaning blade 18.
トナー画像が二次転写された用紙Ｐは、搬送路９３を通って定着ユニット９５に送られ、そこで定着領域を通過することによりトナー画像が用紙Ｐに定着される。そして、用紙Ｐは排紙トレイ９８に排出される。 The sheet P onto which the toner image has been secondarily transferred is sent to the fixing unit 95 through the conveyance path 93, where the toner image is fixed on the sheet P by passing through the fixing region. Then, the paper P is discharged to the paper discharge tray 98.
プリンタ１では、不図示の離接機構によって、各一次転写ローラ３０Ｙ，３０Ｍ，３０Ｃ，３０Ｂは、中間転写ベルト１１を挟んで各感光体２１Ｙ，２１Ｍ，２１Ｃ，２１Ｂに対して圧接した状態と離間した状態とに移動可能に設けられている。一次転写ローラ３０Ｙ，３０Ｍ，３０Ｃ，３０Ｂが圧接状態にあるとき、その押圧力によって中間転写ベルト１１も感光体２１Ｙ，２１Ｍ，２１Ｃ，２１Ｂに圧接した状態となる。一方、一次転写ローラ３０Ｙ，３０Ｍ，３０Ｃ，３０Ｂが離間状態になると、押しバネＳによってテンションローラ１３が外側へスライドし、中間転写ベルト１１も、感光体２１Ｙ，２１Ｍ，２１Ｃ，２１Ｂから離間した状態となる。プリンタ１が停止中、中間転写ベルト１１は、感光体２１Ｙ，２１Ｍ，２１Ｃ，２１Ｂから離間した位置にある。 In the printer 1, the primary transfer rollers 30Y, 30M, 30C, and 30B are separated from the state in which the primary transfer rollers 30Y, 30M, 30C, and 30B are in pressure contact with the photoreceptors 21Y, 21M, 21C, and 21B with the intermediate transfer belt 11 interposed therebetween. It is provided so that it can move to the state. When the primary transfer rollers 30Y, 30M, 30C, and 30B are in a pressure contact state, the intermediate transfer belt 11 is also in pressure contact with the photoreceptors 21Y, 21M, 21C, and 21B by the pressing force. On the other hand, when the primary transfer rollers 30Y, 30M, 30C, and 30B are separated from each other, the tension roller 13 is slid outward by the pressing spring S, and the intermediate transfer belt 11 is also separated from the photoreceptors 21Y, 21M, 21C, and 21B. It becomes. While the printer 1 is stopped, the intermediate transfer belt 11 is located away from the photoconductors 21Y, 21M, 21C, and 21B.
なお、本実施形態では、感光体の位置を固定し、一次転写ローラ３０を移動させることによって中間転写ベルト１１を離接させているが、中間転写ベルト１１の位置を固定し、感光体２１を移動させる、あるいは中間転写ベルト１１及び感光体２１の双方を移動させるようにしても構わない。また、各感光体２１を中間転写ベルト１１に圧接させてカラー画像を形成するフルカラーモードと、ブラック用の感光体２１Ｂのみを中間転写ベルト１１に圧接させ、その他の感光体２１Ｙ，２１Ｍ，２１Ｃは中間転写ベルト１１から離間させて、白黒画像を形成するモノクロモードとに切り換え可能としても構わない。 In this embodiment, the position of the photoconductor is fixed and the primary transfer roller 30 is moved to move the intermediate transfer belt 11 apart. However, the position of the intermediate transfer belt 11 is fixed and the photoconductor 21 is fixed. Alternatively, the intermediate transfer belt 11 and the photosensitive member 21 may be moved. Further, a full color mode in which each photoconductor 21 is pressed against the intermediate transfer belt 11 to form a color image, and only the black photoconductor 21B is pressed against the intermediate transfer belt 11, and the other photoconductors 21Y, 21M, and 21C are It may be possible to switch to a monochrome mode in which a monochrome image is formed by separating from the intermediate transfer belt 11.
次に、プリンタ１において画像形成する際の駆動制御について説明する。本発明のプリンタ１の駆動制御の特徴を明らかにするために、まず、従来のプリンタの駆動制御について説明する。なお、各作像部２では、各色のトナー画像が中間転写ベルト１１上に重なり合うように、同じ制御がタイミングをづらしてなされるので、以下、一つの作像部における駆動制御について説明する。図４は、従来の画像形成装置の駆動制御を示すタイミングチャートであって、２枚のトナー画像を連続形成する場合である。 Next, drive control when forming an image in the printer 1 will be described. In order to clarify the characteristics of drive control of the printer 1 of the present invention, first, drive control of a conventional printer will be described. In each image forming unit 2, the same control is performed with timing so that the toner images of the respective colors overlap each other on the intermediate transfer belt 11. Therefore, drive control in one image forming unit will be described below. FIG. 4 is a timing chart showing drive control of a conventional image forming apparatus, in which two toner images are continuously formed.
外部装置からプリンタ１に画像形成のジョブ信号が入力されると、感光体２１が回転を開始するとともに、帯電ローラ２２にバイアス電圧が印加される。また同時に、中間転写ベルト１１が、感光体２１と離間した状態で回転を開始する。次いで、感光体１１の回転が安定したところで、一次転写ローラ３０が感光体２１の方向に移動し、中間転写ベルト１１が感光体２１に圧接するとともに、一次転写ローラ３０にバイアス電圧が印加される。このとき、現像ローラはまだ駆動していないので、感光体２１上にはスペーサ効果を奏するトナーが供給されず、感光体２１上の外添剤が中間転写ベルト１１の表面で強く摺擦され、中間転写ベルト１１にフィルミングが生じる。 When an image forming job signal is input from the external device to the printer 1, the photosensitive member 21 starts rotating and a bias voltage is applied to the charging roller 22. At the same time, the intermediate transfer belt 11 starts to rotate while being separated from the photoconductor 21. Next, when the rotation of the photoconductor 11 is stabilized, the primary transfer roller 30 moves in the direction of the photoconductor 21, the intermediate transfer belt 11 is pressed against the photoconductor 21, and a bias voltage is applied to the primary transfer roller 30. . At this time, since the developing roller has not been driven yet, the toner exhibiting the spacer effect is not supplied onto the photosensitive member 21, and the external additive on the photosensitive member 21 is rubbed strongly on the surface of the intermediate transfer belt 11, Filming occurs in the intermediate transfer belt 11.
その後、感光体２１上の静電潜像の形成とタイミングを合わせて、現像ローラが回転を開始するとともに、現像ローラに現像バイアス電圧が印加される。これによって、感光体２１上の静電潜像が現像されてトナー画像が形成される。感光体２１に形成されたトナー画像は、感光体２１の回転によって一次転写領域に搬送され、一次転写ローラ３０のバイアス電圧によって中間転写ベルト１１に一次転写される。 Thereafter, the developing roller starts rotating in synchronization with the formation of the electrostatic latent image on the photosensitive member 21 and a developing bias voltage is applied to the developing roller. As a result, the electrostatic latent image on the photoconductor 21 is developed to form a toner image. The toner image formed on the photoconductor 21 is conveyed to the primary transfer region by the rotation of the photoconductor 21 and is primarily transferred to the intermediate transfer belt 11 by the bias voltage of the primary transfer roller 30.
感光体２１上の静電潜像の現像が終了すると、現像ローラの回転が停止されるとともに、現像バイアス電圧の印加が停止されるが、感光体２１及び帯電ローラ２２、中間転写ベルト１１、一次転写ローラ３０の駆動状態は継続される。前述のように、ここでも、感光体２１上にはスペーサ効果を奏するトナーが供給されないので、感光体２１上の外添剤が中間転写ベルト１１の表面で強く摺擦され、中間転写ベルト１１にフィルミングが生じる。 When the development of the electrostatic latent image on the photosensitive member 21 is completed, the rotation of the developing roller is stopped and the application of the developing bias voltage is stopped. However, the photosensitive member 21, the charging roller 22, the intermediate transfer belt 11, and the primary are stopped. The driving state of the transfer roller 30 is continued. As described above, also here, the toner having the spacer effect is not supplied onto the photosensitive member 21, so that the external additive on the photosensitive member 21 is rubbed strongly on the surface of the intermediate transfer belt 11, and the intermediate transfer belt 11 is rubbed. Filming occurs.
そして、次のトナー画像に対応する静電潜像が感光体２１上に形成されるのとタイミングを合わせて、現像ローラが再び回転を開始するとともに、現像ローラに現像バイアス電圧が印加され、感光体２１上の静電潜像が現像されてトナー画像が形成される。前記と同様にして、形成された２枚目のトナー画像は、感光体２１の回転によって一次転写領域に搬送され、一次転写ローラ３０のバイアス電圧によって中間転写ベルト１１に一次転写される。 The developing roller starts to rotate again at the same timing as the electrostatic latent image corresponding to the next toner image is formed on the photosensitive member 21, and a developing bias voltage is applied to the developing roller. The electrostatic latent image on the body 21 is developed to form a toner image. In the same manner as described above, the formed second toner image is conveyed to the primary transfer region by the rotation of the photosensitive member 21 and is primarily transferred to the intermediate transfer belt 11 by the bias voltage of the primary transfer roller 30.
感光体２１上の静電潜像の現像が終了すると、現像ローラの回転が停止され、現像ローラへの現像バイアス電圧の印加も停止される。次いで、感光体２１から中間転写ベルト１１へのトナー画像の一次転写が終了すると、中間転写ベルト１１及び一次転写ローラ３０が感光体２１から離間すると同時に、一次転写ローラ３０へのバイアス電圧の印加が停止される。その後、感光体２１の回転及び帯電ローラ２２のバイアス電圧印加、中間転写ベルト１１の回転が停止し、一連のジョブが終了する。このジョブ終了工程においても、現像ローラの回転停止と現像バイアス電圧の印加停止した後に、感光体２１及び帯電ローラ２２、中間転写ベルト１１、一次転写ローラ３０の駆動状態が継続されるので、前記と同様に、中間転写ベルト１１にフィルミングが生じる。 When the development of the electrostatic latent image on the photoreceptor 21 is completed, the rotation of the developing roller is stopped and the application of the developing bias voltage to the developing roller is also stopped. Next, when the primary transfer of the toner image from the photoconductor 21 to the intermediate transfer belt 11 is completed, the intermediate transfer belt 11 and the primary transfer roller 30 are separated from the photoconductor 21 and at the same time, a bias voltage is applied to the primary transfer roller 30. Stopped. Thereafter, the rotation of the photosensitive member 21, the application of a bias voltage to the charging roller 22, and the rotation of the intermediate transfer belt 11 are stopped, and a series of jobs is completed. Also in this job end process, after the rotation of the developing roller and the application of the developing bias voltage are stopped, the driving state of the photosensitive member 21, the charging roller 22, the intermediate transfer belt 11, and the primary transfer roller 30 is continued. Similarly, filming occurs in the intermediate transfer belt 11.
これに対し本発明のプリンタ１の駆動制御では、前記従来の駆動制御の問題を解消すべく、少なくとも感光体２１と中間転写ベルト１１とが圧接している間は、現像ローラを駆動させるようにして、中間転写ベルト１１のフィルミングを抑制している。図２に、本発明のプリンタ１の駆動制御例を示すタイミングチャートを示す。このタイミングチャートは、図４と同じように、２枚のトナー画像を連続形成する場合である。 On the other hand, in the drive control of the printer 1 of the present invention, the developing roller is driven at least while the photosensitive member 21 and the intermediate transfer belt 11 are in pressure contact with each other in order to solve the problem of the conventional drive control. Thus, filming of the intermediate transfer belt 11 is suppressed. FIG. 2 is a timing chart showing an example of drive control of the printer 1 of the present invention. This timing chart is a case where two toner images are continuously formed as in FIG.
外部装置からプリンタ１に画像形成のジョブ信号が入力されると、感光体２１が回転を開始するとともに、帯電ローラ２２にバイアス電圧が印加される。また同時に、中間転写ベルト１１が、感光体２１と離間した状態で回転を開始する。次いで、感光体２１上の静電潜像の形成とタイミングを合わせて、現像ローラが回転を開始するとともに、現像ローラに現像バイアス電圧が印加される。これによって、感光体２１上の静電潜像が現像されてトナー画像が形成される。そして、感光体２１上に形成されたトナー画像の回転方向先端部が、感光体２１の回転によって一次転写領域に搬送されると、中間転写ベルト１１及び一次転写ローラ３０が感光体２１に圧接するとともに、一次転写ローラ３０にバイアス電圧が印加される。これによって、感光体２１に形成されたトナー画像は中間転写ベルト１１に一次転写される。 When an image forming job signal is input from the external device to the printer 1, the photosensitive member 21 starts rotating and a bias voltage is applied to the charging roller 22. At the same time, the intermediate transfer belt 11 starts to rotate while being separated from the photoconductor 21. Next, in synchronization with the formation of the electrostatic latent image on the photosensitive member 21, the developing roller starts rotating, and a developing bias voltage is applied to the developing roller. As a result, the electrostatic latent image on the photoconductor 21 is developed to form a toner image. When the leading end portion of the toner image formed on the photoconductor 21 is conveyed to the primary transfer region by the rotation of the photoconductor 21, the intermediate transfer belt 11 and the primary transfer roller 30 are pressed against the photoconductor 21. At the same time, a bias voltage is applied to the primary transfer roller 30. As a result, the toner image formed on the photoreceptor 21 is primarily transferred to the intermediate transfer belt 11.
現像ローラの回転及びバイアス電圧の印加は、感光体２１上の静電潜像の現像が終了した後も継続される。そして、感光体２１上に形成されたトナー画像の中間転写ベルト１１への一次転写が終了した後、中間転写ベルト１１の感光体２１からの離間及び一次転写ローラ３０へのバイアス印加の停止と同時に、現像ローラの回転及び現像バイアス電圧の印加が停止される。 The rotation of the developing roller and the application of the bias voltage are continued even after the development of the electrostatic latent image on the photoconductor 21 is completed. After the primary transfer of the toner image formed on the photosensitive member 21 to the intermediate transfer belt 11 is completed, the separation of the intermediate transfer belt 11 from the photosensitive member 21 and the stop of the bias application to the primary transfer roller 30 are performed simultaneously. Then, the rotation of the developing roller and the application of the developing bias voltage are stopped.
そして、次のトナー画像に対応する静電潜像が感光体２１上に形成されるのとタイミングを合わせて、現像ローラが再び回転を開始するとともに、現像ローラに現像バイアス電圧が印加され、感光体２１上の静電潜像が現像されてトナー画像が形成される。前記と同様にして、感光体２１上に形成された２枚目のトナー画像の回転方向先端部が、感光体２１の回転によって一次転写領域に搬送されると、中間転写ベルト１１及び一次転写ローラ３０が感光体２１に圧接するとともに、一次転写ローラ３０にバイアス電圧が印加され、感光体２１に形成されたトナー画像は中間転写ベルト１１に一次転写される。次いで、２枚目のトナー画像の中間転写ベルト１１への一次転写が終了すると、中間転写ベルト１１の感光体２１からの離間及び一次転写ローラ３０へのバイアス印加の停止と同時に、現像ローラの回転及び現像バイアス電圧の印加が停止される。その後、感光体２１の回転及び帯電ローラ２２のバイアス電圧印加、中間転写ベルト１１の回転がそれぞれ停止し、一連のジョブが終了する。 The developing roller starts to rotate again at the same timing as the electrostatic latent image corresponding to the next toner image is formed on the photosensitive member 21, and a developing bias voltage is applied to the developing roller. The electrostatic latent image on the body 21 is developed to form a toner image. In the same manner as described above, when the leading end portion in the rotation direction of the second toner image formed on the photosensitive member 21 is conveyed to the primary transfer region by the rotation of the photosensitive member 21, the intermediate transfer belt 11 and the primary transfer roller 30 is pressed against the photosensitive member 21 and a bias voltage is applied to the primary transfer roller 30, and the toner image formed on the photosensitive member 21 is primarily transferred to the intermediate transfer belt 11. Next, when the primary transfer of the second toner image to the intermediate transfer belt 11 is completed, the development roller rotates simultaneously with the separation of the intermediate transfer belt 11 from the photosensitive member 21 and the stop of the bias application to the primary transfer roller 30. And the application of the developing bias voltage is stopped. Thereafter, the rotation of the photosensitive member 21, the application of the bias voltage to the charging roller 22, and the rotation of the intermediate transfer belt 11 are stopped, and the series of jobs is completed.
このように、図２に示した本発明の駆動制御では、図４に示した従来の駆動制御と異なって、現像ローラの回転及び現像バイアス印加後に、中間転写ベルト１１を感光体２１に圧接させ、また現像ローラの回転停止及び現像バイアス電圧の印加停止と同時に、中間転写ベルト１１を感光体２１から離間させ、一次転写ローラ３０へのバイアス印加を停止させるので、中間転写ベルト１１が感光体２１に圧接している間は、感光体２１に形成されたトナー像及び非画像形成部分に付着したかぶりトナーが、感光体２１と中間転写ベルト１１とのニップ部において、いわゆるスペーサ効果を奏するので、中間転写ベルト１１のフィルミングが抑制される。 Thus, in the drive control of the present invention shown in FIG. 2, unlike the conventional drive control shown in FIG. 4, after the rotation of the developing roller and the application of the developing bias, the intermediate transfer belt 11 is brought into pressure contact with the photosensitive member 21. Simultaneously with the stop of the rotation of the developing roller and the stop of the application of the developing bias voltage, the intermediate transfer belt 11 is separated from the photosensitive member 21 and the bias application to the primary transfer roller 30 is stopped. Since the toner image formed on the photosensitive member 21 and the fog toner attached to the non-image forming portion exhibit a so-called spacer effect at the nip portion between the photosensitive member 21 and the intermediate transfer belt 11 while being in pressure contact with each other. Filming of the intermediate transfer belt 11 is suppressed.
図２に示した駆動制御では、１枚目のトナー画像の中間転写ベルト１１への転写終了から、２枚目のトナー画像の転写開始まで中間転写ベルト１１を感光体２１から離間させているが、１枚目のトナー画像形成から２枚目のトナー画像形成までが短時間の場合には、中間転写ベルト１１を感光体２１から離間及び圧接させるための時間を確保できないことがある。このような場合には、図３に示すように、１枚目のトナー画像の中間転写ベルト１１への転写終了後も継続して、中間転写ベルト１１を感光体２１に圧接させた状態とするとともに、現像ローラの回転及び現像バイアス印加も継続して行うようにする。 In the drive control shown in FIG. 2, the intermediate transfer belt 11 is separated from the photoreceptor 21 from the end of the transfer of the first toner image to the intermediate transfer belt 11 until the start of the transfer of the second toner image. When the time from the first toner image formation to the second toner image formation is short, it may not be possible to secure time for separating and pressing the intermediate transfer belt 11 from the photoreceptor 21. In such a case, as shown in FIG. 3, after the transfer of the first toner image to the intermediate transfer belt 11 is completed, the intermediate transfer belt 11 is kept in pressure contact with the photoreceptor 21. At the same time, the rotation of the developing roller and the application of the developing bias are continuously performed.
中間転写ベルト１１を感光体２１から離接させるための時間は、通常０．５〜１秒程度であるため、複数枚の画像形成を連続して行う場合には、図３に示すような、中間転写ベルト１１を離接させない駆動制御を行い、単発の画像形成や用紙両面への画像形成の場合などには、図２に示すような、中間転写ベルト１１を離接させる駆動制御を行うことが好適である。 Since the time for separating and contacting the intermediate transfer belt 11 from the photoreceptor 21 is usually about 0.5 to 1 second, when a plurality of images are continuously formed, as shown in FIG. The drive control is performed so that the intermediate transfer belt 11 is not separated and contacted. In the case of single image formation or image formation on both sides of the paper, the drive control for separating and contacting the intermediate transfer belt 11 as shown in FIG. 2 is performed. Is preferred.
図２及び図３では、２枚の画像形成を行う場合の駆動制御であったが、３枚以上の画像形成を行う場合についても、同様の駆動制御が適用できる。 In FIG. 2 and FIG. 3, the drive control is performed when two images are formed, but the same drive control can be applied when three or more images are formed.
本発明の画像形成装置では、”中抜け”を防止しながら、装置の大型化・複雑化を招くことなく、中間転写ベルトのフィルミングを抑制でき有用である。 The image forming apparatus according to the present invention is useful because it can suppress filming of the intermediate transfer belt without increasing the size and complexity of the apparatus while preventing “missing”.
１ プリンタ（画像形成装置）
２ 作像部
１１ 中間転写ベルト（中間転写体）
１８ クリーニングブレード
２１ 感光体（静電潜像担持体）
２２ 帯電ローラ（帯電手段）
２４ 現像装置（現像手段）
３０ 一次転写ローラ（一次転写手段）
1 Printer (image forming device)
2 Image forming section 11 Intermediate transfer belt (intermediate transfer body)
18 Cleaning blade 21 Photoconductor (electrostatic latent image carrier)
22 Charging roller (charging means)
24 Developing device (developing means)
30 Primary transfer roller (primary transfer means)
Claims (3)
前記静電潜像担持体の表面に圧接又は離間しながら回転する中間転写体と、
前記中間転写体を挟んで前記静電潜像担持体と対向する位置に配置され、前記静電潜像担持体の表面に形成されたトナー画像を前記中間転写体に転写させる一次転写手段とを有する画像形成装置において、
前記静電潜像担持体と前記中間転写体との相対速度が異なり、
前記静電潜像担持体と前記中間転写体とは圧接位置と離間位置とに相対的に移動可能であり、
画像形成信号が入力されると、前記静電潜像担持体に形成されたトナー画像の前記中間転写体への転写開始と略同時に、前記静電潜像担持体と前記中間転写体とを離間位置から圧接位置とし、
前記静電潜像担持体から前記中間転写体へのトナー画像の転写が終了すると、当該転写終了から次のトナー画像の転写開始までの時間が、所定時間以上の場合は、前記トナー画像の転写終了と略同時に、前記静電潜像担持体と前記中間転写体とを圧接位置から離間位置にするとともに、前記現像手段を停止させる一方、
前記転写終了から次のトナー画像の転写開始までの時間が、所定時間未満の場合は、前記トナー画像の転写終了後も、前記静電潜像担持体と前記中間転写体とを継続して圧接位置とするとともに、前記現像手段も継続して駆動させることを特徴とする画像形成装置。 A rotatable electrostatic latent image carrier, a charging means for uniformly charging the surface of the electrostatic latent image carrier, and an exposure device for forming an electrostatic latent image on the charged electrostatic latent image carrier; An image forming unit comprising: a developing unit that visualizes the electrostatic latent image with toner;
An intermediate transfer member that rotates while being pressed against or separated from the surface of the electrostatic latent image carrier;
A primary transfer unit disposed at a position facing the electrostatic latent image carrier with the intermediate transfer member interposed therebetween, and transferring a toner image formed on the surface of the electrostatic latent image carrier to the intermediate transfer member; In an image forming apparatus having
The relative speed of the electrostatic latent image carrier and the intermediate transfer member is different,
The electrostatic latent image carrier and the intermediate transfer member are relatively movable between a pressure contact position and a separation position,
When an image forming signal is input, the electrostatic latent image carrier and the intermediate transfer member are separated from each other substantially simultaneously with the start of transfer of the toner image formed on the electrostatic latent image carrier to the intermediate transfer member. From the position to the pressure contact position,
When the transfer of the toner image from the latent electrostatic image bearing member to the intermediate transfer member is completed, if the time from the end of the transfer to the start of the transfer of the next toner image is a predetermined time or more, the transfer of the toner image is performed. At substantially the same time as the end, the electrostatic latent image carrier and the intermediate transfer member are moved away from the press contact position and the developing unit is stopped.
When the time from the end of the transfer to the start of the transfer of the next toner image is less than a predetermined time, the electrostatic latent image carrier and the intermediate transfer body are continuously pressed against each other even after the transfer of the toner image is completed. The image forming apparatus is characterized in that the developing unit is continuously driven as well as the position.
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| JP2017083825A (en) * | 2015-10-23 | 2017-05-18 | 株式会社リコー | Image formation device, method for controlling image formation device, and program |
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