JP2011112752A - Apparatus and method for forming image - Google Patents

Apparatus and method for forming image Download PDF

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JP2011112752A
JP2011112752A JP2009267188A JP2009267188A JP2011112752A JP 2011112752 A JP2011112752 A JP 2011112752A JP 2009267188 A JP2009267188 A JP 2009267188A JP 2009267188 A JP2009267188 A JP 2009267188A JP 2011112752 A JP2011112752 A JP 2011112752A
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transfer material
transfer
image
roller
image forming
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Noritoshi Yano
文紀 矢野
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Seiko Epson Corp
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Abstract

<P>PROBLEM TO BE SOLVED: To obtain an excellent image even when a transfer nip, a transfer material releasing position and a transfer material conveying part start point position are arranged in virtual almost triangle shape when performing transfer in a state where transfer material is gripped. <P>SOLUTION: An image on an intermediate transfer belt 8 is transferred to the transfer material 20 gripped by a gripper 17 of a secondary transfer roller 14 at a secondary transfer nip 13a, and the transfer material 20 is conveyed by a transfer material conveying part 25. Moving speed of a transfer material conveying belt 25a when starting conveyance of the transfer material 20 is controlled to be higher than moving speed of the intermediate transfer belt 8. The terminal position ζ of the secondary transfer nip, the transfer material releasing position ε which is arranged vertically upper on the side of a transfer material moving direction than the position of the secondary transfer nip, and the transfer material conveying part start point position η which is arranged vertically upper on the side in the transfer material moving direction than the transfer material releasing position ε and where a leading edge of the transfer material 20 abuts on the transfer material conveying part 25 first are arranged in the virtual almost triangle shape. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

本発明は、転写材の把持状態で転写を行う画像形成装置および画像形成方法に関する。   The present invention relates to an image forming apparatus and an image forming method for performing transfer while holding a transfer material.

従来、画像形成装置においては、転写材の先端部を把持する転写材把持部材を有する転写ローラーを用いた画像形成装置が提案されている（例えば、特許文献１参照）。この特許文献１に記載の画像形成装置では、転写ローラーが回転することにより、転写材把持部材で転写材の先端部が把持された状態で転写材が転写ニップを通過して像担持体の像が転写材に転写される。そして、転写材の先端部が転写ニップを通過した後、転写材の把持が解除されて転写材が解放される。この画像形成装置によれば、転写材把持部材で転写材の先端部を把持することで、転写後に像担持体からの転写材の剥離が確実となる。   Conventionally, in an image forming apparatus, an image forming apparatus using a transfer roller having a transfer material gripping member that grips a leading end portion of a transfer material has been proposed (for example, see Patent Document 1). In the image forming apparatus described in Patent Document 1, when the transfer roller rotates, the transfer material passes through the transfer nip with the transfer material gripping member gripping the leading end of the transfer material, and the image on the image carrier. Is transferred to the transfer material. Then, after the leading end of the transfer material passes through the transfer nip, the transfer material is released and the transfer material is released. According to this image forming apparatus, the transfer material gripping member grips the leading end portion of the transfer material, so that the transfer material is surely peeled off from the image carrier after the transfer.

一方、転写ローラーが回転することにより、転写材が転写ニップを通過して像担持体の像が転写材に転写されるとともに、転写材の先端部が転写ニップを通過すると気流発生装置により転写材が像担持体から剥離され、その後、転写材はその転写画像面が鉛直方向の下方に向いた状態で鉛直方向の下方位置から斜め上方位置へ移動して転写材搬送部の転写材搬送ベルトで定着部の方へ搬送される画像形成装置が提案されている（例えば、特許文献２参照）。   On the other hand, when the transfer roller rotates, the transfer material passes through the transfer nip and the image on the image carrier is transferred to the transfer material. When the leading end of the transfer material passes through the transfer nip, the air flow generator generates the transfer material. Is then peeled off from the image carrier, and then the transfer material is moved from the lower position in the vertical direction to the oblique upper position with the transfer image surface facing downward in the vertical direction. An image forming apparatus conveyed toward the fixing unit has been proposed (see, for example, Patent Document 2).

特表２０００−５０８２８０号公報。JP 2000-508280 gazette. 特開２００９−２０５１３１号公報。JP2009-205131A.

ところで、特許文献２に記載の画像形成装置に、転写後の像担持体からの転写材の剥離性を向上させるために、特許文献１に記載の転写材先端部を把持する技術を適用することが考えられる。この場合、転写材先端部の把持が転写材搬送部の手前で解除されるため、転写ニップの転写材移動方向のニップ終端位置、転写材解放位置、および転写材先端が最初に当接する転写材搬送ベルトの転写材搬送部始点位置が仮想略三角形に配置される。したがって、転写ニップを通過した転写材は、転写ローラーと像担持体との回転で仮想略三角形の転写ニップのニップ終端位置および転写材解放位置間の辺と転写材解放位置および転写材搬送ベルトの転写材搬送部始点位置間の辺との二辺にほぼ沿う移動経路で移動する。   By the way, in order to improve the releasability of the transfer material from the image carrier after transfer, the technique for gripping the transfer material front end portion described in Patent Document 1 is applied to the image forming apparatus described in Patent Document 2. Can be considered. In this case, since the grip of the transfer material front end is released before the transfer material transport unit, the nip end position in the transfer material movement direction of the transfer nip, the transfer material release position, and the transfer material with which the transfer material front end first comes into contact. The start point position of the transfer material transfer portion of the transfer belt is arranged in a virtual substantially triangular shape. Therefore, the transfer material that has passed through the transfer nip is rotated between the transfer roller and the image carrier, and the edge between the nip end position and the transfer material release position of the virtual substantially triangular transfer nip, the transfer material release position, and the transfer material conveyance belt. The transfer material moves along a movement path substantially along two sides with the side between the start point positions.

しかしながら、転写材の先端が転写材搬送ベルトの転写材搬送部始点位置に到達すると、転写材はその自重によりこの転写材搬送部始点位置と転写ニップのニップ終端位置とを支点に鉛直方向の下方に撓んで、これらの転写材搬送部始点位置およびニップ終端位置間の仮想略三角形の他の一辺にほぼ沿って移動しようとする。このため、転写材の移動経路の長さが短くなり、転写材は弛んで鉛直方向の更に下方に撓む。すると、転写ニップを通過した転写材の転写画像面が再び像担持体に接触したり、あるいは転写材の移動経路の鉛直方向の下方に配設される画像形成装置の部材に接触したりする。その結果、転写画像が乱れる。また、転写材の弛みにより転写材の転写姿勢が微妙に変化し、転写ニップの幅が変化して画像ずれが生じる。このように、特許文献２に記載の画像形成装置に、特許文献１に記載の転写材の把持技術を単純に適用しただけでは、良好な画像を得ることは難しい。   However, when the leading edge of the transfer material reaches the transfer material conveyance unit start point position of the transfer material conveyance belt, the transfer material is lowered in the vertical direction with the transfer material conveyance unit start point position and the nip end position of the transfer nip as fulcrums due to its own weight. And tends to move along the other side of the virtual substantially triangular shape between the start position of the transfer material conveyance unit and the end position of the nip. For this reason, the length of the transfer material moving path is shortened, the transfer material is slackened and bent further downward in the vertical direction. Then, the transfer image surface of the transfer material that has passed through the transfer nip again comes into contact with the image carrier, or comes into contact with a member of an image forming apparatus disposed below the transfer material movement path in the vertical direction. As a result, the transferred image is disturbed. Further, the transfer posture of the transfer material slightly changes due to the slackness of the transfer material, and the width of the transfer nip changes to cause an image shift. Thus, it is difficult to obtain a good image by simply applying the transfer material gripping technique described in Patent Document 1 to the image forming apparatus described in Patent Document 2.

本発明の目的は、転写材を把持した状態で転写を行う場合、転写ニップ、転写材解放位置、および転写材搬送部始点位置が仮想略三角形に配置されても、良好な画像を得ることのできる画像形成装置および画像形成方法を提供することである。   It is an object of the present invention to obtain a good image even when the transfer nip, the transfer material release position, and the transfer material transport unit start point position are arranged in a substantially virtual triangle when performing transfer while holding the transfer material. An image forming apparatus and an image forming method are provided.

前述の課題を解決するために、本発明に係る画像形成装置および画像形成方法では、把持部材で転写材が把持されて、転写ニップで像担持体の像が転写材に転写されるとともに、転写後に像担持体と転写材とが離間する。更に、転写材は、把持部材が転写材を解放する位置で解放される。次いで、転写材は転写ローラーの回転力で転写材搬送部に向かって移動する。そして、転写材が、転写材搬送部が転写材を吸引開始する位置に到達すると、転写材は転写材搬送部の転写材搬送部材によって搬送開始される。その場合、像担持体と転写材とが離間する位置、把持部材が転写材を解放する位置、および転写材搬送部が転写材を吸引開始する位置が転写材移動方向と直交またはほぼ直交する方向（転写ローラーの軸方向と平行またはほぼ平行の方向）から見て仮想略三角形に配置されている。そして、像担持体と転写材とが離間する位置と転写材搬送部が転写材を吸引開始する位置とを結ぶ距離をＬとし、また像担持体と転写材とが離間する位置と把持部材が転写材を解放する位置とを結ぶ距離をＬ１とし、更に把持部材が転写材を解放する位置と転写材搬送部が転写材を吸引開始する位置とを結ぶ距離をＬ２とすると、ＬはＬ１およびＬ２に対して、Ｌ＜Ｌ１＋Ｌ２の関係を有する。したがって、転写材搬送部が転写材を吸引開始する位置に到達すると、転写材はその自重で像担持体と転写材とが離間する位置と転写材搬送部が転写材を吸引開始する位置とを支点にして鉛直方向の下方に撓み、像担持体と転写材とが離間する位置および転写材搬送部が転写材を吸引開始する位置間の仮想略三角形の他の一辺にほぼ沿う移動経路で移動しようとする。そこで、制御部が、転写材搬送部の転写材搬送部材の移動速度を制御する。すなわち、制御部は、転写材搬送部材が転写材を搬送開始するときの転写材搬送部材の移動速度（つまり、転写材搬送部材によって搬送される転写材の移動速度）が、像担持体の移動速度（つまり、像担持体によって搬送される転写材の移動速度）より速くなるように制御する。これにより、移動する転写材を仮想略三角形の他の一辺より仮想略三角形の残りの二辺側（把持部材が転写材を解放する位置側）に位置させることが可能となる。したがって、転写材の移動経路の長さの変化を小さくすることができ、この転写材の移動経路の長さの変化による転写材弛みを抑制できる。その結果、転写ニップを通過した転写材の転写画像面が、転写ニップおよび転写材搬送部始点位置間の転写材の移動経路の鉛直方向の下方に配設される像担持体等の画像形成装置の部材に接触することを防止することができる。その結果、転写画像の乱れを防止できる。また、転写材の弛みが小さくなることから、転写材の転写姿勢の微妙な変化による転写ニップの幅の変化を小さくでき、画像ずれの発生を抑制することができる。このようにして、転写材を把持した状態で転写を行う場合、転写ニップ位置、転写材解放位置、および転写材搬送部始点位置が仮想略三角形に配置されても、良好な画像を得ることができる画像形成装置および画像形成方法を実現することが可能となる。   In order to solve the above-described problems, in the image forming apparatus and the image forming method according to the present invention, the transfer material is held by the holding member, and the image on the image carrier is transferred to the transfer material by the transfer nip. Later, the image carrier and the transfer material are separated. Further, the transfer material is released at a position where the gripping member releases the transfer material. Next, the transfer material moves toward the transfer material conveyance unit by the rotational force of the transfer roller. When the transfer material reaches a position where the transfer material conveyance unit starts sucking the transfer material, the transfer material is started to be conveyed by the transfer material conveyance member of the transfer material conveyance unit. In this case, the position where the image carrier and the transfer material are separated from each other, the position where the gripping member releases the transfer material, and the position where the transfer material transport unit starts sucking the transfer material are perpendicular or almost perpendicular to the transfer material movement direction. They are arranged in a substantially triangular shape when viewed from (a direction parallel or substantially parallel to the axial direction of the transfer roller). The distance between the position where the image carrier and the transfer material are separated from the position where the transfer material conveyance unit starts sucking the transfer material is L, and the position where the image carrier and the transfer material are separated is When the distance connecting the position where the transfer material is released is L1, and further, the distance connecting the position where the gripping member releases the transfer material and the position where the transfer material transport unit starts sucking the transfer material is L2, L is L1 and L2 has a relationship of L <L1 + L2. Therefore, when the transfer material conveyance unit reaches the position where the transfer material starts to be sucked, the transfer material has a position where the image carrier and the transfer material are separated by its own weight and a position where the transfer material conveyance unit starts sucking the transfer material. Bends in the vertical direction as a fulcrum, and moves along a movement path almost along the other side of the virtual triangle between the position where the image carrier and the transfer material are separated from each other and the position where the transfer material transport unit starts sucking the transfer material try to. Therefore, the control unit controls the moving speed of the transfer material conveyance member of the transfer material conveyance unit. That is, the control unit determines that the movement speed of the transfer material conveyance member when the transfer material conveyance member starts conveying the transfer material (that is, the movement speed of the transfer material conveyed by the transfer material conveyance member) is the movement of the image carrier. Control is performed so as to be faster than the speed (that is, the moving speed of the transfer material conveyed by the image carrier). Accordingly, the moving transfer material can be positioned on the remaining two sides of the virtual substantially triangular shape (the position where the gripping member releases the transfer material) from the other side of the virtual substantially triangular shape. Therefore, the change in the length of the transfer material moving path can be reduced, and the transfer material slack due to the change in the length of the transfer material moving path can be suppressed. As a result, an image forming apparatus such as an image carrier in which the transfer image surface of the transfer material that has passed through the transfer nip is disposed below the transfer material moving path between the transfer nip and the transfer material conveyance unit start position in the vertical direction. It is possible to prevent contact with the members. As a result, the transfer image can be prevented from being disturbed. Further, since the looseness of the transfer material is reduced, the change in the width of the transfer nip due to a subtle change in the transfer posture of the transfer material can be reduced, and the occurrence of image shift can be suppressed. In this way, when transfer is performed with the transfer material held, a good image can be obtained even if the transfer nip position, the transfer material release position, and the transfer material transport unit start point position are arranged in a substantially virtual triangle. An image forming apparatus and an image forming method that can be realized can be realized.

また、転写材は、転写画像面を鉛直方向の下方に向けて転写材搬送部により鉛直方向の上方に吸引されながら搬送される。このとき、転写材搬送部転写材が吸引する圧力が、転写ローラーと像担持体とが当接する当接圧力（つまり、転写ローラーの転写ニップ圧）より小さい。これにより、転写材は転写ローラーの回転力により確実に移動可能となる。   The transfer material is transported while being attracted upward in the vertical direction by the transfer material transport unit with the transfer image surface facing downward in the vertical direction. At this time, the pressure sucked by the transfer material conveyance unit transfer material is smaller than the contact pressure at which the transfer roller and the image carrier are in contact (that is, the transfer nip pressure of the transfer roller). As a result, the transfer material can be reliably moved by the rotational force of the transfer roller.

更に、転写材搬送部が加熱部材を有し、この加熱部材で転写材を加熱する。これにより、定着部が転写材搬送部を兼ねることが可能となる。したがって、転写材搬送部を不要にでき、画像形成装置の全体構成をコンパクトに形成することが可能となる。   Further, the transfer material transport unit has a heating member, and the transfer material is heated by the heating member. As a result, the fixing unit can also serve as the transfer material conveying unit. Therefore, the transfer material conveyance unit can be omitted, and the entire configuration of the image forming apparatus can be formed compactly.

更に、転写ニップで像が転写された転写材に気流発生装置により、鉛直方向の上方に向
けて気流を吹き付ける。これにより、転写材搬送部に移動した直後の転写材の弛みを更に効果的に抑制することが可能となる。 Further, an airflow is blown upward in the vertical direction by the airflow generator onto the transfer material onto which the image has been transferred at the transfer nip. As a result, it is possible to more effectively suppress the looseness of the transfer material immediately after moving to the transfer material transport unit.

更に、転写ニップで像が転写された転写材を吸引ガイド部により、像が転写された面を鉛直方向の下方に向けて鉛直方向の上方に吸引するとともに転写材搬送部へガイドする。これにより、転写材搬送部に移動した直後の転写材の弛みを更に効果的に抑制することが可能となる。   Further, the transfer material onto which the image has been transferred at the transfer nip is sucked upward in the vertical direction with the surface on which the image has been transferred directed downward in the vertical direction and guided to the transfer material transport unit. As a result, it is possible to more effectively suppress the looseness of the transfer material immediately after moving to the transfer material transport unit.

本発明にかかる画像形成装置の実施の形態の一例の一部を模式的にかつ部分的に示す図である。1 is a diagram schematically and partially showing a part of an example of an embodiment of an image forming apparatus according to the present invention. 図１における画像形成装置の部分拡大図である。FIG. 2 is a partially enlarged view of the image forming apparatus in FIG. 1. （ａ）は転写材の先端部の把持直前の状態を示す図、（ｂ）は転写材の先端部の把持状態を示す図、（ｃ）は転写材の先端部の把持解除後の突き出し状態を示す図である。(A) is a diagram showing a state immediately before gripping the front end of the transfer material, (b) is a diagram showing a gripping state of the front end of the transfer material, and (c) is a protruding state after releasing the grip of the front end of the transfer material. FIG. 転写材搬送解放後の転写材が仮想略三角形の移動経路に沿って移動することを説明する図である。FIG. 10 is a diagram for explaining that the transfer material after the transfer material conveyance is released moves along a virtual substantially triangular movement path. 像担持体と転写材が離間する位置、転写材解放位置、および転写材搬送部が転写材を吸引開始する位置を示す図である。FIG. 4 is a diagram illustrating a position where an image carrier and a transfer material are separated, a transfer material release position, and a position where a transfer material transport unit starts sucking the transfer material. 転写後の転写材の弛みにより転写材画像面が鉛直方向の下方に配置される部材に接触することを説明する図である。It is a figure explaining that a transfer material image surface contacts the member arrange | positioned below in the perpendicular direction by the slack of the transfer material after transfer. 転写後の転写材の弛みにより転写材画像面が中間転写ベルトに再接触することを説明する図である。FIG. 6 is a diagram for explaining that a transfer material image surface re-contacts an intermediate transfer belt due to looseness of a transfer material after transfer. 転写材搬送ベルトの駆動モーターの制御のブロック図である。It is a block diagram of control of the drive motor of a transfer material conveyance belt. 転写材搬送ベルトの速度制御のタイミングチャートを示す図である。It is a figure which shows the timing chart of the speed control of a transfer material conveyance belt. 本発明の画像形成装置の実施の形態の他の例を部分的に示す、図２と同様の図である。FIG. 10 is a view similar to FIG. 2, partially showing another example of the embodiment of the image forming apparatus of the present invention. 図１０に示す例の転写材の移動を説明する、図４と同様の図である。It is a figure similar to FIG. 4 explaining the movement of the transfer material of the example shown in FIG.

以下、図面を用いて本発明を実施するための形態について説明する。
図１は、本発明にかかる画像形成装置の実施の形態の一例の一部を模式的にかつ部分的に示す図である。 Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a diagram schematically and partially showing a part of an embodiment of an image forming apparatus according to the present invention.

この例の画像形成装置１はトナーとキャリアー液とを含む液体現像剤を用いて画像形成を行う。図１に示すように、この画像形成装置１は、水平またはほぼ水平にタンデムに配置されたイエロー（Ｙ）、マゼンタ（Ｍ）、シアン（Ｃ）およびブラック（Ｋ）の像担持体である感光体２Ｙ,２Ｍ,２Ｃ,２Ｋを備えている。ここで、各感光体２Ｙ,２Ｍ,２Ｃ,２Ｋにおいて、２Ｙはイエローの感光体、２Ｍはマゼンタの感光体、２Ｃはシアンの感光体、２Ｋはブラックの感光体を表す。また、他の部材についても同じように、部材の符号にそれぞれ各色のＹ,Ｍ,Ｃ,Ｋを添えて各色の部材を表す。   The image forming apparatus 1 of this example performs image formation using a liquid developer containing toner and carrier liquid. As shown in FIG. 1, the image forming apparatus 1 is a photosensitive image forming body of yellow (Y), magenta (M), cyan (C), and black (K) arranged in tandem horizontally or substantially horizontally. The body 2Y, 2M, 2C, 2K is provided. Here, in each of the photoreceptors 2Y, 2M, 2C, and 2K, 2Y represents a yellow photoreceptor, 2M represents a magenta photoreceptor, 2C represents a cyan photoreceptor, and 2K represents a black photoreceptor. Similarly, the members of the respective colors are represented by adding Y, M, C, and K of the respective colors to the reference numerals of the members.

また、各感光体２Ｙ,２Ｍ,２Ｃ,２Ｋの周囲には、それぞれ、帯電部３Ｙ,３Ｍ,３Ｃ,３Ｋが配設されている。更に、各帯電部３Ｙ,３Ｍ,３Ｃ,３Ｋから、それぞれ、各感光体２
Ｙ,２Ｍ,２Ｃ,２Ｋの回転方向に向かって、順に、露光部４Ｙ,４Ｍ,４Ｃ,４Ｋ、現像部５Ｙ,５Ｍ,５Ｃ,５Ｋ、一次転写部６Ｙ,６Ｍ,６Ｃ,６Ｋ、および感光体クリーニング部７Ｙ,７Ｍ,７Ｃ,７Ｋが配設されている。なお、各感光体２Ｙ,２Ｍ,２Ｃ,２Ｋは一次転写後に、図示しない除電部によって除電される。これらの各感光体２Ｙ,２Ｍ,２Ｃ,２Ｋ、各帯
電部３Ｙ,３Ｍ,３Ｃ,３Ｋ、各露光部４Ｙ,４Ｍ,４Ｃ,４Ｋ、各現像部５Ｙ,５Ｍ,５Ｃ,５
Ｋ、各一次転写部６Ｙ,６Ｍ,６Ｃ,６Ｋ、各感光体クリーニング部７Ｙ,７Ｍ,７Ｃ,７Ｋ、
および各除電部により、この例の画像形成装置１の画像形成ユニットが構成される。 In addition, charging units 3Y, 3M, 3C, and 3K are disposed around the photoreceptors 2Y, 2M, 2C, and 2K, respectively. Further, from each of the charging units 3Y, 3M, 3C, 3K, each photoconductor 2
Exposure units 4Y, 4M, 4C, and 4K, developing units 5Y, 5M, 5C, and 5K, primary transfer units 6Y, 6M, 6C, and 6K, and a photoconductor in turn in the rotational directions of Y, 2M, 2C, and 2K Cleaning units 7Y, 7M, 7C, and 7K are provided. The photoreceptors 2Y, 2M, 2C, and 2K are neutralized by a neutralizing unit (not shown) after primary transfer. Each of these photoreceptors 2Y, 2M, 2C, 2K, each charging unit 3Y, 3M, 3C, 3K, each exposure unit 4Y, 4M, 4C, 4K, each developing unit 5Y, 5M, 5C, 5K
K, each primary transfer unit 6Y, 6M, 6C, 6K, each photoconductor cleaning unit 7Y, 7M, 7C, 7K,
And the image forming unit of the image forming apparatus 1 of this example is configured by each of the static eliminating units.

また、画像形成装置１は、本発明の像担持体である無端状の中間転写ベルト８を備えている。この中間転写ベルト８は、各感光体２Ｙ,２Ｍ,２Ｃ,２Ｋの鉛直方向の上方に配置
されている。そして、中間転写ベルト８は各一次転写部６Ｙ,６Ｍ,６Ｃ,６Ｋで各感光体
２Ｙ,２Ｍ,２Ｃ,２Ｋに圧接されている。 Further, the image forming apparatus 1 includes an endless intermediate transfer belt 8 that is an image carrier of the present invention. The intermediate transfer belt 8 is disposed above the photosensitive members 2Y, 2M, 2C, and 2K in the vertical direction. The intermediate transfer belt 8 is pressed against the photoreceptors 2Y, 2M, 2C, and 2K at the primary transfer portions 6Y, 6M, 6C, and 6K.

図示しないが、中間転写ベルト８は、例えば樹脂等の可撓性の基材と、この基材の表面に形成されたゴム等の弾性層と、この弾性層の表面に形成された表層とを有する３層構造の比較的柔らかい弾性ベルトに形成されている。もちろん、これに限定されることはない。中間転写ベルト８は図示しないモーターの駆動力が伝達される中間転写ベルト駆動ローラー９、第１の巻掛けローラー１０，第２の巻掛けローラー１１、および中間転写ベルトテンションローラー１２に巻き掛けられている。そして、中間転写ベルト８はテンションを付与された状態で、矢印方向に回転するようにされている。なお、各色Ｙ、Ｍ、Ｃ、Ｋに対応する感光体等の部材の配置順は、図１に示す例に限定されることはなく、任意に設定することができる。   Although not shown, the intermediate transfer belt 8 includes a flexible base material such as a resin, an elastic layer such as rubber formed on the surface of the base material, and a surface layer formed on the surface of the elastic layer. It is formed in a relatively soft elastic belt having a three-layer structure. Of course, it is not limited to this. The intermediate transfer belt 8 is wound around an intermediate transfer belt driving roller 9, a first winding roller 10, a second winding roller 11, and an intermediate transfer belt tension roller 12 to which a driving force of a motor (not shown) is transmitted. Yes. The intermediate transfer belt 8 is rotated in the direction of the arrow in a state where a tension is applied. Note that the arrangement order of members such as photoconductors corresponding to the respective colors Y, M, C, and K is not limited to the example shown in FIG. 1 and can be arbitrarily set.

中間転写ベルト８の中間転写ベルト駆動ローラー９側には二次転写部１３が設けられている。二次転写部１３は、二次転写ローラー１４および二次転写ローラークリーニング部１５を備えている。二次転写ローラー１４は回転軸１４ａを中心に矢印で示す方向に回転する。この二次転写ローラー１４は、中間転写ベルト駆動ローラー９に巻き掛けられる中間転写ベルト８に圧接される。このとき、図２に示すように、この二次転写ローラー１４は、二次転写ローラー１４の回転中心１４ｄを通る仮想鉛直線αより図２において左側で、かつ回転中心１４ｄを通る仮想水平線βより図２において鉛直方向下側で中間転写ベルト８に圧接される。また、中間転写ベルト駆動ローラー９は二次転写ローラー１４の押圧に対するバックアップローラーとして機能する。更に、二次転写ローラー１４は中間転写ベルト８に圧接されることで、中間転写ベルト８（つまり、中間転写ベルト駆動ローラー９）とともに連れ回りする。   A secondary transfer unit 13 is provided on the intermediate transfer belt 8 on the side of the intermediate transfer belt driving roller 9. The secondary transfer unit 13 includes a secondary transfer roller 14 and a secondary transfer roller cleaning unit 15. The secondary transfer roller 14 rotates in the direction indicated by the arrow about the rotation shaft 14a. The secondary transfer roller 14 is pressed against the intermediate transfer belt 8 wound around the intermediate transfer belt driving roller 9. At this time, as shown in FIG. 2, the secondary transfer roller 14 is on the left side in FIG. 2 from the virtual vertical line α passing through the rotation center 14d of the secondary transfer roller 14 and from the virtual horizontal line β passing through the rotation center 14d. In FIG. 2, it is pressed against the intermediate transfer belt 8 on the lower side in the vertical direction. Further, the intermediate transfer belt driving roller 9 functions as a backup roller against the pressing of the secondary transfer roller 14. Further, the secondary transfer roller 14 is brought into pressure contact with the intermediate transfer belt 8 and is rotated together with the intermediate transfer belt 8 (that is, the intermediate transfer belt driving roller 9).

更に、二次転写ローラー１４は、基材１４ｂの円弧部の外周面に巻かれたシート状の弾性部材１４ｃを有している。この弾性部材１４ｃにより二次転写ローラー１４の円弧部の外周面に抵抗層が形成されている。そして、図１に示すように中間転写ベルト８と二次転写ローラー１４の弾性部材１４ｃとの間に二次転写ニップ１３ａが形成される。図２に示すように、この二次転写ニップ１３ａは、仮想鉛直線αより前述の画像形成ユニット側（図２において左側）に配置されるとともに、仮想水平線βより画像形成ユニット側（図２において鉛直方向下側）に配置される。   Further, the secondary transfer roller 14 has a sheet-like elastic member 14c wound around the outer peripheral surface of the arc portion of the base material 14b. A resistance layer is formed on the outer peripheral surface of the arc portion of the secondary transfer roller 14 by the elastic member 14c. As shown in FIG. 1, a secondary transfer nip 13 a is formed between the intermediate transfer belt 8 and the elastic member 14 c of the secondary transfer roller 14. As shown in FIG. 2, the secondary transfer nip 13a is disposed on the above-described image forming unit side (left side in FIG. 2) from the virtual vertical line α, and on the image forming unit side (in FIG. 2) from the virtual horizontal line β. (Vertical direction lower side).

図１、図２、図３（ａ）ないし（ｃ）に示すように、二次転写ローラー１４は、凹部１６を有している。この凹部１６内には、転写材把持部材としてのグリッパー１７、グリッパー１７が着座する転写材把持部材受け部材であるグリッパー支持部１８、および転写材剥離部材としての突き出し爪１９が配設されている。   As shown in FIGS. 1, 2, and 3 (a) to 3 (c), the secondary transfer roller 14 has a recess 16. A gripper 17 as a transfer material gripping member, a gripper support portion 18 as a transfer material gripping member receiving member on which the gripper 17 is seated, and a protruding claw 19 as a transfer material peeling member are disposed in the recess 16. .

グリッパー１７は、図３（ａ）に示す転写材把持解除位置と図３（ｂ）に示す転写材把持位置との間で回動するように設けられる。その場合、グリッパー１７は、転写材把持解除位置ではその一部が二次転写ローラー１４の弾性部材１４ｃの外周面１４ｃ1と同径の
仮想円δの円周より外方に、つまり凹部１６の外方に突出されるとともに転写材把持位置ではその全体が仮想円δの円周より内方、つまり凹部１６内に収容される。また、突き出し爪１９は、図３（ａ）に示す退避位置と図３（ｃ）に示す突き出し位置との間でほぼ直線状に移動するように設けられる。その場合、突き出し爪１９は、退避位置ではその全体が凹部１６内に収容されるとともに突き出し位置ではその一部が凹部１６から突出される
。図示しないが、これらのグリッパー１７および突き出し爪１９の各作動は、それぞれ、画像形成装置１の装置本体等に固定された各カムによって制御される。 The gripper 17 is provided so as to rotate between the transfer material grip release position shown in FIG. 3A and the transfer material grip position shown in FIG. In that case, the gripper 17 is partially outside the circumference of the virtual circle δ having the same diameter as the outer peripheral surface 14c 1 of the elastic member 14c of the secondary transfer roller 14 at the transfer material grip releasing position, that is, the concave portion 16. At the transfer material gripping position, the entirety is accommodated inward from the circumference of the virtual circle δ, that is, in the recess 16 at the transfer material gripping position. Further, the protruding claw 19 is provided so as to move substantially linearly between the retracted position shown in FIG. 3A and the protruding position shown in FIG. In this case, the protrusion claw 19 is entirely accommodated in the recess 16 at the retracted position, and a part of the protrusion claw 19 protrudes from the recess 16 at the protrusion position. Although not shown, the operations of the gripper 17 and the protruding claw 19 are controlled by cams fixed to the apparatus main body of the image forming apparatus 1.

その場合、グリッパー１７が転写材２０の先端部２０ａを把持開始する転写材把持開始位置は、凹部１６が二次転写ニップ１３ａの位置に到達する前の所定位置に設けられている。したがって、凹部１６がこの転写材把持開始位置より少し手前の図３（ａ）に示す位置に到達すると、ゲートローラー２１から転写材供給ガイド２２を介して給送されてくる転写材２０の先端部２０ａが図３（ａ）に示すように凹部１６に対向する位置に到達する。そして、カムによりグリッパー１７が回動開始する。凹部１６が前述の所定位置に到達したとき、図３（ｂ）に示すようにグリッパー１７は転写材把持開始位置となり、グリッパー支持部１８との間に転写材２０の先端部２０ａを把持する。そして、転写材２０は二次転写ローラー１４の回転とともに弾性部材１４ｃの外周面に巻き付くようにして二次転写ニップ１３ａの方へ移動する。   In this case, the transfer material grip start position at which the gripper 17 starts gripping the leading end portion 20a of the transfer material 20 is provided at a predetermined position before the concave portion 16 reaches the position of the secondary transfer nip 13a. Therefore, when the concave portion 16 reaches the position shown in FIG. 3A slightly before the transfer material grip start position, the leading end portion of the transfer material 20 fed from the gate roller 21 via the transfer material supply guide 22 is obtained. 20a reaches a position facing the recess 16 as shown in FIG. Then, the gripper 17 starts to rotate by the cam. When the recess 16 reaches the above-mentioned predetermined position, the gripper 17 reaches the transfer material grip start position as shown in FIG. 3B, and grips the leading end portion 20 a of the transfer material 20 between the gripper support portion 18. Then, the transfer material 20 moves toward the secondary transfer nip 13 a so as to wind around the outer peripheral surface of the elastic member 14 c as the secondary transfer roller 14 rotates.

二次転写ローラー１４は、中間転写ベルト８に転写されたトナー像を、転写紙等の転写材２０に転写させる転写バイアスが印加される。そして、二次転写ローラー１４は、図１に示すように中間転写ベルト８の矢印方向の回転時に矢印方向に回転するとともに転写バイアスが印加されることにより、中間転写ベルト８に担持されているトナー像が二次転写ニップ１３ａで、グリッパー１７により把持された転写材２０に転写される。   The secondary transfer roller 14 is applied with a transfer bias for transferring the toner image transferred to the intermediate transfer belt 8 to a transfer material 20 such as transfer paper. As shown in FIG. 1, the secondary transfer roller 14 rotates in the direction of the arrow when the intermediate transfer belt 8 rotates in the direction of the arrow, and a transfer bias is applied, whereby the toner carried on the intermediate transfer belt 8 is transferred. The image is transferred to the transfer material 20 held by the gripper 17 at the secondary transfer nip 13a.

二次転写ローラークリーニング部１５は、そのクリーニング部材により二次転写ローラー１４の弾性部材１４ｃに付着する液体現像剤を除去するとともに、除去した液体現像剤を液体現像剤回収容器に回収して貯留する。   The secondary transfer roller cleaning unit 15 removes the liquid developer adhering to the elastic member 14c of the secondary transfer roller 14 by the cleaning member, and collects and stores the removed liquid developer in the liquid developer collection container. .

図１に示すように、画像形成装置１は、更に中間転写ベルト８の鉛直方向の上方位置で二次転写ニップ１３ａより転写材搬送方向に向かう位置に第１の気流発生装置２３、第２の気流発生装置２４、転写材搬送部２５、第３の気流発生装置２６、および定着部２７を備えている。   As shown in FIG. 1, the image forming apparatus 1 further includes a first airflow generation device 23 and a second airflow generation device 23 at a position above the intermediate transfer belt 8 in the vertical direction from the secondary transfer nip 13 a toward the transfer material conveyance direction. An airflow generator 24, a transfer material transport unit 25, a third airflow generator 26, and a fixing unit 27 are provided.

二次転写ニップ１３ａを通過した転写材２０は、グリッパー１７による把持から解放される。図２に示すように、このグリッパー１７が転写材２０を解放する凹部１６の位置（より具体的には、二次転写ローラー１４の外周方向のグリッパー支持部１８の中心と二次転写ローラー１４の回転中心１４ｄ1とを結ぶ仮想直線γと、二次転写ローラー１４の外
周の径と同径の仮想円δとのほぼ交点位置）である転写材解放位置εは、転写材移動方向の二次転写ニップ１３ａの二次転写ニップ終端位置ζより転写材２０の移動方向（画像形成ユニット側；図２において左側）に位置する（つまり、仮想鉛直線αより左側に位置する）とともに、仮想鉛直線βより画像形成ユニット側（図２において下側）に位置する。その場合、転写材解放位置εは、グリッパー１７が転写材２０の先端の把持を解除して転写材２０を解放する位置である。また、二次転写ニップ終端位置ζは、中間転写ベルト８と転写材２０とが離間する位置である。したがって、転写材解放位置εと二次転写ニップ１３ａの二次転写ニップ終端位置ζは、ともに仮想鉛直線αと仮想水平線βとが成す第３象限内に位置する。グリッパー１７による転写材２０の把持部がこの転写材解放位置εより少し手前の位置に到達すると、カムによりグリッパー１７が回動開始する。グリッパー１７による転写材２０の把持部が転写材解放位置εに到達したとき、図２に示すようにグリッパー１７は転写材把持解除位置となり、転写材２０の先端部２０ａの把持を解除する。これにより、転写材２０が解放される。 The transfer material 20 that has passed through the secondary transfer nip 13 a is released from gripping by the gripper 17. As shown in FIG. 2, the position of the recess 16 where the gripper 17 releases the transfer material 20 (more specifically, the center of the gripper support 18 in the outer peripheral direction of the secondary transfer roller 14 and the position of the secondary transfer roller 14). The transfer material release position ε, which is a substantially intersection point between the virtual straight line γ connecting the rotation center 14d 1 and the virtual circle δ having the same diameter as the outer circumference of the secondary transfer roller 14, is a secondary in the transfer material moving direction. The transfer material 20 is positioned in the moving direction (on the image forming unit side; left side in FIG. 2) from the secondary transfer nip end position ζ of the transfer nip 13a (that is, positioned on the left side of the virtual vertical line α), and the virtual vertical line It is located on the image forming unit side (lower side in FIG. 2) from β. In this case, the transfer material release position ε is a position where the gripper 17 releases the transfer material 20 by releasing the grip of the tip of the transfer material 20. The secondary transfer nip end position ζ is a position where the intermediate transfer belt 8 and the transfer material 20 are separated from each other. Accordingly, the transfer material release position ε and the secondary transfer nip end position ζ of the secondary transfer nip 13a are both located in the third quadrant formed by the virtual vertical line α and the virtual horizontal line β. When the gripping portion of the transfer material 20 by the gripper 17 reaches a position slightly before the transfer material release position ε, the gripper 17 starts to rotate by the cam. When the gripping portion of the transfer material 20 by the gripper 17 reaches the transfer material release position ε, the gripper 17 enters the transfer material grip releasing position as shown in FIG. 2 and releases the grip of the leading end portion 20 a of the transfer material 20. Thereby, the transfer material 20 is released.

このグリッパー１７による転写材２０の解放とほぼ同時に、カムにより突き出し爪１９が移動開始する。そして、図３（ｃ）に示すように突き出し爪１９が二次転写ローラー１４の凹部１６から突出して転写材２０の背面（転写画像面の反対側の面）を突き出しなが
ら突き出し位置となる。これにより、転写材２０は二次転写ローラー１４から剥離され、図４に点線で示すように第２の気流発生装置２４の方へ移動する。グリッパー１７はカムによって、転写材２０の解放後に所定位置になると凹部１６内に収容されるとともに、転写材把持開始位置より手前の所定位置になると、転写材把持解除位置にされる。また、突き出し爪１９はカムによって、転写材２０の突き出し後に所定位置になると凹部１６内に収容される。すなわち、グリッパー１７および突き出し爪１９は第２の気流発生装置２４の干渉（接触）しないようにされている。 Almost simultaneously with the release of the transfer material 20 by the gripper 17, the protruding claw 19 starts to move by the cam. Then, as shown in FIG. 3C, the protrusion claw 19 protrudes from the concave portion 16 of the secondary transfer roller 14 to reach the protrusion position while protruding the back surface (the surface opposite to the transfer image surface) of the transfer material 20. As a result, the transfer material 20 is peeled off from the secondary transfer roller 14 and moved toward the second airflow generator 24 as shown by the dotted line in FIG. The gripper 17 is accommodated in the recess 16 by a cam when it is in a predetermined position after the transfer material 20 is released, and is placed in a transfer material grip releasing position when it is in a predetermined position before the transfer material grip start position. Further, the protrusion claw 19 is accommodated in the recess 16 by a cam when it reaches a predetermined position after the transfer material 20 is protruded. That is, the gripper 17 and the protruding claw 19 are configured not to interfere (contact) with the second airflow generation device 24.

図１に示すように、第１の気流発生装置２３は、ダクト状の送気部材２３ａとファン（例えば、シロッコファン）等の気流発生部２３ｂとを有する。気流発生部２３ｂの駆動で、送気部材２３ａに気流が発生し、送気部材２３ａの送気口２３ｃからエアーが吐出される。   As shown in FIG. 1, the first airflow generation device 23 includes a duct-shaped air supply member 23 a and an airflow generation unit 23 b such as a fan (for example, a sirocco fan). By driving the air flow generation unit 23b, an air flow is generated in the air supply member 23a, and air is discharged from the air supply port 23c of the air supply member 23a.

図１に示すように、第２の気流発生装置２４は本発明の吸引ガイド部であるとともに、ダクト状の吸引部材２４ａとファン（例えばシロッコファン）等の気流発生部２４ｂとを有する。吸引部材２４ａは、図示しない所定数の吸引孔が設けられたガイド面２４ａ1を
有する。このガイド面２４ａ1は図１および図２において右下から斜め左上に向かう傾斜
面とされている。気流発生部２４ｂの駆動で、吸引部材２４ａが各吸引孔を通して重力と反対の矢印で示す方向にエアーを吸引して気流を発生する。そして、図４に点線で示すように二次転写ローラー１４から剥離された転写材２０はほぼ転写材解放位置εで湾曲して、その背面を第２の気流発生装置２４が発生する気流により吸引部材２４ａで鉛直方向の斜め上方（ガイド面２４ａ1とほぼ直交する方向で鉛直方向の上方）に吸引されながら、
吸引部材２４ａのガイド面２４ａ1に沿ってガイドされる。その場合、転写材２０は中間
転写ベルト８と二次転写ローラー１４の各回転力で転写材搬送部２５の方へ移動する。 As shown in FIG. 1, the second airflow generation device 24 is a suction guide portion of the present invention, and includes a duct-shaped suction member 24a and an airflow generation portion 24b such as a fan (for example, a sirocco fan). The suction member 24a has a guide surface 24a 1 provided with a predetermined number of suction holes (not shown). The guide surface 24a 1 is an inclined surface that extends obliquely from the lower right to the upper left in FIGS. With the driving of the airflow generation unit 24b, the suction member 24a sucks air in the direction indicated by the arrow opposite to gravity through each suction hole to generate an airflow. Then, as shown by a dotted line in FIG. 4, the transfer material 20 peeled off from the secondary transfer roller 14 is curved substantially at the transfer material release position ε, and the back surface thereof is sucked by the air current generated by the second air current generating device 24. while being attracted to the vertical obliquely upward (guide surface 24a 1 to the vertical direction of the upper almost orthogonal directions) in member 24a,
It is guided along the guide surface 24a 1 of the suction member 24a. In this case, the transfer material 20 moves toward the transfer material transport unit 25 by the rotational forces of the intermediate transfer belt 8 and the secondary transfer roller 14.

転写材搬送部２５は転写材搬送部材である転写材搬送ベルト２５ａ、ダクト状の吸引部材２５ｂ、およびファン（例えばシロッコファン）等の気流発生部２５ｃを有する。転写材搬送ベルト２５ａは、図示しない多数の吸引孔を有する無端ベルトに形成されて３つの巻架ローラー２５ｄに巻き掛けられる（３つの巻架ローラー２５ｄのうち、１つは、転写材搬送ベルト２５ａを回転する転写材搬送ベルト駆動ローラーである）。そして、転写材搬送ベルト２５ａは、図１、図２、および図４に矢印で示す方向（時計回りに）回転する。転写材搬送ベルト２５ａの転写材搬送ベルト部分の転写材搬送方向は、図１および図２において右下から斜め左上の方向に傾斜している。その場合、転写材搬送ベルト２５ａの転写材搬送方向の水平に対する傾斜角度は、第２の気流発生装置２４のガイド面２４ａ1
のガイド方向の水平に対する傾斜角度は同じであるか、またはほぼ同じである。 The transfer material transport unit 25 includes a transfer material transport belt 25a that is a transfer material transport member, a duct-shaped suction member 25b, and an airflow generation unit 25c such as a fan (for example, a sirocco fan). The transfer material transport belt 25a is formed into an endless belt having a number of suction holes (not shown) and is wound around three winding rollers 25d (one of the three winding rollers 25d includes the transfer material transport belt 25a). Is a transfer material transport belt drive roller that rotates. Then, the transfer material transport belt 25a rotates in the direction indicated by the arrow in FIG. 1, FIG. 2, and FIG. 4 (clockwise). The transfer material conveyance direction of the transfer material conveyance belt portion of the transfer material conveyance belt 25a is inclined from the lower right to the upper left in FIGS. In this case, the inclination angle of the transfer material transport belt 25a with respect to the horizontal in the transfer material transport direction is determined by the guide surface 24a 1 of the second airflow generator 24.
The inclination angle of the guide direction with respect to the horizontal is the same or substantially the same.

なお、図１には転写材搬送ベルト２５ａは３つの巻架ローラー２５ｄに巻き掛けられるように示されているが、２つまたは４つ以上の巻架ローラー２５ｄに巻き掛けられるようにすることもできる。吸引部材２５ｂは、転写材２０の搬送経路の近傍に位置するとともに転写材搬送ベルト２５ａと対向する対向面に多数の吸引孔２５ｂ1を有する。 In FIG. 1, the transfer material transport belt 25a is shown to be wound around three winding rollers 25d, but may be wound around two or four or more winding rollers 25d. it can. The suction member 25b is located in the vicinity of the transfer path of the transfer material 20 and has a number of suction holes 25b 1 on the opposite surface facing the transfer material transfer belt 25a.

図４に示すように、第２の気流発生装置２４により吸引ガイドされてきた転写材２０が転写材搬送部２５の転写材搬送ベルト２５ａに吸引開始される位置が、転写材搬送部始点位置ηとなる。この転写材搬送部始点位置ηは、転写材搬送部２５が転写材２０を吸引開始する位置である。そして、二次転写ローラー１４の転写材解放位置εと二次転写ニップ１３ａの二次転写ニップ終端位置ζと転写材搬送部始点位置ηとが、転写材移送方向と直交またはほぼ直交する方向（二次転写ローラー１４の軸方向と平行またはほぼ平行の方向）から見て仮想略三角形を形成するように配置される。   As shown in FIG. 4, the position at which the transfer material 20 that has been suction-guided by the second airflow generation device 24 starts to be sucked by the transfer material conveyance belt 25a of the transfer material conveyance unit 25 is the transfer material conveyance unit start position η. It becomes. The transfer material conveyance unit start point position η is a position where the transfer material conveyance unit 25 starts sucking the transfer material 20. Then, the transfer material release position ε of the secondary transfer roller 14, the secondary transfer nip end position ζ of the secondary transfer nip 13 a, and the transfer material transport unit start position η are orthogonal to or substantially orthogonal to the transfer material transport direction ( They are arranged so as to form a virtual substantially triangular shape when viewed from a direction parallel to or substantially parallel to the axial direction of the secondary transfer roller 14.

その場合、仮想略三角形の各辺の長さを次のように定義する。いま、図５に示すように
中間転写ベルト８と転写材２０とが離間する二次転写ニップ終端位置ζとグリッパー１７が転写材２０を解放する転写材解放位置εとを結ぶ距離（つまり、二次転写ニップ終端位置ζと転写材解放位置εとの間の仮想略三角形の辺の長さにほぼ相当）をＬ１とする。また、グリッパー１７が転写材２０を解放する転写材解放位置εと転写材搬送部２５が転写材２０を吸引する転写材搬送部始点位置ηとを結ぶ距離（つまり、転写材解放位置εと転写材搬送部始点位置ηとの間の仮想略三角形の辺の長さにほぼ相当）をＬ２とする。更に、中間転写ベルト８と転写材２０とが離間する二次転写ニップ終端位置ζと転写材搬送部２５が転写材２０を吸引開始する位置ηとを結ぶ距離（つまり、二次転写ニップ終端位置ζと転写材搬送部始点位置ηとの間の仮想略三角形の辺の長さにほぼ相当）をＬとする。そして、距離Ｌは、他の２つの距離Ｌ１,Ｌ２に対して、
Ｌ＜Ｌ１＋Ｌ２
の関係を有する。 In that case, the length of each side of the virtual approximate triangle is defined as follows. Now, as shown in FIG. 5, the distance (that is, the second transfer nip end position ζ where the intermediate transfer belt 8 and the transfer material 20 are separated) and the transfer material release position ε where the gripper 17 releases the transfer material 20 (that is, two L1 is substantially equivalent to the length of the side of the virtual approximate triangle between the next transfer nip end position ζ and the transfer material release position ε. Further, the distance between the transfer material release position ε at which the gripper 17 releases the transfer material 20 and the transfer material transport unit starting point η at which the transfer material transport unit 25 sucks the transfer material 20 (that is, the transfer material release position ε and the transfer material 20 are transferred). L2 is substantially equivalent to the length of the side of the virtual approximate triangle between the material transport unit start point position η. Furthermore, the distance (ie, the secondary transfer nip end position) connecting the secondary transfer nip end position ζ where the intermediate transfer belt 8 and the transfer material 20 are separated from the position η where the transfer material transport unit 25 starts sucking the transfer material 20 is established. L is substantially equivalent to the length of the side of the virtual approximate triangle between ζ and the transfer material conveyance unit start position η. And the distance L is relative to the other two distances L1 and L2.
L <L1 + L2
Have the relationship.

また、この仮想略三角形は、二次転写ニップ終端位置ζおよび転写材解放位置ε間の辺と、転写材解放位置εおよび転写材搬送部始点位置η間の辺との成す角度が鈍角の略三角形に形成することが、転写材２０をスムーズに搬送するうえで好ましい。また、第１の気流発生装置２３はこの仮想略三角形より鉛直方向の下方に配設されるとともに、二次転写ニップ終端位置ζおよび転写材搬送部始点位置η間の仮想三角形の辺の直交またはほぼ直交する方向で鉛直方向の上方に吐出口２３ｃからエアーを吐出する。そして、転写材２０は点線で示す仮想略三角形の二辺の移動経路に沿って二次転写ニップ終端位置ζからほぼ転写材解放位置εを通って転写材搬送部始点位置ηに向かって図１および図２において鉛直方向の右下から左上に移動する。   The virtual substantially triangular shape is an approximately obtuse angle formed between the side between the secondary transfer nip end position ζ and the transfer material release position ε and the side between the transfer material release position ε and the transfer material conveyance unit start position η. Forming in a triangular shape is preferable for smoothly transferring the transfer material 20. The first airflow generation device 23 is disposed below the virtual substantially triangular shape in the vertical direction, and is orthogonal to the side of the virtual triangle between the secondary transfer nip end position ζ and the transfer material conveyance unit start position η. Air is discharged from the discharge port 23c in the substantially orthogonal direction and upward in the vertical direction. Then, the transfer material 20 is moved from the secondary transfer nip end position ζ substantially along the transfer path of two sides of a substantially triangular shape indicated by the dotted line substantially through the transfer material release position ε toward the transfer material conveyance unit start position η in FIG. And in FIG. 2, it moves from the lower right in the vertical direction to the upper left.

気流発生部２５ｃの駆動で、吸引部材２５ｂが転写材搬送ベルト２５ａの吸引孔および吸引部材２５ｂの吸引孔２５ｂ1を通して重力と反対の矢印で示す方向にエアーを吸引し
て気流を発生する。そして、転写材２０は、その先端が転写材搬送部始点位置ηに到達すると、その背面を吸引部材２５ｂが発生する気流により鉛直方向の斜め上方（転写材搬送ベルト２５ａの転写材搬送ベルト部分の傾斜方向とほぼ直交する方向でかつ鉛直方向の上方）に吸引されながら、転写材搬送ベルト２５ａで第３の気流発生装置２６の方へ搬送される。その場合、転写材２０が転写材搬送ベルト２５ａに重力と反対方向に吸引されても、転写材２０はより効果的に吸引され、転写材搬送ベルト２５ａとともに移動する。 By driving the airflow generating unit 25c, the suction member 25b generates an airflow by sucking air in the direction indicated by opposite arrows gravity through the suction holes 25b 1 of the suction holes and the suction member 25b of the transfer material conveyance belt 25a. When the leading edge of the transfer material 20 reaches the transfer material conveyance unit start position η, the back surface of the transfer material 20 is inclined upward in the vertical direction by the air flow generated by the suction member 25b (the transfer material conveyance belt 25a of the transfer material conveyance belt 25a). While being sucked in a direction substantially perpendicular to the inclination direction and above the vertical direction), the sheet is conveyed toward the third airflow generator 26 by the transfer material conveyance belt 25a. In this case, even if the transfer material 20 is sucked by the transfer material conveyance belt 25a in the direction opposite to the gravity, the transfer material 20 is more effectively sucked and moves together with the transfer material conveyance belt 25a.

このときの転写材搬送部２５の吸引部材２５ｂが転写材２０を吸引する圧力（吸引圧）は、二次転写ニップ１３ａで中間転写ベルト８と二次転写ローラー１４とが転写材２０を介して当接する圧力（二次転写ローラー１４の二次転写ニップ圧）より小さい。例えば、転写材２０の吸引圧が二次転写ローラー１４の二次転写ニップ圧より小さくするために、二次転写ローラー１４の中間転写ベルト駆動ローラー９への当接力が約４５０〜６００Ｎであるとき、吸引部材２５ｂによる転写材２０の吸引力は約１２Ｎ程度が好ましい。転写材２０の吸引力が約１２Ｎ程度に制御されるためには、制御部２８により転写材搬送部２５の吸引部材２５ｂのエアー吸引量（風量）が約０.４３ｍ3／ｍｉｎ程度に制御される。このように、吸引部材２５ａによる転写材２０の吸引圧が二次転写ローラー１４の二次転写ニップ圧より小さいことで、転写材２０は中間転写ベルト８と二次転写ローラー１４の各回転力により確実に移動可能となる。 The pressure (suction pressure) at which the suction member 25b of the transfer material transport unit 25 sucks the transfer material 20 at this time is determined by the intermediate transfer belt 8 and the secondary transfer roller 14 via the transfer material 20 at the secondary transfer nip 13a. It is smaller than the contact pressure (secondary transfer nip pressure of the secondary transfer roller 14). For example, when the contact force of the secondary transfer roller 14 to the intermediate transfer belt drive roller 9 is about 450 to 600 N in order to make the suction pressure of the transfer material 20 smaller than the secondary transfer nip pressure of the secondary transfer roller 14. The suction force of the transfer material 20 by the suction member 25b is preferably about 12N. In order to control the suction force of the transfer material 20 to about 12 N, the control unit 28 controls the air suction amount (air volume) of the suction member 25 b of the transfer material transport unit 25 to about 0.43 m 3 / min. The As described above, since the suction pressure of the transfer material 20 by the suction member 25 a is smaller than the secondary transfer nip pressure of the secondary transfer roller 14, the transfer material 20 is caused by each rotational force of the intermediate transfer belt 8 and the secondary transfer roller 14. It can move reliably.

転写材搬送ベルト２５ａによる転写材２０の搬送が開始されると、前述のように二次転写ニップ１３ａを通過した転写材２０はその自重により、転写材搬送部始点位置ηと二次転写ニップ１３ａの二次転写ニップ終端位置ζとをそれぞれ支点に鉛直方向の下方に撓む。すると、転写材２０は図４に実線で示す転写材搬送部始点位置ηと二次転写ニップ１３ａの二次転写ニップ終端位置ζとを結ぶ略直線状の移動経路にほぼ沿って移動しようとする。このため、転写材２０の移動経路が短く変化する。そして、転写材２０は更に弛んで
鉛直方向の下方に撓むと、図６に示すように定着前の転写材２０の転写画像面が第１の気流発生装置２３に接触したり、図７に示すように定着前の転写材２０の転写画像面が中間転写ベルト８に再び接触してしまい、前述の課題が生じる。 When conveyance of the transfer material 20 by the transfer material conveyance belt 25a is started, the transfer material 20 that has passed through the secondary transfer nip 13a as described above is caused by its own weight, and the transfer material conveyance unit start position η and the secondary transfer nip 13a. The secondary transfer nip end position ζ is bent downward in the vertical direction. Then, the transfer material 20 tends to move along a substantially linear movement path connecting the transfer material conveyance unit start point position η and the secondary transfer nip end position ζ of the secondary transfer nip 13a shown by a solid line in FIG. . For this reason, the moving path of the transfer material 20 changes short. When the transfer material 20 is further loosened and bent downward in the vertical direction, the transfer image surface of the transfer material 20 before fixing comes into contact with the first airflow generator 23 as shown in FIG. Thus, the transfer image surface of the transfer material 20 before fixing comes into contact with the intermediate transfer belt 8 again, and the above-described problem occurs.

そこで、この例の画像形成装置１では、第２の気流発生装置２４で二次転写ニップ１３ａを通過した転写紙２０が鉛直方向の下方に大きく撓むことを抑制し、転写紙２０の転写画像面が転写紙２０の移動経路より鉛直方向の下方に配置される画像形成装置の他の部材に接触するのを防止している。   Therefore, in the image forming apparatus 1 of this example, the transfer paper 20 that has passed through the secondary transfer nip 13a by the second airflow generator 24 is prevented from being greatly bent downward in the vertical direction, and the transfer image of the transfer paper 20 is transferred. This prevents the surface from coming into contact with other members of the image forming apparatus disposed below the transfer path 20 in the vertical direction.

図８は転写材搬送ベルト駆動モーターのブロック図であり、図９は転写材搬送ベルト駆動モーターの制御のタイミングチャートを示す図である。
図８に示すように、画像形成装置１の制御部２８には転写材位置情報出力部２９が接続される。この転写材位置情報出力部２９は、転写材２０の搬送位置（つまり、転写材２０の移動位置）の情報が入力されるとともに、この情報を制御部２８に出力する。その場合、転写材２０の搬送位置は、転写材２０の先端および後端の各位置である。この転写材２０の搬送位置は、図示しない搬送位置検出部で検出されるとともに、搬送位置検出部で検出された転写材２０の搬送位置の情報が転写材位置情報入力部２９に入力される。この搬送位置検出部は、転写材解放位置εに対応する二次転写ローラー１４の回転位置を検出する機械的あるいは光学的な回転位置検出器として配設される。なお、これに限定されることはなく、グリッパー１７の作動（位置変化）を検知する検出器、あるいは転写紙２０の先端に二次転写ニップ１３ａの位置からの転写材解放位置εまでの時間を計測するタイマーを用いることもできる。 FIG. 8 is a block diagram of the transfer material transport belt drive motor, and FIG. 9 is a timing chart of control of the transfer material transport belt drive motor.
As shown in FIG. 8, a transfer material position information output unit 29 is connected to the control unit 28 of the image forming apparatus 1. The transfer material position information output unit 29 receives information about the transfer position of the transfer material 20 (that is, the movement position of the transfer material 20) and outputs this information to the control unit 28. In that case, the transfer positions of the transfer material 20 are the positions of the front end and the rear end of the transfer material 20. The transfer position of the transfer material 20 is detected by a transfer position detection unit (not shown), and information on the transfer position of the transfer material 20 detected by the transfer position detection unit is input to the transfer material position information input unit 29. This transport position detector is disposed as a mechanical or optical rotational position detector that detects the rotational position of the secondary transfer roller 14 corresponding to the transfer material release position ε. However, the present invention is not limited to this. A detector for detecting the operation (position change) of the gripper 17 or the time from the position of the secondary transfer nip 13a to the transfer material release position ε at the leading end of the transfer paper 20 is used. A timer for measuring can also be used.

制御部２８は、画像形成装置１の画像形成動作時に中間転写ベルト駆動ローラー９の周速度および二次転写ローラー１４の周速度が予め設定された二次転写ローラー周速度（つまり、二次転写ローラー１４で搬送される転写紙２０の移動速度）Ｖ0ｍｍ／ｓｅｃとな
るように、中間転写ベルト駆動ローラー９を駆動する中間転写ベルト駆動モーター３０を制御する。また、制御部２８は、転写材位置情報出力部２９からの転写材位置情報、つまり二次転写ニップ１３ａの通過後の転写紙２０の位置に基づいて転写材搬送ベルト駆動モーター３１を制御する。以下、転写紙２０に転写紙を用いた場合の転写材搬送ベルト駆動モーター３１の制御について説明する。 The controller 28 is a secondary transfer roller peripheral speed (that is, a secondary transfer roller) in which the peripheral speed of the intermediate transfer belt drive roller 9 and the peripheral speed of the secondary transfer roller 14 are set in advance during the image forming operation of the image forming apparatus 1. 14, the intermediate transfer belt drive motor 30 that drives the intermediate transfer belt drive roller 9 is controlled so that the transfer speed of the transfer paper 20 conveyed at 14 is V 0 mm / sec. The control unit 28 also controls the transfer material conveyance belt drive motor 31 based on the transfer material position information from the transfer material position information output unit 29, that is, the position of the transfer paper 20 after passing through the secondary transfer nip 13a. Hereinafter, control of the transfer material conveyance belt drive motor 31 when transfer paper is used as the transfer paper 20 will be described.

例えば転写材２０として転写紙を用いた場合について説明する。
まず、前述の仮想略三角形の辺の長さは、二次転写ニップ終端位置ζおよび転写材解放位置ε間の辺の長さ（距離Ｌ１）が８５ｍｍであるとともに転写材解放位置εおよび転写材搬送部始点位置η間の辺の長さ（距離Ｌ２）が７６ｍｍであり、更に、二次転写ニップ終端位置ζおよび転写材搬送部始点位置η間の長さ（距離Ｌ）が１５０ｍｍであるとする。したがって、Ｌ＜Ｌ１＋Ｌ２である。この場合は、仮想略三角形の二辺の和は１６１ｍｍあるとともに他の一辺の長さが１５０ｍｍであり、二辺の長さの和と他の一辺の長さとの差が１１ｍｍである。また、第２の気流発生装置２４のガイド面２４ａ1の転写材ガイ
ド方向および転写材搬送ベルト２５ａの転写材搬送方向の水平に対する各傾斜角度（鋭角）は、ともに同じ約２５°である。 For example, a case where transfer paper is used as the transfer material 20 will be described.
First, the length of the side of the above-described virtual substantially triangular shape is that the length of the side (distance L1) between the secondary transfer nip end position ζ and the transfer material release position ε is 85 mm, and the transfer material release position ε and the transfer material. The side length (distance L2) between the conveyance unit start point position η is 76 mm, and the length (distance L) between the secondary transfer nip end position ζ and the transfer material conveyance unit start point position η is 150 mm. To do. Therefore, L <L1 + L2. In this case, the sum of the two sides of the virtual approximate triangle is 161 mm, the length of the other side is 150 mm, and the difference between the sum of the lengths of the two sides and the length of the other side is 11 mm. Further, the inclined angle with respect to the transfer material conveying direction of the horizontal second air flow generating device 24 guide surface 24a 1 of the transfer material guide direction and the transfer material conveying belt 25a (acute) are both equal to about 25 °.

図９に示すように、画像形成指令により制御部２８は中間転写ベルト駆動モーターを駆動制御することにより中間転写ベルト８を回転移動するとともに、タイミングＴ０（ｓｅｃ）でゲートローラー２１を駆動する。これにより、画像形成動作が行われるとともに、転写紙の給紙が開始される。このとき、制御部２８が転写材搬送ベルト駆動モーター３１を駆動制御することにより、転写材搬送部２５の転写材搬送ベルト２５ａが第１の移動速度（周速度）Ｖ１ｍｍ／ｓｅｃ（例えば、２６０ｍｍ／ｓｅｃ等）で回転される。また、中間転写ベルト８の移動速度（周速度）は、この第１の移動速度より遅い転写材搬送ベル
ト２５ａの第２の移動速度（周速度）Ｖ２ｍｍ／ｓｅｃ（例えば、２５０ｍｍ／ｓｅｃ等）と等しいかまたはほぼ等しい。したがって、転写紙が転写材搬送ベルト２５ａにより搬送開始される時の転写材搬送ベルト２５ａの移動速度は中間転写ベルト８の移動速度より速い。 As shown in FIG. 9, the control unit 28 drives and controls the intermediate transfer belt drive motor to rotate and move the intermediate transfer belt 8 and drives the gate roller 21 at timing T0 (sec). As a result, an image forming operation is performed, and transfer paper feeding is started. At this time, the control unit 28 drives and controls the transfer material conveyance belt drive motor 31 so that the transfer material conveyance belt 25a of the transfer material conveyance unit 25 has a first moving speed (circumferential speed) V1 mm / sec (for example, 260 mm / sec). for example, sec). Further, the moving speed (peripheral speed) of the intermediate transfer belt 8 is a second moving speed (peripheral speed) V2 mm / sec (for example, 250 mm / sec) of the transfer material transport belt 25a that is slower than the first moving speed. Equal or nearly equal. Accordingly, the transfer speed of the transfer material transport belt 25a when the transfer paper is started to be transported by the transfer material transport belt 25a is faster than that of the intermediate transfer belt 8.

制御部２８は転写材位置情報出力部２９から出力される転写材位置情報に基づいて、第２の気流発生装置２４で吸引ガイドされてきた転写紙の先端が転写材搬送部始点位置ηに到達したと判断するとともに転写材搬送部始点位置ηに到達してから所定時間が経過したと判断したタイミングＴ１（ｓｅｃ）で、転写材搬送ベルト２５ａの移動速度（ｍｍ／ｓｅｃ）を第２の移動速度Ｖ２ｍｍ／ｓｅｃに変更する。したがって、転写材搬送部２５が転写紙を吸引開始する時、転写紙の移動速度が二次転写ニップ１３ａで中間転写ベルト８および二次転写ローラー１４により搬送される転写紙の移動速度より速く制御される。これにより、転写紙の先端が転写材搬送ベルト２５ａに移動した直後の前述の転写紙の弛みが抑制される。その結果、移動する転写紙を仮想略三角形の他の一辺より仮想略三角形の残りの二辺側（グリッパー１７が転写紙を解放する位置側）に位置させることが可能となる。また、前述の転写紙の弛みが抑制された状態で、転写材搬送ベルト２５ａの移動速度は第２の移動速度Ｖ２ｍｍ／ｓｅｃに維持され、転写紙は後端側から押し込まれるようにして仮想略三角形の二辺側にほぼ沿うようにして移動する。   Based on the transfer material position information output from the transfer material position information output unit 29, the control unit 28 reaches the transfer material conveyance unit start position η, with the leading edge of the transfer paper guided by the second airflow generator 24. At the timing T1 (sec) when it is determined that a predetermined time has elapsed since the transfer material conveyance unit start position η is reached, the movement speed (mm / sec) of the transfer material conveyance belt 25a is changed to the second movement. The speed is changed to V2 mm / sec. Therefore, when the transfer material transport unit 25 starts sucking the transfer paper, the transfer speed of the transfer paper is controlled faster than the transfer speed of the transfer paper transported by the intermediate transfer belt 8 and the secondary transfer roller 14 in the secondary transfer nip 13a. Is done. As a result, the aforementioned loosening of the transfer paper immediately after the leading edge of the transfer paper moves to the transfer material transport belt 25a is suppressed. As a result, the moving transfer paper can be positioned on the other two sides of the virtual approximate triangle from the other side of the virtual approximate triangle (position side where the gripper 17 releases the transfer sheet). Further, in a state where the above-described loosening of the transfer paper is suppressed, the moving speed of the transfer material transport belt 25a is maintained at the second moving speed V2 mm / sec, and the transfer paper is pushed substantially from the rear end side so as to be virtually omitted. Move so that it is almost along the two sides of the triangle.

制御部２８は転写材位置情報出力部２９から出力される転写材位置情報に基づいて、転写紙の後端が二次転写ニップ１３ａを通過したと判断したタイミングＴ２（ｓｅｃ）で、転写材搬送ベルト２５ａの移動速度（ｍｍ／ｓｅｃ）を再び第１の移動速度Ｖ１ｍｍ／ｓｅｃに変更する。したがって、転写紙の後端が二次転写ニップ１３ａを通過した時点では転写紙の後端が二次転写ニップ１３ａから自由となり、転写紙は転写材搬送ベルト２５ａの駆動力によって搬送され、二次転写ローラー１４の駆動力によっては搬送されなくなる。そこで、転写材搬送ベルト２５ａの移動速度が速い側の第１の移動速度Ｖ１ｍｍ／ｓｅｃにすることで、転写紙の移動速度が速くなる。これにより、自由となった転写紙の後端部が鉛直下方に撓むことが抑制される。   Based on the transfer material position information output from the transfer material position information output unit 29, the control unit 28 transfers the transfer material at timing T2 (sec) when it is determined that the trailing edge of the transfer paper has passed through the secondary transfer nip 13a. The moving speed (mm / sec) of the belt 25a is changed again to the first moving speed V1 mm / sec. Therefore, when the trailing edge of the transfer sheet passes through the secondary transfer nip 13a, the trailing edge of the transfer sheet becomes free from the secondary transfer nip 13a, and the transfer sheet is conveyed by the driving force of the transfer material conveying belt 25a, and the secondary sheet is conveyed. It is not conveyed by the driving force of the transfer roller 14. Therefore, by setting the first moving speed V1 mm / sec on the side where the moving speed of the transfer material conveying belt 25a is fast, the moving speed of the transfer paper is increased. Thereby, it is suppressed that the rear end portion of the transfer paper that has become free is bent downward in the vertical direction.

制御部２８は転写材位置情報出力部２９から出力される転写材位置情報に基づいて、転写紙の後端が転写材搬送部始点位置ηに到達したと判断したタイミングＴ３（ｓｅｃ）で、転写材搬送ベルト２５ａの移動速度（ｍｍ／ｓｅｃ）を再び遅い側の第２の移動速度Ｖ２ｍｍ／ｓｅｃに変更する。これにより、転写材搬送ベルト２５ａは転写紙を鉛直方向の上方に向かって吸引しながら定常の搬送速度の第２の移動速度Ｖ２ｍｍ／ｓｅｃで搬送する。   Based on the transfer material position information output from the transfer material position information output unit 29, the control unit 28 determines that the rear end of the transfer paper has reached the transfer material transport unit start position η, and at the timing T3 (sec). The moving speed (mm / sec) of the material conveying belt 25a is changed again to the second moving speed V2 mm / sec on the slow side. Thereby, the transfer material transport belt 25a transports the transfer paper at the second moving speed V2 mm / sec, which is a steady transport speed, while sucking the transfer paper upward in the vertical direction.

第３の気流発生装置２６は、ダクト状の吸引部材２６ａとファン等の気流発生部２６ｂとを有する。吸引部材２６ａは、図示しない所定数の吸引孔を有するガイド面２６ａ1を
有する。ガイド面２６ａ1の吸引孔は、前述の第２の気流発生装置２４の吸引孔と同様に
または略同様に配設される。 The third airflow generation device 26 includes a duct-shaped suction member 26a and an airflow generation unit 26b such as a fan. The suction member 26a has a guide surface 26a 1 having a predetermined number of suction holes (not shown). The suction hole of the guide surface 26a 1 is disposed in the same or substantially the same manner as the suction hole of the second airflow generation device 24 described above.

気流発生部２６ｂの駆動で、吸引部材２６ａがガイド面２６ａ1の各吸引孔を通して矢
印で示す方向にエアーを吸引し気流を発生する。そして、転写材搬送ベルト２５ａから搬送された転写材２０が、その背面を吸引部材２６ａにより鉛直方向の斜め上方に吸引されながら、ガイド面２６ａ1に沿って定着部２７の方へガイドされる。 With the driving of the air flow generation unit 26b, the suction member 26a sucks air in the direction indicated by the arrow through each suction hole of the guide surface 26a 1 to generate an air flow. Then, the transfer material conveyance belt 25a transfer material 20 conveyed from the can while being sucked obliquely upward in the vertical direction by the rear suction member 26a, it is guided toward the fixing portion 27 along the guide surface 26a 1.

定着部２７は、加熱ローラー２７ａとこの加熱ローラー２７ａに圧接される加圧ローラー２７ｂとを含む定着ローラーを有している。そして、転写材２０のトナー像がこれらの加熱ローラー２７ａおよび加圧ローラー２７ｂにより加熱加圧されて定着される。その後、転写材は図示しない排出トレイに排出される。
この例の画像形成装置１の他の構成および他の画像形成動作は、液体現像剤を用いた従来の同種の画像形成装置と同様であるので、その説明は省略する。 The fixing unit 27 includes a fixing roller including a heating roller 27a and a pressure roller 27b that is pressed against the heating roller 27a. Then, the toner image on the transfer material 20 is heated and pressed by the heating roller 27a and the pressure roller 27b to be fixed. Thereafter, the transfer material is discharged to a discharge tray (not shown).
Since other configurations and other image forming operations of the image forming apparatus 1 of this example are the same as those of the conventional image forming apparatus of the same type using a liquid developer, the description thereof is omitted.

この例の画像形成装置１および画像形成方法によれば、グリッパー１７で転写材２０の先端部２０ａが把持されて二次転写ニップ１３ａで、中間転写ベルト８の像が転写材２０に転写されるとともに、二次転写後にグリッパー１７による先端部２０ａの把持が転写材解放位置εで転写材２０が解放される。次いで、転写材２０は第２の気流発生装置２４のガイド面２４ａ1により吸引されながら転写材搬送部２５に向かって鉛直方向の下方位置
から斜め上方位置へガイドされて、転写材２０の先端が転写材搬送部始点位置ηに到達する。このとき、二次転写ニップ１３ａの二次転写ニップ終端位置ζ、転写材解放位置ε、および転写材２０の先端が最初に当接する転写材搬送ベルト２５ａの転写材搬送部始点位置ηが仮想略三角形に配置される。そして、二次転写ニップ終端位置ζと転写材搬送部２５が転写材搬送部始点位置ηとを結ぶ距離をＬとし、また二次転写ニップ終端位置ζと転写材解放位置εとを結ぶ距離をＬ１とし、更に転写材解放位置εと転写材搬送部始点位置ηとを結ぶ距離をＬ２とすると、ＬはＬ１およびＬ２に対して、Ｌ＜Ｌ１＋Ｌ２の関係を有する。したがって、転写材２０の先端が転写材搬送部始点位置ηに到達すると、転写材２０はその自重で二次転写ニップ終端位置ζと転写材搬送部始点位置ηとを支点にして鉛直方向の下方に撓み、二次転写ニップ終端位置ζおよび転写材搬送部始点位置η間の仮想略三角形の他の一辺にほぼ沿う移動経路で移動しようとする。このため、転写材２０の先端が転写材搬送ベルト２５ａに当接したとき、転写材２０は弛む。そこで、転写材２０の先端が転写材搬送部始点位置ηに到達したとき、転写材搬送ベルト２５ａの移動速度が、中間転写ベルト８の移動速度より速い第１の速度Ｖ１ｍｍ／ｓｅｃに制御される。これにより、転写材２０の先端が転写材搬送ベルト２５ａに移動した直後の前述の転写材２０の弛みが抑制される。その結果、移動する転写材２０を仮想略三角形の他の一辺より仮想略三角形の残りの二辺側（グリッパー１７が転写材２０を解放する位置側）に位置させることが可能となる。したがって、二次転写ニップ１３ａを通過した転写材２０の転写画像面が中間転写ベルト８や第１の気流装置２３等の転写材２０の移動経路の鉛直方向の下方に配設される画像形成装置１の部材に接触することを防止することができる。その結果、転写画像の乱れを防止できる。また、転写材２０の弛みが小さくなることから、転写材２０の転写姿勢の微妙な変化による二次転写ニップ１３ａの幅の変化を小さくでき、画像ずれの発生を抑制することができる。このようにして、転写材２０を把持した状態で二次転写を行う場合、二次転写ニップ１３ａの二次転写ニップ終端位置ζ、転写材解放位置ε、および転写材搬送部始点位置ηが仮想略三角形に配置されても、良好な画像を得ることができる画像形成装置１を実現することが可能となる。 According to the image forming apparatus 1 and the image forming method of this example, the leading end 20a of the transfer material 20 is gripped by the gripper 17, and the image of the intermediate transfer belt 8 is transferred to the transfer material 20 by the secondary transfer nip 13a. At the same time, after the secondary transfer, the transfer material 20 is released at the transfer material release position ε when the gripper 17 holds the tip 20a. Next, the transfer material 20 is guided from the lower position in the vertical direction to the obliquely upper position toward the transfer material transport section 25 while being sucked by the guide surface 24a 1 of the second airflow generation device 24, and the tip of the transfer material 20 is moved. The transfer material transport unit start point position η is reached. At this time, the secondary transfer nip end position ζ, the transfer material release position ε of the secondary transfer nip 13a, and the transfer material conveyance portion start point position η of the transfer material conveyance belt 25a with which the leading edge of the transfer material 20 first contacts are virtually omitted. Arranged in a triangle. The distance connecting the secondary transfer nip end position ζ and the transfer material transport unit 25 to the transfer material transport unit start position η is L, and the distance connecting the secondary transfer nip end position ζ and the transfer material release position ε is set to L. If L1 is L1, and the distance between the transfer material release position ε and the transfer material conveyance unit start position η is L2, L has a relationship of L <L1 + L2 with respect to L1 and L2. Therefore, when the leading edge of the transfer material 20 reaches the transfer material conveyance unit start point position η, the transfer material 20 is lowered in the vertical direction by its own weight with the secondary transfer nip terminal position ζ and the transfer material conveyance unit start point position η as fulcrums. The second transfer nip end position ζ and the transfer material transport unit start position η tend to move along a moving path substantially along the other side of the virtual approximate triangle. For this reason, when the front end of the transfer material 20 comes into contact with the transfer material conveyance belt 25a, the transfer material 20 is loosened. Therefore, when the leading edge of the transfer material 20 reaches the transfer material conveyance unit start position η, the movement speed of the transfer material conveyance belt 25a is controlled to a first speed V1 mm / sec that is faster than the movement speed of the intermediate transfer belt 8. . As a result, the aforementioned loosening of the transfer material 20 immediately after the front end of the transfer material 20 moves to the transfer material transport belt 25a is suppressed. As a result, it is possible to position the moving transfer material 20 on the other two sides of the virtual substantially triangular side (position side where the gripper 17 releases the transfer material 20) from the other side of the virtual substantially triangular shape. Accordingly, the image forming apparatus in which the transfer image surface of the transfer material 20 that has passed through the secondary transfer nip 13a is disposed below the moving path of the transfer material 20 such as the intermediate transfer belt 8 and the first airflow device 23 in the vertical direction. It is possible to prevent contact with one member. As a result, the transfer image can be prevented from being disturbed. Further, since the looseness of the transfer material 20 is reduced, the change in the width of the secondary transfer nip 13a due to a subtle change in the transfer posture of the transfer material 20 can be reduced, and the occurrence of image misalignment can be suppressed. When secondary transfer is performed with the transfer material 20 held in this manner, the secondary transfer nip end position ζ, the transfer material release position ε, and the transfer material conveyance unit start position η of the secondary transfer nip 13a are virtually determined. Even when arranged in a substantially triangular shape, it is possible to realize the image forming apparatus 1 that can obtain a good image.

また、転写材搬送部２５の吸引部材２５ｂによる転写材２０の吸引圧が、二次転写ローラー１４の二次転写ニップ圧より小さい。これにより、転写材２０は中間転写ベルト８と二次転写ローラー１４の各回転力により確実に移動可能となる。   Further, the suction pressure of the transfer material 20 by the suction member 25 b of the transfer material transport unit 25 is smaller than the secondary transfer nip pressure of the secondary transfer roller 14. As a result, the transfer material 20 can be reliably moved by the rotational forces of the intermediate transfer belt 8 and the secondary transfer roller 14.

更に、二次転写部１３でトナー像が転写された転写材２０に、第１の気流発生装置２３でエアーを鉛直方向の上方に吹き付けるとともに、この転写材２０を第２の気流発生装置２４で転写画像面を鉛直方向の下方に向けて鉛直方向の上方に吸引する。これにより、転写材搬送ベルト２５ａに移動した直後の転写材２０の弛みを更に効果的に抑制することが可能となる。   Further, air is blown upward in the vertical direction by the first airflow generation device 23 onto the transfer material 20 onto which the toner image has been transferred by the secondary transfer unit 13, and the transfer material 20 is applied by the second airflow generation device 24. The transfer image surface is drawn downward in the vertical direction and sucked upward in the vertical direction. Thereby, it is possible to more effectively suppress the looseness of the transfer material 20 immediately after moving to the transfer material conveyance belt 25a.

図１０および図１１は、本発明の画像形成装置の実施の形態の他の例を部分的に示す、それぞれ図２および図４と同様の図である。
前述の実施の形態の例では、二次転写ニップ１３ａを通過した転写材２０は、転写材搬送部材としての転写材搬送ベルト１５ａによって定着部１７の方へ搬送されるが、図１０および図１１に示すようにこの例の画像形成装置１では、転写材搬送部材として定着部１
７の加熱ローラー２７ａと加圧ローラー２７ｂとにより構成される。つまり、加熱ローラー２７ａと加圧ローラー２７ｂは転写材２０の定着機能と転写材２０の搬送機能とを兼ね備える。その場合、加熱ローラー２７ａは定着のために転写材２０を加熱する加熱部材である。また、定着部１７は前述の転写材搬送部２５における吸引部材２５ｂおよび気流発生部２５ｃを有していない。したがって、この例の画像形成装置１では、加熱ローラー２７ａと加圧ローラー２７ｂによる転写材２０の搬送時には、転写材２０は吸引されずに移動する。また、前述の例の転写材搬送部２５と第３の気流発生装置２６は設けられない。更に、この例の画像形成装置１では、前述の例の転写材搬送部始点位置ηは、転写材２０の先端が加圧ローラー１７ｂに最初に当接する転写材搬送部始点位置η′となる。そして、この例の画像形成装置１においても、転写材解放位置ε、定着部１７の転写材搬送部始点位置η′、および二次転写ニップ終端位置ζが仮想略三角形に配置される。 FIGS. 10 and 11 are views similar to FIGS. 2 and 4, respectively, partially showing another example of the embodiment of the image forming apparatus of the present invention.
In the example of the above-described embodiment, the transfer material 20 that has passed through the secondary transfer nip 13a is conveyed toward the fixing unit 17 by the transfer material conveyance belt 15a serving as a transfer material conveyance member. As shown in FIG. 1, in the image forming apparatus 1 of this example, the fixing unit 1 is used as a transfer material conveying member.
7 heating roller 27a and pressure roller 27b. That is, the heating roller 27 a and the pressure roller 27 b have both a fixing function of the transfer material 20 and a transport function of the transfer material 20. In this case, the heating roller 27a is a heating member that heats the transfer material 20 for fixing. The fixing unit 17 does not include the suction member 25b and the airflow generation unit 25c in the transfer material transport unit 25 described above. Therefore, in the image forming apparatus 1 of this example, when the transfer material 20 is conveyed by the heating roller 27a and the pressure roller 27b, the transfer material 20 moves without being sucked. Further, the transfer material transport unit 25 and the third airflow generation device 26 in the above example are not provided. Furthermore, in the image forming apparatus 1 of this example, the transfer material conveyance unit start point position η in the above example is the transfer material conveyance unit start point position η ′ where the tip of the transfer material 20 first contacts the pressure roller 17b. Also in the image forming apparatus 1 of this example, the transfer material release position ε, the transfer material conveyance unit start point position η ′ of the fixing unit 17, and the secondary transfer nip end position ζ are arranged in a virtually triangular shape.

この例の画像形成装置１および画像形成方法によれば、定着部１７を転写材搬送部として兼用することで、転写材搬送部２５と第３の気流発生装置２６を不要にでき、画像形成装置１の全体構成をコンパクトに形成することが可能となる。その場合、定着部１７による転写材搬送時には転写材２０は吸引されない。
この例の画像形成装置１の他の構成および他の作用効果は、前述の例と同じである。 According to the image forming apparatus 1 and the image forming method of this example, since the fixing unit 17 is also used as the transfer material conveyance unit, the transfer material conveyance unit 25 and the third airflow generation device 26 can be made unnecessary, and the image formation apparatus. 1 can be formed compactly. In this case, the transfer material 20 is not sucked when the transfer material is conveyed by the fixing unit 17.
Other configurations and other operational effects of the image forming apparatus 1 of this example are the same as those of the above-described example.

なお、本発明の転写材搬送装置および画像形成装置は、前述の実施の形態の各例に限定されることはない。例えば、前述の例の第１および第２の気流発生部２３,２４は必ずし
も必要ではなく、省略することもできる。 The transfer material conveying device and the image forming apparatus of the present invention are not limited to the examples of the above-described embodiments. For example, the first and second airflow generation units 23 and 24 in the above-described example are not necessarily required and can be omitted.

また、像担持体として中間転写ベルト８を用いているが、中間転写ドラムを用いることもできるし、像担持体として感光体とすることもできる。像担持体に感光体を用いる場合は、感光体のトナー像が転写材に直接転写されることは言うまでもない。更に、前述の各例の画像形成装置では、タンデム型の画像形成装置としているが、他の形式の画像形成装置でもよいし、単色の画像形成装置でもよい。要は、本発明は特許請求の範囲に記載されている事項の範囲内で種々の設計変更が可能である。   Further, although the intermediate transfer belt 8 is used as the image carrier, an intermediate transfer drum can be used, and a photoconductor can be used as the image carrier. Needless to say, when a photoreceptor is used as the image carrier, the toner image on the photoreceptor is directly transferred to the transfer material. Further, in each of the image forming apparatuses described above, the tandem type image forming apparatus is used. However, other types of image forming apparatuses or single color image forming apparatuses may be used. In short, the present invention can be modified in various ways within the scope of the matters described in the claims.

１…画像形成装置、２Ｙ,２Ｍ,２Ｃ,２Ｋ…感光体、５Ｙ,５Ｍ,５Ｃ,５Ｋ…現像部、６Ｙ,６Ｍ,６Ｃ,６Ｋ…一次転写部、８…中間転写ベルト、９…ベルト駆動ローラー、１３…
二次転写部、１３ａ…二次転写ニップ、１４…二次転写ローラー、２０…転写材、２０ａ…先端部、１７…グリッパー、２４…第２の気流発生装置、２４ａ…吸引部材、２４ａ1
…ガイド面、２４ｂ…気流発生部、２５…転写材搬送部、２５ａ…転写材搬送ベルト、２５ｂ…吸引部材、２５ｂ1…吸引孔、２５ｃ…気流発生部、２７…定着部、２７ａ…加熱
ローラー、２７ｂ…加圧ローラー、２８…制御部、２９…転写材位置情報入力部、ε…転写材解放位置、ζ…二次転写ニップの終端位置、η,η′…転写材搬送部始点位置 DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2Y, 2M, 2C, 2K ... Photoconductor, 5Y, 5M, 5C, 5K ... Developing part, 6Y, 6M, 6C, 6K ... Primary transfer part, 8 ... Intermediate transfer belt, 9 ... Belt drive Roller, 13 ...
Secondary transfer section, 13a ... secondary transfer nip, 14 ... secondary transfer roller, 20 ... transfer material, 20a ... tip, 17 ... gripper, 24 ... second air flow generator, 24a ... suction member, 24a 1
... guide surface, 24b ... airflow generating unit, 25 ... transfer material conveying section, 25a ... transfer material conveyance belt, 25b ... suction member, 25b 1 ... suction holes, 25c ... air flow generating unit, 27 ... fixing portion, 27a ... heating roller 27b, pressure roller, 28, control unit, 29, transfer material position information input unit, ε, transfer material release position, ζ, secondary transfer nip end position, η, η ′, transfer material conveyance unit start position.

Claims (7)

像を担持して移動する像担持体と、
移動により転写材を把持もしくは解放する把持部材を有するとともに、前記転写材を搬送して前記像担持体と前記転写材を介して当接することにより形成される転写ニップで前記像担持体に担持された前記像を前記転写材に転写する転写ローラーと、
前記転写材を搬送する転写材搬送部材を有し、前記転写ローラーで前記像が転写された前記転写材を前記像が転写された面が鉛直方向の下方に向けて前記転写材を鉛直方向の上方に吸引して前記転写材搬送部材で搬送するとともに、前記転写材を吸引する位置が前記把持部材から前記転写材を解放する位置と前記像担持体が前記転写材と離間する位置と、
Ｌ＜Ｌ１＋Ｌ２
の関係を有する位置に配設された転写材搬送部と、
前記転写材搬送部材の移動速度を制御する制御部と、
を備えることを特徴とする画像形成装置。
ここで、
Ｌ：前記像担持体と前記転写材とが離間する位置と、前記転写材搬送部が前記転写材を吸引開始する位置とを結ぶ距離、
Ｌ１：前記像担持体と前記転写材とが離間する位置と、前記把持部材が前記転写材を解放する位置とを結ぶ距離、
Ｌ２：前記把持部材が前記転写材を解放する位置と、前記転写材搬送部が前記転写材を吸引開始する位置とを結ぶ距離。 An image carrier that carries and moves the image;
It has a gripping member for gripping or releasing the transfer material by movement, and is carried on the image carrier at a transfer nip formed by conveying the transfer material and contacting the image carrier with the transfer material. A transfer roller for transferring the image to the transfer material;
A transfer material conveying member that conveys the transfer material, the transfer material on which the image is transferred by the transfer roller, the surface on which the image is transferred facing downward in the vertical direction, and the transfer material in the vertical direction A position where the transfer material is sucked upward and conveyed by the transfer material conveying member, a position where the transfer material is sucked from the gripping member, and a position where the image carrier is separated from the transfer material;
L <L1 + L2
A transfer material transport unit disposed at a position having the relationship of
A control unit for controlling the moving speed of the transfer material conveying member;
An image forming apparatus comprising:
here,
L: a distance connecting a position where the image carrier and the transfer material are separated from a position where the transfer material transport unit starts sucking the transfer material,
L1: a distance connecting a position where the image carrier and the transfer material are separated from each other and a position where the gripping member releases the transfer material;
L2: a distance connecting a position where the gripping member releases the transfer material and a position where the transfer material transport unit starts sucking the transfer material. 前記制御部は、前記転写材が前記転写材搬送部材により搬送し始める時の前記転写材搬送部材の移動速度を、前記像担持体の移動速度より速くする請求項１に記載の画像形成装置。   2. The image forming apparatus according to claim 1, wherein the control unit makes a movement speed of the transfer material conveyance member when the transfer material starts to be conveyed by the transfer material conveyance member faster than a movement speed of the image carrier. 前記転写材搬送部が前記転写材を吸引する時の吸引の圧力は、前記転写ニップで前記転写ローラーと前記像担持体とが前記転写材を介して当接する時の転写ニップの当接圧力より小さい請求項１または請求項２に記載の画像形成装置。   The suction pressure when the transfer material transport unit sucks the transfer material is higher than the contact pressure of the transfer nip when the transfer roller and the image carrier are in contact with each other through the transfer material in the transfer nip. The image forming apparatus according to claim 1, wherein the image forming apparatus is small. 前記転写材搬送部は、前記転写材を加熱する加熱部材を有する請求項１ないし請求項３のいずれか１項に記載の画像形成装置。   The image forming apparatus according to claim 1, wherein the transfer material transport unit includes a heating member that heats the transfer material. 前記転写ローラーで前記像が転写された前記転写材に、鉛直方向の上方に向けて気流を吹き付ける気流発生部を有する請求項１ないし請求項４のいずれか１項に記載の画像形成装置。   5. The image forming apparatus according to claim 1, further comprising an airflow generation unit that blows an airflow upward in a vertical direction on the transfer material onto which the image has been transferred by the transfer roller. 前記転写ローラーで前記像が転写された前記転写材を、前記像が転写された面を鉛直方向の下方に向けて鉛直方向の上方に吸引し、前記転写材搬送部へガイドする吸引ガイド部を有する請求項１ないし請求項５のいずれか１項に記載の画像形成装置。   A suction guide portion for sucking the transfer material, onto which the image has been transferred by the transfer roller, with the surface on which the image has been transferred facing downward in the vertical direction upward in the vertical direction, and guiding the transfer material to the transfer material conveyance unit; The image forming apparatus according to claim 1, comprising: an image forming apparatus according to claim 1; 転写ローラーの周面に配設された把持部材で転写材を把持し、
前記把持部材で把持された前記転写材を移動する像担持体と前記転写ローラーとで形成される転写ニップに搬送して前記像担持体に担持された像を前記転写材に転写し、
前記像を前記転写材に転写した後、前記把持部材を移動させて前記把持部材から前記像が転写された前記転写材を解放し、
解放された前記転写材を、前記転写材を吸引開始する位置が
Ｌ＜Ｌ１＋Ｌ２
の関係を有する位置に配設された転写材搬送部で吸引するとともに、前記像担持体の移動速度よりも速く移動する前記転写材搬送部の転写材搬送部材で搬送することを特徴とする
画像形成方法。
ここで、
Ｌ：前記像担持体と前記転写材とが離間する位置と、前記転写材搬送部が前記転写材を吸引開始する位置とを結ぶ距離、
Ｌ１：前記像担持体と前記転写材とが離間する位置と、前記把持部材が前記転写材を解放する位置とを結ぶ距離、
Ｌ２：前記把持部材が前記転写材を解放する位置と、前記転写材搬送部が前記転写材を吸引開始する位置とを結ぶ距離。 Grasping the transfer material with the gripping member disposed on the peripheral surface of the transfer roller,
The transfer material gripped by the gripping member is transported to a transfer nip formed by an image carrier that moves and the transfer roller, and the image carried on the image carrier is transferred to the transfer material,
After transferring the image to the transfer material, the grip member is moved to release the transfer material onto which the image has been transferred from the grip member,
The position at which the released transfer material starts to suck the transfer material is L <L1 + L2.
The image is sucked by a transfer material conveyance unit disposed at a position having the above relationship and conveyed by a transfer material conveyance member of the transfer material conveyance unit that moves faster than the moving speed of the image carrier. Forming method.
here,
L: a distance connecting a position where the image carrier and the transfer material are separated from a position where the transfer material transport unit starts sucking the transfer material,
L1: a distance connecting a position where the image carrier and the transfer material are separated from each other and a position where the gripping member releases the transfer material;
L2: a distance connecting a position where the gripping member releases the transfer material and a position where the transfer material transport unit starts sucking the transfer material.
JP2009267188A 2009-11-25 2009-11-25 Apparatus and method for forming image Withdrawn JP2011112752A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020261614A1 (en) * 2019-06-28 2020-12-30 富士ゼロックス株式会社 Conveying device, fixing device, and image forming apparatus

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020261614A1 (en) * 2019-06-28 2020-12-30 富士ゼロックス株式会社 Conveying device, fixing device, and image forming apparatus
US11754950B2 (en) 2019-06-28 2023-09-12 Fujifilm Business Innovation Corp. Conveying device, fixing device, and image forming apparatus

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