JP2006168973A - Recording medium transfer device and image forming apparatus - Google Patents
Recording medium transfer device and image forming apparatus Download PDFInfo
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Abstract
Description
本発明は、記録媒体搬送装置及び画像形成装置に関し、さらに詳しくは、プリンタ、複写機、ＦＡＸ、印刷機等及びそれらを複数搭載した複合機等に用いられる静電吸着方式の記録媒体搬送装置及び該記録媒体搬送装置を搭載した画像形成装置に関する。 The present invention relates to a recording medium conveying apparatus and an image forming apparatus. More specifically, the present invention relates to an electrostatic attraction type recording medium conveying apparatus used for a printer, a copying machine, a FAX, a printing machine, etc. The present invention relates to an image forming apparatus equipped with the recording medium conveying apparatus.
インクジェット記録装置において、無端状の搬送ベルトの表面に帯電ローラを介して高電圧を印加し、搬送ベルト上に形成された電荷によって用紙等の記録媒体を静電吸着して搬送する静電吸着方式の記録媒体搬送装置が知られている。例えば、特許文献１には、インクジェット記録装置に用いられる静電吸着方式の記録媒体搬送装置において、ベルト上に形成する電荷を一様ではなく、電位の異なる帯電幅を複数形成することにより静電吸着力を実用的なものとする技術が開示されている。ここで、電位の異なる帯電幅は、１本の帯電ローラに印加する高電圧値を変化させることにより得ている。 In an inkjet recording apparatus, an electrostatic adsorption system that applies a high voltage to the surface of an endless conveyance belt via a charging roller and electrostatically adsorbs a recording medium such as paper by the charge formed on the conveyance belt. There is known a recording medium conveying apparatus. For example, in Patent Document 1, in an electrostatic attraction type recording medium conveyance device used in an ink jet recording apparatus, the charges formed on the belt are not uniform, and a plurality of charge widths having different potentials are formed to form electrostatic charges. A technique for making the adsorptive power practical is disclosed. Here, the charging widths having different potentials are obtained by changing the high voltage value applied to one charging roller.
図８は、従来例の記録媒体搬送装置において、帯電ローラに印加される高電圧の波形、及び搬送ベルトが帯電した様子を示す図である。
従来例の記録媒体搬送装置においては、図８に示すように１本の帯電ローラに−Ｖ〜＋Ｖをピークとする矩形波電圧が印加され、このＡＣバイアスにより搬送ベルトの絶縁層に、正と負の電荷が搬送ベルトの移動方向に対して交互に帯電される。
In the conventional recording medium conveying apparatus, as shown in FIG. 8, a rectangular wave voltage having a peak of −V to + V is applied to one charging roller, and this AC bias causes positive and negative to the insulating layer of the conveying belt. Negative charges are alternately charged with respect to the moving direction of the conveyor belt.
従来例のように１本の帯電ローラを用いて搬送ベルトの表面に電位の異なる帯電幅を得るためには、印加する高電圧のピーク−ピーク値（peak to peak値）が大きくなり、高電圧電源にとって大きな負荷となってしまうという問題があった。すなわち、１本の帯電ローラを用いて、−Ｖ〜＋Ｖまで高電圧を切り替えることは、高電圧電源にとって大きな負荷であり、切り替え周波数を速くすることの妨げとなっていた。
そこで、請求項１の発明は、少なくとも２本以上の帯電ローラを用いて、それぞれの帯電ローラにおける高電圧の変化を少なくし、高電圧電源に対する負荷を低減することを目的とする。
In order to obtain different charging widths on the surface of the conveyor belt using a single charging roller as in the conventional example, the applied high voltage peak-to-peak value (peak to peak value) increases and the high voltage There was a problem that it would be a heavy load on the power supply. That is, switching a high voltage from −V to + V using a single charging roller is a heavy load for a high voltage power supply, and hinders an increase in switching frequency.
Accordingly, an object of the present invention is to use at least two or more charging rollers to reduce a change in high voltage in each charging roller and reduce a load on a high voltage power source.
また、請求項２の発明は、搬送ベルトの回転方向上流側に位置する帯電ローラにＤＣ電圧を印加し、下流側に位置する帯電ローラにＡＣ電圧を印加するという簡単な構成により、従来例が有する問題点を克服することを目的とする。 Further, the invention of claim 2 is based on a simple configuration in which a DC voltage is applied to the charging roller located upstream in the rotation direction of the conveyor belt and an AC voltage is applied to the charging roller located downstream. The purpose is to overcome the problems.
また、請求項１及び２発明の目的を達成するためには、少なくとも２種類以上の高電圧値を、タイミングによっては同時に出力することが必要である。しかし、それぞれの電圧値に対し高電圧電源を複数用意することはコスト削減及び省スペース化にとって弊害となる問題があった。
そこで、請求項３の発明は、複数電圧値を１つの高電圧電源から発生させることにより前記問題を克服することを目的とする。
In order to achieve the objects of the first and second aspects of the invention, it is necessary to output at least two kinds of high voltage values at the same time depending on the timing. However, preparing a plurality of high voltage power supplies for each voltage value has a problem that is detrimental to cost reduction and space saving.
Accordingly, an object of the present invention is to overcome the above problem by generating a plurality of voltage values from one high voltage power supply.
また、吐出口からインク液滴を吐出して記録媒体に記録を行うインクジェット記録装置では、インクに含まれる水分により記録媒体が波打つコックリングと呼ばれる現象を抑えるため、無端状のベルトに記録媒体を静電的に吸着して用紙を搬送する方法が知られている。
しかしながら、この静電吸着搬送方式では、ベルトの帯電によって記録媒体表面と記録ヘッドとの間に電界が生じ、この電界が記録ヘッドから吐出されたインク液滴に影響を与えて良好な記録ができないという問題があった。
In addition, in an ink jet recording apparatus that performs recording on a recording medium by discharging ink droplets from an ejection port, the recording medium is placed on an endless belt in order to suppress a phenomenon called cockling in which the recording medium undulates due to moisture contained in the ink. A method of conveying a sheet by electrostatic adsorption is known.
However, in this electrostatic attraction conveyance system, an electric field is generated between the surface of the recording medium and the recording head due to the charging of the belt, and this electric field affects the ink droplets ejected from the recording head, so that good recording cannot be performed. There was a problem.
図９は、搬送ベルト上の電荷により、記録ヘッドから吐出されたインク液滴が影響を受ける様子を経時的に示す図である。
図９（Ａ）に示すように、搬送ベルト表面には搬送ベルト上の電荷により記録媒体が静電吸着される。搬送ベルト上の電荷により記録媒体表面に電荷が誘起され、表面電位を生じる。同時にノズル面は搬送ベルト表面の極性と逆の電荷が誘起される。
FIG. 9 is a diagram showing, over time, how ink droplets ejected from the recording head are affected by the charge on the transport belt.
As shown in FIG. 9A, the recording medium is electrostatically attracted to the surface of the conveying belt by the electric charge on the conveying belt. A charge is induced on the surface of the recording medium by the charge on the conveying belt, and a surface potential is generated. At the same time, a charge opposite to the polarity of the conveying belt surface is induced on the nozzle surface.
一方、図９（Ｂ）に示すように、記録ヘッドの吐出口から吐出されたインク液滴が飛翔中に、図９（Ｃ）に示すようにインク液滴が***して生じるミスト（サテライト、もしくは従滴）は、前記表面電位の影響で、表面電位と同極性に帯電する。このため、同極性の帯電が反発し合って、ミストはＵターンして図９（Ｄ）に示すように吐出口付近に付着してしまう。この場合、記録媒体へのインクの付着量が低下し画質に影響を与える。さらに、以後の正常なインクの吐出が妨げられて、インクが曲がって飛翔したり、インク吐出が行われなくなる。 On the other hand, as shown in FIG. 9B, while ink droplets ejected from the ejection port of the recording head are flying, a mist (satellite, Or a follower droplet) is charged to the same polarity as the surface potential due to the influence of the surface potential. For this reason, electrification with the same polarity repels each other, and the mist makes a U-turn and adheres to the vicinity of the discharge port as shown in FIG. In this case, the amount of ink adhering to the recording medium is reduced, affecting the image quality. Further, the subsequent normal ink ejection is hindered, and the ink bends and flies, or the ink is not ejected.
この問題に対しては、搬送ベルト表面に形成される帯電の幅を小さくすることが有効であることが知られている。帯電幅を小さくするためには搬送ベルトに印加する高電圧の電圧値切り替え周波数を高くすることが必要である。しかしながら、周波数を高くすればＡＣ電圧の性質上出力電流が増大する。これは負荷の容量が増大することに等しく、高圧電源にとって厳しい条件となる問題があった。 For this problem, it is known that it is effective to reduce the width of the charge formed on the surface of the conveyor belt. In order to reduce the charging width, it is necessary to increase the voltage value switching frequency of the high voltage applied to the conveyor belt. However, if the frequency is increased, the output current increases due to the nature of the AC voltage. This is equivalent to an increase in the capacity of the load, and there is a problem that becomes a severe condition for the high-voltage power supply.
請求項４の発明は、前記記録媒体搬送装置をインクジェット画像形成装置に用いることによって、搬送ベルト表面の帯電幅を小さくすることを可能とし、ミストの記録ヘッドへの付着を低減することを目的とする。 The invention of claim 4 aims to reduce the adhesion of the mist to the recording head by making it possible to reduce the charging width of the surface of the conveying belt by using the recording medium conveying device in an inkjet image forming apparatus. To do.
請求項１の発明は、無端状の搬送ベルトに高電圧を印加することにより前記搬送ベルトを帯電させ、帯電した前記搬送ベルトの表面に記録媒体を吸着して搬送する記録媒体搬送装置において、前記搬送ベルトの帯電手段は少なくとも２本の帯電ローラを有し、該各々の帯電ローラに異なる電圧値を印加することを特徴とする。 The invention according to claim 1 is a recording medium conveying apparatus that charges the conveying belt by applying a high voltage to an endless conveying belt, and adsorbs and conveys the recording medium to the surface of the charged conveying belt. The charging means of the conveying belt has at least two charging rollers, and different voltage values are applied to the respective charging rollers.
請求項２の発明は、請求項１記載の記録媒体搬送装置において、前記搬送ベルトの回転方向上流に位置する帯電ローラにＤＣ電圧を印加し、前記搬送ベルトの回転方向下流に位置する帯電ローラにＡＣ電圧を印加することを特徴とする。 According to a second aspect of the present invention, in the recording medium conveying apparatus according to the first aspect, a DC voltage is applied to the charging roller located upstream in the rotation direction of the conveying belt, and the charging roller located downstream in the rotation direction of the conveying belt. An AC voltage is applied.
請求項３の発明は、請求項１または２記載の記録媒体搬送装置において、前記２本の帯電ローラに高電圧を供給する高電圧電源は１つであることを特徴とする。 According to a third aspect of the present invention, in the recording medium conveying apparatus according to the first or second aspect, the number of the high-voltage power supplies that supply a high voltage to the two charging rollers is one.
請求項４の発明は、無端状の搬送ベルトの表面を帯電させて記録媒体を搬送する記録媒体搬送装置を備え、前記記録媒体に液滴吐出ヘッドから液滴を吐出して画像を形成する画像形成装置において、前記記録媒体搬送装置は請求項１乃至３のいずれかに記載の記録媒体搬送装置からなることを特徴とする。 According to a fourth aspect of the present invention, there is provided a recording medium conveying device for conveying a recording medium by charging the surface of an endless conveying belt, and forming an image by ejecting droplets from the droplet ejection head onto the recording medium. In the forming apparatus, the recording medium conveyance device includes the recording medium conveyance device according to any one of claims 1 to 3.
請求項１に記載の用紙搬送装置は、複数の帯電ローラを用い、異なる電圧値を印加することにより搬送ベルトの帯電を行うので、高電圧電源にとって負荷が軽くなり高電圧電源の構成を簡単なものにすることができる。 The sheet conveying apparatus according to the first aspect uses a plurality of charging rollers to charge the conveying belt by applying different voltage values. Therefore, the load on the high voltage power source is reduced and the configuration of the high voltage power source is simplified. Can be a thing.
請求項２に記載の用紙搬送装置は、搬送ベルト回転方向上流側に位置する帯電ローラにＤＣ電圧を印加し、下流側に位置する帯電ローラにＡＣ電圧を印加するので、簡単な構成でそれぞれの帯電ローラにおける高電圧の変化を少なくし、高電圧電源に対する負荷を低減する。 According to the second aspect of the present invention, since the DC voltage is applied to the charging roller located upstream in the rotation direction of the conveying belt and the AC voltage is applied to the charging roller located downstream, The change of the high voltage in the charging roller is reduced, and the load on the high voltage power source is reduced.
請求項３に記載の用紙搬送装置は、前記複数の電圧値を１つの高電圧電源で出力する構成をとっているので、コストの上昇を押さえ、かつ装置の小型化を達成することができる。 Since the sheet conveying apparatus according to the third aspect is configured to output the plurality of voltage values with one high voltage power supply, it is possible to suppress an increase in cost and achieve downsizing of the apparatus.
請求項４に記載の用紙搬送装置は、搬送ベルトに形成される帯電幅を小さくすることができるので、インク滴が飛翔中に***して形成されるミストが記録ヘッドへ付着するのを低減することができ、高品位の画像を形成することができる。 According to the fourth aspect of the present invention, since the charging width formed on the conveying belt can be reduced, it is possible to reduce the adhesion of the mist formed by the ink droplet splitting during the flight to the recording head. And a high-quality image can be formed.
本発明は、帯電ローラを用いて、搬送ベルトの移動方向に対して正と負の電荷を交互に帯電させる際、高電圧を印加するために少なくとも２本の帯電ローラを用いることにより、高電圧電源において切り替える電圧値を小さくして、高電圧電源の負荷を軽くし、電圧値切り替え周波数を高くし、それによって搬送ベルト上の帯電幅を小さくすることを目的とする。そのため、無端状の搬送ベルトの表面に帯電ローラを用いて高電圧を印加して帯電させるが、帯電ローラは、少なくとも第１帯電ローラ、第２帯電ローラの２本を使用し、搬送ベルトの回転方向上流に位置する第１帯電ローラにＤＣ電圧を印加し、下流に位置する第２帯電ローラにＡＣ電圧を印加する。
以下、本発明の記録媒体搬送装置及び該記録媒体搬送装置を搭載したインクジェット画像形成装置の実施例について説明する。
The present invention uses a charging roller to alternately charge positive and negative charges with respect to the moving direction of the conveyor belt, thereby using at least two charging rollers to apply a high voltage. The purpose is to reduce the voltage value to be switched in the power source, lighten the load of the high voltage power source, increase the voltage value switching frequency, and thereby reduce the charging width on the conveyor belt. For this reason, a charging roller is used to apply a high voltage to the surface of the endless conveyance belt for charging, but at least two of the first charging roller and the second charging roller are used to rotate the conveyance belt. A DC voltage is applied to the first charging roller located upstream in the direction, and an AC voltage is applied to the second charging roller located downstream.
Hereinafter, embodiments of the recording medium conveyance device of the present invention and an inkjet image forming apparatus equipped with the recording medium conveyance device will be described.
図１は、本発明の記録媒体搬送装置を搭載したインクジェットプリンタの実施例を示す図である。
図１に示すように、実施例のインクジェットプリンタ１は、シアンＣ，マゼンタＭ，イエロＹ，ブラックＢｋの各色のインクをそれぞれ収納した４個のインクカートリッジと、複数のノズル列を有し、各インクカートリッジからインクが供給されるインクジェットヘッド２と、インクカートリッジとインクジェットヘッド２を搭載しガイドロッド４に案内されて主走査方向に移動するキャリッジ３と、記録媒体６を収納した記録媒体積載部５や手差し給紙経路１５から、先端コロ１３を経て記録媒体６をインクジェットヘッド２下方に搬送する搬送ベルト１２と、印字した記録媒体６を排出する排紙トレイ１４を有する。そして、ホスト装置から送られる画像データを記録媒体６に印字するときは、キャリッジ３をガイドロッド４に沿って主走査しながら、搬送ベルト１２により副走査方向に搬送され、インクジェットヘッド２下方に送られた記録媒体６にインクジェットヘッド２のノズルから画像データに応じてインク滴を噴射して文字や画像を記録する。
FIG. 1 is a diagram showing an embodiment of an ink jet printer equipped with a recording medium conveying apparatus of the present invention.
As shown in FIG. 1, the inkjet printer 1 according to the embodiment includes four ink cartridges each storing ink of each color of cyan C, magenta M, yellow Y, and black Bk, and a plurality of nozzle rows. An ink jet head 2 to which ink is supplied from an ink cartridge, a carriage 3 on which the ink cartridge and the ink jet head 2 are mounted, guided by a guide rod 4 and moved in the main scanning direction, and a recording medium stacking unit 5 in which a recording medium 6 is stored. In addition, a conveyance belt 12 that conveys the recording medium 6 to the lower side of the inkjet head 2 from the manual feed path 15 through the leading end roller 13 and a paper discharge tray 14 that discharges the printed recording medium 6 are provided. Then, when printing image data sent from the host device on the recording medium 6, the carriage 3 is transported in the sub-scanning direction by the transport belt 12 while performing main scanning along the guide rod 4, and is sent below the inkjet head 2. Characters and images are recorded on the recording medium 6 by ejecting ink droplets from the nozzles of the inkjet head 2 in accordance with the image data.
記録媒体搬送装置において、用紙等の記録媒体６は記録媒体積載部５に図１に示すように積載保持されており、記録媒体６を取り出す給紙コロ７と、記録媒体を１枚ずつ分離する分離パッド８を有しており、分離パッド８によって１枚ずつに分離した記録媒体６は搬送ガイド９に送り出される。搬送状の搬送ベルト１２はベルト搬送ローラ１０とテンションローラ１１間に巻回され、記録媒体積載部５より取り出された記録媒体６は搬送ガイド９に案内されて先端コロ１３と搬送ベルト１２間に送られる。記録媒体６を搬送する際、搬送ベルト１２の表面に第１帯電ローラ２１ａ及び第２帯電ローラ２１ｂによって電荷が形成され、搬送ベルト１２に対し静電吸着力によって張り付いた状態で搬送される。 In the recording medium transport apparatus, recording media 6 such as paper are stacked and held on the recording medium stacking unit 5 as shown in FIG. 1, and the recording rollers 6 for taking out the recording media 6 and the recording media are separated one by one. The recording medium 6 having the separation pad 8 and separated by the separation pad 8 one by one is sent to the conveyance guide 9. The conveying belt 12 is wound between the belt conveying roller 10 and the tension roller 11, and the recording medium 6 taken out from the recording medium stacking unit 5 is guided by the conveying guide 9 to be between the leading roller 13 and the conveying belt 12. Sent. When the recording medium 6 is transported, electric charges are formed on the surface of the transport belt 12 by the first charging roller 21a and the second charging roller 21b, and the transport medium 12 is transported while being stuck to the transport belt 12 by electrostatic attraction.
図２は、搬送ベルトの構成を示す断面図である。
無端状の搬送ベルト１２の構成は、図２に示すように２層構造で、表層は抵抗制御を行っていない純粋な樹脂材で構成された絶縁層１２ａであり、その膜厚は４０μｍである。また、裏層は、表層と同材質にカーボンによる抵抗制御を行った中抵抗層１２ｂ（アース層）であって、表層と裏層が積層されている。帯電ローラは絶縁層１２ａに接触するように配置され、加圧力が第１，第２帯電ローラ２１ａ，２１ｂの軸の両端に２．５Ｎ付加される。ベルト搬送ローラ１０はアースローラの役目を担っており、搬送ベルト１２の中抵抗層１２ｂと接触配置される。
FIG. 2 is a cross-sectional view showing the configuration of the conveyor belt.
As shown in FIG. 2, the endless transport belt 12 has a two-layer structure, and the surface layer is an insulating layer 12a made of a pure resin material not subjected to resistance control, and the film thickness is 40 μm. . The back layer is a medium resistance layer 12b (ground layer) in which the same material as the surface layer is subjected to resistance control with carbon, and the surface layer and the back layer are laminated. The charging roller is disposed in contact with the insulating layer 12a, and a pressure of 2.5N is applied to both ends of the shafts of the first and second charging rollers 21a and 21b. The belt conveyance roller 10 serves as an earth roller, and is disposed in contact with the medium resistance layer 12 b of the conveyance belt 12.
図３は、インクジェットヘッドを搭載するキャリッジの走査方向と搬送ベルトとの位置関係を示す図で、図１を右側より見た図に相当する。
図３に示すように、インクジェットヘッド２を搭載するキャリッジ３は搬送ベルト１２の搬送方向、すなわち記録媒体の搬送方向（副走査方向）と直交する方向（主走査方向）に走査され、搬送ベルト１２上の記録媒体にインクジェットヘッド２からインク滴が吐出され、１行分の帯状領域の画像が形成された後、搬送ベルト１２を１行分副走査方向に駆動し、同様にして次の帯状領域に画像を形成する動作を繰り返し、記録媒体の全領域に所定の画像を形成する。
FIG. 3 is a diagram showing the positional relationship between the scanning direction of the carriage on which the inkjet head is mounted and the conveyor belt, and corresponds to the diagram when FIG. 1 is viewed from the right side.
As shown in FIG. 3, the carriage 3 on which the inkjet head 2 is mounted is scanned in the conveyance direction of the conveyance belt 12, that is, in the direction (main scanning direction) orthogonal to the conveyance direction (sub-scanning direction) of the recording medium. After the ink droplets are ejected from the inkjet head 2 onto the upper recording medium and an image of the belt-like region for one row is formed, the transport belt 12 is driven in the sub-scanning direction for one row, and the next belt-like region is similarly formed. Then, the image forming operation is repeated to form a predetermined image on the entire area of the recording medium.
図４は、搬送ベルトに形成される電荷によって記録媒体が吸着される様子を示す図である。
帯電ローラによって、搬送ベルト１２の絶縁層１２ａにプラスとマイナスの電荷が帯電され、そこへ記録媒体６が給紙される。搬送ベルト１２の表面にはベルト上のプラス電荷からマイナス電荷に向かって電気力線が発生している。この電気力線の影響で記録媒体の搬送ベルトと接触している側とその反対側には同極の電荷が誘電される。記録媒体６の搬送ベルト１２と接触する側の電気力線密度は高く、記録媒体６の非ベルト接触面側の密度は疎となる。そのとき、記録媒体６の下側と上側で電荷の差異が生じて、その差異分、搬送ベルトと吸着する向きに力が作用する。これはマクスウェル応力と呼ばれるもので、正負極性帯電の境目で発生する。
FIG. 4 is a diagram illustrating a state in which the recording medium is adsorbed by the electric charges formed on the conveyance belt.
By the charging roller, positive and negative charges are charged on the insulating layer 12a of the transport belt 12, and the recording medium 6 is fed thereto. Electric force lines are generated on the surface of the conveyor belt 12 from the positive charge on the belt toward the negative charge. Due to the influence of the electric lines of force, charges having the same polarity are generated on the side of the recording medium in contact with the conveying belt and the opposite side. The density of electric lines of force on the side of the recording medium 6 in contact with the conveying belt 12 is high, and the density on the non-belt contact surface side of the recording medium 6 is sparse. At this time, a difference in charge occurs between the lower side and the upper side of the recording medium 6, and a force acts in the direction in which the recording medium 6 is attracted to the conveyance belt. This is called Maxwell stress and occurs at the boundary between positive and negative polarity charging.
図５は、電荷が形成された搬送ベルトを上側から見た図である。
搬送ベルト１２の表面に形成される帯電幅について説明する。
搬送ベルト１２の表面にはプラスとマイナスの電荷がある幅（帯電幅）で形成される。図１に示すように、搬送ベルト１２上の残留電荷を除去する除電装置、好ましくは除電ブラシ２３を帯電ベルト表面電荷のうち記録媒体の搬送を終えて不要となった電荷を除去できる位置に設置する。
FIG. 5 is a view of the transport belt on which charges are formed as viewed from above.
The charging width formed on the surface of the conveyor belt 12 will be described.
The surface of the conveyor belt 12 is formed with a width (charge width) having positive and negative charges. As shown in FIG. 1, a neutralizing device for removing residual charges on the conveyor belt 12, preferably a neutralizing brush 23, is installed at a position where the charge on the surface of the charging belt can be removed when it is no longer needed after the recording medium is conveyed. To do.
図５に示すように，ベルト搬送ローラ１０の軸にはエンコーダ２５が固定され、エンコーダ読み取りセンサ２６によりエンコーダ２５の回転量を検出し、それに基づき搬送ベルト１２の位置及び移動量が制御部２７によって算出される。また、制御部２７は、高圧電源２８を制御し、搬送ベルト１２に形成される電荷の量及び帯電幅が所定の値となるように、第１帯電ローラ２１ａ，第２帯電ローラ２１ｂに印加するそれぞれの電圧の電圧値及び切り替え周波数等を制御し、また記録媒体搬送装置のモータの駆動タイミング等を制御する。 As shown in FIG. 5, an encoder 25 is fixed to the shaft of the belt conveyance roller 10, and the encoder reading sensor 26 detects the rotation amount of the encoder 25, and based on this, the position and movement amount of the conveyance belt 12 are controlled by the control unit 27. Calculated. In addition, the control unit 27 controls the high-voltage power supply 28 and applies it to the first charging roller 21a and the second charging roller 21b so that the amount of charge formed on the transport belt 12 and the charging width become predetermined values. The voltage value and switching frequency of each voltage are controlled, and the drive timing of the motor of the recording medium transport device is controlled.
図６は、搬送ベルトと帯電ローラとの位置関係を示す図で、図１の搬送ベルトを下側より見た図に相当する。
帯電ローラは複数設けられるが、本実施例では２本の帯電ローラ、すなわち第１帯電ローラ２１ａ、第２帯電ローラ２１ｂが、図６に示すように搬送ベルト１２に接触配置されている。第１帯電ローラ２１ａ，第２帯電ローラ２１ｂの２本の帯電ローラに高電圧を供給する高電圧電源２８には、２個のＤＣトランス（Ｔ１，Ｔ２）２８ａ，２８ｂが１枚の基板上に搭載されている。
FIG. 6 is a diagram showing the positional relationship between the conveyance belt and the charging roller, and corresponds to a view of the conveyance belt of FIG. 1 as viewed from below.
Although a plurality of charging rollers are provided, in this embodiment, two charging rollers, that is, a first charging roller 21a and a second charging roller 21b are arranged in contact with the conveying belt 12 as shown in FIG. In the high voltage power supply 28 for supplying a high voltage to the two charging rollers of the first charging roller 21a and the second charging roller 21b, two DC transformers (T1, T2) 28a, 28b are provided on one substrate. It is installed.
図７は、帯電ローラに印加される高電圧の波形、及び搬送ベルトが帯電した様子を示す図である。
第１帯電ローラ２１ａ、第２帯電ローラ２１ｂには、それぞれ図７に示すような波形の高電圧が印加される。正極性のＤＣ高電圧＋Ｖが搬送ベルトの回転方向上流側に位置する第１帯電ローラ２１ａに印加され、下流側に位置する第２帯電ローラ２１ｂには０Ｖ〜−Ｖをピークとする矩形波が印加される。つまり、上流の第１帯電ローラ２１ａで一度＋Ｖにて一様な正極性帯電を行い、下流の第２帯電ローラ２１ｂで負極性の帯電幅を作る形となる。
FIG. 7 is a diagram illustrating a waveform of a high voltage applied to the charging roller and a state in which the conveyance belt is charged.
A high voltage having a waveform as shown in FIG. 7 is applied to the first charging roller 21a and the second charging roller 21b. A positive DC high voltage + V is applied to the first charging roller 21a located upstream in the rotation direction of the conveyor belt, and a rectangular wave having a peak of 0V to -V is applied to the second charging roller 21b located downstream. Applied. In other words, uniform positive polarity charging is performed once at + V with the upstream first charging roller 21a, and negative polarity charging width is created with the downstream second charging roller 21b.
なお、２本の帯電ローラに印加される高電圧の波形を、図７に示す例と極性を逆にして、上流側の第１帯電ローラ２１ａに負極性の−Ｖ、下流側の第２帯電ローラ２１ｂに０Ｖ〜＋Ｖを印加しても同様の効果が得られる。２個のＤＣトランスＴ１，Ｔ２は、１つの高電圧電源基板に搭載されている。２本の帯電ローラによって、最終的には図５、図７に示すような、帯電幅を持った帯電が搬送ベルト１２上に形成される。 It should be noted that the waveform of the high voltage applied to the two charging rollers is reversed in polarity from the example shown in FIG. 7, the upstream first charging roller 21 a is negative -V, and the downstream second charging is performed. The same effect can be obtained by applying 0 V to + V to the roller 21b. The two DC transformers T1, T2 are mounted on one high voltage power supply board. The two charging rollers eventually form a charge having a charging width on the conveying belt 12 as shown in FIGS.
従来例である特許文献１に開示された技術としては、先に示した図８に示すように、１本の帯電ローラに−Ｖ〜＋Ｖをピークとする矩形波を印加する方法であったが、１本の帯電ローラを用いて、−Ｖ〜＋Ｖまで高電圧を切り替えることは、高電圧電源にとって大きな負荷であり、切り替え周波数を速くすることの妨げとなっていた。 As a technique disclosed in Patent Document 1 as a conventional example, as shown in FIG. 8 described above, a rectangular wave having a peak of −V to + V is applied to one charging roller. Switching a high voltage from −V to + V using a single charging roller is a heavy load for a high voltage power supply, and hinders an increase in switching frequency.
本発明によれば、切り替える電圧値が０〜−Ｖであり、従来の半分の切り替え幅ですむので、その分切り替え周波数を早くし、搬送ベルトに小さな帯電幅を作ることが可能となる。 According to the present invention, the voltage value to be switched is 0 to −V, which is half the conventional switching width. Therefore, the switching frequency can be increased by that amount, and a small charge width can be formed on the conveyor belt.
１…インクジェットプリンタ、２…インクジェットヘッド、３…キャリッジ、４…ガイドロッド、５…記録媒体積載部、６…記録媒体、７…給紙コロ、８…分離パッド、９…搬送ガイド、１０…ベルト搬送ローラ、１１…テンションローラ、１２…搬送ベルト、１２ａ…絶縁層（表層）、１２ｂ…中抵抗層（裏層）、１３…先端コロ、１４…排紙トレイ、１５…手差し給紙経路、２１ａ…第１帯電ローラ、２１ｂ…第２帯電ローラ、２３…除電ブラシ、２５…エンコーダ、２６…エンコーダ読み取りセンサ、２７…制御部、２８…高圧電源。 DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2 ... Inkjet head, 3 ... Carriage, 4 ... Guide rod, 5 ... Recording medium loading part, 6 ... Recording medium, 7 ... Paper feed roller, 8 ... Separation pad, 9 ... Conveyance guide, 10 ... Belt Conveying roller, 11 ... tension roller, 12 ... conveying belt, 12a ... insulating layer (surface layer), 12b ... medium resistance layer (back layer), 13 ... tip roller, 14 ... discharge tray, 15 ... manual feed path, 21a DESCRIPTION OF SYMBOLS 1st charging roller, 21b ... 2nd charging roller, 23 ... Static elimination brush, 25 ... Encoder, 26 ... Encoder reading sensor, 27 ... Control part, 28 ... High voltage power supply.
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| JP2014088241A (en) * | 2012-10-30 | 2014-05-15 | Kyocera Document Solutions Inc | Sheet transport device,image forming device,sheet transport method,charging control program,and recording medium |
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