JP4043738B2 - Image forming apparatus - Google Patents

Description

【０１０７】
上記表１において、○印しは良好、△は概ね良好、×は不良の評価である。上記表１の評価結果からからわかるように、トナーの流動度としては、（７．７）、（８．５）、（９．５）、（１４．３）が文字の中抜け及びニジミについて許容できる評価を得ている。表１では、流動度が７．７〜１４．３であるが、発明者による実験データの評価では流動度８〜１５において良好と判断された。よって、ワックスを有する着色粉体の流動性を８〜１５のものを使用することで、トナーの帯電量の変動が少なくなり安定した画像を得ることができ、中抜けも許容できたといえる。
【０１０８】
なお、参考として中間転写体に樹脂ベルトを使用して同評価を行ったところ、わずかではあるが文字の中抜けが発生した。
【０１０９】
［トナーの製造例］
結着樹脂
ポリエステル樹脂（テレフタル酸、フマル酸、ポリオキシプロピレン−（２，２）−２，２−ビス（４−ヒドロキシフェニル）プロパン、トリメリット酸から合成されたポリエステル樹脂、Ｔｇ：６２℃、軟化点：１０６℃）→１００部
着色剤
イエロートナー用顔料（ジスアゾイエロー顔料：Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｙｅｌｌｏｗ １７）→７．０部
マゼンタトナー用顔料（キナクリドン系マゼンタ顔料：Ｃ．Ｉ．ＰｉｇｍｅｎｔＲｅｄ １２２）→７．０部
シアントナー用顔料（銅フタロシアニンブルー顔料：Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌｕｅ １５：３）→３．５部
ブラックトナー用顔料（カーボンブラック：Ｃ．Ｉ．Ｐｉｇｍｅｎｔ Ｂｌａｃｋ ７）→６．０部
帯電制御剤
サリチル酸誘導体亜鉛塩→２．５部
離型剤
カルナウバワックス（融点：８５℃）→（５）部又は０部（前記表１に対応）
上記原材料を、ヘンシェルミキサーにて混合したのち、１１０℃に設定した２軸混練機にて溶融混練した。混練物を水冷後、カッターミルで粗粉砕し、ジェット気流を用いた微粉砕機で粉砕後、風力分級装置を用いて母体粒子を得た。
【０１１０】
更に、
上記母体粒子→１００部
添加剤
シリカ（ヘキサメチルジシラザン表面処理品、平均一次粒子径：０．０１μｍ）→（０．４〜０．８５）部（前記表１に対応）
チタニア（イソブチルトリメトキシシラン表面処理品、平均一次粒子径：０．０１５μｍ）→１．０部
をヘンシェルミキサーにて混合を行い、その後、さらに目開き１００μｍの篩により風篩を行い、製造例のトナー（重量平均径：６．８μｍ）を得た。
【０１１１】
ここで、トナーの粒度分布は種々の方法で測定可能であるが、本例においてはコールターマルチサイザーを用いて行なった。即ち、測定装置としてはコールターマルチサイザーIIｅ型（コールター社製）を用い、個数分布，体積分布を出力するインターフェイス(日科機社製)及びパーソナルコンピュータを接続し、電解液は１級塩化ナトリウムを用いて１％ＮａＣｌ水溶液を調製した。
【０１１２】
測定法としては、前記電解水溶液１００〜１５０ｍｌ中に分散剤として界面活性剤、好ましくはアルキルベンゼンスルフォン酸塩を０．１〜５ｍｌ加え、更に測定試料を２〜２０ｍｇ加え、超音波分散器で約１〜３分の分散処理を行った。
【０１１３】
さらに、別のビーカーに電解水溶液１００〜２００ｍｌを入れ、その中に前記サンプル分散液を所定の濃度になるように加え、前記コールターマルチサイザーIIｅ型によりアパーチャーとして１００μｍアパーチャーを用い、５０，０００個の粒子の平均を測定することにより行った。
【０１１４】
流動度については、以下の方法で各トナーについて測定した。
パウダーテスター（ホソカワミクロン社製）を用い、目開き１５０μｍ（例えば篩ａ）、７５μｍ（例えば篩ｂ）、及び４５μｍ（例えば篩ｃ）の各篩を記載順に上からａ、ｂ、ｃの順に上下方向に重なるように並べ、目開き１５０μｍの篩ａに２ｇの被検トナーを投入して、振幅１ｍｍ、５Ｈｚで３０秒間、振動を与え振動後における各篩ａ、ｂ、ｃ上のトナー重量を測定した。
【０１１５】
次に、これら各篩上の重量測定値、つまり、篩ａ上にあるトナー重量測定値をａ'とすればこのａ'に０．３を掛け、同様に篩ｂ上にあるトナー重量測定値ｂ'には０．３を掛け、また、篩ｃ上にあるトナー重量測定値ｃ'には０．１の各重み付けの定数を掛け、これらの各積の総和を全体重量２ｇで割り、百分率で表した。各種トナーについて上記の評価を行なった。
【０１１６】
中間転写体クリーニング装置１７で除去するトナーは、（＋）、（−）の各極性に帯電したものが混在する。そこで、これらのいずれの極性に帯電しているトナーについても除去できるように本例では、対をなすクリーニング部材のそれぞれに印加される電圧の極性を切り換える極性切換手段を具備することとした。
【０１１７】
前記図４の変形例を示した図６において、金属ローラ９２と電源９４との間にスイッチ９８、金属ローラ９３と電源９５との間にスイッチ９９をそれぞれ設けた。スイッチ９８については、実線で示すように電源９４の（−）極を金属ローラ９２に接続する状態と、破線で示すように電源９４の（−）極を金属ローラ９３に接続する状態とを切り換えることができる。
【０１１８】
同様に、スイッチ９９については、実線で示すように電源９５の（＋）極を金属ローラ９２に接続する状態と、破線で示すように電源９５の（＋）極を金属ローラ９２に接続する状態とを切り換えることができる。
【０１１９】
電気的な操作により、スイッチ９８、９９の上記切換が同時に行なわれ、これらは切換スイッチを構成している。これにより、金属ローラ９０、９１は適宜、印加される電圧の極性が切り換えの前後で逆極性に切り換えられる。スイッチ９８、９９からなる切換スイッチは極性切換手段の一例である。
【０１２０】
バイアス印加のタイミングの一例を図７に示す。
コピー動作中に、ジャムが発生すると機械は停止する。ドアーを開き、搬送経路の用紙を除去してドア―を閉じると「ドアー閉信号」が発生し、「メインモータ」が回転を開始してジャム処理後の動作が行なわれる。
【０１２１】
２次転写クラッチの「オン」信号により、中間転写体を感光体から離間させる。離間後、メインモータが動作を開始し、中間転写体に印されたマークをセンサで検知し、定間隔で「マーク信号」を出力する。同時に図６に示した切換スイッチが破線の状態に切り換えられることにより、ファーブラシ９０には（＋）のバイアス、ファーブラシ９１には（−）のバイアス電圧が印加される。
【０１２２】
ジャム時に中間転写体上に残った（−）極性のトナーをファーブラシ９０に（＋）極性を印加し効率よく除去する。除去されずに残ったトナーは（＋）傾向の極性となり、（−）のバイアス電圧が印加されているファーブラシ９１で除去される。
【０１２３】
ここで除去されずに残ったトナーは、中間転写体たるベルトの内側から（＋）の「１次転写バイアス」が印加されることで中間転写体の表面側は（−）に帯電し、このため、１次転写装置６２を通過するときには（−）電荷をもつ。このトナーがつぎに中間転写体クリーニング装置１７部に到来するまでの間に切換スイッチが実線の状態に切換られる。これにより（−）極性に切り換えられたブラシ９０により中間転写体上のトナーはさらに（−）帯電され、（＋）極性に切り換えられたブラシ９１で確実に除去される。
【０１２４】
こうして中間転写体クリーニング装置１７を通過したトナーは（＋）極に帯電されており、（＋）極の１次転写装置６２で感光体４０へ転写され、感光体クリーニング装置６３で回収されることとなり、中間転写体１０への残留の可能性は極めて少なくなっている。
【０１２５】
なお、中間転写体クリーニング装置として仮に通常使用されているクリーニングブレードを使用した場合には、クリーニングブレードが弾性層を含むことにより弾性を有する中間転写体に対して喰い込み状態となるため、中間転写体を駆動する際に駆動トルクが大きくなったり、表層部にクリーニングによる擦れ、引っ掻き傷が発生し易くなる。しかし、本例のように、中間転写体クリーニング装置１７として回転するクリーニング部材を使用した構成ではこのような不都合は生じない。
【０１２６】
【発明の効果】
請求項１記載の発明では、ブラシ回転による中間転写体負荷へ与える影響を低減させることでバンディングのない良好な画像を得ると共に中間転写体をクリーニングするクリーニング部材を通過したトナーを感光体に転写させ、さらに感光体クリーニング装置で回収してトナーリサイクル装置を介して現像装置へ戻すことにより再利用を図ることができ、中間転写体のクリーニングをより確実に行ない、かつ、転写時に各１次転写装置により印加するバイアスが隣の各画像形成手段に流れ込むのを阻止することができると共に極性転換手段の電気的操作によりクリーニングされるトナーの帯電極性は混在していても（＋）、（−）両者のトナーを効率よく除去することで中間転写体のクリーニングをより完全に行なうことが可能である。
【図面の簡単な説明】
【図１】本発明にかかる画像形成装置の概略構成図である。
【図２】本発明にかかる中間転写体の断面図である。
【図３】本発明にかかる画像形成装置の要部断面図である。
【図４】本発明にかかる画像形成装置の要部断面図である。
【図５】本発明にかかる中間転写体クリーニング装置の一例を示した図である。
【図６】本発明にかかる中間転写体クリーニング装置の一例を示した図である。
【図７】クリーニング部材の極性切り換えのタイミングを示したタイミングチャートである。
【符号の説明】
１０ 中間転写体
６２ 一次転写装置
７４ 補助ローラ
９０、９１ ファーブラシ
９８、９９ （極性転換手段の一例としての）スイッチ [0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a facsimile, and more particularly to an image forming apparatus provided with a cleaning unit for an intermediate transfer member.
[0002]
[Prior art]
A so-called tandem in which a plurality of photosensitive members made of a rotating member are arranged along an intermediate transfer member made of a rotating member, and an image formed on the photosensitive member is transferred to the intermediate transferring member to form a superimposed image. A type of image forming apparatus is known.
[0003]
Regarding this type of image forming apparatus, there is a technique disclosed in Japanese Patent Laid-Open No. 10-254251. In the technique disclosed in this publication, a toner image is transferred from a photosensitive member to an intermediate transfer member, and toner remaining on the intermediate transfer member after being transferred from the intermediate transfer member to a recording medium is removed from the intermediate transfer member with a brush. However, the portion that cannot be removed by this brush is transferred (reversely transferred) to the photoconductor using the bias electric field of the primary transfer means, which is a transfer means for the intermediate transfer body, from the photoconductor to the photoconductor. The technique of removing by this cleaning means is disclosed.
[0004]
In this disclosed technique, the toner remaining on the intermediate transfer body without being transferred from the intermediate transfer body to the recording medium is cleaned with a brush to which (+) polarity is applied, and the remaining toner without being cleaned is ( By charging (+), the (+) charged toner is reversely transferred to the photosensitive member side by the (+) electric field of the primary transfer means.
[0005]
As a technique related to this, it has been reported that a bias roller or a charger for charging toner with the same polarity as that in the primary transfer is used before the primary transfer means.
[0006]
The charged polarity of the toner to be cleaned is mixed. The toner remaining without being transferred has been changed to (+) polarity because it is affected by the secondary transfer electric field by the secondary transfer means which is a means for transferring the toner image from the intermediate transfer member to the recording medium. In addition, toner with (−) polarity remains mixed, and toner on the recording paper or the intermediate transfer member at the time of jamming or a toner pattern formed in a non-image area for image adjustment is developed on the photosensitive member. This is because the charge amount of (−) polarity, which is the charged polarity as it is, is substantially maintained.
[0007]
Therefore, the cleaning method using the charged polarity of the toner efficiently removes both the (+) and (-) toners if the toner has a polarity of either (+) or (-). I can't do it.
[0008]
For this reason, it is adjusted to the cleaning condition of the transfer residual toner on the intermediate transfer member. Further, the problem after the jam is generally dealt with by increasing the rotation time of the intermediate transfer member after the jam. However, if the rotation time increases, the waiting time after jam processing increases.
[0009]
In Japanese Patent Laid-Open No. 11-24424, in order to prevent image unevenness due to a shock at the time of contact with and separation from the intermediate transfer member by the intermediate transfer member cleaning unit with respect to the intermediate transfer member, the contact and separation of the cleaning unit to the intermediate transfer member is disclosed. And a technique for controlling the write timing. However, although it is possible to prevent the occurrence of image unevenness due to shock at the time of contact and separation by taking the timing of writing, there is a possibility that the writing interval becomes long and the copying speed becomes slow.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to provide an image forming apparatus capable of solving the problems in the prior art.
[0011]
  In the first aspect of the invention, in order to eliminate a shock at the time of contact with and separation from the intermediate transfer body by the intermediate transfer body cleaning means for the intermediate transfer body, the rotary brush for cleaning is always in contact with the intermediate transfer body, When doing so, if the brush is rotated in the reverse direction with respect to the belt rotation direction, the force that hinders the rotation of the intermediate transfer member will act greatly, causing load fluctuations, which will affect the rotation of the photoconductor and cause banding. Conversely, the forward rotation of the intermediate transfer member in the forward direction advances the rotation of the intermediate transfer member, speeds up the rotation of the photosensitive member, and similarly causes banding. By reducing the impact on the load, you get a good image without banding,Even if the charged polarity of the toner to be cleaned is mixed, it is possible to remove both (+) and (-) toner efficiently.It is an object to more reliably clean the intermediate transfer member.
[0017]
[Means for Solving the Problems]
  In order to achieve the object, the present invention has the following configuration.
  A tandem type in which a plurality of image forming means including the photoconductor are arranged on the intermediate transfer body so that an image formed on the photoconductor of the rotating body is transferred to an intermediate transfer body of the rotating body to form a superimposed image In the image forming apparatus,
  The image forming unit includes a charging device, a developing device, a primary transfer device, and a photosensitive member cleaning device around the photosensitive member, and a toner recycling device that returns the toner collected by the photosensitive member cleaning device to the developing device. Has
  A pair of cleaning members that contact the intermediate transfer member and rotate in the forward and reverse directions with respect to the rotation direction of the intermediate transfer member are provided, and one of the pair of cleaning members is a pair. A polarity voltage different from that of the other cleaning members forming the pair is applied, and the bias voltage is applied to the photosensitive member on the downstream side of the pair of cleaning members in the rotation direction of the intermediate transfer member with the intermediate transfer member interposed therebetween. The primary transfer device is applied, and a conductive auxiliary roller that contacts the base layer of the intermediate transfer member is disposed between the adjacent primary transfer devices, and the primary transfer device The intermediate transfer member is cleaned in cooperation with the pair of cleaning members, and the toner that has passed through the cleaning member is transferred to the photoreceptor.And polarity switching means for switching the polarity of the voltage applied to each of the pair of cleaning members, and the polarity switching means reverses the polarity of the voltage applied to each of the cleaning members before and after switching. Switch to polarity(Claim 1).
[0018]
DETAILED DESCRIPTION OF THE INVENTION
[1] Example of image forming apparatus to which the present invention is applied
2. Description of the Related Art Image forming apparatuses based on electrophotography are increasingly used in color, such as color copiers and color printers, according to market demands.
[0019]
In such a color image forming apparatus, a plurality of color developing devices are provided around one photoconductor, and a toner is attached to each of the developing devices to form a composite toner image on the photoconductor. A so-called one-drum type that records a color image on a sheet, and a plurality of photoconductors provided side by side, each having a developing device, and forming a single color toner image on each photoconductor, There is a so-called tandem type in which monochromatic toner images are sequentially transferred to record a composite color image on a sheet.
[0020]
Comparing the 1-drum type and the tandem type, since the 1-drum type has one photoconductor, it can be reduced in size and reduced in cost. (Normally 4 times) Since image formation is repeated to form a full-color image, there is a disadvantage that speeding up the image formation is limited, while the tandem type has the disadvantage that the size is increased and the cost is increased. There is an advantage that the speed can be increased. Recently, however, tandem-type cameras have been attracting attention because full-color and monochrome-like speeds are desired.
[0021]
The tandem type electrophotographic apparatus includes a direct transfer system in which images on each photoconductor are sequentially transferred to a sheet conveyed by a sheet conveying belt by a transfer device, and an image on each photoconductor by a primary transfer device. There is an indirect transfer type in which images are sequentially transferred to an intermediate transfer member and then transferred onto a sheet by a secondary transfer device.
[0022]
Comparing the direct transfer method with the indirect transfer method, the direct transfer method requires a paper feeder to be arranged upstream of a tandem image forming apparatus in which photoconductors are arranged, and a fixing device to be arranged downstream. However, there is a disadvantage that the size is increased. On the other hand, since the secondary transfer position can be set relatively freely, the indirect transfer method can be arranged so that the paper feeding device and the fixing device overlap with the tandem type image forming device, and can be downsized. There is an advantage to become.
[0023]
Further, the direct transfer method places the fixing device close to the tandem type image forming apparatus so as not to increase the size, and therefore the fixing device cannot be arranged with a sufficient margin that the sheet can bend. There is a drawback that the fixing device affects the image formation on the rear end side due to an impact when the leading edge of the sheet enters the fixing device or a difference in sheet conveyance speed when passing through the fixing device. On the other hand, in the indirect transfer method, the fixing device can be arranged with a sufficient margin that the sheet can be bent, so that the fixing device hardly affects the image formation.
[0024]
For these reasons, attention has recently been paid to the indirect transfer type among tandem type image forming apparatuses. The present invention is mainly applicable to an indirect transfer method.
[0025]
In this type of color image forming apparatus, the transfer residual toner remaining on the photoconductor after the primary transfer is removed by a photoconductor cleaning device to clean the surface of the photoconductor to prepare for another image formation. Further, the transfer residual toner remaining on the intermediate transfer member after the secondary transfer is removed by an intermediate transfer member cleaning device to clean the surface of the intermediate transfer member to prepare for another image transfer.
[0026]
  A tandem indirect transfer type image forming apparatus to which the present invention can be applied will be described below with reference to the drawings. Figure1In the figure, reference numeral 100 denotes a copying machine main body, 200 denotes a paper feed table on which the copying machine is placed, 300 denotes a scanner mounted on the copying machine main body 100, and 400 denotes an automatic document feeder (ADF) further mounted thereon.
[0027]
The copying machine main body 100 is provided with an endless belt-shaped intermediate transfer member 10 in the center. As shown in FIG. 2, in the intermediate transfer member 10, the base layer 11 is made of a material that is not easily stretched, such as a fluororesin having a thickness of 150 μm or a canvas, and an elastic layer 12 having a thickness of 150 μm is provided thereon. The elastic layer 12 is made of, for example, fluorine rubber or acrylonitrile-butadiene copolymer rubber. The surface of the elastic layer 12 is covered with a coating layer 13 having good smoothness by coating a fluorine resin having a thickness of 5 μm, for example.
[0028]
As shown in FIG. 1, in the illustrated example, it is wound around three support rollers 14, 15, 16 and can be rotated and conveyed clockwise in the figure. In this illustrated example, an intermediate transfer body cleaning device 17 for removing residual toner remaining on the intermediate transfer body 10 after image transfer is provided on the left of the second support roller 15 among the three.
[0029]
Four image forming units of black, cyan, magenta, and yellow are arranged on the intermediate transfer body 10 stretched between the first support roller 14 and the second support roller 15 among the three along the conveyance direction. The tandem image forming apparatus 20 is configured by arranging 18 horizontally. An exposure device 21 is further provided on the tandem image forming apparatus 20 as shown in FIG.
[0030]
A secondary transfer device 22 is provided on the side opposite to the tandem image forming apparatus 20 with the intermediate transfer body 10 interposed therebetween. In the illustrated example, the secondary transfer device 22 is configured by spanning a secondary transfer belt 24, which is an endless belt, between two rollers 23, and is pressed against the third support roller 16 via the intermediate transfer body 10. The image on the intermediate transfer body 10 is transferred to a sheet.
[0031]
A fixing device 25 for fixing the transfer image on the sheet is provided beside the secondary transfer device 22. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 that is an endless belt.
[0032]
The secondary transfer device 22 described above is also provided with a sheet transport function for transporting the image-transferred sheet to the fixing device 25. Of course, a non-contact charger may be arranged as the secondary transfer device 22, and in such a case, it is difficult to provide this sheet conveyance function together.
[0033]
In the illustrated example, a sheet reversing device 28 for reversing the sheet so as to record an image on both sides of the sheet is provided below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming device 20 described above. Is provided.
[0034]
When making a copy using this color copying machine, the document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed by it.
[0035]
When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. At that time, the scanner 300 is immediately driven to travel the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.
[0036]
When a start switch (not shown) is pressed, one of the support rollers 14, 15 and 16 is rotationally driven by a drive motor (not shown), the other two support rollers are driven to rotate, and the intermediate transfer member 10 is rotated and conveyed. At the same time, the individual image forming means 18 rotates the photoconductor 40 to form black, yellow, magenta, and cyan monochrome images on each photoconductor 40. Then, along with the conveyance of the intermediate transfer member 10, the single color images are sequentially transferred to form a composite color image on the intermediate transfer member 10.
[0037]
When a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and a sheet is fed out from one of paper feed cassettes 44 provided in multiple stages in the paper bank 43. The sheets are separated one by one and put into the paper feed path 46, transported by the transport roller 47, guided to the paper feed path 48 in the copying machine main body 100, and abutted against the registration roller 49 and stopped.
[0038]
Alternatively, the sheet feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped.
[0039]
The registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer member 10, the sheet is fed between the intermediate transfer member 10 and the secondary transfer device 22, and transferred on the sheet by the secondary transfer device 22. Record a color image on
[0040]
The image-transferred sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to fix the transferred image, and then the switching roller 55 is used to switch the discharge roller. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.
[0041]
After the image transfer, the intermediate transfer body 10 removes residual toner remaining on the intermediate transfer body 10 after the image transfer by the intermediate transfer body cleaning device 17, and prepares for the image formation by the tandem image forming apparatus 20 again.
[0042]
In the tandem type image forming apparatus 20, the individual image forming means 18 includes, for example, a charging device 60, a developing device 61, and a bias roller in this example, around a drum-shaped photoconductor 40 as shown in FIG. Primary transfer device 62, photoconductor cleaning device 63, static eliminator 64, and the like. In the illustrated example, the photoreceptor 40 is a drum-like rotating body in which a photosensitive organic photosensitive material is applied to a base tube such as aluminum and a photosensitive layer is formed. However, the photoreceptor 40 is an endless belt-like rotating body. Also good.
[0043]
Although not shown in the drawing, at least the photoconductor 40 is provided, and a process cartridge is formed by all or a part of the part constituting the image forming unit 18, and is removable from the copying machine main body 100 in a lump to improve maintenance. You may do it.
[0044]
Of the portions constituting the image forming unit 18, the charging device 60 is formed in a roller shape in the illustrated example, and charges the photosensitive member 40 by applying a voltage in contact with the photosensitive member 40.
[0045]
The developing device 61 may use a one-component developer. However, in the illustrated example, a two-component developer composed of a magnetic carrier and a nonmagnetic toner is used. Then, the agitation unit 66 conveys the two-component developer while stirring and adheres to the developing sleeve 65, and the developing unit 67 transfers the toner of the two-component developer attached to the developing sleeve 65 to the photoreceptor 40. The stirring unit 66 is positioned lower than the developing unit 67.
[0046]
The stirring unit 66 is provided with two parallel screws 68. A toner density sensor 71 is attached to the developing case 70.
[0047]
On the other hand, the developing portion 67 is provided with a developing sleeve 65 facing the photoreceptor 40 through the opening of the developing case 70, and a magnet 72 is fixedly provided in the developing sleeve 65. Further, a doctor blade 73 is provided with the tip approaching the developing sleeve 65.
[0048]
The two-component developer is conveyed and circulated while being stirred by two screws 68-and supplied to the developing sleeve 65. The developer supplied to the developing sleeve 65 is drawn up and held by the magnet 72 to form a magnetic brush on the developing sleeve 65. The magnetic brush is trimmed to an appropriate amount by the doctor blade 73 as the developing sleeve 65 rotates. The developer that has been cut off is transferred to the photosensitive member, the latent image is visualized, and the remaining part is returned to the stirring unit 66.
[0049]
Of the developer on the developing sleeve 65, the toner is transferred to the photoconductor 40 by the developing bias voltage applied to the developing sleeve 65, and the electrostatic latent image on the photoconductor 40 is visualized. After the visualization, the developer remaining on the developing sleeve 65 leaves the developing sleeve 65 and returns to the stirring unit 66 where there is no magnetic force of the magnet 72. When the toner concentration in the stirring unit 66 becomes light by this repetition, it is detected by the toner concentration sensor 71 and the stirring unit 66 is replenished with toner.
[0050]
Incidentally, in the illustrated example, the linear velocity of the photosensitive member 40 is 200 mm / s, and the linear velocity of the developing sleeve 65 is 240 mm / s. The developing process is performed with the diameter of the photoconductor 40 being 50 mm and the diameter of the developing sleeve 65 being 18 mm.
[0051]
The thickness of the photoreceptor 40 is 30 μm, the beam spot diameter of the optical system is 50 × 60 μm, and the light quantity is 0.47 mW. Further, the charging (pre-exposure) potential V of the photosensitive member 40.₀-700V, post-exposure potential V_LThe development process is performed with a development bias voltage of −470V, that is, a development potential of 350V.
[0052]
Next, the primary transfer device 62 is formed in a roller shape and is pressed against the photoconductor 40 with the intermediate transfer body 10 interposed therebetween. Separately, it is not limited to a roller shape, and may be a non-contact corona charger or the like.
[0053]
The photoconductor cleaning device 63 is provided with a cleaning blade 75 made of polyurethane rubber, for example, with its tip pressed against the photoconductor 40, and the outer periphery of the photoconductor cleaning device 63 contacts the photoconductor 40 and rotates the conductive fur brush 76 in the direction of the arrow. Prepare freely. Further, a metal electric field roller 77 for applying a bias to the fur brush 76 is rotatably provided in the direction of the arrow, and the tip of the scraper 78 is pressed against the electric field roller 77. Further, a collection screw 79 for collecting the removed toner is provided.
[0054]
Residual toner on the photoconductor 40 is removed by a fur brush 76 that rotates in the counter direction with respect to the photoconductor 40. The toner adhering to the fur brush 76 is removed by applying a bias by the electric field roller 77 that contacts the fur brush 76 and rotates in the counter direction. The electric field roller 77 is cleaned by a scraper 78. The toner recovered by the photoconductor cleaning device 63 is brought to one side of the photoconductor cleaning device 63 by the recovery screw 79 and returned to the developing device 61 by the toner recycling device 80 for reuse. The static eliminator 64 is a lamp, for example, and initializes the surface potential of the photoreceptor 40 by irradiating light.
[0055]
As the photoconductor 40 rotates, the surface of the photoconductor 40 is first uniformly charged by the charging device 60, and then the writing light Lb from the exposure device 21 described above is emitted from the exposure device 21 according to the reading content of the scanner 300. Thus, an electrostatic latent image is formed on the photoconductor 40.
[0056]
Thereafter, toner is attached by the developing device 61 to visualize the electrostatic latent image, and the visible image is transferred onto the intermediate transfer member 10 by the primary transfer device 62. The surface of the photoconductor 40 after the image transfer is cleaned by removing residual toner with the photoconductor cleaning device 63, and is neutralized with the static eliminator 64 to prepare for another image formation.
[0057]
FIG. 4 is an enlarged view of a main part of the color copying machine shown in FIG. In the figure, each image forming unit 18 of the tandem image forming apparatus 20, each photoconductor 40 of the image forming unit 18, each developing device 61, each photoconductor cleaning device 63, and each photoconductor 40 of each image forming unit 18. After the respective symbols of the respective primary transfer devices 62 provided opposite to each other, BK is added for black, Y for yellow, M for magenta, and C for cyan. Show.
[0058]
4 is a conductive auxiliary roller provided in contact with the base layer 11 side of the intermediate transfer body 10 between the primary transfer devices 62, although not shown in FIGS. . The auxiliary roller 74 has a bias applied by each primary transfer device 62 (62BK, 62Y, 62M, 62C) at the time of transfer, and the adjacent image forming means 18 (18BK, 18Y, 18M, 18C).
[0059]
The toner is mixed with a charge control agent (CCA) and a colorant in a resin such as polyester, polyol, and styrene acrylic, and by adding a substance such as silica and titanium oxide around the resin, its charging characteristics and fluidity. Is increasing. The particle size of the additive is usually in the range of 0.01 to 1.5 [μm]. Examples of the colorant include carbon black, phthalocyanine blue, quinacridone, and carmine. The charging polarity is negative charging in the illustrated example.
[0060]
The particle diameter of the toner is preferably 4 to 9 μm, particularly preferably 5 to 8 μm, in terms of weight average diameter.
[0061]
Magnetic particles (carriers) contain a magnetic material such as ferrite with a metal or resin as a core, and the surface layer is coated with a silicon resin or the like. The particle size is preferably in the range of 10 to 100 μm, preferably 30 to 60 μm. The resistance is a dynamic resistance of 10⁴-10⁶The range of Ω is optimal. However, the measurement method is to carry a magnet (65 mm; 600 RPM) and contact an electrode with a width of 65 mm and a length of 1 mm with a gap of 0.9 mm, and the upper limit voltage level (high resistance silicon coating) It is a measured value when an applied voltage of 400 V is applied to the carrier and several volts is applied to the iron powder carrier. The mixing ratio of toner and magnetic particles (carrier) is suitably about 0.5 to 7.0 parts by weight of toner with respect to 100 parts by weight of magnetic particles.
[0062]
  [2]Example corresponding to a claim
  FigureAs shown in FIG. 4, the cleaning device 17 that cleans the intermediate transfer belt 10 makes two brush-shaped rotating bodies contact each other as a cleaning member. These rotating bodies include fur brushes 90 and 91. A bias is applied to each of the fur brushes 90 and 91.
[0063]
The fur brushes 90 and 91 are in contact with the intermediate transfer body 10 with the same diameter and the same contact pressure. In the rotational direction of the intermediate transfer member 10, the fur brush 90 on the upstream side is rotationally driven so that the contact portion with the intermediate transfer member 10 moves in the direction opposite to the rotational direction of the intermediate transfer member 10. That is, the intermediate transfer member 10 rotates in the same direction as the rotation direction (clockwise direction).
[0064]
The fur brush 91 is rotationally driven so that the contact portion with the intermediate transfer member 10 moves in the same direction as the rotation direction of the intermediate transfer member 10. That is, the intermediate transfer member 10 rotates in the opposite direction (counterclockwise direction) to the rotation direction.
[0065]
For the fur brush 90 on the upstream side, the outer peripheral speed of the brush is 234 mm / sec (linear speed ratio: 1.3) with respect to the peripheral surface speed of 180 mm / sec of the intermediate transfer member 10.
[0066]
The fur brush 91 on the downstream side rotates in the forward direction (counterclockwise direction), and the outer peripheral speed of the brush is 234 mm / sec (linear speed ratio: 1.3), which is the same as the fur brush 90 on the upstream side. It is. If the diameters of the fur brushes 91 and 90 are the same, the drive transmission system can be configured with the same gear ratio and the drive source can be shared if both rotation speeds are the same. Convenient.
[0067]
By configuring the fur brushes 90 and 91 that make a pair in this manner so that one of them rotates in the forward direction and the other in the reverse direction, the fur brush 91 that rotates in the forward direction promotes the rotation of the intermediate transfer member 10, The fur brush 91 that rotates in the reverse direction functions to suppress the rotation of the intermediate transfer member 10, and the rotation of the intermediate transfer member 10 is stabilized by the action of both of them.
[0068]
That is, since the cleaning brushes 90 and 91 rotate in the reverse direction with respect to the intermediate transfer body 10, the brush rotation speed can be set low without increasing the torque with respect to the belt, and the load of driving the brush is reduced. Can prevent banding and the like, and can apply residual (+) and (-) polarities to the fur brushes 90 and 91 to provide residual toner after transfer or toner after jamming. It seems that the removal can be done completely.
[0069]
If the cleaning member (brush, blade, roller, etc.) is simply in contact with the intermediate transfer member 10 without being configured as in this example, a load is applied to the load of the intermediate transfer member 10, and the load Fluctuation is likely to affect the rotation of the photoconductor and cause banding.
[0070]
On the other hand, as in this example, one of the paired fur brushes 90 and 91 rotates in the forward direction with respect to the rotation direction of the intermediate transfer member, and the other one rotates in the direction opposite to the rotation direction of the intermediate transfer member. Thus, without increasing the torque with respect to the intermediate transfer member 10, the load fluctuation of the intermediate transfer member 10 can be suppressed, the rotation of the photosensitive member 40 can be stabilized, the occurrence of banding can be suppressed, and the rotation of the fur brush can be suppressed. Since the speed can be set low, the driving load can be reduced.
[0071]
In particular, in an image forming apparatus that includes a plurality of photoconductors 40 around the intermediate transfer member 10 and forms a color image as in the present example, banding can be suppressed for each color. An image with an image quality can be obtained.
[0072]
In the tandem intermediate transfer belt system in which a plurality of photoconductors abut on the intermediate transfer body 40, a plurality of photoconductors abut at the same time, and a slight speed difference occurs between the intermediate transfer body 40 and the photoconductor. Due to the fact that load fluctuation is likely to occur due to the generated electrostatic force or physical frictional force, if a cleaning brush that rotates only in one direction is provided and abuts against the intermediate transfer member 10, the load fluctuation will be further increased. This is likely to occur and causes banding unevenness called banding. In this example, such a point can be eliminated.
[0073]
Each of the fur brushes 90 and 91 that are driven to rotate are brought into contact with metal rollers 92 and 93 as bias rollers, respectively, so that the toner attached to the brush is collected by an electric field. . The metal rollers 92 and 93 are pressed against the tips of the blades 96 and 97, respectively, so that the objects to be cleaned collected on the metal rollers 92 and 93 are removed. The toner scraped off by these blades is discharged through a collection pipe (not shown).
[0074]
Each fur brush 90, 91 is connected to a high voltage power supply for bias to apply a bias. In this example, a (−) voltage is applied from the power source 94 to the metal roller 92 on the upstream side in the rotation direction of the intermediate transfer member 10, and the metal roller 92 is applied to the fur brush 91 on the downstream side of the fur brush 90 in the rotation direction of the intermediate transfer belt 10. A (+) voltage is applied from a power source 95 to the metal roller 93 that rotates in contact therewith.
[0075]
  In this way, a voltage drop is caused by applying a voltage only to the metal rollers 92 and 93 and causing a current to flow through the intermediate transfer member 10."Metal rollers 92, 93"~"Conductive fur brush 90, 91"~"Intermediate transfer member 10"A potential difference is generated in each of the toners, and toner movement occurs. Of course, it is possible to apply a bias to the fur brushes 90 and 91 instead of the metal rollers 92 and 93.
[0076]
For example, when -700V is applied to the power supply 94, the fur brush 90 has a potential of -500V. When +800 V is applied to the power supply 95, the fur brush 91 has a potential of + 450V.
[0077]
Due to the potential difference, the toner moves from the intermediate transfer member 10 to the fur brushes 90 and 91 and from the fur brushes 90 and 91 to the metal rollers 92 and 93. The toner that is not removed by the fur brush 90 to which the (−) polarity is applied becomes (−) polarity after passing through the fur brush 90, and is removed by the fur brush 91 to which the (+) polarity is applied.
[0078]
Further, the toner that has not been removed by the fur brush 91 is charged to (+) after passing through the fur brush 91, and (+) polarity is applied by the primary transfer devices 62BK, 62Y, 62M, and 62C composed of rollers, and photosensitive. It moves to the body 40C and is collected by the photoreceptor cleaning 63C, and is collected in a collection container by a discharge coil (not shown).
[0079]
As described above, the cleaning of the intermediate transfer body 10 is further performed in cooperation with the primary transfer device 62C applied with a bias voltage provided downstream of the fur brushes 90 and 91 as the cleaning members in the rotation direction of the intermediate transfer body 10. It can be done reliably.
[0080]
In this example, the fur brushes 90 and 91 are used as the cleaning members. However, there is an example in which a conductive hydrin rubber roller is provided in place of the fur brushes 90 and 91 and a bias is applied thereto.
[0081]
In the example shown in FIG. 5, a conductive hydrin rubber roller 105 is provided in place of the fur brush 90, and the blade 101 can be directly applied. A power source 102 is provided in place of the power source 94 shown in FIG. 4 to bias the conductive hydrin rubber roller 105, and a power source 103 is provided in place of the power source 95 to apply a bias voltage to the metal 93. The conductive hydrin rubber roller 105 is rotated in the forward direction with respect to the intermediate transfer member 10, and the fur brush 91 is rotated in the reverse direction.
[0082]
  During ~Insulating materials such as polypropylene and rayon are used as the brush material used for fur brush cleaning, which uses a fur brush as a cleaning means for the intermediary transfer member. In order to remove it, it is generally necessary to increase the brush rotation speed. Usually, the linear velocity ratio with respect to the photoreceptor is 3 or more.
[0083]
If an insulating brush is used as a cleaning means for the intermediate transfer member 10, the brush must be rotated at a high speed as described above, and a large load is applied to the driving load of the brush and the driving of the intermediate transfer member due to contact with the intermediate transfer member 10. As a result, it becomes difficult to form a high-quality image using an intermediate transfer member that requires a uniform image such as a photograph, particularly in color image formation.
[0084]
Therefore, in this example, the fur brushes 90 and 91 constituting the brush-shaped cleaning member are medium resistance fibers, so that an electrostatic force can be used in addition to a physical scratching force on the intermediate transfer member 10. The toner is removed by utilizing this electrostatic force, the fur brush is rotated at a relatively low rotation, and the load on the intermediate transfer member 10 due to the brush rotation can be reduced. I was able to get a good image.
[0085]
The conductive fur brush is either grounded or used with a bias voltage applied, but it can be used at a relatively low rotational speed because the electrostatic attraction force acts to remove the toner. it can.
[0086]
But 1x10⁴If it is less than Ω, a discharge occurs between the surface of the charged image carrier (intermediate transfer member) and the tip of the brush, and local charge unevenness is likely to occur, and control abnormalities are likely to occur. When a bias voltage is applied to the brush, a large amount of current flows, so it is necessary to increase the high-voltage power source capacity, and the current becomes excessive when the humidity is high. Conversely, 1x10⁸If it exceeds Ω, it becomes difficult for current to flow and the applied voltage also increases, and in any case, it is difficult to obtain an electric field between the brush tip and the image carrier (intermediate transfer member) necessary for cleaning. Therefore, the resistance value of the fur brush is 1 × 10⁴Ω ～ 1 × 10⁸It is recommended to use Ω medium resistance fiber.
[0087]
In this example, the above medium resistance fibers are used as the fur brushes 91 and 92. As the brush, carbon black-dispersed acrylic fiber (SA7: manufactured by Toray) was used. Fiber thickness is 6.5D / F, 100,000 pieces / inch²Was wound around a metal core having a diameter of 10 mm to obtain a brush having a diameter of 20 mm. The brush raw cloth is electrically connected to the cored bar by conducting a conductive treatment. Since a voltage is applied to the brush, it is electrically floating with respect to the machine body.
[0088]
The fur brushes 90 and 91 manufactured in this way are 1 × 10.⁵Has Ω resistance. The measurement of resistance was performed by applying an electrode having a width of 10 mm to the brush by 1 mm and applying 100 V between the metal core and the electrode, and the measured value after 10 seconds was taken as the resistance value.
[0089]
The bias application conditions for the fur brushes 90 and 91 are as described in the above section 2-1. Incidentally, even if the evaluation environment is changed from room temperature 10 ° C. and relative humidity 15% to room temperature 27 ° C. and relative humidity 80%, good cleaning can be performed, and the occurrence of poor cleaning such as background stains and afterimages can be generated. I was able to prevent it.
[0090]
In this example, the fur brushes 90 and 91 are used as the cleaning members, but there is an example in which a bias is applied to the conductive hydrin rubber roller instead of the fur brushes 90 and 91. Such roller resistance is obtained by placing a roller on a metal flat plate, 2 kg / cm.²The measured value 10 seconds after applying 500V in the state which applied this pressure is made into resistance value. 1 × 10⁵Good results were obtained using Ω rubber rollers.
[0091]
  ArrivalBy including at least a wax in the colored powder (toner) for forming a color image, it is possible to perform oilless fixing without using silicone oil for fixing. Such oil-less fixing does not apply silicone oil to the fixing roller, which improves copy writing and erasability, improves running costs, eliminates the need for oil leakage during machine transportation, and eliminates the need for oil replenishment. There are benefits.
[0092]
However, the wax used is partially distributed on the toner surface, and the fluidity is lowered (deteriorated).
[0093]
When the fluidity of the toner decreases (deteriorates), the toner image is condensed by the respective transfer pressures in the primary transfer from the photosensitive member to the intermediate transfer member and the secondary transfer from the intermediate transfer member to the final recording medium paper. Is not transferred, so-called character dropout phenomenon occurs.
[0094]
Further, the wax component is easy to form a film, and is rubbed by cleaning of the photosensitive member and the intermediate transfer member during image formation, so that a thin layer is formed on the surface of the image carrier and so-called filming is likely to occur. When filming occurs, an abnormal image such as image unevenness occurs.
[0095]
Therefore, in this example, the intermediate transfer member 10 having at least one elastic layer is used to prevent the hollowing out phenomenon. At least one layer as an intermediate transfer member has an elastic layer according to the toner image when the toner image is transferred from the photosensitive member 40 to the intermediate transfer member 10 and from the intermediate transfer member 10 to the final recording medium by using an elastic belt. When an intermediate transfer member is used, even in a portion of a toner image having a low fluidity, a dent is generated in the belt portion of the intermediate transfer member due to elasticity, so that it is difficult to cause a void.
[0096]
Here, the relationship between the character dropout phenomenon and the toner fluidity will be described. In a conventional configuration that does not have an elastic layer as an intermediate transfer body, it is considered that the cause of missing characters is due to aggregation of toner images. When the toner has a low fluidity, the toner image moves integrally during transfer from the photosensitive member to the intermediate transfer member and from the intermediate transfer member to the transfer paper (final transfer member). For this reason, the toner image remains on the intermediate transfer member and the transfer paper on the side having a strong adhesion.
[0097]
In general, the adhesive force between the intermediate transfer member receiving the transfer pressure during transfer and the toner is strong, and the toner tends to remain on the intermediate transfer member side. Since a line image has a large amount of toner near the center of the image, a toner with low fluidity has a strong cohesive force at the center portion, and a void phenomenon occurs due to the toner remaining on the intermediate transfer member side only at the center portion. . Such a hollow phenomenon is not improved by the transfer electric field.
[0098]
However, when a belt having an elastic layer is used as an intermediate transfer member, the elastic layer stretches and dents elastically with respect to the toner image (toner layer), so that excessive pressure does not act on the toner, and the toner image (toner The layer is transferred without being hollowed out.
[0099]
On the other hand, in order to change the fluidity of the toner, an additive such as silica is generally added. However, since silica or the like has a high charging capability, the amount of charge as a developer is changed, or the amount of charge is fluctuated due to environmental fluctuations, and image fluctuations such as image unevenness are likely to occur.
[0100]
The interrelation between the voids, the toner fluidity, the charge amount, and the inclusion of an elastic layer in the intermediate transfer member is as follows.
By adding wax to the toner, the fluidity of the toner decreases. When the transfer pressure is applied due to the decrease in the fluidity, the toner image (the toner image corresponding to the document formed in a laminated state on the intermediate transfer member) is aggregated. This agglomerated state is similar to, for example, a phenomenon that smooth powder does not return to smooth powder when it is gripped with force.
[0101]
An additive such as silica is added to improve the toner having lowered fluidity. By interposing the silica between the toners, aggregation of the toners is prevented, and the fluidity is improved.
[0102]
However, if the amount of the additive added to improve the fluidity is increased, the charge amount of the toner is likely to change this time. Further, the additive separated from the toner adheres to the surface of the photoconductor and grows in dots to easily appear on an image, thereby impairing the image quality.
[0103]
In this regard, by using a belt having an elastic layer in at least one layer as an intermediate transfer member, a toner having a lower fluidity than a toner used in a conventional resin belt not including an elastic layer as an intermediate transfer member. Even if it is used, the toner portion is recessed as described above, and an image without voids can be obtained. Therefore, the additive added to the toner can be reduced, and the charge amount can be prevented from easily changing.
[0104]
In this example, a toner containing wax is used, and at least one layer having an elastic layer is used as an intermediate transfer member to form an image. (Two combinations of (red), G (green), and B (blue)) were evaluated. Bleeding is caused by toner scattering at the time of transfer for toner having a high fluidity, and the fluidity is unlikely to increase and shows a tendency opposite to that of a void. Therefore, what is the value of the fluidity that can be reduced to the extent that the image quality is not impaired for both hollow and blemishes, and what value should be set for the silica content ratio corresponding to the fluidity? Is required. Therefore, an experiment was conducted.
[0105]
As described with reference to FIG. 2, the intermediate transfer member used was one made of an elastic layer, and the toner manufactured by the manufacturing method described later was used.
In the toner, the addition amount of carnauba wax and silica was changed according to the toner production conditions in the above examples.
Using the toner manufactured according to the following table, copy image evaluation was performed using imgioColor 3100 manufactured by Ricoh. As the manuscript, R (red), G (green), B (blue), and Bk (black) character manuscripts were appropriately created and output to the printer.
[0106]
[Table 1]

[0107]
In Table 1 above, ◯ indicates good, Δ is generally good, and x is poor. As can be seen from the evaluation results in Table 1 above, as the toner fluidity, (7.7), (8.5), (9.5), and (14.3) are the character omission and blurring. It has an acceptable rating. In Table 1, the fluidity is 7.7 to 14.3, but in the evaluation of the experimental data by the inventor, it was judged that the fluidity was 8 to 15. Therefore, it can be said that by using a colored powder having wax having a fluidity of 8 to 15, fluctuations in the charge amount of the toner are reduced, a stable image can be obtained, and voids can be allowed.
[0108]
As a reference, the same evaluation was performed using a resin belt as an intermediate transfer member.
[0109]
[Example of toner production]
Binder resin
Polyester resin (terephthalic acid, fumaric acid, polyoxypropylene- (2,2) -2,2-bis (4-hydroxyphenyl) propane, polyester resin synthesized from trimellitic acid, Tg: 62 ° C., softening point: 106 ° C) → 100 parts
Colorant
Yellow toner pigment (disazo yellow pigment: CI Pigment Yellow 17) → 7.0 parts
Magenta Toner Pigment (Quinacridone Magenta Pigment: CI Pigment Red 122) → 7.0 parts
Pigment for cyan toner (copper phthalocyanine blue pigment: CI Pigment Blue 15: 3) → 3.5 parts
Black toner pigment (carbon black: CI Pigment Black 7) → 6.0 parts
Charge control agent
Salicylic acid derivative zinc salt → 2.5 parts
Release agent
Carnauba wax (melting point: 85 ° C.) → (5) part or 0 part (corresponding to Table 1 above)
The raw materials were mixed with a Henschel mixer and then melt-kneaded with a biaxial kneader set at 110 ° C. The kneaded product was cooled with water, coarsely pulverized with a cutter mill, pulverized with a fine pulverizer using a jet stream, and mother particles were obtained using an air classifier.
[0110]
Furthermore,
The base particle → 100 parts
Additive
Silica (hexamethyldisilazane surface-treated product, average primary particle size: 0.01 μm) → (0.4 to 0.85) part (corresponding to Table 1 above)
Titania (isobutyltrimethoxysilane surface-treated product, average primary particle size: 0.015 μm) → 1.0 part
Were mixed with a Henschel mixer, and then further subjected to air sieving with a sieve having an opening of 100 μm to obtain a toner (weight average diameter: 6.8 μm) of Production Example.
[0111]
Here, the particle size distribution of the toner can be measured by various methods. In this example, the particle size distribution was performed using a Coulter Multisizer. That is, Coulter Multisizer IIe type (manufactured by Coulter Co.) is used as a measuring device, and an interface (manufactured by Nikkaki Co., Ltd.) for outputting the number distribution and volume distribution is connected to a personal computer. A 1% NaCl aqueous solution was prepared.
[0112]
As a measurement method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added to 100 to 150 ml of the electrolytic aqueous solution, and 2 to 20 mg of a measurement sample is further added. A dispersion treatment of ˜3 minutes was performed.
[0113]
Further, 100 to 200 ml of the electrolytic aqueous solution was put into another beaker, and the sample dispersion was added to a predetermined concentration, and 50,000 pieces were used as the aperture by the Coulter Multisizer IIe type. This was done by measuring the average of the particles.
[0114]
The fluidity was measured for each toner by the following method.
Using a powder tester (manufactured by Hosokawa Micron Co., Ltd.), each sieve having an aperture of 150 μm (for example, sieve a), 75 μm (for example, sieve b), and 45 μm (for example, sieve c) is arranged in the vertical direction from top to bottom in the order of description. 2 g of test toner is put on a sieve a having an opening of 150 μm, and vibration is applied for 30 seconds at an amplitude of 1 mm and 5 Hz. did.
[0115]
Next, if the weight measurement value on each sieve, that is, the toner weight measurement value on the sieve a is a ′, this a ′ is multiplied by 0.3, and similarly the toner weight measurement value on the sieve b b ′ is multiplied by 0.3, and the toner weight measurement c ′ on the sieve c is multiplied by each weighting constant of 0.1, and the sum of these products is divided by the total weight of 2 g to obtain a percentage. Expressed in The above evaluation was performed on various toners.
[0116]
  During ~The toner to be removed by the intermediary transfer body cleaning device 17 is a mixture of toners charged to the respective polarities (+) and (−). Therefore, in this example, polarity switching means for switching the polarity of the voltage applied to each of the pair of cleaning members is provided so that any of these charged toners can be removed.
[0117]
In FIG. 6 showing the modification of FIG. 4, a switch 98 is provided between the metal roller 92 and the power source 94, and a switch 99 is provided between the metal roller 93 and the power source 95. The switch 98 switches between a state in which the (−) pole of the power source 94 is connected to the metal roller 92 as indicated by a solid line and a state in which the (−) pole of the power source 94 is connected to the metal roller 93 as indicated by a broken line. be able to.
[0118]
Similarly, the switch 99 has a state in which the (+) pole of the power source 95 is connected to the metal roller 92 as shown by a solid line and a state in which the (+) pole of the power source 95 is connected to the metal roller 92 as shown by a broken line. And can be switched.
[0119]
By the electric operation, the switches 98 and 99 are switched at the same time, and these constitute a change-over switch. Thereby, the polarity of the voltage applied to the metal rollers 90 and 91 is appropriately switched to the reverse polarity before and after switching. The changeover switch including the switches 98 and 99 is an example of the polarity changeover means.
[0120]
An example of bias application timing is shown in FIG.
If a jam occurs during the copy operation, the machine stops. When the door is opened, the paper in the transport path is removed, and the door is closed, a “door close signal” is generated, and the “main motor” starts rotating to perform the operation after the jam processing.
[0121]
The intermediate transfer member is separated from the photosensitive member by an “ON” signal of the secondary transfer clutch. After the separation, the main motor starts to operate, the mark marked on the intermediate transfer member is detected by the sensor, and the “mark signal” is output at regular intervals. At the same time, the changeover switch shown in FIG. 6 is switched to the state of the broken line, whereby a (+) bias voltage is applied to the fur brush 90 and a (−) bias voltage is applied to the fur brush 91.
[0122]
The (−) polarity toner remaining on the intermediate transfer member during the jam is applied to the fur brush 90 with the (+) polarity and is efficiently removed. The toner that remains without being removed has a polarity of (+) tendency and is removed by the fur brush 91 to which a bias voltage of (−) is applied.
[0123]
The toner remaining without being removed here is charged with (−) on the surface side of the intermediate transfer member by applying a (+) “primary transfer bias” from the inside of the belt as the intermediate transfer member. Therefore, when passing through the primary transfer device 62, it has a (−) charge. The changeover switch is changed to a solid line until the toner next reaches the intermediate transfer member cleaning device 17. As a result, the toner on the intermediate transfer member is further (-) charged by the brush 90 switched to the (-) polarity and reliably removed by the brush 91 switched to the (+) polarity.
[0124]
The toner passing through the intermediate transfer body cleaning device 17 is charged to the (+) pole, transferred to the photoreceptor 40 by the primary transfer device 62 of the (+) pole, and collected by the photoreceptor cleaning device 63. Therefore, the possibility of remaining on the intermediate transfer member 10 is extremely reduced.
[0125]
If a cleaning blade that is normally used as an intermediate transfer member cleaning device is used, the cleaning blade includes an elastic layer, so that the intermediate transfer member has an elastic state, so that the intermediate transfer member is in an ingested state. When the body is driven, the driving torque is increased, and the surface layer part is easily rubbed and scratched by cleaning. However, such a problem does not occur in the configuration using the rotating cleaning member as the intermediate transfer member cleaning device 17 as in this example.
[0126]
【The invention's effect】
  According to the first aspect of the present invention, it is possible to obtain a good image without banding by reducing the influence of the brush rotation on the load on the intermediate transfer member, and to transfer the toner that has passed through the cleaning member for cleaning the intermediate transfer member to the photosensitive member. Further, it can be reused by being collected by the photoconductor cleaning device and returned to the developing device via the toner recycling device, so that the intermediate transfer member can be more reliably cleaned and each primary transfer device at the time of transfer. Can prevent the bias applied from flowing into the adjacent image forming means.At the same time, even if the charged polarity of the toner to be cleaned by electrical operation of the polarity changing means is mixed, the intermediate transfer member can be more completely cleaned by efficiently removing both the (+) and (-) toners. Is possibleRu.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present invention.
FIG. 2 is a cross-sectional view of an intermediate transfer member according to the present invention.
FIG. 3 is a cross-sectional view of a main part of the image forming apparatus according to the present invention.
FIG. 4 is a cross-sectional view of a main part of the image forming apparatus according to the present invention.
FIG. 5 is a diagram showing an example of an intermediate transfer member cleaning device according to the present invention.
FIG. 6 is a diagram showing an example of an intermediate transfer member cleaning device according to the present invention.
FIG. 7 is a timing chart showing the timing for switching the polarity of the cleaning member.
[Explanation of symbols]
10 Intermediate transfer member
62 Primary transfer device
74 Auxiliary roller
90, 91 Fur brush
98, 99 (as an example of polarity changing means) switch

Claims (1)

A tandem type in which a plurality of image forming means including the photoconductor are arranged on the intermediate transfer body so that an image formed on the photoconductor of the rotating body is transferred to an intermediate transfer body of the rotating body to form a superimposed image In the image forming apparatus,
The image forming unit includes a charging device, a developing device, a primary transfer device, and a photosensitive member cleaning device around the photosensitive member, and a toner recycling device that returns the toner collected by the photosensitive member cleaning device to the developing device. Has
A pair of cleaning members that contact the intermediate transfer member and rotate in the forward and reverse directions with respect to the rotation direction of the intermediate transfer member are provided, and one of the pair of cleaning members is a pair. A polarity voltage different from that of the other cleaning members forming the pair is applied, and the bias voltage is applied to the photosensitive member on the downstream side of the pair of cleaning members in the rotation direction of the intermediate transfer member with the intermediate transfer member interposed therebetween. The primary transfer device is applied, and a conductive auxiliary roller that contacts the base layer of the intermediate transfer member is disposed between the adjacent primary transfer devices, and the primary transfer device together perform cleaning of the intermediate transfer body in cooperation with the cleaning member forming the pair, to transfer the toner having passed through the cleaning member to the photosensitive member, and, chestnut forming the pair Comprises a polarity switching means for switching the polarity of the voltage applied to each of the training members, the polarity of the voltage of the polar switching means applied to each of the cleaning member, a switch between the reversed polarity before and after the switching An image forming apparatus.

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