JP2007127903A

JP2007127903A - Image forming apparatus

Info

Publication number: JP2007127903A
Application number: JP2005321625A
Authority: JP
Inventors: Hideki Kimura; 秀樹木村; Shunji Kato; 俊次加藤; Hideo Yoshizawa; 秀男吉沢; Katsumi Masuda; 克己増田; Yoshio Hattori; 良雄服部; Kiyotaka Sakai; 清敬堺; Kenji Nakajima; 研二中島
Original assignee: Ricoh Co Ltd
Current assignee: Ricoh Co Ltd
Priority date: 2005-11-04
Filing date: 2005-11-04
Publication date: 2007-05-24

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer carrier capable of suppressing occurrence of pitch-like vertical black streaks and horizontal black streaks. <P>SOLUTION: In the developer carrier having twill line-like grooves formed in such a way that a plurality of grooves extending in a direction inclined at a sharp angle to a rotation thrust direction intersect with a plurality of grooves extending in a direction inclined at a sharp angle to a direction opposite to the thrust direction, the distance (a) between groove intersection points of the twill line-like grooves in the thrust direction is set to the range of 1.3-4.8 mm. The distance b (mm) between groove intersection points in a circumferential direction is set to a predetermined range in consideration of the ratio between the linear velocity of the surface of the developer carrier and that of the surface of a latent image carrier. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、複写機、プリンタ、ファクシミリ等の画像形成装置において感光体上に形成した潜像をトナーを付着させ可視像化するのに用いる現像スリーブ、この現像スリーブを備える現像装置、この現像装置を備えるプロセスカートリッジ、及び、画像形成装置に関する。 The present invention relates to a developing sleeve used for making a latent image formed on a photosensitive member a visible image by attaching a toner to an image forming apparatus such as a copying machine, a printer, and a facsimile, a developing device including the developing sleeve, and a developing device. The present invention relates to a process cartridge including the apparatus and an image forming apparatus.

最近の複写機、プリンタは高画質、高信頼、高安定性に対する要求が非常に高い。これらを満足させるには現像剤担持体上の現像剤量の経時安定性及び均一性が重要なポイントとなる。従来は、サンドブラストによって表面に凹凸を形成した現像スリーブや現像ローラ回転軸に対して平行に延びる複数のＶ溝を表面に形成した現像スリーブを一般的に使用していた。サンドブラストを用いて凹凸を持たせた現像スリーブは、凹凸量が小さいと現像剤搬送能力が低下し、現像剤搬送能力を上げる為に凹凸量を大きくすると、加工時に現像スリーブを変形させるという問題があった。また、Ｖ溝を備えた現像スリーブは、現像剤規制部材に対して平行な各現像剤搬送溝の各部が同じ瞬間に規制部材上を通過するため、現像剤へ与えるストレスが大きいという問題があった。また、加工時の溝偏差に起因してスリーブ一周ピッチの汲み上げ量のムラが発生するという問題もあった。特許文献１〜４に記載の現像スリーブは、このような従来の技術課題を解決できる可能性がある。これらの現像スリーブは、あやめ状の溝が形成された現像スリーブである。 Recent copiers and printers have very high demands for high image quality, high reliability, and high stability. In order to satisfy these requirements, the temporal stability and uniformity of the developer amount on the developer carrying member are important points. Conventionally, a developing sleeve in which irregularities are formed on the surface by sandblasting and a developing sleeve in which a plurality of V-grooves extending in parallel with the rotation axis of the developing roller are formed on the surface are generally used. Developer sleeves with irregularities using sandblasting have a problem in that the developer conveying ability decreases if the irregularity amount is small, and if the irregularity amount is increased to increase the developer conveying ability, the developing sleeve is deformed during processing. there were. In addition, the developing sleeve provided with the V-groove has a problem that a large stress is applied to the developer because each portion of each developer conveying groove parallel to the developer regulating member passes over the regulating member at the same moment. It was. In addition, there is a problem that unevenness in the pumping amount of the sleeve circumferential pitch occurs due to the groove deviation at the time of processing. The developing sleeves described in Patent Documents 1 to 4 may solve such conventional technical problems. These developing sleeves are developing sleeves in which iris-like grooves are formed.

特開２００３−３１６１４６号公報JP 2003-316146 A 特開２００３−２０８０１２号公報JP 2003-208021 A 特開２０００−２４２０７３号公報JP 2000-242073 A 特開平０７−１３４１０号公報Japanese Unexamined Patent Publication No. 07-13410

しかしながら、あやめ状の溝を形成した現像スリーブを用いる場合にも、あやめ状の溝の具体的な条件によっては現像スリーブの周方向（回転方向）の所定のピッチで、スラスト方向に延びる現像濃度が高い部分が生じて横の黒スジ状に見える異常画像（以下、ピッチ状横黒スジという）が発生することがわかった。また、あやめ状の溝の具体的な条件によっては現像スリーブの周方向（回転方向）の所定のピッチで、スラスト方向に延びる現像濃度が高い部分が生じて横の黒スジ状に見える異常画像（以下、ピッチ状横黒スジという）が発生することがわかった。
本発明は、上記問題に鑑みなされたものであり、その目的とするところは、上記ピッチ状横黒スジや上記ピッチ状横黒スジの発生を抑制できる現像剤担持体、この現像剤担持体を備える現像装置、この現像装置を備えるプロセスカートリッジ、及び、画像形成装置を提供することである。 However, even when a developing sleeve having an iris groove is used, depending on the specific conditions of the iris groove, the developing density extending in the thrust direction at a predetermined pitch in the circumferential direction (rotating direction) of the developing sleeve may be low. It was found that an abnormal image (hereinafter referred to as a pitch-shaped horizontal black streak) appears in which a high portion appears and looks like a horizontal black stripe. Also, depending on the specific conditions of the iris-shaped groove, an abnormal image (like a horizontal black streak) appears at a predetermined pitch in the circumferential direction (rotation direction) of the developing sleeve and a portion having a high development density extending in the thrust direction. Hereinafter, it was found that a pitch-like horizontal black stripe was generated.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a developer carrier that can suppress the occurrence of the pitch-like horizontal black stripes and the pitch-like horizontal black stripes, and the developer carrier. A developing device, a process cartridge including the developing device, and an image forming apparatus are provided.

上記目的を達成するために、請求項１の発明は、回転スラスト方向に対して傾斜した方向に延びる複数の溝と、スラスト方向に対して反対側に傾斜した方向に延びる複数の溝とが交差するように形成されてなるアヤメ状の溝を有し、潜像担持体との対向部で互いの表面が同じ向きに移動するように回転させて使用される現像剤担持体において、前記あやめ状の溝のスラスト方向における溝交点間距離が、１．３ｍｍ以上かつ４．８ｍｍ以下の範囲内であり、かつ前記あやめ状の溝の周方向における溝交点間距離ａ（単位ｍｍ）が、次式の下限以上かつ上限以下の範囲内であることを特徴とするものである。
（下限）＝０．３８×（現像剤担持体表面の線速）／（潜像担持体表面の線速）（上限）＝１．１×（現像剤担持体表面の線速）／（潜像担持体表面の線速）また、請求項２の発明は、請求項１の現像剤担持体において、外直径が１０ｍｍ以上かつ３２ｍｍ以下の範囲内であることを特徴とするものである。
また、請求項３の発明は、現像装置において、請求項１又は２の現像剤担持体と、トナー粒子と磁性粒子からなる２成分現像剤を収容する現像容器と、該現像容器内に収容された２成分現像剤を攪拌しつつ搬送する現像剤搬送手段と、現像剤担持体上の現像剤の量を一定量に規制する現像剤規制手段とを有することを特徴とするものである。
また、請求項４の発明は、プロセスカートリッジにおいて、請求項３の現像装置と、感光体、帯電手段及びクリーニング手段より選ばれる少なくとも１つの手段とを一体に支持し、画像形成装置本体に着脱自在であることを特徴とするものである。
また、請求項５の発明は、画像形成装置において、請求項４のプロセスカートリッジを備えたことを特徴するものである。
また、請求項６の発明は、カラー画像形成装置において、請求項４のプロセスカートリッジを複数個備えたことを特徴とするものである。。
また、請求項７の発明は、請求項５又は６の画像形成装置において、前記現像手段で用いられるトナーは、体積平均粒径が３〜８μｍで、体積平均粒径（Ｄｖ）と個数平均粒径（Ｄｎ）との比（Ｄｖ／Ｄｎ）が１．００〜１．４０の範囲にあることを特徴とするものである。
また、請求項８の発明は、請求項５又は６に記載の画像形成装置において、前記現像手段で用いられるトナーは、形状係数ＳＦ−１が１００〜１８０の範囲にあり、形状係数ＳＦ−２が１００〜１８０の範囲にあることを特徴とするものである。 In order to achieve the above object, according to the first aspect of the present invention, the plurality of grooves extending in the direction inclined with respect to the rotational thrust direction intersect with the plurality of grooves extending in the direction inclined opposite to the thrust direction. In the developer carrying member having an iris-shaped groove formed so as to be rotated so that the surfaces thereof move in the same direction at the portion facing the latent image carrying member, The distance between the groove intersections in the thrust direction of the grooves is in the range of 1.3 mm or more and 4.8 mm or less, and the distance a (unit: mm) between the groove intersections in the circumferential direction of the iris groove is It is characterized by being within the range of the lower limit and the upper limit.
(Lower limit) = 0.38 × (Linear velocity on developer carrier surface) / (Linear velocity on latent image carrier surface) (Upper limit) = 1.1 × (Linear velocity on developer carrier surface) / (Latent Further, the invention of claim 2 is characterized in that, in the developer carrier of claim 1, the outer diameter is in the range of 10 mm to 32 mm.
According to a third aspect of the present invention, in the developing device, the developer carrying member according to the first or second aspect, a developer container containing the two-component developer composed of toner particles and magnetic particles, and the developer container are accommodated in the developer container. And a developer conveying means for conveying the two-component developer while stirring, and a developer regulating means for regulating the amount of the developer on the developer carrying member to a constant amount.
According to a fourth aspect of the present invention, in the process cartridge, the developing device of the third aspect and at least one means selected from a photosensitive member, a charging means, and a cleaning means are integrally supported and detachable from the main body of the image forming apparatus. It is characterized by being.
According to a fifth aspect of the present invention, in the image forming apparatus, the process cartridge according to the fourth aspect is provided.
According to a sixth aspect of the present invention, a color image forming apparatus includes a plurality of process cartridges according to the fourth aspect. .
Further, in the image forming apparatus according to claim 5 or 6, the toner used in the developing unit has a volume average particle size of 3 to 8 μm, a volume average particle size (Dv) and a number average particle size. The ratio (Dv / Dn) to the diameter (Dn) is in the range of 1.00 to 1.40.
According to an eighth aspect of the present invention, in the image forming apparatus according to the fifth or sixth aspect, the toner used in the developing unit has a shape factor SF-1 in the range of 100 to 180, and the shape factor SF-2. Is in the range of 100-180.

請求項１乃至８の発明によれば、ピッチ状縦黒スジやピッチ状横黒スジの発生を抑制できるという効果がある。 According to the first to eighth aspects of the invention, there is an effect that generation of pitch-like vertical black stripes and pitch-like horizontal black stripes can be suppressed.

以下、本発明の実施形態に係る画像形成装置の一例を説明する。図１はその作像部分の概略構成図である。この画像形成装置はいわゆるタンデム型のカラー複写機で、中間転写ベルト５を備えるタイプである。この中間転写ベルト５の展張部に対向するように複数の感光体１ａ〜ｄが配設されている。帯電手段である帯電ローラ２ａ〜ｄによって均一に帯電された感光体１ａ〜ｄに対し書込位置３ａ〜ｄで書込手段３による書き込みがされて光学的に潜像が形成される。この潜像が現像手段４ａ〜ｄで現像されトナーからなる可視像が形成される。各感光体１ａ〜ｄに形成されたトナー像は中間転写ベルト転写手段１２ａ〜ｄによって中間転写ベルト５に順次重ね合わせて転写される。中間転写ベルト５のトナー像は、レジストローラ対６を経て搬送された転写紙に紙転写手段である紙転写ベルト７によって転写紙に転写される。転写紙に転写されたトナー像は紙転写ベルト７により定着手段８に搬送され転写紙上に熱により定着される。トナー像が定着された転写は図示しない排紙トレイなどに上に排出される。感光体１ａ〜ｄ上の中間転写ベルト５に転写されなかった未転写トナーは感光体クリーニングブレード９ａ〜ｄによって感光体上から掻き落とされる。感光体は、感光体上の残留電荷が図示しない除電手段により除電され、次の作像動作に備える。感光体クリーニングブレード９ａ〜ｄによって掻き落とされた未転写トナーは回収トナー搬送経路１４ａ〜ｄを通って廃トナー収容容器１５に収容される。また中間転写ベルト上の未転写トナーやプロセスコントロール用のパターン像は中間転写クリーニングブレード１３によって中間転写ベルト５上から掻き落とされ、同じく回収トナー搬送経路１４ｅを通って廃トナー収容容器１５に収容される。 Hereinafter, an example of an image forming apparatus according to an embodiment of the present invention will be described. FIG. 1 is a schematic configuration diagram of the image forming portion. This image forming apparatus is a so-called tandem type color copier and is of a type provided with an intermediate transfer belt 5. A plurality of photoconductors 1 a to 1 d are arranged so as to face the extended portion of the intermediate transfer belt 5. Writing is performed by the writing unit 3 at the writing positions 3a to d on the photoconductors 1a to d uniformly charged by the charging rollers 2a to d which are charging units, and a latent image is optically formed. The latent image is developed by the developing means 4a to 4d to form a visible image made of toner. The toner images formed on the photoreceptors 1a to 1d are sequentially transferred onto the intermediate transfer belt 5 by the intermediate transfer belt transfer units 12a to 12d. The toner image on the intermediate transfer belt 5 is transferred onto the transfer paper by the paper transfer belt 7 serving as a paper transfer means onto the transfer paper conveyed through the resist roller pair 6. The toner image transferred onto the transfer paper is conveyed to the fixing means 8 by the paper transfer belt 7 and fixed on the transfer paper by heat. The transfer on which the toner image is fixed is discharged upward to a paper discharge tray (not shown). Untransferred toner that has not been transferred to the intermediate transfer belt 5 on the photoreceptors 1a to 1d is scraped off from the photoreceptor by the photoreceptor cleaning blades 9a to 9d. The remaining charge on the photoreceptor is neutralized by a neutralizing unit (not shown) to prepare for the next image forming operation. The untransferred toner scraped off by the photoconductor cleaning blades 9a to 9d is accommodated in the waste toner container 15 through the collected toner conveyance paths 14a to 14d. Further, the untransferred toner on the intermediate transfer belt and the pattern image for process control are scraped off from the intermediate transfer belt 5 by the intermediate transfer cleaning blade 13, and are also stored in the waste toner storage container 15 through the recovered toner transport path 14e. The

上記現像装置４ａ〜ｄへはニュートナーが補給される。トナーボトルに充填されたニュートナーがトナー補給装置１０ａ〜ｄにより機械本体の後側のトナーホッパ部１１ａ〜ｄへ補給される。現像装置内のトナー濃度検知手段（図２の符号２１）により現像装置内のトナー濃度が低いと判断された場合、トナーホッパ内のトナー補給スクリュを（図示せず）を回転させ、適量のトナーをトナーホッパ内から現像装置へ供給する。トナーボトルのトナー残量検知はトナーホッパ内にトナー有り無しセンサ（図示せず）を用いて行う。具体的には、このセンサがトナー無しを検知した場合にトナー補給装置１０ａ〜ｄにトナーの供給を要求する。そして所定時間要求してもトナー有りを検知しなかった場合にトナー無しと判断する。 New toner is supplied to the developing devices 4a to 4d. The new toner filled in the toner bottle is supplied to the toner hoppers 11a to 11d on the rear side of the machine body by the toner supply devices 10a to 10d. When the toner concentration detection means (reference numeral 21 in FIG. 2) in the developing device determines that the toner concentration in the developing device is low, the toner replenishing screw (not shown) in the toner hopper is rotated to supply an appropriate amount of toner. The toner is supplied from the toner hopper to the developing device. The toner remaining amount in the toner bottle is detected using a toner presence / absence sensor (not shown) in the toner hopper. Specifically, when this sensor detects the absence of toner, the toner supply devices 10a to 10d are requested to supply toner. If the presence of toner is not detected even if requested for a predetermined time, it is determined that there is no toner.

図２は１つの感光体についての作像部の拡大図である。何れの感光体についても同様の構成であるので、この図２では符号の添え字ａ〜ｄは省略している。この画像形成装置では、感光体１と、現像部４、帯電手段である帯電ローラ２、及びクリーニング手段であるクリーニングブレード９とを一体としたプロセスカートリッジになっている。装置本体に対してこのプロセスカートリッジが脱着可能である。現像装置４は感光体にトナーを供給する現像ローラ１６を有する。その現像ローラ１６が感光体１に対向する現像領域の上流側で現像ローラ１６上の現像剤量をある一定量に規制する規制部材としての現像ドクタ１７も有する。現像装置内の現像タンク部にはトナー粒子と磁性粒子（キャリア）を混合した２成分現像剤が納められており、その現像剤は第１搬送スクリュ１８と第２搬送スクリュ１９の２本の搬送スクリュで循環されるようになっている。この第２搬送スクリュ１９の下側にトナー濃度センサ２１が配置され、現像タンク内のトナー濃度を随時計測し、適正値に収まるよう制御している。トナー補給部からのトナーは一旦サブホッパ部（図示せず）に蓄えられ、現像タンク内のトナー濃度の値がトナー濃度センサにより低いと検知されたとき、所定の換算式により換算された時間だけトナー補給スクリュ２２を回転させ適切な量のトナーを現像トナー供給口２３へ補給する。また、現像ドクタ１７の図中右側には現像ニップ部からのトナー飛散を防止するための入口シール２０が配置されている。 FIG. 2 is an enlarged view of an image forming unit for one photoconductor. Since all the photoconductors have the same configuration, the suffixes a to d are omitted in FIG. In this image forming apparatus, a photosensitive cartridge 1, a developing unit 4, a charging roller 2 as a charging unit, and a cleaning blade 9 as a cleaning unit are integrated into a process cartridge. The process cartridge can be attached to and detached from the apparatus main body. The developing device 4 includes a developing roller 16 that supplies toner to the photoreceptor. The developing roller 16 also has a developing doctor 17 as a regulating member that regulates the amount of developer on the developing roller 16 to a certain fixed amount upstream of the developing region where the developing roller 16 faces the photoreceptor 1. A two-component developer in which toner particles and magnetic particles (carriers) are mixed is stored in a developing tank portion in the developing device, and the developer is transported by two transports of a first transport screw 18 and a second transport screw 19. It is designed to be circulated with a screw. A toner concentration sensor 21 is disposed below the second conveying screw 19, and the toner concentration in the developing tank is measured at any time and controlled so as to be within an appropriate value. The toner from the toner replenishing unit is temporarily stored in a sub hopper unit (not shown), and when the toner concentration value in the developing tank is detected to be low by the toner concentration sensor, the toner is supplied for the time converted by a predetermined conversion formula. The supply screw 22 is rotated to supply an appropriate amount of toner to the developing toner supply port 23. An inlet seal 20 for preventing toner scattering from the developing nip portion is disposed on the right side of the developing doctor 17 in the drawing.

図３は現像装置４全体の斜視図である。現像装置４の上ケース２８にはこのユニットの出荷時に現像剤を入れるプリセットスペース２８’がある。これはユニットとして輸送時にこの部分に現像剤を入れ、除去可能なシール部材によりシールさせることで、着荷時にこのシールをひき、使用可能な状態にさせるもので、輸送時の剤漏れ防止の為の機構である。図４は上ケース２８（図３参照）を外した状態の現像装置の斜視図である。現像ローラ１６、第１搬送スクリュ１８、第２搬送スクリュ１９が見える状態になっており、これらの搬送スクリュにより第１現像剤溜まりと第２現像剤溜まりの間で現像剤を循環している。 FIG. 3 is a perspective view of the entire developing device 4. The upper case 28 of the developing device 4 has a preset space 28 'in which a developer is placed when the unit is shipped. This is because the developer is put into this part during transportation as a unit and sealed with a removable seal member, and this seal is pulled when it arrives, so that it can be used. Mechanism. FIG. 4 is a perspective view of the developing device with the upper case 28 (see FIG. 3) removed. The developing roller 16, the first conveying screw 18, and the second conveying screw 19 are visible, and the developer is circulated between the first developer reservoir and the second developer reservoir by these conveying screws.

図５は現像装置の一部の分解斜視図である。現像ローラ１６は、内部に固定されているマグネット部２５とこのマグネット部２５の内蔵し現像剤を搬送するため回転可能な現像スリーブ部２６にて構成されている。内部の固定マグネット部２５は作像領域のやや外側まで存在し、転写紙の搬送バラツキを考慮したマグネット長さの位置関係になっている。外側の現像スリーブ２６は、通常アルミ材により構成され、現像剤を搬送しやすくするために、あやめ状の溝を設けている。このあやめ状の溝については後に詳述する。上記現像ドクタ１７は非磁性部材にて構成されている現像ドクタ母体１７’と磁性部材により構成されている現像ドクタ補助２４の２部品により構成されている。現像ドクタ母体１７’を現像ケーシング２７に固定することにより、現像ローラ１６に対して所定の間隔を開けて対向する構成となっている。現像ドクタ母体１７’は現像ローラ上の現像剤量をある一定量に規制する役割をもち、かつ現像剤を規制する際に現像剤圧をこのドクタにて受けることになるので、非磁性部材である程度の厚さ（約１．５〜２ｍｍ）と先端部０．０５ｍｍ程度の真直性を要求されるのが一般的である。現像ドクタ補助２４は現像領域に搬送されるトナーの帯電を補う役割をもち、通常現像ドクタ母体よりかなり薄い板金（０．２ｍｍ程度）にて構成されている。この２部品の位置関係はトナー帯電性を長手方向にて均一にするため、精度良く維持される必要性があるので、スポット溶接やカシメ等により一体化し現像ローラ上からの距離が一定になるようにしている。また、図示の例では現像ローラ中心に対し現像ドクタが下方にある。現像ケーシング２７には、第１搬送スクリュ１８と第２搬送スクリュ１９が軸受（図示せず）を介し組み込まれる。現像ケーシング２７の前後の側板の内側には、現像ローラ端部からの現像剤飛散を抑えるための磁性板２８が取り付けられている。 FIG. 5 is an exploded perspective view of a part of the developing device. The developing roller 16 includes a magnet portion 25 fixed inside and a developing sleeve portion 26 that is built in the magnet portion 25 and is rotatable to convey the developer. The internal fixed magnet portion 25 exists slightly outside the image forming area, and has a magnet length positional relationship in consideration of transfer paper transfer variation. The outer developing sleeve 26 is usually made of an aluminum material, and is provided with an iris-like groove to facilitate transport of the developer. This iris-shaped groove will be described in detail later. The developing doctor 17 is composed of two parts, a developing doctor base 17 'made of a nonmagnetic member and a developing doctor auxiliary 24 made of a magnetic member. By fixing the developing doctor base 17 ′ to the developing casing 27, the developing doctor base 17 ′ is opposed to the developing roller 16 with a predetermined gap. The developing doctor base 17 ′ has a role of regulating the amount of developer on the developing roller to a certain fixed amount, and receives the developer pressure at the doctor when regulating the developer. Generally, a certain degree of thickness (about 1.5 to 2 mm) and straightness of about 0.05 mm at the tip are required. The developing doctor auxiliary 24 has a role of supplementing the charging of the toner conveyed to the developing area, and is usually constituted by a sheet metal (about 0.2 mm) that is considerably thinner than the developing doctor base. The positional relationship between the two parts needs to be maintained with high accuracy in order to make the toner charging property uniform in the longitudinal direction, so that the distance from the developing roller is made constant by integration by spot welding or caulking. I have to. In the illustrated example, the developing doctor is below the center of the developing roller. A first conveying screw 18 and a second conveying screw 19 are incorporated into the developing casing 27 via bearings (not shown). On the inner side of the front and rear side plates of the developing casing 27, a magnetic plate 28 is attached to suppress the developer scattering from the end of the developing roller.

次に、以上の画像形成装置に好適に使用されるトナーについて説明する。
６００ｄｐｉ以上の微少ドットを再現するために、トナーの体積平均粒径は３〜８μｍが好ましい。体積平均粒径（Ｄｖ）と個数平均粒径（Ｄｎ）との比（Ｄｖ／Ｄｎ）は１．００〜１．４０の範囲にあることが好ましい。（Ｄｖ／Ｄｎ）が１．００に近いほど粒径分布がシャープであることを示す。このような小粒径で粒径分布の狭いトナーでは、トナーの帯電量分布が均一になり、地肌かぶりの少ない高品位な画像を得ることができ、また、静電転写方式では転写率を高くすることができる。 Next, a toner suitably used in the above image forming apparatus will be described.
In order to reproduce minute dots of 600 dpi or more, the toner preferably has a volume average particle diameter of 3 to 8 μm. The ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) is preferably in the range of 1.00 to 1.40. The closer (Dv / Dn) is to 1.00, the sharper the particle size distribution. With such a toner having a small particle size and a narrow particle size distribution, the toner charge amount distribution is uniform, a high-quality image with little background fogging can be obtained, and the electrostatic transfer method has a high transfer rate. can do.

トナーの形状係数ＳＦ−１は１００〜１８０、形状係数ＳＦ−２は１００〜１８０の範囲にあることが好ましい。図６は形状係数ＳＦ−１を、図７は形状係数ＳＦ−２をそれぞれ説明するためにトナーの形状を模式的に表した図である。形状係数ＳＦ−１は、トナー形状の丸さの割合を示すものであり、下記式（１）で表される。トナーを２次元平面に投影してできる形状の最大長ＭＸＬＮＧの二乗を図形面積ＡＲＥＡで除して、１００π／４を乗じた値である。
ＳＦ−１＝｛（ＭＸＬＮＧ）^２／ＡＲＥＡ｝×（１００π／４）・・・式（１）
ＳＦ−１の値が１００の場合トナーの形状は真球となり、ＳＦ−１の値が大きくなるほど不定形になる。また、形状係数ＳＦ−２は、トナー形状の凹凸の割合を示すものであり、下記式（２）で表される。トナーを２次元平面に投影してできる図形の周長ＰＥＲＩの二乗を図形面積ＡＲＥＡで除して、１００π／４を乗じた値である。
ＳＦ−２＝｛（ＰＥＲＩ）^２／ＡＲＥＡ｝×（１００π／４）・・・式（２）
ＳＦ−２の値が１００の場合トナー表面に凹凸が存在しなくなり、ＳＦ−２の値が大きくなるほどトナー表面の凹凸が顕著になる。形状係数の測定は、具体的には、走査型電子顕微鏡（Ｓ−８００：日立製作所製）でトナーの写真を撮り、これを画像解析装置（ＬＵＳＥＸ３：ニレコ社製）に導入して解析して計算した。トナーの形状が球形に近くなると、トナーとトナーあるいはトナーと感光体との接触状態が点接触になるために、トナー同士の吸着力は弱くなり従って流動性が高くなり、また、トナーと感光体との吸着力も弱くなって、転写率は高くなる。形状係数ＳＦ−１、ＳＦ−２のいずれかが１８０を超えると、転写率が低下するため好ましくない。 The toner shape factor SF-1 is preferably in the range of 100 to 180, and the shape factor SF-2 is preferably in the range of 100 to 180. FIG. 6 is a diagram schematically illustrating the shape of the toner in order to explain the shape factor SF-1, and FIG. 7 is a diagram illustrating the shape factor SF-2. The shape factor SF-1 indicates the ratio of the roundness of the toner shape and is represented by the following formula (1). This is a value obtained by dividing the square of the maximum length MXLNG of the shape formed by projecting the toner on a two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-1 = {(MXLNG) ² / AREA} × (100π / 4) (1)
When the value of SF-1 is 100, the shape of the toner becomes a true sphere, and becomes larger as the value of SF-1 increases. The shape factor SF-2 indicates the ratio of the unevenness of the toner shape, and is represented by the following formula (2). A value obtained by dividing the square of the perimeter PERI of the figure formed by projecting the toner on the two-dimensional plane by the figure area AREA and multiplying by 100π / 4.
SF-2 = {(PERI) ² / AREA} × (100π / 4) Expression (2)
When the value of SF-2 is 100, there is no unevenness on the toner surface, and as the value of SF-2 increases, the unevenness of the toner surface becomes more prominent. Specifically, the shape factor is measured by taking a photograph of the toner with a scanning electron microscope (S-800: manufactured by Hitachi, Ltd.), introducing it into an image analyzer (LUSEX 3: manufactured by Nireco) and analyzing it. Calculated. When the shape of the toner is close to a spherical shape, the contact state between the toner and the toner or the toner and the photoconductor becomes a point contact, so that the adsorbing force between the toners becomes weak and the fluidity increases, and the toner and the photoconductor The attraction force becomes weaker and the transfer rate becomes higher. If either of the shape factors SF-1 and SF-2 exceeds 180, the transfer rate is lowered, which is not preferable.

本発明の現像担持体として現像ローラについて説明する。図８は現像スリーブ２６の斜視図、図９は現像スリーブ２６表面の拡大図である。本発明の現像ローラ表面（現像スリーブ表面）上にはあやめ状の溝を形成している。あやめ状の溝とは、現像ローラ回転軸方向（スラスト方向）に対して傾斜した複数の溝と、スラスト方向に対して反対側に傾斜した複数の溝とが交差するように形成されるものである。前者の複数の溝における傾斜の角度と、後者の複数の溝における傾斜の角度とは、必ずしも互いに同一でなくてもよい。このようなあやめ溝形状のスリーブによれば、現像剤が現像剤量をある一定量に規制する現像ドクタ１７を通過する際に、搬送溝が斜めでストレスを受けることがなくなるので、現像剤寿命を延ばすことが出来ると共に、剤搬送溝が斜めのためドクタ通過時の衝撃が緩和できショックジターも改善される。 A developing roller will be described as the developing carrier of the present invention. FIG. 8 is a perspective view of the developing sleeve 26, and FIG. 9 is an enlarged view of the surface of the developing sleeve 26. An iris-like groove is formed on the surface of the developing roller (the surface of the developing sleeve) of the present invention. The iris-shaped groove is formed such that a plurality of grooves inclined with respect to the developing roller rotation axis direction (thrust direction) and a plurality of grooves inclined opposite to the thrust direction intersect. is there. The angle of inclination in the former plurality of grooves and the angle of inclination in the latter plurality of grooves are not necessarily the same. According to such an iris groove-shaped sleeve, when the developer passes through the developing doctor 17 that regulates the developer amount to a certain amount, the conveying groove is not inclined and stressed, so that the developer life is shortened. In addition, since the agent conveying groove is slanted, the impact when passing through the doctor can be mitigated and the shock jitter can be improved.

図９中、符号ａはで示すのはあやめ溝のスラスト方向における交点間距離、符号ｂはで示すのはあやめ溝の周方向における交点間距離、符号ｃで示すのは外径である。本実施形態に係る現像スリーブは、交点間距離ａを１．３ｍｍ以上かつ４．８ｍｍ以下の範囲内にした。また、交点間距離ｂ（単位ｍｍ）を次式の下限以上かつ上限以下の範囲内にした。
（下限）＝０．３８×（現像剤担持体表面の線速）／（潜像担持体表面の線速）
（上限）＝１．１×（現像剤担持体表面の線速）／（潜像担持体表面の線速） In FIG. 9, the symbol a indicates the distance between the intersections in the thrust direction of the iris groove, the symbol b indicates the distance between the intersections in the circumferential direction of the iris groove, and the symbol c indicates the outer diameter. In the developing sleeve according to the present embodiment, the distance a between the intersections is in the range of 1.3 mm or more and 4.8 mm or less. In addition, the distance b (unit: mm) between the intersection points was set within the range of the lower limit and the upper limit of the following formula.
(Lower limit) = 0.38 × (Linear velocity on developer carrier surface) / (Linear velocity on latent image carrier surface)
(Upper limit) = 1.1 × (Linear speed on developer carrier surface) / (Linear speed on latent image carrier surface)

スラスト方向の交点間距離について下限を１．３ｍｍとしたのは次の理由による。すなわち、最近は高画質化のために現像ローラと感光体１とのギャップは１ｍｍ以下に設定されているが一般的である。このように現像ギャップを狭く設定するのに応じて現像ローラ表面での単位面積当たりの現像剤保持量（搬送量）も少なくてすむようになってきている。例えば４０ｍｇ／ｃｍ^２である。上記交点間距離ｍの設定が狭いほど溝の本数が多くなり現像剤保持量が多くなるが、以上のように最近の現像ギャップに応じた現像剤保持量を確保するには交点間距離ｍが１．３ｍｍに対応する本数あれば十分である。これより交点間距離ｍを狭くして本数を多くしても、溝加工の時間がながくかかったり、加工時に現像スリーブにかかるストレスが増大してひずみを生じたりするといった不具合がでる。よって、下限を１．３ｍｍに設定した。上限を４．８ｍｍに設定したのは次の理由による。上記交点間距離ｍが４．８ｍｍ超の場合、縦黒スジ画像が発生する。溝でない表面部分に比して溝では剤搬送が多いため溝部に現像剤は溜まっている。あやめ溝の場合、溝が交差しているため溝交点部分とそれ以外の溝部分では汲み上げ量に差が生じ、交点部分の方が多い。この結果、溝の交点部分とそれ以外の部分とで現像濃度差が生じる。実際に画像で顕著になるには濃い部分の間隔が広くならないと顕著にならない。すなわち、人の目にはめだたない。評価した結果では４．８ｍｍを超えると縦黒スジのムラとなって顕在化する。よって、上限を４．８ｍｍに設定した。 The reason why the lower limit of the distance between the intersections in the thrust direction is 1.3 mm is as follows. That is, in recent years, the gap between the developing roller and the photosensitive member 1 is generally set to 1 mm or less in order to improve image quality. In this way, as the development gap is set narrower, the developer holding amount (conveyance amount) per unit area on the surface of the developing roller can be reduced. For example, 40 mg / cm ² . The narrower the setting of the distance between the intersections m, the more the number of grooves and the larger the developer holding amount. However, as described above, in order to secure the developer holding amount according to the recent development gap, A number corresponding to 1.3 mm is sufficient. Even if the distance m between the intersections is made narrower and the number is increased, there are problems that it takes a long time for the grooving process, or stress is applied to the developing sleeve during the process and distortion occurs. Therefore, the lower limit was set to 1.3 mm. The upper limit is set to 4.8 mm for the following reason. When the distance m between the intersections exceeds 4.8 mm, a vertical black streak image is generated. Since the amount of the agent transported in the groove is larger than that in the surface portion that is not the groove, the developer is accumulated in the groove portion. In the case of the iris groove, since the grooves intersect, there is a difference in the pumping amount between the groove intersection portion and the other groove portions, and there are more intersection points. As a result, a development density difference occurs between the intersection of the grooves and the other portion. In order to actually become prominent in an image, it does not become prominent unless the interval between dark portions becomes wide. In other words, it is inconspicuous. As a result of the evaluation, if the thickness exceeds 4.8 mm, vertical black streaks appear and become apparent. Therefore, the upper limit was set to 4.8 mm.

周方向のの交点間距離について、下限は次の理由から設定した。すなわち、上述のように、最近は高画質化のために現像ローラと感光体１とのギャップは１ｍｍ以下に設定されているが一般的である。このように現像ギャップを狭く設定するのに応じて現像ローラ表面での単位面積当たりの現像剤保持量（搬送量）も少なくてすむようになってきている。この現像剤保持量は感光体１と現像スリーブ２６との対向部で線速関係にも左右される。また、溝の本数が多くなるほど現像剤保持量が多くなる。以上のように最近の現像ギャップに応じた現像剤保持量を確保するには上記下限以上であれば、十分であることが確認された。これより交点間距離ｍが狭くなるように溝の本数を多くしても、溝加工の時間がながくかかったり、加工時に現像スリーブにかかるストレスが増大してひずみを生じたりするといった不具合がである。よって、下限を上記のように設定した。上限は次の理由から設定した。上記交点間距離ａが上記上限を超える場合、ピッチ状横黒スジ画像が発生する。溝でない表面部分に比して溝では剤搬送が多いため溝部に現像剤は溜まっている。あやめ溝の場合、溝が交差しているため溝交点部分とそれ以外の溝部分では汲み上げ量に差が生じ、交点部分の方が多い。この結果、溝の交点部分とそれ以外の部分とで現像濃度差が生じる。実際に画像で顕著になるには濃い部分の間隔が広くならないと顕著にならない。すなわち、人の目にはめだたない。評価した結果では１．１ｍｍを超えると横黒スジのムラとなって顕在化する。よって、感光体１と現像スリーブ２６の線速比を考慮し、上限を上述のように設定した。 Regarding the distance between the intersections in the circumferential direction, the lower limit was set for the following reason. That is, as described above, recently, the gap between the developing roller and the photoreceptor 1 is generally set to 1 mm or less in order to improve the image quality. In this way, as the development gap is set narrower, the developer holding amount (conveyance amount) per unit area on the surface of the developing roller can be reduced. This developer holding amount depends on the linear velocity relationship at the facing portion between the photosensitive member 1 and the developing sleeve 26. Further, the developer holding amount increases as the number of grooves increases. As described above, it has been confirmed that the above-mentioned lower limit is sufficient to secure the developer holding amount corresponding to the recent development gap. Even if the number of grooves is increased so that the distance m between the intersections becomes narrower than this, there is a problem that it takes a long time for the groove processing or the stress applied to the developing sleeve during processing increases to cause distortion. . Therefore, the lower limit was set as described above. The upper limit was set for the following reasons. When the distance a between the intersections exceeds the upper limit, a pitch-like horizontal black streak image is generated. Since the amount of the agent transported in the groove is larger than that in the surface portion that is not the groove, the developer is accumulated in the groove portion. In the case of the iris groove, since the grooves intersect, there is a difference in the pumping amount between the groove intersection portion and the other groove portions, and there are more intersection points. As a result, a development density difference occurs between the intersection of the grooves and the other portion. In order to actually become prominent in an image, it does not become prominent unless the interval between dark portions becomes wide. In other words, it is inconspicuous. As a result of the evaluation, if the thickness exceeds 1.1 mm, horizontal black stripes appear and become apparent. Therefore, the upper limit is set as described above in consideration of the linear velocity ratio between the photosensitive member 1 and the developing sleeve 26.

また、現像スリーブ２６の外径をｂは１０ｍｍ以上かつ３２ｍｍ以下の範囲内に設定することが好ましい。下限の理由は内部固定のマグネット部２５のパターン磁力との関係による搬送性からの設定で、上限は加工上の実用性の観点からの設定である。例えば、感光体１の線速１５０ｍｍ／秒、現像スリーブ２６の線速２９０ｍｍ／秒、上記交点ピッチが２．２ｍｍ（ほぼ前述の上限値に相当）とした場合、外径が１０ｍｍでは、交点数は１４点となりその角度は中心よりピッチ約２５度となる。これでは、内部固定マグネットのパターン磁力の半値角度の半分以上となり搬送性に問題が生じる。また外径３２ｍｍとすると、０．７５ｍｍピッチでは交点数１３４点と多点となり加工上困難になる事が確認された。 The outer diameter of the developing sleeve 26 is preferably set within the range of 10 mm to 32 mm. The reason for the lower limit is setting from the transportability due to the relationship with the pattern magnetic force of the internally fixed magnet portion 25, and the upper limit is setting from the viewpoint of practicality in processing. For example, when the linear velocity of the photosensitive member 1 is 150 mm / second, the linear velocity of the developing sleeve 26 is 290 mm / second, and the intersection pitch is 2.2 mm (corresponding to the above-described upper limit), the number of intersections is 10 mm. Is 14 points, and the angle is about 25 degrees from the center. This causes more than half of the half-value angle of the pattern magnetic force of the internal fixed magnet, causing a problem in transportability. Further, when the outer diameter is 32 mm, it is confirmed that the number of intersections is as many as 134 at a pitch of 0.75 mm, which makes it difficult to process.

現像ローラとして次の現像ローラをもちいて図１に示す画像形成装置で画像を形成したところ、ピッチ状横黒スジのムラが生じない良好な画像を形成できた。
現像ローラの直径は１８ｍｍ。
感光体１の線速１５０ｍｍ／秒、現像スリーブ２６の線速２９０ｍｍ／秒。
上記スラスト方向の交点間距離を１．３ｍｍ以上かつ４．８ｍｍ以下の範囲内の各種の現像スリーブを形成して実験した。
上記周方向の交点間距離０．７５ｍｍ〜２．２ｍｍの範囲内の各種の現像スリーブを形成して実験した。 When the next developing roller was used as the developing roller and an image was formed by the image forming apparatus shown in FIG. 1, a good image in which unevenness of pitch-like horizontal black stripes did not occur was formed.
The diameter of the developing roller is 18 mm.
The linear velocity of the photosensitive member 1 is 150 mm / second, and the linear velocity of the developing sleeve 26 is 290 mm / second.
Experiments were conducted by forming various developing sleeves having a distance between intersections in the thrust direction of 1.3 mm or more and 4.8 mm or less.
Experiments were conducted by forming various developing sleeves having a distance of 0.75 mm to 2.2 mm between the intersections in the circumferential direction.

以上、本実施の画像形成装置によれば、あやめ状の溝のスラスト方向及び周方向それぞれにおける溝交点間距離が所定範囲内であるので、ピッチ状縦黒スジやピッチ状横黒スジの発生を抑制できる。
また、トナーとして、体積平均粒径が３〜８μｍで、体積平均粒径（Ｄｖ）と個数平均粒径（Ｄｎ）との比（Ｄｖ／Ｄｎ）が１．００〜１．４０の範囲にある粒径分布のものを使用すれば、さらに高画質な画像をえることができる。
また、トナーは、形状係数ＳＦ−１が１００〜１８０の範囲にあり、形状係数ＳＦ−２が１００〜１８０の範囲にあるものを使用すれば、さらに高画質な画像をえることができる。 As described above, according to the image forming apparatus of the present embodiment, since the distance between the groove intersections in the thrust direction and the circumferential direction of the iris-shaped grooves is within a predetermined range, the occurrence of pitch-shaped vertical black lines and pitch-shaped horizontal black lines is prevented. Can be suppressed.
The toner has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) in the range of 1.00 to 1.40. If one having a particle size distribution is used, a higher quality image can be obtained.
Further, if a toner having a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180 is used, a higher quality image can be obtained.

本発明の実施形態に係るプリンタの概略構成図。1 is a schematic configuration diagram of a printer according to an embodiment of the present invention. 上記プリンタのトナー像形成部を構成するプロセスカートリッジの概略構成図。FIG. 2 is a schematic configuration diagram of a process cartridge constituting a toner image forming unit of the printer. 現像装置の全体斜視図。1 is an overall perspective view of a developing device. 現像装置の内部構成をしめす斜視図。The perspective view which shows the internal structure of a developing device. 現像装置の一部の分解斜視図。FIG. 3 is an exploded perspective view of a part of the developing device. 形状係数ＳＦ−１を説明するためにトナー形状を模式的に表した説明図。FIG. 3 is an explanatory diagram schematically showing a toner shape for explaining a shape factor SF-1. 形状係数ＳＦ−２を説明するためにトナー形状を模式的に表した説明図。FIG. 4 is an explanatory diagram schematically showing a toner shape for explaining a shape factor SF-2. 現像スリーブの斜視図。The perspective view of a developing sleeve. 現像スリーブ表面の拡大図。The enlarged view of the surface of a developing sleeve.

Explanation of symbols

１感光体
２現像ローラ 1 Photoconductor 2 Developing roller

Claims

A plurality of grooves extending in a direction inclined with respect to the rotational thrust direction and a plurality of grooves extending in a direction inclined in the opposite direction with respect to the thrust direction; In the developer carrier used by rotating so that the surfaces of each other move in the same direction at the portion facing the latent image carrier,
The distance between the groove intersections in the thrust direction of the iris-shaped groove is in the range of 1.3 mm or more and 4.8 mm or less, and the distance a (unit: mm) between the groove intersections in the circumferential direction of the iris-shaped groove is A developer carrying member characterized by being within the range of the lower limit and the upper limit of the following formula.
(Lower limit) = 0.38 × (Linear velocity on developer carrier surface) / (Linear velocity on latent image carrier surface)
(Upper limit) = 1.1 × (Linear speed on developer carrier surface) / (Linear speed on latent image carrier surface)

The developer carrier of claim 1,
A developer carrier having an outer diameter in the range of 10 mm to 32 mm.

A developer carrying member according to claim 1, a developer container containing a two-component developer composed of toner particles and magnetic particles, and a developer for conveying the two-component developer contained in the developer container while stirring. A developing device comprising transport means and developer regulating means for regulating the amount of developer on the developer carrying member to a constant amount.

A process cartridge which integrally supports the developing device according to claim 3 and at least one means selected from a photosensitive member, a charging means and a cleaning means, and is detachable from an image forming apparatus main body.

An image forming apparatus comprising the process cartridge according to claim 4.

A color image forming apparatus comprising a plurality of process cartridges according to claim 4.

The image forming apparatus according to claim 5 or 6,
The toner used in the developing unit has a volume average particle diameter of 3 to 8 μm and a ratio (Dv / Dn) of the volume average particle diameter (Dv) to the number average particle diameter (Dn) of 1.00 to 1.40. An image forming apparatus characterized by being in the range.

The image forming apparatus according to claim 5 or 6,
The image forming apparatus according to claim 1, wherein the toner used in the developing unit has a shape factor SF-1 in the range of 100 to 180 and a shape factor SF-2 in the range of 100 to 180.