JPH11218975A - Image forming device - Google Patents
Image forming deviceInfo
- Publication number
- JPH11218975A JPH11218975A JP10032364A JP3236498A JPH11218975A JP H11218975 A JPH11218975 A JP H11218975A JP 10032364 A JP10032364 A JP 10032364A JP 3236498 A JP3236498 A JP 3236498A JP H11218975 A JPH11218975 A JP H11218975A
- Authority
- JP
- Japan
- Prior art keywords
- image
- transfer
- charging
- roller
- photosensitive drum
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Electrostatic Charge, Transfer And Separation In Electrography (AREA)
- Control Or Security For Electrophotography (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、像担持体上に形成
された潜像に現像剤を付着させて可視化する、電子写真
方式や静電記録方式などの複写機、プリンタ等の画像形
成装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, such as an electrophotographic or electrostatic recording system, for visualizing a latent image formed on an image carrier by attaching a developer thereto. It is about.
【０００２】[0002]
【従来の技術】従来、画像形成装置としては種々のもの
が知られているが、つぎに示すようなレーザービームプ
リンタが広く実用に供されている。2. Description of the Related Art Conventionally, various types of image forming apparatuses are known, and the following laser beam printers are widely used in practice.
【０００３】このレーザービームプリンタは、帯電手段
で一様に帯電された像担持体上の表面を、ディジタル画
像信号に対応してレーザ発光素子から発光されたレーザ
ービームで走査して、像担持体の表面に静電潜像を形成
し、この静電潜像を現像装置により現像剤（トナーまた
はトナーとキャリア）を用いて現像して可視化し、得ら
れたトナー像を転写手段で記録材に転写し、その後、定
着手段でトナー像を記録材に定着して出力するものであ
る。This laser beam printer scans the surface of an image carrier, which is uniformly charged by a charging means, with a laser beam emitted from a laser light emitting element in accordance with a digital image signal. An electrostatic latent image is formed on the surface of the recording medium, and the electrostatic latent image is developed by a developing device using a developer (toner or toner and carrier) to be visualized, and the obtained toner image is recorded on a recording material by a transfer unit. The image is transferred, and then the toner image is fixed on the recording material by a fixing unit and output.
【０００４】[0004]
【発明が解決しようとする課題】上記従来のプリンタで
は、帯電手段や転写手段での放電による像担持体表面の
ダメージや、クリーニング手段、特にいわゆるクリーニ
ングブレードでの像担持体表面の摺擦により、画像形成
を繰り返すにともない、像担持体表面の感光層に小さな
傷やミクロな凹凸が発生し、像担持体の表面粗さが大き
くなる。In the above-mentioned conventional printer, damage to the surface of the image carrier due to discharge in the charging means and transfer means, and rubbing of the surface of the image carrier with cleaning means, particularly a so-called cleaning blade, cause the following problems. As the image formation is repeated, small scratches and microscopic irregularities occur on the photosensitive layer on the surface of the image carrier, and the surface roughness of the image carrier increases.
【０００５】像担持体の表面粗さが大きくなると、一般
にトナーと像担持体との吸着力が強くなる。そのメカニ
ズムは完全には解明されていないが、像担持体表面のト
ナーとの接触面積が大きくなるため、トナーの像担持体
表面への物理的吸着が強くなると考えられる。[0005] As the surface roughness of the image carrier increases, the attraction between the toner and the image carrier generally increases. Although the mechanism is not completely elucidated, it is considered that the physical adsorption of the toner to the surface of the image carrier increases because the contact area of the surface of the image carrier with the toner increases.
【０００６】トナーと像担持体との吸着力が強くなる
と、像担持体上のトナー像の転写材への転写効率が低下
し、その結果、画像濃度が低下したり、文字、細線など
のラインの中央部が転写しなくなる、いわゆる中抜け現
象が顕著に発生する問題があった。[0006] When the attraction force between the toner and the image carrier increases, the transfer efficiency of the toner image on the image carrier to the transfer material is reduced. As a result, the image density is reduced, and lines such as characters and fine lines are reduced. There is a problem in that the central portion of the image does not transfer, that is, the so-called hollow phenomenon occurs remarkably.
【０００７】本発明の目的は、画像形成の繰り返しにと
もなって、像担持体の表面粗さが大きくなっても、トナ
ー像の転写効率の低下や中抜けの発生を抑制することを
可能とした画像形成装置を提供することである。SUMMARY OF THE INVENTION An object of the present invention is to make it possible to suppress a decrease in transfer efficiency of a toner image and the occurrence of voids even when the surface roughness of an image carrier increases with the repetition of image formation. An object of the present invention is to provide an image forming apparatus.
【０００８】[0008]
【課題を解決するための手段】上記目的は、本発明にか
かる画像形成装置にて達成される。要約すれば、本発明
は、帯電手段により像担持体の表面を帯電し、像露光し
て静電潜像を形成し、この潜像を現像手段により現像剤
を用いて現像して可視化し、得られた可視画像を転写手
段により転写材に転写する画像形成装置において、前記
像担持体の表面を形成する感光層の膜厚を膜厚測定手段
により測定して、前記測定された感光層の膜厚に応じ
て、前記可視画像の転写条件を制御することを特徴とす
る画像形成装置である。The above object is achieved by an image forming apparatus according to the present invention. In summary, the present invention charges the surface of the image carrier by charging means, forms an electrostatic latent image by image exposure, develops the latent image using a developer by developing means, and visualizes the latent image. In an image forming apparatus that transfers the obtained visible image to a transfer material by a transfer unit, a film thickness of a photosensitive layer forming the surface of the image carrier is measured by a film thickness measurement unit, and the measured photosensitive layer An image forming apparatus, wherein the transfer condition of the visible image is controlled according to the film thickness.
【０００９】本発明によれば、前記可視画像の転写条件
は、前記転写手段から流れる転写電流である。あるい
は、前記転写手段は像担持体の表面に接触する転写ロー
ラであり、前記転写条件は、転写ローラ表面の周速と像
担持体表面の周速の差である。もしくは、前記転写条件
は、像担持体への転写ローラの当接圧である。また、前
記帯電手段は像担持体表面に接触する帯電ローラであ
り、前記帯電ローラに直流電圧またはこれに交流電圧を
重畳した帯電バイアスを印加し、前記膜厚測定手段は、
そのとき流れる帯電バイアスの直流成分の電流値を検出
することにより、前記感光層の膜厚を測定する。According to the present invention, the visible image transfer condition is a transfer current flowing from the transfer means. Alternatively, the transfer unit is a transfer roller that comes into contact with the surface of the image carrier, and the transfer condition is a difference between the peripheral speed of the transfer roller surface and the peripheral speed of the image carrier surface. Alternatively, the transfer condition is a contact pressure of the transfer roller on the image carrier. Further, the charging unit is a charging roller that comes into contact with the surface of the image carrier, applies a charging bias in which an AC voltage is superimposed on the charging roller with a DC voltage, and the film thickness measuring unit includes:
The thickness of the photosensitive layer is measured by detecting the current value of the DC component of the charging bias flowing at that time.
【００１０】[0010]
【発明の実施の形態】以下、本発明の実施例を図面に即
して詳細に説明する。Embodiments of the present invention will be described below in detail with reference to the drawings.
【００１１】実施例１ 図１は、本発明の画像形成装置の一実施例を示す概略構
成図である。Embodiment 1 FIG. 1 is a schematic structural view showing an embodiment of the image forming apparatus of the present invention.
【００１２】本発明が適用できる画像形成装置は、感光
体、誘電体等の像担持体、たとえば感光ドラム１０の表
面を帯電ローラ１１により一様帯電し、その感光ドラム
１０の表面上に電子写真方式、静電記録方式等によって
画像情報信号に対応した像露光１２を行って、画像情報
信号に対応した静電潜像を形成し、この静電潜像を現像
剤を用いた現像手段１３によって現像して、潜像をトナ
ー像として可視化し、このトナー像を転写ローラ１４で
記録材１５に転写し、最後に定着手段１８でトナー像を
記録材１５に定着して、出力するものである。An image forming apparatus to which the present invention can be applied includes an image carrier such as a photosensitive member or a dielectric, for example, the surface of a photosensitive drum 10 is uniformly charged by a charging roller 11, and an electrophotographic image is formed on the surface of the photosensitive drum 10. Exposure 12 corresponding to an image information signal is performed by a method, an electrostatic recording method, or the like, an electrostatic latent image corresponding to the image information signal is formed, and the electrostatic latent image is developed by a developing unit 13 using a developer. The toner image is developed to visualize the latent image as a toner image, the toner image is transferred to the recording material 15 by the transfer roller 14, and finally the toner image is fixed to the recording material 15 by the fixing means 18 and output. .
【００１３】現像手段１３は、現像剤担持体として感光
ドラム１０と対向配置された現像スリーブ１６を有し、
この現像スリーブ１６上に現像剤（トナーまたはトナー
とキャリア）を担持して、感光ドラム１０と対向した現
像部に搬送する。そして現像バイアス電源１７で現像ス
リーブ１６に少なくとも直流電圧を含む現像バイアス電
圧を印加することにより、現像スリーブ１６上のトナー
または現像剤中のトナーを感光ドラム１０の表面上に形
成された静電潜像に付着させて現像し、潜像をトナー像
として可視化する。The developing means 13 has a developing sleeve 16 which is arranged opposite to the photosensitive drum 10 as a developer carrier,
A developer (toner or toner and carrier) is carried on the developing sleeve 16 and is conveyed to a developing section facing the photosensitive drum 10. By applying a developing bias voltage including at least a DC voltage to the developing sleeve 16 with the developing bias power supply 17, the toner on the developing sleeve 16 or the toner in the developer is electrostatically charged on the surface of the photosensitive drum 10. The latent image is visualized as a toner image by attaching to the image and developing.
【００１４】一次帯電手段や転写手段として用いられて
いる帯電手段は、コロナ放電を用いたコロナ帯電器が広
く用いられてきたが、近年、環境問題に対する意識の高
まりから、コロナ帯電で発生するオゾン量を著しく低減
可能な帯電ローラが、特に小型プリンターや低速複写機
において使用される。As a charging means used as a primary charging means or a transfer means, a corona charger using corona discharge has been widely used. Charging rollers that can significantly reduce the amount are used, especially in small printers and low speed copiers.
【００１５】本実施例では、上述したように、一次帯電
手段および転写手段として帯電ローラ１１および転写ロ
ーラ１４を使用している。これら帯電ローラ１１および
転写ローラ１４には、それぞれ帯電バイアス電源３０お
よび転写バイアス電源２０から所定のバイアスが印加さ
れる。In this embodiment, as described above, the charging roller 11 and the transfer roller 14 are used as primary charging means and transfer means. A predetermined bias is applied to the charging roller 11 and the transfer roller 14 from a charging bias power supply 30 and a transfer bias power supply 20, respectively.
【００１６】帯電ローラ１１は、金属の芯金の周りに適
度な抵抗と弾性を有するゴム層を形成してなっており、
コロナ帯電器に比べてバイアスの総電流、電圧の低減も
可能である。ゴム材料としては、エピクロルヒドリンゴ
ム、ニトリルゴム、ウレタンゴムなどに各種の導電材を
混合、分散して、所望の抵抗値にしたものが使用可能で
ある。The charging roller 11 has a rubber layer having an appropriate resistance and elasticity formed around a metal core.
Compared with the corona charger, the total bias current and voltage can be reduced. As the rubber material, a material having a desired resistance value obtained by mixing and dispersing various conductive materials in epichlorohydrin rubber, nitrile rubber, urethane rubber, or the like can be used.
【００１７】本実施例では、帯電ローラ１１として、抵
抗値が１０6 Ω（２００Ｖ印加時）程度、硬度が約６０
度（アスカーＣ硬度、５００ｇ加重）のものを用いた。
帯電ローラ１１の直径は１６ｍｍ、長さは３００ｍｍで
ある。In this embodiment, the charging roller 11 has a resistance value of about 10 6 Ω (when 200 V is applied) and a hardness of about 60.
A grade (Asker C hardness, 500 g weight) was used.
The charging roller 11 has a diameter of 16 mm and a length of 300 mm.
【００１８】帯電バイアス電源３０は、直流電圧と交流
電圧を重畳して帯電ローラ１１に印加できるようになっ
ている。本実施例では、帯電バイアス３０により帯電ロ
ーラ１１に、周波数約１ｋＨz 、電圧約２ｋＶppの正弦
波電圧に、約−７００Ｖの直流電圧を重畳した電圧を印
加することにより、感光ドラム１０の表面を約−７００
Ｖの一定電位に帯電させた。The charging bias power supply 30 can apply a DC voltage and an AC voltage to the charging roller 11 in a superimposed manner. In this embodiment, the surface of the photosensitive drum 10 is applied to the charging roller 11 by applying a voltage obtained by superimposing a DC voltage of about -700 V on a sine wave voltage of about 1 kHz and a voltage of about 2 kVpp to the charging roller 11 by the charging bias 30. -700
It was charged to a constant potential of V.
【００１９】本実施例によれば、帯電バイアス電源３０
にドラム膜厚測定回路１９が接続されている。この膜厚
測定回路１９は、電源３０による帯電バイアスの印加で
帯電ローラ１１に流れた直流成分の電流値を測定するよ
うになっており、後述するように、その電流値から感光
ドラム１０の感光層膜厚が求められる。この膜厚測定回
路１９の出力側は転写バイアス電源２０に接続されてい
る。According to the present embodiment, the charging bias power supply 30
Is connected to a drum film thickness measuring circuit 19. The film thickness measuring circuit 19 measures a current value of a DC component flowing to the charging roller 11 by application of a charging bias from a power supply 30. As described later, the photosensitive drum 10 The layer thickness is required. The output side of the film thickness measuring circuit 19 is connected to a transfer bias power supply 20.
【００２０】前述したように、画像形成が繰り返され、
画像形成装置の使用が進むと、帯電ローラ１１や転写ロ
ーラ１４による放電で感光ドラム１０の表面がダメージ
を受け、またクリーナ２１のクリーニングブレード２１
ａによる転写残りのトナーの掻き取りで、感光ドラム１
０の表面が摺擦されることにより、感光ドラム１０の表
面が粗され、かつ徐々に削られていく。As described above, image formation is repeated,
As the use of the image forming apparatus progresses, the surface of the photosensitive drum 10 is damaged by discharge by the charging roller 11 and the transfer roller 14, and the cleaning blade 21 of the cleaner 21 is used.
a, the photosensitive drum 1
By rubbing the surface of No. 0, the surface of the photosensitive drum 10 is roughened and gradually scraped.
【００２１】そこで、画像形成枚数と感光ドラム１０表
面の感光層膜厚の変化および帯電ローラ１１に流れた直
流成分電流値との関係を調べるために、図１の画像形成
装置を用いて、３０×１０3 枚（３万枚）の間欠画像形
成の耐久試験を行った。この間、帯電ローラ１１の直流
成分電流値Ｉdc［ｍＡ］は、上記のドラム膜厚測定回路
１９により、５０００枚ごとの前回転時（感光ドラム１
０が回転し始めてから画像形成を始めるまでの時間）に
測定した。また感光層の膜厚［μｍ］は、渦電流を用い
た膜厚計により別途、１万枚ごとに測定した。結果を図
２に示す。In order to examine the relationship between the number of formed images and the change in the thickness of the photosensitive layer on the surface of the photosensitive drum 10 and the DC component current flowing through the charging roller 11, the image forming apparatus shown in FIG. A durability test of intermittent image formation of × 10 3 sheets (30,000 sheets) was performed. During this time, the DC component current value Idc [mA] of the charging roller 11 is measured by the drum film thickness measuring circuit 19 during the pre-rotation of every 5,000 sheets (photosensitive drum 1).
0 (time from the start of rotation to the start of image formation). The film thickness [μm] of the photosensitive layer was separately measured every 10,000 sheets by a film thickness meter using eddy current. The results are shown in FIG.
【００２２】この図２の画像形成枚数と感光層膜厚の変
化および直流成分電流値との関係、および膜厚が既知の
種々の感光ドラムについて調べた膜厚と直流成分電流値
との関係から、感光層膜厚と直流成分電流値との関係を
調べると、図３のように、感光層膜厚と直流成分電流値
とは１対１の関係にある。すなわち、直流成分電流値に
よって感光ドラム１０の感光層膜厚が求められることが
分かる。The relationship between the number of formed images and the change in the thickness of the photosensitive layer and the DC component current value shown in FIG. 2 and the relationship between the film thickness and the DC component current value of various photosensitive drums having known film thicknesses are shown in FIG. When the relationship between the photosensitive layer thickness and the DC component current value is examined, as shown in FIG. 3, there is a one-to-one relationship between the photosensitive layer thickness and the DC component current value. That is, it is understood that the thickness of the photosensitive layer of the photosensitive drum 10 can be obtained from the DC component current value.
【００２３】一方、感光ドラム１０の表面粗さＲｚ［μ
ｍ］（１０点平均粗さ）は、図４のように、画像形成枚
数が増すにつれて徐々に大きくなっている。前述したよ
うに、感光ドラム１０の表面が粗れると、トナーと感光
ドラム１０との物理的吸着力が強まるために、感光ドラ
ム１０上のトナー像の転写材への転写効率の低下や、線
画像等の中抜け発生が引き起こされる。On the other hand, the surface roughness Rz [μ
m] (10-point average roughness) gradually increases as the number of formed images increases, as shown in FIG. As described above, when the surface of the photosensitive drum 10 is rough, the physical attraction between the toner and the photosensitive drum 10 is increased, so that the transfer efficiency of the toner image on the photosensitive drum 10 to the transfer material is reduced, Occurrence of a void in an image or the like is caused.
【００２４】これらを抑制するには、転写電界を大きく
して、トナーに働く転写材方向への静電気力を大きくし
てやればよく、従って転写電流を大きくしてやればよ
い。しかし、画像形成の初期から過剰な転写電流を流す
と、感光ドラム１０表面へのトナーの融着や、感光ドラ
ム１０表面の傷、削れ、あるいは感光ドラム１０表面の
メモリ（ドラムメモリ）などの弊害がもたらされる。To suppress these, the transfer electric field may be increased to increase the electrostatic force acting on the toner in the direction of the transfer material, and therefore the transfer current may be increased. However, if an excessive transfer current is applied from the initial stage of image formation, adverse effects such as fusion of toner to the surface of the photosensitive drum 10, scratches and abrasion on the surface of the photosensitive drum 10, and memory (drum memory) on the surface of the photosensitive drum 10 are caused. Is brought.
【００２５】そこで、本実施例では、非画像形成時に、
膜厚測定回路１９により感光ドラム１０の感光層膜厚を
測定し、膜厚が薄くなるに従って（すなわち感光ドラム
１０の表面粗さが大きくなるにつれて）、転写電流を徐
々に大きくなるように、測定回路１９の測定出力に基づ
き転写バイアス電源２０を制御した。具体的には、感光
ドラム１０の膜厚に対して転写電流Ｉtrを、図５に示す
ように制御した。Therefore, in this embodiment, at the time of non-image formation,
The film thickness of the photosensitive layer of the photosensitive drum 10 is measured by the film thickness measuring circuit 19, and the transfer current is gradually increased as the film thickness decreases (ie, as the surface roughness of the photosensitive drum 10 increases). The transfer bias power supply 20 was controlled based on the measurement output of the circuit 19. Specifically, the transfer current Itr was controlled with respect to the thickness of the photosensitive drum 10 as shown in FIG.
【００２６】本実施例に従い間欠３万枚の画像形成を行
ったときの画像の中抜け、画像濃度（Ｏ．Ｄ．＝Optica
l Density）および感光ドラム１０表面の傷等の結果を
表１に示す。比較のために、膜厚による転写電流の増加
制御を行わなかった場合の結果も表１に示す。表１にお
いて、符号は、○：非常に良好、□：かなり良好、△：
普通ないしやや不良、×：不良を意味する。In the case where 30,000 sheets of images are formed intermittently according to the present embodiment, image dropout, image density (OD = Optica)
l Density) and the results such as scratches on the surface of the photosensitive drum 10 are shown in Table 1. For comparison, Table 1 also shows the results when the increase control of the transfer current by the film thickness was not performed. In Table 1, the symbols are ○: very good, □: fairly good, Δ:
Normal or somewhat poor, x: means defective.
【００２７】[0027]
【表１】 [Table 1]
【００２８】本実施例１では、感光ドラム１０の感光層
膜厚が薄くなるに従って、転写電流を徐々に大きくなる
ように制御したので、表１に示されるように、３万枚の
画像形成によっても画像の中抜けが防止が、ほとんど悪
化していないことが分かる。また、転写電流を増加する
ことによって、感光ドラム１０の傷の発生はわずかに悪
化するものの、転写効率の低下を抑制して画像濃度を維
持することができている。In the first embodiment, the transfer current is controlled so as to gradually increase as the thickness of the photosensitive layer of the photosensitive drum 10 becomes thinner. Also, it can be seen that the prevention of image dropout is hardly worsened. Further, by increasing the transfer current, although the occurrence of scratches on the photosensitive drum 10 is slightly deteriorated, it is possible to maintain the image density while suppressing a decrease in transfer efficiency.
【００２９】以上の実施例では、帯電ローラ１１に印加
する帯電バイアスは直流電圧に交流電圧を重畳したもの
としたが、本発明はこれに限られず、直流電圧のみを印
加してもよく、同様な効果を得ることができる。In the above embodiment, the charging bias applied to the charging roller 11 is obtained by superimposing an AC voltage on a DC voltage. However, the present invention is not limited to this, and only a DC voltage may be applied. Effects can be obtained.
【００３０】実施例２ 図６は、本発明の画像形成装置の他の実施例を示す概略
構成図である。Embodiment 2 FIG. 6 is a schematic structural view showing another embodiment of the image forming apparatus of the present invention.
【００３１】本実施例では、感光ドラム１０の感光層膜
厚に応じて制御する転写条件として、（１）転写電流の
増加の他に、（２）転写ローラ１４の感光ドラム１０に
対する表面の移動速度の差、すなわち周速の差も加え
た。In this embodiment, the transfer conditions controlled in accordance with the thickness of the photosensitive layer of the photosensitive drum 10 include (1) increase in transfer current and (2) movement of the surface of the transfer roller 14 with respect to the photosensitive drum 10. The difference in speed, that is, the difference in peripheral speed, was also added.
【００３２】これに対応して、転写ローラ１４に駆動装
置２２を設けて、転写ローラ１４の回転を感光ドラム１
０の従動回転でなく、駆動装置２２により駆動回転する
ようにした。本実施例における感光ドラム１０の膜厚測
定法方法などその他の点は実施例１と同様で、図６にお
いて図１に付した符号と同一の符号は同一の部材を示
す。In response to this, a transfer roller 14 is provided with a driving device 22 to rotate the transfer roller 14 to rotate the photosensitive drum 1.
Instead of the zero driven rotation, the driving device 22 is driven to rotate. In other respects, such as a method for measuring the thickness of the photosensitive drum 10 in this embodiment, the same members as those in the first embodiment are shown. In FIG. 6, the same reference numerals as those shown in FIG.
【００３３】駆動装置２２による転写ローラ１４の駆動
回転での周速差は、具体的には、転写ローラ１４が感光
ドラム１０よりも約１．５％速くなるように設定した。
そして、感光ドラム１０の感光層膜厚が若干薄くなる程
度の画像形成枚数１０4 枚（１万枚）までは、転写ロー
ラ１４を感光ドラム１０と等速とし、画像形成枚数が１
０4 枚以降は、感光ドラム１０に対する転写ローラ１４
の周速差を１．５％に制御した。Specifically, the peripheral speed difference in the drive rotation of the transfer roller 14 by the drive device 22 was set so that the transfer roller 14 was about 1.5% faster than the photosensitive drum 10.
The transfer roller 14 is set at the same speed as the photosensitive drum 10 until the number of image forming sheets reaches 10 4 (10,000 sheets) such that the thickness of the photosensitive layer of the photosensitive drum 10 is slightly reduced.
0 four later, transfer onto the photosensitive drum 10 roller 14
Was controlled to 1.5%.
【００３４】本実施例における画像の中抜け防止等の結
果を先の表１に示す。Table 1 shows the results of the present embodiment, such as the prevention of image dropout.
【００３５】表１に示されるように、本実施例２では、
感光ドラム１０の傷発生が、実施例１のときよりも少し
悪くなるものの、中抜けの発生は実施例１よりもさらに
改善された。As shown in Table 1, in the second embodiment,
Although the occurrence of scratches on the photosensitive drum 10 was slightly worse than in the first embodiment, the occurrence of hollow was further improved than in the first embodiment.
【００３６】実施例３ 図７は、本発明の画像形成装置のさらに他の実施例を示
す概略構成図である。Embodiment 3 FIG. 7 is a schematic structural view showing still another embodiment of the image forming apparatus of the present invention.
【００３７】本実施例では、感光ドラム１０の感光層膜
厚に応じて制御する転写条件として、（１）転写電流の
増加、（２）転写ローラ１４の感光ドラム１０に対する
周速差の他に、図７に示すように、（３）バネ部材２３
による転写ローラ１４の感光ドラム１０への当接圧を可
変にして、感光ドラム１０の感光層の膜厚が減少するに
従って、転写ローラ１４の当接圧を低減できるようにし
た。In this embodiment, the transfer conditions controlled in accordance with the thickness of the photosensitive layer of the photosensitive drum 10 include (1) an increase in the transfer current and (2) a difference in the peripheral speed of the transfer roller 14 with respect to the photosensitive drum 10. As shown in FIG. 7, (3) the spring member 23
The contact pressure of the transfer roller 14 against the photosensitive drum 10 is made variable so that the contact pressure of the transfer roller 14 can be reduced as the thickness of the photosensitive layer of the photosensitive drum 10 decreases.
【００３８】具体的には、感光ドラム１０の感光層の膜
厚が若干薄くなる程度の画像形成枚数１０4 枚（１万
枚）までは、転写ローラ１４の感光ドラム１０への当接
圧（線圧）は、初期の１５ｋｇｆ／ｃｍを維持し、画像
形成枚数が１０4 枚以降は当接圧を減少して、５ｋｇｆ
／ｃｍの軽圧とした。[0038] Specifically, the contact pressure of the film thickness of the photosensitive layer of the photosensitive drum 10 is the number of image formation 10 four Slightly thinner until (10,000) is the photosensitive drum 10 of the transfer roller 14 ( linear pressure) is to maintain the initial 15 kgf / cm, image number 10 four subsequent decrease the contact pressure, 5 kgf
/ Cm.
【００３９】転写ローラ１４の感光ドラム１０との周速
差は、実施例２と同様、駆動装置２での転写ローラ１４
の回転駆動により、転写ローラ１４が感光ドラム１０よ
りも約１．５％速くなるように設定し、画像形成枚数１
０4 枚までは等速、画像形成枚数が１０4 枚以降は周速
差１．５％とする。The peripheral speed difference between the transfer roller 14 and the photosensitive drum 10 is the same as in the second embodiment.
Is set so that the transfer roller 14 is about 1.5% faster than the photosensitive drum 10 by the rotation of
0 to four constant velocity, the number of formed images is 10 four subsequent to 1.5% peripheral speed difference.
【００４０】本実施例における結果を先の表２に示す。The results of this example are shown in Table 2 above.
【００４１】感光ドラム１０の膜厚が画像形成装置の使
用にともなって薄くなり、かつ感光ドラム１０の表面粗
さが大きくなるのに対し、表１に示すように、転写電流
を初期の１５μＡから徐々に増していくことによって、
転写効率は低下することがなく、従って本実施例３で
も、画像濃度（Ｏ．Ｄ．）が実施例１、２同様に安定し
ている結果が得られた。While the film thickness of the photosensitive drum 10 becomes thinner and the surface roughness of the photosensitive drum 10 becomes larger as the image forming apparatus is used, as shown in Table 1, the transfer current is increased from the initial value of 15 μA. By gradually increasing,
The transfer efficiency did not decrease. Therefore, in Example 3, the result that the image density (OD) was stable as in Examples 1 and 2 was obtained.
【００４２】また中抜けレベルは初期から画像形成枚数
３×１０4 まで常に実用上問題なく、さらに転写ローラ
１４の当接力を軽くしたので、感光ドラム１０表面の傷
の発生も抑制できた。また表１に示さなかったが、感光
ドラム１０の表面の傷防止とともに、感光ドラム１０表
面へのトナーの融着の発生も抑制できた。Further, the hollow level was always practically satisfactory from the initial stage to the number of image formations of 3 × 10 4 , and the contact force of the transfer roller 14 was reduced, so that the occurrence of scratches on the surface of the photosensitive drum 10 could be suppressed. Although not shown in Table 1, it was possible to prevent the surface of the photosensitive drum 10 from being damaged and to suppress the toner from being fused to the surface of the photosensitive drum 10.
【００４３】なお、本発明の実施例において、感光層膜
厚の測定は、１万枚ごとの前回転時に帯電ローラに直流
電圧と交流電圧を重畳した帯電バイアスを印加し、その
とき流れる直流成分の電流値を検出することにより行っ
た。In the embodiment of the present invention, the thickness of the photosensitive layer is measured by applying a charging bias in which a DC voltage and an AC voltage are superimposed on the charging roller during the pre-rotation of every 10,000 sheets, and the DC component flowing at that time. This was performed by detecting the current value of
【００４４】しかし、感光層膜厚の測定方法やタイミン
グは、上記実施例に限定するものではない。タイミング
としては、前回転時や後回転時（感光ドラムの画像形成
プロセスが終了してから、感光ドラムの回転が止まるま
での時間）を用いてもよい。However, the method and timing for measuring the thickness of the photosensitive layer are not limited to those in the above embodiment. The timing may be the time of pre-rotation or the time of post-rotation (the time from the end of the image forming process of the photosensitive drum to the stop of the rotation of the photosensitive drum).
【００４５】また測定間隔は短いほど正確な制御を行う
ことができるが、あまり頻繁に測定しても膜厚の変化は
小さく、また測定時に印加する帯電バイアスにより感光
ドラムの表面がダメージを受けて削れやすくなる。The shorter the measurement interval, the more accurate the control can be performed. However, even if the measurement is performed too frequently, the change in the film thickness is small, and the surface of the photosensitive drum is damaged by the charging bias applied during the measurement. It becomes easy to scrape.
【００４６】原稿自動送り装置やソータを用いて連続的
に多量の画像形成を行う場合には、途中で画像形成を止
めることなく一連のジョブの最初か最後に行えばよい。When a large number of images are continuously formed using an automatic document feeder or a sorter, the image formation may be performed at the beginning or end of a series of jobs without stopping image formation.
【００４７】また測定は一定ごとに行ってもよいし、多
数枚画像形成の初期やある枚数以後のみ頻度を上げるな
どしてもよい。Further, the measurement may be performed at regular intervals, or the frequency may be increased only at the initial stage of forming a large number of sheets or after a certain number of sheets.
【００４８】実施例４ 本実施例は、実施例３において、転写ローラ１４の回転
速度を感光ドラム１０と等速（すなわち感光ドラムに従
動）とし、感光ドラム１０の膜厚の減少にともなって制
御する転写条件を、転写電流の増加と転写ローラ１０の
当接力の減少の２つとした。Embodiment 4 This embodiment is different from Embodiment 3 in that the rotation speed of the transfer roller 14 is set to be the same as the speed of the photosensitive drum 10 (that is, driven by the photosensitive drum), and the control is performed as the film thickness of the photosensitive drum 10 decreases. The transfer conditions to be performed were two, that is, an increase in the transfer current and a decrease in the contact force of the transfer roller 10.
【００４９】このような本実施例によれば、中抜けレベ
ルは実施例３に比較して若干低下する可能性があるが、
転写ローラ１４の当接力が軽くなることと、感光ドラム
１０との周速差がないために、感光ドラム１０表面のダ
メージが一層少なく、感光ドラム１０表面の傷やトナー
融着がより発生しにくい。また転写ローラ１４は感光ド
ラム１０に対して従動回転とするので、画像形成装置の
構成が簡単になる。According to this embodiment, the hollow level may be slightly lower than that of the third embodiment.
Since the contact force of the transfer roller 14 is reduced and there is no difference in peripheral speed with the photosensitive drum 10, damage to the surface of the photosensitive drum 10 is further reduced, and scratches on the surface of the photosensitive drum 10 and toner fusion are less likely to occur. . Further, since the transfer roller 14 is driven to rotate with respect to the photosensitive drum 10, the configuration of the image forming apparatus is simplified.
【００５０】以上では、画像形成装置の転写条件を制御
したが、画像形成装置が分離帯電器や除電針を用いる場
合には、それらのバイアス条件も制御対象とすることが
できる。In the above description, the transfer conditions of the image forming apparatus are controlled. However, when the image forming apparatus uses a separation charger or a static elimination needle, those bias conditions can also be controlled.
【００５１】[0051]
【発明の効果】以上説明したように、本発明によれば、
像担持体の一次帯電に使用する帯電ローラ等の帯電手段
に直流電圧またはこれに交流電圧を重畳した帯電バイア
スを印加し、そのとき帯電手段に流れる直流成分の電流
値を検出するなどの方法により、像担持体表面の感光層
の膜厚を測定し、感光層の膜厚に応じて、像担持体上に
形成したトナー像を転写材に転写する転写条件の、転写
電流、像担持体に対する転写ローラの周速差および転写
ローラの像担持体への当接圧などのうちの少なくとも１
つを変更するようにしたので、画像形成の繰り返しによ
って像担持体の表面粗さが大きくなっても、トナー像の
転写効率の低下や中抜けの発生を抑制して、濃度が十分
で高品質な画像を得ることができ、また像担持体表面の
トナー融着や傷などの弊害も防止される。As described above, according to the present invention,
A DC voltage or a charging bias obtained by superimposing an AC voltage is applied to charging means such as a charging roller used for primary charging of the image carrier, and a current value of a DC component flowing to the charging means at that time is detected. Measuring the film thickness of the photosensitive layer on the surface of the image carrier, and, according to the film thickness of the photosensitive layer, the transfer conditions for transferring the toner image formed on the image carrier to the transfer material; At least one of the peripheral speed difference of the transfer roller, the contact pressure of the transfer roller with the image carrier, and the like.
As a result, even if the surface roughness of the image carrier increases due to repetition of image formation, a reduction in the transfer efficiency of toner images and the occurrence of voids are suppressed, and the density is sufficient and high quality is achieved. A good image can be obtained, and adverse effects such as toner fusion and scratches on the surface of the image carrier can be prevented.
【図１】本発明の画像形成装置の一実施例を示す概略構
成図である。FIG. 1 is a schematic configuration diagram showing one embodiment of an image forming apparatus of the present invention.
【図２】画像形成装置での画像形成枚数に対する感光ド
ラムの感光層膜厚の変化および帯電ローラから流れる直
流成分電流値の変化を示すグラフである。FIG. 2 is a graph showing a change in a photosensitive layer thickness of a photosensitive drum and a change in a DC component current value flowing from a charging roller with respect to the number of formed images in the image forming apparatus.
【図３】感光ドラムの感光層膜厚と帯電ローラから流れ
る直流成分電流値の関係を示すグラフである。FIG. 3 is a graph showing a relationship between the thickness of a photosensitive layer of a photosensitive drum and a DC component current value flowing from a charging roller.
【図４】画像形成装置での画像形成枚数に対する感光ド
ラムの表面粗さの変化を示すグラフである。FIG. 4 is a graph showing a change in the surface roughness of the photosensitive drum with respect to the number of images formed in the image forming apparatus.
【図５】図１の画像形成装置での画像形成における感光
ドラムの感光層膜厚の減少に対する転写電流の制御法を
示すグラフである。5 is a graph showing a method of controlling a transfer current with respect to a decrease in the thickness of a photosensitive layer of a photosensitive drum in image formation in the image forming apparatus of FIG.
【図６】本発明の画像形成装置の他の実施例を示す概略
構成図である。FIG. 6 is a schematic configuration diagram showing another embodiment of the image forming apparatus of the present invention.
【図７】本発明の画像形成装置のさらに他の実施例を示
す概略構成図である。FIG. 7 is a schematic configuration diagram showing still another embodiment of the image forming apparatus of the present invention.
１０ 感光ドラム １１ 帯電ローラ １４ 転写ローラ １９ ドラム膜厚測定回路 ２０ 転写バイアス電源 ２３ バネ部材 ３０ 帯電バイアス電源 Reference Signs List 10 photosensitive drum 11 charging roller 14 transfer roller 19 drum film thickness measurement circuit 20 transfer bias power supply 23 spring member 30 charging bias power supply
Claims (5)
し、像露光して静電潜像を形成し、この潜像を現像手段
により現像剤を用いて現像して可視化し、得られた可視
画像を転写手段により転写材に転写する画像形成装置に
おいて、前記像担持体の表面を形成する感光層の膜厚を
膜厚測定手段により測定して、前記測定された感光層の
膜厚に応じて、前記可視画像の転写条件を制御すること
を特徴とする画像形成装置。1. An electrostatic latent image is formed by charging the surface of an image carrier by a charging unit, exposing the image to an image, developing the latent image with a developing agent by a developing unit, and visualizing the latent image. In an image forming apparatus that transfers a visible image to a transfer material by a transfer unit, a film thickness of a photosensitive layer that forms the surface of the image carrier is measured by a film thickness measurement unit, and the measured thickness of the photosensitive layer is measured. An image forming apparatus, wherein the transfer condition of the visible image is controlled accordingly.
段から流れる転写電流である請求項１の画像形成装置。2. The image forming apparatus according to claim 1, wherein the transfer condition of the visible image is a transfer current flowing from the transfer unit.
る転写ローラであり、前記転写条件は、転写ローラ表面
の周速と像担持体表面の周速の差である請求項１の画像
形成装置。3. The image according to claim 1, wherein the transfer unit is a transfer roller that contacts a surface of the image carrier, and the transfer condition is a difference between a peripheral speed of the transfer roller surface and a peripheral speed of the image carrier surface. Forming equipment.
る転写ローラであり、前記転写条件は、像担持体への転
写ローラの当接圧である請求項１の画像形成装置。4. The image forming apparatus according to claim 1, wherein the transfer unit is a transfer roller that contacts a surface of the image carrier, and the transfer condition is a contact pressure of the transfer roller on the image carrier.
帯電ローラであり、非画像形成時、前記帯電ローラに直
流電圧またはこれに交流電圧を重畳した帯電バイアスを
印加し、前記膜厚測定手段は、そのとき流れる帯電バイ
アスの直流成分の電流値を検出することにより、前記感
光層の膜厚を測定する請求項１〜４のいずれかの項に記
載の画像形成装置。5. The image forming apparatus according to claim 1, wherein the charging unit is a charging roller that comes into contact with the surface of the image carrier, and applies a DC bias or a charging bias obtained by superimposing an AC voltage on the charging roller during non-image formation to measure the film thickness. The image forming apparatus according to claim 1, wherein the unit measures the thickness of the photosensitive layer by detecting a current value of a DC component of a charging bias flowing at that time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03236498A JP3542488B2 (en) | 1998-01-30 | 1998-01-30 | Image forming device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03236498A JP3542488B2 (en) | 1998-01-30 | 1998-01-30 | Image forming device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11218975A true JPH11218975A (en) | 1999-08-10 |
| JP3542488B2 JP3542488B2 (en) | 2004-07-14 |
Family
ID=12356910
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03236498A Expired - Fee Related JP3542488B2 (en) | 1998-01-30 | 1998-01-30 | Image forming device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3542488B2 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005234301A (en) * | 2004-02-20 | 2005-09-02 | Ricoh Co Ltd | Image forming apparatus |
| JP2007218977A (en) * | 2006-02-14 | 2007-08-30 | Fuji Xerox Co Ltd | Image forming apparatus and method of controlling electrification of electrifying roll |
| JP2009063894A (en) * | 2007-09-07 | 2009-03-26 | Fuji Xerox Co Ltd | Image forming apparatus, method and program for generating life information of image support |
| JP2012215703A (en) * | 2011-03-31 | 2012-11-08 | Kyocera Document Solutions Inc | Image forming apparatus |
-
1998
- 1998-01-30 JP JP03236498A patent/JP3542488B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005234301A (en) * | 2004-02-20 | 2005-09-02 | Ricoh Co Ltd | Image forming apparatus |
| JP2007218977A (en) * | 2006-02-14 | 2007-08-30 | Fuji Xerox Co Ltd | Image forming apparatus and method of controlling electrification of electrifying roll |
| JP2009063894A (en) * | 2007-09-07 | 2009-03-26 | Fuji Xerox Co Ltd | Image forming apparatus, method and program for generating life information of image support |
| JP2012215703A (en) * | 2011-03-31 | 2012-11-08 | Kyocera Document Solutions Inc | Image forming apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3542488B2 (en) | 2004-07-14 |
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