JPH06214497A - Electrophotographic method - Google Patents

Abstract

PURPOSE:To efficiently reduce residual potential caused by a DCL film, to attain electrical stabilization and to maintain stable excellent image quality for a long period by imparting the charge of a reverse polarity and executing the full surface exposure with light of wavelength in the vicinity of the maximum sensitivity, between cleaning and uniform electrification. CONSTITUTION:For reducing the residual potential, the charge of the polarity opposite to that of electrification by a uniform electrifier 11 is imparted by a reverse polarity charge imparting device 17 and then, the full surface exposure is executed by a full surface exposing device 18 (a). Or the electrification of the reverse polarity is imparted and simultaneously the full surface exposure is executed (b). Or after the full surface exposure is first executed, the electrification of the reverse polarity is attained (c). In these ways, there is a little difference in the effect. However, the effect is hardly obtained in the charge of the reverse polarity by itself or the full surface exposure by itself and the operations of both devices 17 and 18 are surely required. As a potential applied by the reverse polarity charge imparting device 17, 200-700V is desirable. It is desirable that the full surface exposing device 18 is by a light source having the wavelength in the vicinity of the maximum sensitivity possessed by a photosensitive body 10.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は電子写真法に関し、詳し
くは、感光体の残留電位を有効に低減化し、繰返し特性
を安定化するための電子写真法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic method, and more particularly to an electrophotographic method for effectively reducing the residual potential of a photoconductor and stabilizing the repeating characteristics.

【０００２】[0002]

【従来の技術】従来、電子写真感光体用の感光材料とし
てセレン（Ｓｅ）、アモルファスシリコン（ａ−Ｓ
ｉ）、硫化カドミウム（ＣｄＳ）が主として用いられて
きたが、近年では価格、製造、電子写真特性等といった
点で有利な有機感光体へと置きかわってきている。しか
しながら、有機系感光材料はビッカース硬度で２０〜４
０ｋｇ／ｍｍ²程度と軟らかいため機械的耐久性が低
く、これを電子写真複写機やレーザービームプリンター
等の画像形成装置で使用した場合、５〜１５万枚程度で
交換を余儀なくされる。そのため有機系感光体の最表面
を何らかの方法で硬度アップを計り耐摩耗性を向上する
必要がある。そして、その一手段として、感光体の最表
面に高硬度の保護層を形成する方法がある。2. Description of the Related Art Conventionally, selenium (Se) and amorphous silicon (a-S) have been used as photosensitive materials for electrophotographic photoreceptors.
i) and cadmium sulfide (CdS) have been mainly used, but in recent years, they have been replaced by organic photoreceptors which are advantageous in terms of price, manufacturing, electrophotographic characteristics and the like. However, the organic photosensitive material has a Vickers hardness of 20 to 4
Since it is as soft as about 0 kg / mm ² , it has low mechanical durability, and when it is used in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer, it is inevitably replaced after about 50,000 to 150,000 sheets. Therefore, it is necessary to increase the hardness of the outermost surface of the organic photoreceptor by some method to improve the abrasion resistance. Then, as one of the means, there is a method of forming a protective layer of high hardness on the outermost surface of the photoreceptor.

【０００３】表面保護層はオーバーコートされる感光体
の電子写真特性を損なうものであってはならない。従っ
て、表面保護層は光学特性や電気特性などを電子写真特
性的に満足するとともに機械的にも優れた薄膜でなけれ
ばならない。耐久性があり電荷保持能力が高く、表面保
護層として適用可能な薄膜として、炭素または炭素を主
成分として構成されるものが好適である。その薄膜の代
表的な例にはダイヤモンド状カーボン膜（ＤＬＣ膜）が
あり、このＤＬＣ膜はメタン、エタン、ブタン、プロパ
ン、ブタジエン等の炭化水素系のガス、必要に応じて水
素、フッ素、窒素ガス等を流入しつつ、プラズマＣＶＤ
法、光ＣＶＤ法、スパッタリング法などの真空製膜法で
作製される。この膜は製膜条件によって物理特性が大き
く変化する。硬度は１０〜２０００ｋｇ／ｍｍ²、電気
抵抗は１０⁶〜１０¹⁷Ω・ｃｍ、光透過率は着色のため
短波長での吸収が大きくなり、数％〜１００％等であ
る。感光体の保護層とする場合には、表面電位、感度等
の特性安定性の他、機械特性等で長期にわたって使用し
ても十分使用に耐え得る物理特性をが必要である。ＤＬ
Ｃ膜を有機系感光体にオーバーコートする場合、製膜装
置での基盤温度条件は感光層のガラス転移温度の関係か
ら、室温または室温以下にする必要があるが、製膜の際
の各種原料ガス、反応圧、ＲＦ電力などといった製膜条
件を適当に選定することにより、電子写真感光体として
の表面保護層が作製可能である。The surface protective layer must not impair the electrophotographic properties of the overcoated photoreceptor. Therefore, the surface protective layer must be a thin film that satisfies the electro-optical characteristics such as optical characteristics and electrical characteristics and is mechanically excellent. As the thin film which is durable and has a high charge retention ability and which can be applied as the surface protection layer, carbon or a film mainly composed of carbon is preferable. A typical example of the thin film is a diamond-like carbon film (DLC film). This DLC film is a hydrocarbon-based gas such as methane, ethane, butane, propane and butadiene, and if necessary, hydrogen, fluorine and nitrogen. Plasma CVD while flowing gas etc.
Method, a photo-CVD method, a sputtering method, or another vacuum film-forming method. The physical properties of this film change greatly depending on the film forming conditions. The hardness is 10 to 2000 kg / mm ² , the electric resistance is 10 ⁶ to 10 ¹⁷ Ω · cm, and the light transmittance is colored, so that absorption at a short wavelength is large, and is several% to 100%. When it is used as a protective layer of a photoconductor, in addition to characteristics stability such as surface potential and sensitivity, it is necessary to have physical characteristics such as mechanical characteristics that can be sufficiently used even if used for a long period of time. DL
When the C film is overcoated on the organic photoconductor, the substrate temperature condition in the film forming apparatus needs to be room temperature or lower than room temperature because of the glass transition temperature of the photosensitive layer. By appropriately selecting the film forming conditions such as gas, reaction pressure, RF power, etc., the surface protective layer as an electrophotographic photoreceptor can be prepared.

【０００４】だが、上記特性を満足する表面保護層であ
っても、時として、画像形成装置のコピースピードによ
っては、有機系感光体を繰返し使用すると残留電位が生
じて、濃度低下、ディテールの消失、地肌汚れ等の画像
品質を低下させるという問題が生じる。これはＤＬＣ膜
への正孔もしくは電子の注入効率、および膜中の移動度
が小さいためであると考えられる。However, even with a surface protective layer satisfying the above characteristics, depending on the copy speed of an image forming apparatus, sometimes a residual potential is generated when an organic photoreceptor is repeatedly used, resulting in a decrease in density and loss of detail. However, there arises a problem that the image quality such as background stain deteriorates. It is considered that this is because the efficiency of injecting holes or electrons into the DLC film and the mobility in the film are small.

【０００５】残留電位が生じたり、画像露光前の均一帯
電電位の安定性などが不十分な場合の方策としては、複
写プロセスから感光体廻りの条件を検討したものとし
て、（ｉ）クリーニング工程と均一帯電工程との間に交
流バイアス電圧が印加された導電性可撓性部材をａ−Ｓ
ｉ系感光体に接触させてトラッピングのリリースを行な
う（特開昭６０−１４２３５５号公報）、（ii）クリー
ニング工程と均一帯電工程との間に交流又は直流バイア
ス電圧が印加され、かつ、加温された導電性可撓性部材
をａ−Ｓｉ系感光体に接触させてトラッピングのリリー
スを行なう（特開昭６０−１５６０６８号公報）、（ii
i）均一帯電を行なう前に感光体表面に交番電界を印加
することにより、印加される一方の極性の波形ピーク前
後で感光体表面が帯電し、生ずる電界によりトラッピン
グのリリースを可能とする（特開昭６０−２０３９６４
号公報）、（iv）均一帯電及び／又は除電を行なう前
に、均一帯電と同極性の前帯電を行なう（特開昭６１−
１６５７６４号公報）、（ｖ）除電を均一帯電とは逆極
性の直流コロナ帯電により行なう（特開昭６０−１０２
６６号公報）などがあげられる。As a measure to be taken when residual potential is generated or the stability of the uniform charging potential before image exposure is insufficient, it is necessary to consider the conditions around the photoconductor from the copying process. The conductive flexible member to which an AC bias voltage is applied during the uniform charging process is aS
The trapping is released by bringing it into contact with the i-type photosensitive member (Japanese Patent Laid-Open No. 60-142355). (ii) An AC or DC bias voltage is applied between the cleaning step and the uniform charging step, and heating is performed. The trapped conductive flexible member is brought into contact with the a-Si photosensitive member to release the trapping (Japanese Patent Laid-Open No. 60-156068), (ii)
i) By applying an alternating electric field to the surface of the photoconductor before performing uniform charging, the surface of the photoconductor is charged before and after the waveform peak of one polarity that is applied, and the trapping can be released by the generated electric field. Kaisho 60-203964
(Iv), (iv) Before uniform charging and / or static elimination, pre-charging of the same polarity as uniform charging is performed (Japanese Patent Laid-Open No. 61-
(157664), (v) static elimination is performed by DC corona charging having a polarity opposite to that of uniform charging (JP-A-60-102).
No. 66 publication).

【０００６】これらのうち（ｉ）（ii）（iii）及び（i
v）は何れも保護層のないａ−Ｓｉ系感光体であり、感
光体中にトラップされた正孔及び／又は電子を帯電工程
に入る前に交流バイアス（及び光除電、加熱）の印加に
より開放させ、電気抵抗、静電容量を回復させて繰返し
帯電電位の低下及びメモリー現象を改善しようとするも
のである。また、（ｖ）の方法では逆極性帯電に要する
電流の４０〜９０％を流すことにより、帯電電位の低下
を補正しようとするものである。Of these, (i) (ii) (iii) and (i
v) is an a-Si-based photoconductor without any protective layer, which is formed by applying an AC bias (and photo-electrification, heating) before the holes and / or electrons trapped in the photoconductor enter the charging process. It is intended to open the battery, recover the electric resistance and the electrostatic capacity, and repeatedly reduce the charging potential and improve the memory phenomenon. In the method (v), 40 to 90% of the current required for reverse polarity charging is flowed to correct the decrease in charging potential.

【０００７】[0007]

【発明が解決しようとする課題】しかしながら、前記
（ｉ）（ii）（iii）及び（iv）の場合においては表面
保護層が無いため、交流によるバイアス電圧が比較的容
易に作用し、期待した効果が得られるが、殆ど絶縁層に
近いＤＬＣ膜による表面保護層の場合作用が及びにくい
ため、あまり効果は期待出来ない。一方、前記（ｖ）の
場合においては、複写サイクル初期の電位変動を抑制す
る効果があるが、逆極性の電荷が多くなるに従い長期的
に逆電荷の１部が感光体の内部にトラップし帯電電位低
下が起こるのは表面保護層がある場合でも同じである
が、逆極性の電荷注入の効果が効き過ぎるので、流れ込
み電流は控えめにする必要がある。ところで、有機系感
光体の場合、帯電の際、支持体からの電荷注入により帯
電特性が悪化するのを防止するために、支持体と感光層
との間に電荷注入阻止層（下引き層）を形成するのが一
般的に行なわれるが、この下引き層が時として感光体特
性を左右する要因になる。例えば、金属酸化物の微粉末
を分散した下引き層等では金属酸化物微粉末と樹脂との
界面に電荷がトラップし易いため、電荷のキャンセリン
グを阻害する。このことは光感度の劣化や残留電位の発
生を惹起するものである。かかる理由から、本発明の目
的は複写プロセスからの見直しを行ない、ＤＬＣ膜によ
る残留電位を効率良く低減化させて電気的安定化を計
り、長期的に安定な良好な画像品質が維持出来る電子写
真法を提供することである。However, in the cases (i), (ii), (iii) and (iv) described above, since there is no surface protective layer, the bias voltage due to the AC acts relatively easily, which is expected. Although the effect can be obtained, the effect cannot be expected so much in the case of the surface protective layer made of the DLC film which is almost close to the insulating layer, because the effect is difficult. On the other hand, in the case of (v), there is an effect of suppressing the potential fluctuation at the initial stage of the copying cycle, but as the amount of the opposite polarity charge increases, a part of the opposite charge is trapped inside the photoconductor for a long period of time and charged. The potential drop occurs even when there is a surface protective layer, but the effect of reverse polarity charge injection is too effective, so the flow-in current must be conservative. By the way, in the case of an organic photoreceptor, a charge injection blocking layer (undercoat layer) is provided between the support and the photosensitive layer in order to prevent deterioration of charging characteristics due to charge injection from the support during charging. However, this undercoat layer sometimes becomes a factor that influences the characteristics of the photoreceptor. For example, in an undercoat layer or the like in which fine powder of metal oxide is dispersed, charges are easily trapped at the interface between the fine powder of metal oxide and the resin, which hinders the canceling of charges. This causes deterioration of photosensitivity and generation of residual potential. For this reason, the object of the present invention is to review the copying process, efficiently reduce the residual potential due to the DLC film and electrically stabilize it, and maintain a stable and good image quality for a long time in electrophotography. To provide the law.

【０００８】[0008]

【課題を解決するための手段】本発明の第１は、導電性
支持体と有機感光層との間に下引き層を有し、かつ、そ
の感光層上に炭素または炭素を主成分として構成された
薄膜を表面保護層として有する有機系感光体に均一帯
電、画像露光、現像、転写、分離、除電及びクリーニン
グを繰り返し行なって普通紙等に多数枚のコピーを得る
電子写真法において、該クリーニングと該均一帯電との
間に該均一帯電とは逆極性の電荷付与及びその逆極性電
荷付与の直前あるいは直後、若しくは同時に該感光体が
有する最大感度近傍の波長の全面露光を行なうことを特
徴とする。The first aspect of the present invention is to have an undercoat layer between a conductive support and an organic photosensitive layer, and to form carbon or carbon as a main component on the photosensitive layer. In an electrophotographic method for obtaining a large number of copies on plain paper, etc., by repeatedly performing uniform charging, image exposure, development, transfer, separation, charge removal and cleaning on an organic photoreceptor having the formed thin film as a surface protective layer, the cleaning is performed. Between the uniform charging and the uniform charging, and a whole surface exposure at a wavelength in the vicinity of the maximum sensitivity of the photosensitive member is performed immediately before or after the application of the opposite polarity charge to the uniform charge and the opposite polarity charge application. To do.

【０００９】この本発明の第２の方法は、導電性支持体
と有機感光層との間に下引き層を有し、かつ、その感光
層上に炭素または炭素を主成分として構成された薄膜を
表面保護層として有する有機系感光体に均一帯電、画像
露光、現像、転写、分離、除電及びクリーニングを繰り
返し行なって普通紙等に多数枚のコピーを得る電子写真
法において、該クリーニングと該均一帯電との間に該均
一帯電とは逆極性の電荷付与及びその逆極性電荷付与の
直前あるいは直後、若しくは同時に該感光体が有する最
大感度近傍の波長の全面照射を間歇的に行なうことを特
徴とする。In the second method of the present invention, an undercoat layer is provided between a conductive support and an organic photosensitive layer, and carbon or carbon-based thin film is formed on the photosensitive layer. In an electrophotographic method in which a large number of copies are obtained by repeatedly performing uniform charging, image exposure, development, transfer, separation, charge removal and cleaning on an organic photoreceptor having a surface protective layer, the cleaning and the uniform Between charging and charging, a charge having a polarity opposite to that of the uniform charging and an entire surface irradiation at a wavelength in the vicinity of the maximum sensitivity of the photosensitive member are intermittently performed immediately before or immediately after the charging of the opposite polarity. To do.

【００１０】以下に、本発明を添付の図面に従がいなが
ら更に詳細に説明する。図１（ａ）（ｂ）（ｃ）は本発
明の方法の実施に好適な有機系感光体の三例の概略図で
ある。導電性支持体上１にＳｎＯ₂やＴｉＯ₂などの金属
酸化物を分散した樹脂層やＡｌ₂Ｏ₃等の下引き層（Ｕ
Ｌ）２を形成し、その上にディッピング法やスプレー法
あるいは蒸着法等により製膜される感光層３を積層した
もので、感光層３は下側より電荷発生層（ＣＧＬ）４、
電荷輸送層（ＣＴＬ）より構成された積層型（機能分離
型）感光体〔図１（ａ）〕である。但し、感光層３はＣ
ＧＬ４とＣＴＬ５とが逆の構成の感光体〔図１（ｃ）〕
になっていても良いし、ＣＧＬ４とＣＴＬ５の機能を両
方持ち合わせている単層構成の感光体〔図１（ｂ）〕で
あっても良い。下引き層２は帯電時、導電性支持体１よ
り電荷が注入して、表面電位を悪化させまた画像品質の
Ｓ／Ｎ比を低下させるのを防止するため形成されるが、
一方では、残留電位及びその蓄積を発生させる要因にな
ることもある。The present invention will be described in more detail below with reference to the accompanying drawings. 1 (a), (b) and (c) are schematic views of three examples of organic photoreceptors suitable for carrying out the method of the present invention. A resin layer in which a metal oxide such as SnO ₂ or TiO ₂ is dispersed on the conductive support 1 or an undercoat layer such as Al ₂ O ₃ (U
L) 2 is formed, and a photosensitive layer 3 formed by a dipping method, a spray method, an evaporation method, or the like is laminated on the photosensitive layer 3 and the charge generation layer (CGL) 4,
It is a laminated type (function separation type) photoreceptor [FIG. 1 (a)] composed of a charge transport layer (CTL). However, the photosensitive layer 3 is C
A photoconductor in which GL4 and CTL5 have opposite configurations [FIG. 1 (c)]
The photosensitive member may have a single layer structure having both the functions of CGL4 and CTL5 [FIG. 1 (b)]. The undercoat layer 2 is formed in order to prevent charges from being injected from the conductive support 1 during charging, thereby deteriorating the surface potential and reducing the S / N ratio of image quality.
On the other hand, it may cause a residual potential and its accumulation.

【００１１】感光層３上には、更に機械的耐久性を向上
させるために、表面保護層６が形成される。表面保護層
６は前述したプラズマＣＶＤ法等によって１〜５μｍ程
度の厚さにＤＬＣ膜として製膜したものである。表面保
護層６の比抵抗は１０¹³〜１０¹⁵Ω・ｃｍのオーダーの
範囲が最適で、１０¹³Ω・ｃｍより低い場合シャープ性
に甘さがみられ、更に低いと常湿環境でも画像流れを発
生しやすくなる。一方、比抵抗が１０¹⁵Ω・ｃｍ以上で
あると残留電位が高くなり、一時的に残留電位を下げて
も蓄積しやすいので、プロセスでは補正しきれない。残
留電位の蓄積は画像品質特性の低下や装置の動作不良を
引き起こす。A surface protective layer 6 is formed on the photosensitive layer 3 in order to further improve mechanical durability. The surface protective layer 6 is formed as a DLC film with a thickness of about 1 to 5 μm by the above-described plasma CVD method or the like. The specific resistance of the surface protective layer 6 is optimally in the order of 10 ¹³ to 10 ¹⁵ Ω · cm. If it is lower than 10 ¹³ Ω · cm, the sharpness is unsatisfactory. If it is lower, image deletion occurs even in a normal humidity environment. Easier to do. On the other hand, if the specific resistance is 10 ¹⁵ Ω · cm or more, the residual potential becomes high, and even if the residual potential is temporarily lowered, it is easy to accumulate, so that it cannot be corrected by the process. Accumulation of residual potential causes deterioration of image quality characteristics and malfunction of the apparatus.

【００１２】図２は本発明の逆極性帯電付与装置１７と
全面露光装置１８の配置例を示した説明図である。画像
担持体（感光体）１０に均一帯電装置１１により電荷を
与える。電荷を与えられた画像担持体１０は画像露光装
置１２により入力信号（原稿）に応じた潜像が形成さ
れ、現像装置１３により現像され画像担持体１０上で可
視化される。感光体１０上の可視像は給紙されたコピー
用紙１９に転写・分離装置１４により転写され、そして
画像担持体１０より分離される。転写されたコピー用紙
は定着装置（図示されていない）に搬送されハードコピ
ー化される。FIG. 2 is an explanatory view showing an example of the arrangement of the reverse polarity charging device 17 and the overall exposure device 18 of the present invention. An electric charge is applied to the image carrier (photoreceptor) 10 by the uniform charging device 11. An image exposure device 12 forms a latent image corresponding to an input signal (original) on the image carrier 10 to which electric charges are applied, and the latent image is developed by a developing device 13 to be visualized on the image carrier 10. The visible image on the photoconductor 10 is transferred to the supplied copy paper 19 by the transfer / separation device 14 and separated from the image carrier 10. The transferred copy paper is conveyed to a fixing device (not shown) to be a hard copy.

【００１３】一方、転写後の感光体１０表面はクリーニ
ングを容易にするために除電装置１５により電位が５０
〜１００Ｖ以下になるように除電された後、クリーニン
グ装置１６により清掃される。その後、残留電位を低減
化するための処理が行なわれる。方式は３通りある。ま
ずＡ方式は均一帯電装置１１での帯電とは逆極性の電荷
を逆極性電荷付与装置１７により与えた後、これに全面
露光装置１８で全面露光する方法〔図２（ａ）〕、Ｂ方
式は逆極性帯電を与えると同時に全面露光する方法〔図
２（ｂ）〕、Ｃ方式はまず全面露光した後、逆極性帯電
を行なう方法〔図２（ｃ）〕である。Ａ、Ｂ及びＣ方式
の間で効果に多少の差が見られるが、逆極性電荷単独も
しくは全面露光単独では効果は殆ど無く、かならず両装
置１７及び１８の操作が必要である。On the other hand, the surface of the photoconductor 10 after transfer is kept at a potential of 50 by the static eliminator 15 in order to facilitate cleaning.
After the electricity is removed so that the voltage becomes 100 V or less, it is cleaned by the cleaning device 16. Then, a process for reducing the residual potential is performed. There are three methods. First, the A method is a method in which charges having a polarity opposite to that of the charge in the uniform charging device 11 are applied by a reverse polarity charge applying device 17, and then the entire surface is exposed by an overall exposure device 18 [FIG. 2 (a)], B method. Is a method of exposing the entire surface at the same time as applying opposite polarity charging [FIG. 2 (b)], and method C is a method of first exposing the entire surface and then performing opposite polarity charging [FIG. 2 (c)]. Although there are some differences in the effects among the A, B, and C methods, there is almost no effect when the opposite-polarity charges are used alone or the entire surface exposure is used, and it is necessary to operate both devices 17 and 18.

【００１４】マイナス（−）帯電で使用される感光体で
は、本発明の第１の方法によれば逆電荷はプラス（＋）
であるが、逆極性電荷付与装置１７で印加される電位は
２００〜７００ボルトが望ましい。残留電位は逆極性電
荷付与の量に応じて低減化を示すが、低減化には限度が
有り、感光体を構成する下引き層２、感光層３及び表面
保護層６の電気抵抗、静電容量や電子、正孔の移動度等
の諸物性で制限を受ける傾向がある。２００ボルト以下
の場合は、効果が得られにくい。逆に、７００ボルトよ
り以上帯電させた場合、逆極性電荷付与による帯電位遅
れがより一層大きくなるため、必要な表面電位が得られ
にくくなる傾向を有すると共に、繰返し複写時の均一帯
電時の帯電電位低下が大きくなる傾向がある。In the case of a photoreceptor used for negative (-) charging, the reverse charge is positive (+) according to the first method of the present invention.
However, the potential applied by the reverse polarity charge application device 17 is preferably 200 to 700 volts. The residual potential shows a reduction according to the amount of the opposite polarity charge applied, but there is a limit to the reduction, and the electrical resistance and electrostatic resistance of the undercoat layer 2, the photosensitive layer 3 and the surface protective layer 6 constituting the photoconductor are limited. It tends to be limited by various physical properties such as capacity, electron and hole mobility. When the voltage is 200 V or less, it is difficult to obtain the effect. On the other hand, when the charging voltage is higher than 700 V, the charging potential delay due to the application of the reverse polarity charge is further increased, which tends to make it difficult to obtain the required surface potential, and the charging during uniform charging during repeated copying. The potential drop tends to increase.

【００１５】全面露光装置１８は感光体１０が有する最
大感度近傍の波長を有する光源によるのが望ましい。例
えば、長波長増感したデジタル用の感光体で感度ピーク
が６００〜８００ｎｍにある場合、全面露光用の光源と
しては、その範囲の光源が効果的に使用できる。光源と
してはＬＤやＬＥＤ等の半導体素子の他、赤色ランプ等
が利用できる。長波長である必要性は感光層中にトラッ
プした電荷を可能な限り有効に除去できる様にするため
である。全面露光装置１８による露光を省略した場合、
次の複写サイクルの潜像形成の際、正孔の移動に支障が
生じ、残留電位の要因となりやすくなる。したがって、
全面露光装置１８を働かせて残留電位の要因を排除して
おく必要がある。The entire surface exposure device 18 is preferably a light source having a wavelength near the maximum sensitivity of the photoconductor 10. For example, in the case of a long-wavelength sensitized digital photoconductor having a sensitivity peak of 600 to 800 nm, a light source in that range can be effectively used as a light source for whole surface exposure. As the light source, a red lamp or the like can be used in addition to a semiconductor element such as an LD or LED. The need for a long wavelength is to enable the charges trapped in the photosensitive layer to be removed as effectively as possible. When the exposure by the whole surface exposure device 18 is omitted,
When the latent image is formed in the next copying cycle, the movement of the holes is hindered, which easily causes the residual potential. Therefore,
It is necessary to operate the whole surface exposure device 18 to eliminate the factor of the residual potential.

【００１６】図３は表面保護層６を膜厚を２．３〜２．
５μｍで比抵抗を３〜５×１０¹⁴Ω・ｃｍのＤＬＣ膜で
形成した場合の１万枚複写時の逆極性帯電電位による表
面電位に対する効果を示すグラフの一例である。このグ
ラフは図２（Ａ）方式によるもので、逆極性電荷付与に
よる表面電位が高くなるにつれ、残留電位が低下し画像
部の電位の低減化が計られ、コントラスト電位の拡大に
つながる。しかし一方では帯電電位の低下を生じるの
で、逆極性帯電電位は或る範囲内に収める必要が有る。
この範囲が本発明の第１の方法では２００〜７００ボル
トであり、本発明の第２の方法では３００〜１０００ボ
ルトである。この許容範囲は個々の複写プロセスに依っ
て異なるが、さらに好ましくは、第１の本発明方法では
３００〜６００ボルトであり、第２の本発明方法では４
００〜７００ボルトである。帯電電位を地肌部電位（背
景部電位）とする複写プロセスの場合では、現像バイア
スをあるレベルに設定したとき、帯電電位の低下レベル
はおおよそ、その現像バイアスを越えない範囲まで許容
でき、逆極性電位付与による電荷量を多く架けられ、そ
れだけ画像部電位レベルを低下さすことが可能となる。
この一連の複写プロセスにより、画像部電位が上昇した
としても、逆極性電荷を与えない場合よりも画像部電位
が低下し、明部と暗部の潜像電位座（明暗電位差）が大
きくなり、電気特性上及び画像品質上で余裕が生じるた
め、繰返しコピーに対して有利である。なお、図３にお
いて、三角は横軸（表面電位）−右縦軸（帯電電位低下
量）の関係、丸は横軸−左縦軸（画像部電位低減化量）
の関係をそれぞれ表わしている。In FIG. 3, the surface protective layer 6 has a thickness of 2.3 to 2.
7 is an example of a graph showing the effect on the surface potential due to the opposite polarity charging potential when copying 10,000 sheets when a DLC film having a specific resistance of 3 to 5 × 10 ¹⁴ Ω · cm at 5 μm is formed. This graph is based on the method of FIG. 2A, and as the surface potential due to the application of the opposite polarity charge increases, the residual potential decreases, the potential of the image area is reduced, and the contrast potential is expanded. However, on the other hand, since the charging potential lowers, it is necessary to set the reverse polarity charging potential within a certain range.
This range is 200 to 700 volts in the first method of the present invention and 300 to 1000 volts in the second method of the present invention. This tolerance varies depending on the particular copying process, but more preferably it is 300 to 600 volts in the first inventive method and 4 in the second inventive method.
It is from 00 to 700 volts. In the case of a copying process in which the charging potential is the background potential (background potential), when the development bias is set to a certain level, the reduction level of the charging potential can be tolerated to the extent that the development bias is not exceeded. A large amount of electric charge is applied by applying the electric potential, so that the electric potential level of the image portion can be lowered accordingly.
By this series of copying processes, even if the image portion potential rises, the image portion potential lowers as compared with the case where the opposite polarity charge is not applied, the latent image potential seat (bright and dark potential difference) between the light portion and the dark portion becomes large, and This is advantageous for repetitive copying because there is a margin in terms of characteristics and image quality. In FIG. 3, the triangle represents the relationship between the horizontal axis (surface potential) and the right vertical axis (charging potential reduction amount), and the circle represents the horizontal axis and the left vertical axis (image portion potential reduction amount).
Represents the relationship between.

【００１７】図４は図２に従って説明した（Ａ）（Ｂ）
及び（Ｃ）方式による画像部電位の低減化量を比較した
ものである。残留電位の低減化のもっとも大きい方式は
（Ａ）次いで（Ｂ）、（Ｃ）の順である。これは逆極性
電位付与の下引き層２に作用する効果に相違を生じるた
めと予想される。FIG. 4 is described with reference to FIG. 2 (A) and (B).
3A and 3B are comparisons of the amount of reduction in the image portion potential by the methods (C). The largest method for reducing the residual potential is (A), then (B), and then (C). It is presumed that this is because the effect of exerting the reverse polarity potential on the undercoat layer 2 is different.

【００１８】帯電前荷電を与えるタイミング（逆極性電
荷付与のタイミング）について、停止するタイミングが
不十分であると、逆極性電荷付与装置１７により帯電さ
れた逆極性電荷のために、感光体１０の一部が現像さ
れ、現像剤を構成するトナーの為にトナー汚れを起こ
し、次のコピーの１枚〜３枚目が地汚れを生じ、著しい
画像品質低下となる。この問題を解消するには、本発明
の第１の方法では画像担持体すなわち感光体１０が回転
するとほぼ同時に、逆極性電荷付与装置１７を帯電開始
と同レベルになるように均一帯電装置１１に先だって作
動させ、均一帯電停止時それと同時又はその直前に逆極
性電荷付与装置１７を停止させると共に、複写工程終了
後も除電装置１５及び露光装置１８の作動を継続させ、
少なくとも感光体を一回転以上（除電に問題なければ一
回転で充分である）回転させる間に感光体表面の電位が
１００ボルト以下、好ましくは５０ボルト以下に除電す
ることにより改善される。また、本発明の第２の方法で
は、逆極性電荷付与装置１７をＯＮ／ＯＦＦすることに
より達成可能である。すなわち、逆極性電荷付与装置１
７を電子タイマーにより一定時間ＯＮ／ＯＦＦするよう
に制御を行なったり、チョッパー型や振動容量型等の小
型表面電位計により計測された感光体の表面電位を逆極
性電荷付与装置１７にフィードバックし、一定電位に達
したときに逆極性電荷付与装置１７を一定時間ＯＮ／Ｏ
ＦＦするようにする方法などにより行なうことが出来
る。If the timing for stopping the pre-charging charge (the timing for applying the reverse polarity charge) is insufficient, the reverse polarity charge applied by the reverse polarity charge applying device 17 causes the photosensitive member 10 to be charged. Part of the toner is developed, and the toner constituting the developer causes toner stains, and the first to third sheets of the next copy cause background stains, resulting in a marked deterioration in image quality. In order to solve this problem, in the first method of the present invention, at the same time as the image carrier, that is, the photoreceptor 10, rotates, the reverse polarity charge applying device 17 is set to the uniform charging device 11 so as to reach the same level as the charging start. When the uniform charging is stopped, the reverse polarity charge applying device 17 is stopped at the same time as or immediately before the uniform charging is stopped, and the static eliminator 15 and the exposure device 18 are continuously operated even after the copying process is finished.
This is improved by removing the electric potential of the surface of the photoconductor to 100 V or less, preferably 50 V or less while the photoconductor is rotated at least one revolution (one revolution is sufficient if there is no problem in eliminating the charge). In addition, the second method of the present invention can be achieved by turning on / off the reverse polarity charge applying device 17. That is, the reverse polarity charge applying device 1
7 is controlled by an electronic timer so as to be turned on / off for a certain period of time, or the surface potential of the photoconductor measured by a small surface electrometer such as a chopper type or a vibration capacitance type is fed back to the reverse polarity charge imparting device 17. When the constant potential is reached, the reverse polarity charge imparting device 17 is turned ON / O for a predetermined time.
This can be performed by a method such as FF.

【００１９】本発明において、第１の方法に比べて第２
の方法の方が逆極性電荷付与後の帯電電位が高目である
のは、それらの方法の相違によっている。極性電荷付与
装置１７での電荷量が多くなるにつれ画像部電位の低減
効果が大きくなる反面、帯電電位も大きく低下する。逆
極性電荷量が多過ぎると、感光体の繰返し使用により帯
電電位の低下量が大きくなり過ぎ、設定された現像バイ
アス値に近づき、電位の余裕度が小さくなり局部的に地
汚れを起こすという問題が起こりうる。画像部電位をよ
り低く押さえる為には、高い電位を印加した方が望まし
い。しかし、逆極性電荷量が大きくなると感光体の繰返
し使用により帯電電位は更に低下するので、帯電電位を
安定させようとするとどうしても逆極性電荷量は低くせ
ざるを得ない。このため帯電電位低下を予防する方策が
必要となり、そのための方法が前記の逆極性電荷付与装
置のＯＮ／ＯＦＦである。In the present invention, a second method is used as compared with the first method.
The reason that the method (2) has a higher charging potential after application of the opposite polarity charge is due to the difference between the methods. As the amount of charges in the polar charge applying device 17 increases, the effect of reducing the image portion potential increases, but the charging potential also decreases significantly. If the amount of reverse polarity charge is too large, the amount of decrease in the charging potential will become too large due to repeated use of the photoconductor, approaching the set development bias value, and the margin of the potential will decrease, causing local scumming. Can happen. In order to keep the potential of the image area lower, it is desirable to apply a high potential. However, when the amount of reverse polarity charges becomes large, the charging potential further decreases due to repeated use of the photoconductor, and therefore in order to stabilize the charging potential, the amount of reverse polar charges must be lowered. For this reason, it is necessary to take measures to prevent a decrease in the charging potential, and the method for that purpose is to turn on / off the reverse polarity charge applying device.

【００２０】本発明の第２の方法では、ＤＬＣ膜をオー
バーコートした有機系感光体を−７３０ボルトに帯電し
使用した場合、逆極性電荷付与装置１７により約６００
ボルト与えると、表面電位は−７００〜６８０ボルトに
低下する。すなわち、−７００〜６８０ボルトに低下し
た表面電位は逆電荷付与装置１７をＯＦＦすることによ
り、少なくとも−７３０ボルトに近いレベルにまで回復
させることが可能となる。従って、上記のような制御方
法を使用して繰返し行なうことにより、ほぼ実用的に問
題ない範囲に帯電電位を維持することが出来る。また、
逆極性電荷を更に多く付与することが出来るため、画像
部電位をより低下させられ、電位蓄積性もより低く抑え
ることが可能となる。したがって、逆極性電荷付与装置
１７による逆電位の適用範囲は３００〜１０００ボルト
まで拡大させることが出来る。In the second method of the present invention, when an organic photoconductor overcoated with a DLC film is used after being charged to -730 V, the reverse polarity charge applying device 17 causes about 600
When a voltage is applied, the surface potential drops to -700 to 680 volts. That is, the surface potential lowered to -700 to 680 volts can be restored to a level close to at least -730 volts by turning off the reverse charge applying device 17. Therefore, by repeatedly using the control method as described above, the charging potential can be maintained in a range where there is practically no problem. Also,
Since more reverse polarity charges can be applied, the image portion potential can be further lowered, and the potential accumulating property can be suppressed to a lower level. Therefore, the application range of the reverse potential by the reverse polarity charge applying device 17 can be expanded to 300 to 1000 volts.

【００２１】[0021]

【実施例】次に、実施例をあげて本発明を更に具体的に
説明する。EXAMPLES Next, the present invention will be described more specifically with reference to examples.

【００２２】実施例１、２及び３ 直径８０ｍｍ、長さ３４０ｍｍ、厚さ１ｍｍのアルミニ
ウム製シリンダー（導電性支持体）上にポリアミド樹脂
にＴｉＯ₂（石原産業（株）製）を分散した約２μｍ厚
の下引き層、ついで、トリスアゾ顔料をポリエステル樹
脂に分散した約０．１５μｍ厚の電荷発生層（ＣＧ
Ｌ）、さらにスチルベン系化合物をポリカーボネート樹
脂（パンライト Ｃ−１４００、帝人化成（株）製）に
分散した約２８μｍ厚の電荷輸送層（ＣＴＬ）を積層し
た。これをプラズマＣＶＤ装置にセットし、原料ガスと
してＣ₂Ｈ₄（１００SCCM）、ＮＦ₃、Ｈ₂の３種類を用
い、ＲＦ電力（１３．５６ＭＨｚ）１００Ｗ、自己バイ
アス５Ｗ、反応圧０．０３Ｔｏｒｒの条件で２．１〜
２．４μｍ、ヌープ硬度約５４０〜６２０ｋｇ／ｍ
ｍ²、比抵抗３〜６×１０¹⁴Ω・ｃｍのＤＬＣ膜を表面
保護層として製膜し、感光体を作製した。Examples 1, 2 and 3 TiO ₂ (manufactured by Ishihara Sangyo Co., Ltd.) was dispersed in polyamide resin on an aluminum cylinder (conductive support) having a diameter of 80 mm, a length of 340 mm and a thickness of 1 mm, and the thickness was about 2 μm. Undercoat layer, and then a charge generation layer (CG) with a thickness of about 0.15 μm in which a trisazo pigment is dispersed in a polyester resin.
L) and a charge transport layer (CTL) having a thickness of about 28 μm in which a stilbene compound was dispersed in a polycarbonate resin (Panlite C-1400, manufactured by Teijin Chemicals Ltd.). This was set in a plasma CVD apparatus, and three kinds of source gases, C ₂ H ₄ (100 SCCM), NF ₃ and H ₂ , were used, RF power (13.56 MHz) 100 W, self-bias 5 W, and reaction pressure 0.03 Torr. 2.1-
2.4 μm, Knoop hardness about 540-620 kg / m
A DLC film having m ² and a specific resistance of 3 to 6 × 10 ¹⁴ Ω · cm was formed as a surface protective layer to prepare a photoconductor.

【００２３】効果確認するために、逆極性電荷付与装置
と全面露光装置の位置をクリーニング装置と均一帯電装
置の間で自由に設定可能とした実験機（リコー社製デジ
タル複写機、イマジオ４２０のシステムを採用した）を
用意し、全面露光装置として発光ピーク波長６６０ｎｍ
のＬＥＤアレイ（露光量１５〜１８μＷ／ｃｍ²）を使
用した。また、帯電電位を−７５０〜−７６０ボルト、
逆極性帯電位を＋５９０〜６２０ボルトに設定した。確
認は５０００枚／日の割で作像しながら、４日間適時機
内電位を測定して実施した。結果を図５に示す。 （実施例１）クリーニング装置の後に逆極性電荷付与装
置、全面露光装置の順にセットし効果を確認した。 （実施例２）逆極性電荷付与装置上に全面露光装置をセ
ットし効果を確認した。 （実施例３）クリーニング装置の後に全面露光装置、逆
極性電荷付与装置の順にセットし効果を確認した。In order to confirm the effect, an experimental machine (system of Ricoh's digital copying machine, Imagio 420) in which the positions of the opposite polarity charge applying device and the whole surface exposure device can be freely set between the cleaning device and the uniform charging device Is prepared, and the emission peak wavelength is 660 nm as a full-face exposure device.
LED array (exposure amount: 15 to 18 μW / cm ² ) was used. Also, the charging potential is -750 to -760 volts,
The opposite polarity charge was set to + 590-620 volts. The confirmation was carried out by measuring the in-machine potential at appropriate times for 4 days while forming images at a rate of 5000 sheets / day. Results are shown in FIG. (Example 1) The effect was confirmed by setting the reverse polarity charge applying device and the overall exposure device in this order after the cleaning device. (Example 2) The effect was confirmed by setting the whole surface exposure apparatus on the opposite polarity charge application apparatus. (Embodiment 3) After the cleaning device, the overall exposure device and the reverse polarity charge applying device were set in this order, and the effect was confirmed.

【００２４】比較例１ 実験機、感光体サンプル、確認方法は実施例１と同じに
し、クリーニング装置の後に全面露光装置のみセットし
て効果を確認した。結果を図５に示す。Comparative Example 1 The experimental machine, the photosensitive member sample, and the confirmation method were the same as in Example 1, and the effect was confirmed by setting only the entire surface exposure device after the cleaning device. Results are shown in FIG.

【００２５】比較例２ 実験機、感光体サンプル、確認方法は実施例１と同じに
し、クリーニング装置の後に逆極性電荷付与装置のみセ
ットして効果を確認した。結果を図５に示す。Comparative Example 2 The effect was confirmed by setting the experimental machine, the photoconductor sample, and the confirmation method as in Example 1, and setting only the reverse polarity charge applying device after the cleaning device. Results are shown in FIG.

【００２６】図５に見られるように、方式により効果差
は見られるが、潜像形成時の均一帯電に先だって逆極性
電荷付与と全面露光を付与することによる効果は明らか
で、残留電位の低減による特性向上が大きい。As shown in FIG. 5, although the effect difference is seen depending on the method, the effect by applying the opposite polarity charge and the whole surface exposure prior to the uniform charging at the time of latent image formation is clear, and the residual potential is reduced. The characteristics are greatly improved by.

【００２７】実施例４，５，６，７，８及び９ 実施例１と同じ方式で効果の確認を実施した。但し、感
光体の保護層であるＤＬＣ膜の比抵抗を製造条件（主と
して反応圧を０．０１〜０．０５Ｔｏｒｒ、バイアス電
力を３〜１５Ｗの間で可変した）を変更することにより
変化させ、また逆極性電位を変え効果を確認した。な
お、ＤＬＣ膜の膜厚は２．１〜２．５μｍとした。実施
例４〜９（但し、実施例８及び９は参考例である）に於
ける感光体保護層のＤＬＣ膜の比抵抗と逆極性電位を表
１に示す。結果はまとめて示した表３のとおりで、比抵
抗が１０¹⁶オーダーの場合、画像部電位が高くなり過ぎ
画像品質やトナー補給系に問題が見られた。一方、１０
¹²オーダーの場合、画像のシャープ性に甘さが生じた。Examples 4, 5, 6, 7, 8 and 9 The effects were confirmed in the same manner as in Example 1. However, the specific resistance of the DLC film, which is the protective layer of the photoconductor, is changed by changing the manufacturing conditions (mainly the reaction pressure was varied from 0.01 to 0.05 Torr and the bias power was varied from 3 to 15 W), Also, the effect was confirmed by changing the reverse polarity potential. The thickness of the DLC film was 2.1 to 2.5 μm. Table 1 shows the specific resistance and the reverse polarity potential of the DLC film of the photoconductor protective layer in Examples 4 to 9 (however, Examples 8 and 9 are reference examples). The results are summarized in Table 3, and when the specific resistance is on the order of 10 ^{16 the} potential of the image area becomes too high and problems were observed in the image quality and the toner replenishment system. On the other hand, 10
^In the case of ¹² orders, the sharpness of the image was unsatisfactory.

【００２８】[0028]

【表１】 [Table 1]

【００２９】比較例３及び４ 実施例４〜９と同じように感光体上に比抵抗を変化させ
たＤＬＣ膜を形成し、実施例１の方式で確認した。ただ
し、逆極性電位は０ボルトとした。比較例３〜４に於け
る感光体保護層のＤＬＣ膜の比抵抗と逆極性電位を表２
に示す。結果はまとめて示した表３のとおりで、逆極性
電位を印加しない場合は画像部電位が高くなり過ぎ実施
例８と同じ現象を生じた。Comparative Examples 3 and 4 A DLC film having a changed specific resistance was formed on the photoconductor in the same manner as in Examples 4 to 9 and confirmed by the method of Example 1. However, the reverse polarity potential was 0 volt. Table 2 shows the specific resistance and the reverse polarity potential of the DLC film of the photoconductor protective layer in Comparative Examples 3 and 4.
Shown in. The results are shown in Table 3 collectively. When the reverse polarity potential was not applied, the potential of the image area became too high and the same phenomenon as in Example 8 occurred.

【００３０】[0030]

【表２】 [Table 2]

【００３１】[0031]

【表３】 [Table 3]

【００３２】実施例１０ 実施例１に同等の感光体に実施例２に示す逆極性電荷付
与及び同時全面露光方式のプロセスを用い、複写開始
時、逆極性電荷付与装置作動後０．１９５秒経ってから
全面帯電装置が作動し、複写と複写間では均一帯電停止
と同時に逆極性電荷付与装置を停止するが、除電装置及
び全面露光装置は引き続き作動させ、更に、複写終了後
は感光体を一回転させその間除電装置及び全面露光装置
を働かせ停止する方法により画像品質、機内表面電位を
判定した。結果は画像部及び電位の増加量の傾向は実施
例２に殆ど同じで良好であり、画像は１枚目よりおよび
カセットの切り替わり時でも、ノイズなくシャープ性の
良い画像が得られた。Example 10 Using the process of reverse polarity charge application and simultaneous whole surface exposure system shown in Example 2 on a photoreceptor equivalent to that of Example 1, 0.195 seconds have passed after the operation of the reverse polarity charge application device at the start of copying. Then, the entire surface charging device is activated, and at the same time the uniform charging is stopped between copying, the opposite polarity charge applying device is stopped, but the static eliminator and the entire surface exposure device are continuously operated, and after the copying is completed, the photoconductor is removed. The image quality and the in-machine surface potential were judged by the method of rotating and stopping the static eliminator and the overall exposure device during the rotation. As a result, the tendency of the amount of increase in the image portion and the potential was almost the same as in Example 2, and it was good, and an image with good sharpness was obtained without noise even after the first sheet and when the cassette was switched.

【００３３】比較例５ 複写終了後、全面露光装置のみ働かせ除電装置を停止し
た以外は実施例１０と同じ方法で効果を確認した。結果
は停止後の１枚目コピー先端の地肌部（画像以外の白の
部分）地汚れが生じる問題が生じた。Comparative Example 5 After the completion of copying, the effect was confirmed by the same method as in Example 10 except that the entire surface exposure device was made to work and the static eliminator was stopped. As a result, there was a problem that the background portion (white portion other than the image) on the leading edge of the first copy after the stoppage was stained.

【００３４】比較例６ 逆極性電荷付与装置と均一帯電装置との作動タイミング
を同じに設定した以外、実施例１０と同じ方法にして効
果を確認した。結果はカセットの切り替わり１枚目、複
写機コピーカウンターの切り替わり１枚目のコピー先端
約５０ｍｍが画像濃度差を起こす問題が生じた。Comparative Example 6 The effect was confirmed by the same method as in Example 10 except that the operation timings of the opposite polarity charge applying device and the uniform charging device were set to be the same. As a result, there was a problem that the first copy of the cassette and the copy counter of the copy counter of the copying machine changed the image density by about 50 mm.

【００３５】実施例１１ ＤＬＣ膜を膜厚２．０〜２．３μｍ、ヌープ硬度５８０
〜６５０ｋｇ／ｍｍ²、比抵抗５〜８×１０¹⁴Ω・ｃｍ
のものとした以外は実施例１と同様にして感光体サンプ
ルを作成した。効果の確認には逆極性電荷付与装置及び
全面露光装置をクリーニング装置と均一帯電装置との間
に設置すると共に、逆極性電荷付与装置にはその出力の
タイミングをコントロールするタイミング回路を取り付
けたリコー社製デジタル複写機（イマジオ４２０）の実
験機を用いた。全面露光装置として発光ピーク波長７０
０ｎｍのＬＥＤアレイ（露光量１７〜２０μＷ／ｃ
ｍ²）を使用した。また、帯電電位を−７５０〜−７６
０ボルト、逆極性帯電電位を＋７００〜７５０ボルトに
設定し、逆極性電荷付与装置をＯＮで２０枚、ＯＦＦで
３０枚コントロールするようにタイミング回路を設定し
た。確認は１日５４枚の割で２万枚の作像を行ないなが
ら、適時機内電位を測定し特性評価を実施した。結果を
図６に示す。帯電部電位はほぼ安定した推移を示してお
り全く問題はない。一方、画像部電位は１〜２０枚の間
が低めに推移するが、それ以後はほぼ安定しており、画
像濃度及び再現性に関して不具合は認められなかった。Example 11 A DLC film having a thickness of 2.0 to 2.3 μm and a Knoop hardness of 580
~ 650 kg / mm ² , specific resistance 5-8 x 10 ¹⁴ Ω · cm
A photoconductor sample was prepared in the same manner as in Example 1 except that the above samples were used. To confirm the effect, a reverse polarity charge applying device and a whole surface exposure device were installed between the cleaning device and the uniform charging device, and the reverse polarity charge applying device was equipped with a timing circuit for controlling the timing of its output. An experimental machine of a digital copying machine (Imagio 420) was used. Emission peak wavelength of 70
0 nm LED array (exposure amount: 17-20 μW / c
m ² ) was used. In addition, the charging potential is -750 to -76.
The timing circuit was set so that 0 volt and the reverse polarity charge potential were set to +700 to 750 volt, and the reverse polarity charge applying device was controlled to ON 20 sheets and OFF 30 sheets. For the confirmation, the image formation was performed on 20,000 sheets for 54 sheets a day, and the in-machine electric potential was measured at appropriate times to perform the characteristic evaluation. Results are shown in FIG. There is no problem at all, as the potential of the charging part shows a stable transition. On the other hand, the potential of the image area changed to a lower value between 1 and 20 sheets, but after that, it was almost stable, and no defect was observed in image density and reproducibility.

【００３６】比較例７ 実験機及び感光体サンプルは実施例１１と同じにした。
逆極性電荷付与装置は実験機が稼働中は連続動作状態に
して、１日５４枚の割で２万枚の作像を行ないながら、
適時機内電位測定により特性評価を実施した。逆極性電
位は実施例１１と同じである。結果を図７に示す。画像
部電位は−１５０ボルトに抑えられているが、帯電部電
位が２万枚で７５ボルトの低下を起こし特性安定上問題
が認められる。Comparative Example 7 The experimental machine and the photoreceptor sample were the same as in Example 11.
While the experimental machine is in operation, the reverse polarity charge applying device is in a continuous operation state, and while forming an image of 20,000 sheets for 54 sheets a day,
The characteristics were evaluated by measuring the in-machine potential at appropriate times. The reverse polarity potential is the same as in Example 11. The results are shown in Fig. 7. The electric potential of the image area is suppressed to -150 V, but when the electric potential of the charging area is 20,000 sheets, a decrease of 75 V occurs, and there is a problem in stability of characteristics.

【００３７】比較例８ 実験機及び感光体サンプルは実施例１１に同じものを用
いた。逆極性電荷付与装置はＯＦＦとし、比較例７と同
じ評価法を実施した。結果を図８に示す。図８に見られ
るように、帯電部電位の低下は実用的には問題ない範囲
であるが、画像部電位は蓄積が大きく、画像濃度低下や
低濃度部の再現性の低下を生じ、実用上の問題がある。Comparative Example 8 The same experimental machine and photoconductor sample as in Example 11 were used. The opposite polarity charge applying device was turned off, and the same evaluation method as in Comparative Example 7 was performed. The results are shown in Fig. 8. As shown in FIG. 8, the decrease in the potential of the charging portion is within a practically acceptable range, but the potential of the image portion is highly accumulated, resulting in a decrease in image density and a decrease in reproducibility of a low density portion. I have a problem.

【００３８】実施例１２ 実施例１１に示す実験機を改造し、表面電位検出装置
（ＰＫＥ０１Ａ 村田製作所（株）製）を搭載し、その
出力を逆極性電荷付与装置にフィードバックさせ、逆極
性電荷付与装置が所定の表面電位でＯＮ／ＯＦＦするよ
うにした。実際には帯電部電位は約−７３０ボルトで逆
極性電荷装置がＯＦＦし約−７５０ボルトでＯＮするよ
うにした。なお、表面電位検出用のラベルは２０ｍｍ×
２０ｍｍの大きさで濃度１．８と０．０５の厚紙を実験
機のコンタクトガラス（原稿乗せガラス）の終端部に立
てに一列に貼付た。評価方法は実施例１１に同じように
して行なった。結果は図９に示されるように、機内の表
面電位の推移及び画像の評価は実施例１１とほぼ同じ良
好な結果であった。Example 12 The experimental machine shown in Example 11 was modified and equipped with a surface potential detecting device (PKE01A manufactured by Murata Manufacturing Co., Ltd.), and its output was fed back to the reverse polarity charge imparting device to impart the reverse polarity charge. The device was turned on / off at a predetermined surface potential. Actually, the electric potential of the charging portion was set to about -730 V and the reverse polarity charge device was turned off, and turned on at about -750 V. The label for surface potential detection is 20 mm x
A thick paper having a size of 20 mm and a density of 1.8 and 0.05 was affixed in a row at the end of the contact glass (original mounting glass) of the experimental machine. The evaluation method was the same as in Example 11. As shown in FIG. 9, the transition of the surface potential inside the machine and the evaluation of the images were almost the same as those in Example 11 and were good results.

【００３９】実施例１３，１４，１５，１６，１７及び
１８ 感光体の表面保護層であるＤＬＣ膜の比抵抗及び硬度を
製造条件（主として反応圧を０．０１〜０．０５Ｔｏｒ
ｒ、バイアス電力を３〜１５Ｗの間で可変した）を変え
ることで変化させ、また、逆極性電位を変え効果確認し
た。なお、ＤＬＣ膜の膜厚は２．０〜２．５μｍとし
た。効果の確認は逆極性電荷付与装置を３０枚ＯＮ、２
０枚ＯＦＦで作動させ、実施例１１と同じ評価を行なっ
た。実施例１３〜１８における感光体保護層のＤＬＣ膜
の比抵抗、硬度及び逆極性電位を表４に示し、評価はま
とめて表６に示す。Examples 13, 14, 15, 16, 17, and 18 The specific resistance and hardness of the DLC film, which is the surface protective layer of the photoconductor, were set under the manufacturing conditions (mainly the reaction pressure was 0.01 to 0.05 Torr).
r, the bias power was varied between 3 and 15 W) and the reverse polarity potential was changed to confirm the effect. The film thickness of the DLC film was 2.0 to 2.5 μm. To confirm the effect, turn on 30 reverse polarity charge applying devices, 2
The same evaluation as in Example 11 was performed by operating with 0 sheets turned off. Table 4 shows the specific resistance, hardness, and reverse polarity potential of the DLC film of the photoconductor protective layer in Examples 13 to 18, and the evaluations are shown in Table 6 together.

【００４０】[0040]

【表４】 [Table 4]

【００４１】比較例９，１０及び１１ 実施例１１に示す方法にてＤＬＣ膜をＯＰＣ感光体に製
膜した。この感光体を実験機に搭載し、比較例７と同じ
く逆極性電荷付与装置を連続ＯＮにして２万枚での特性
評価を行なった。結果をまとめて表６に示す。ここでの
感光体保護層のＤＬＣ膜の比抵抗、硬度及び逆帯電位を
表５に示す。Comparative Examples 9, 10 and 11 A DLC film was formed on an OPC photosensitive member by the method shown in Example 11. This photoconductor was mounted in an experimental machine, and similarly to Comparative Example 7, the reverse polarity charge applying device was continuously turned on, and the characteristics of 20,000 sheets were evaluated. The results are summarized in Table 6. Table 5 shows the specific resistance, hardness, and reverse charge position of the DLC film of the photoconductor protective layer.

【００４２】[0042]

【表５】 [Table 5]

【００４３】[0043]

【表６】 （注）＋は増加、−は減少を示す。画像部電位は１００
枚後の電位、電位蓄積量は１枚目と２万枚の最大値を示
す。帯電低下量は１枚目より２万枚の低下量を示す。◎
○は実用上問題無し、×は実用上問題有りを表わす。[Table 6] (Note) + indicates increase and-indicates decrease. Image area potential is 100
The electric potential and the amount of accumulated electric potential after the sheet shows the maximum values of the first sheet and 20,000 sheets. The charge reduction amount is a reduction amount of 20,000 sheets from the first sheet. ◎
○ means that there is no problem in practical use, and × means that there is a problem in practical use.

【００４４】実施例１１以降にみられるように、ＤＬＣ
膜の比抵抗を１０¹³〜１０¹⁴Ω・ｃｍとし、逆極性電位
を約３００〜１０００ボルトとした条件では実用上問題
なく使用出来る。しかし、比抵抗が１０¹²Ω・ｃｍや１
０¹⁶Ω・ｃｍオーダー、逆極性電位が３００ボルト以
下、１０００ボルト以上では早い時期に又は連続使用し
た場合、実用上問題が生じることが判る。機械特性とし
てのキズは主に円周方向に発生するスクラッチ傷で、幅
は約３０μｍ、深さは約２μｍ程度のすり傷で実施例１
６のようにＤＬＣ膜の硬度が低くなると発生し易い。特
性的には帯電電位が高くなるほど帯電電位低下が大きく
なりやすいし、逆極性付与装置のＯＮ／ＯＦＦによるリ
ップルも大きくなるが、ＯＮ／ＯＦＦの間隔をコントロ
ールすることによりある程度補正が可能である。しかし
画像品質的には濃度むらが起こりやすいので、適正条件
で使用するのが望ましい。但し、以上述べたように逆極
性電荷付与装置を間歇作動させることにより感光体の特
性のバラツキを吸収できる範囲が広がりある程度残留電
位が高い感光体でも使用可能となる。As seen from Example 11 onwards, DLC
It can be practically used without any problem under the condition that the specific resistance of the film is 10 ¹³ to 10 ¹⁴ Ω · cm and the reverse polarity potential is about 300 to 1000 volt. However, the specific resistance is 10 ¹² Ω · cm or 1
It can be seen that problems of practical use occur in the case of early use or continuous use at 0 ¹⁶ Ω · cm order and a reverse polarity potential of 300 V or less, and 1000 V or more. The scratches as mechanical properties are mainly scratches generated in the circumferential direction, and are scratches having a width of about 30 μm and a depth of about 2 μm.
When the hardness of the DLC film is low as in No. 6, it is likely to occur. Characteristically, the higher the charging potential, the greater the decrease in the charging potential, and the larger the ripple due to ON / OFF of the reverse polarity applying device, but it can be corrected to some extent by controlling the ON / OFF interval. However, in terms of image quality, uneven density is likely to occur, so it is desirable to use under appropriate conditions. However, as described above, by intermittently operating the opposite polarity charge applying device, the range in which the variations in the characteristics of the photoconductor can be absorbed is widened, and the photoconductor having a high residual potential can be used.

【００４５】[0045]

【発明の効果】請求項１の発明によれば、画像形成時の
感光体への均一帯電に先立ちその帯電とは逆極性の電荷
を適切な量を与えることにより、感光層上に被覆した保
護層によって生じる残留電位の蓄積を有効に抑制するこ
とができるので、潜像電位が安定し、長期にわたって良
好な画像品質を維持に寄与することが可能となる。請求
項２の発明によれば、画像担持体の保護層の比抵抗及び
逆帯電付与装置による帯電電位を特定化することによ
り、画像担持体の残留電位及びその蓄積性を抑制するこ
とができ、安定した画像品質の提供が可能となる。請求
項３の発明によれば、逆極性電荷付与装置を付加するこ
とにより、その作動開始や停止のタイミングによっては
コピーの１枚目の先端部の濃度が低下したり画像担持体
上に電荷の一部が残り、現像部でベタ状にトナーの付着
が生じ、完全にクリーニングしきれず、コピーの最初の
一枚目に地汚れが発生することが起こる。これを防止す
るために、逆極性電荷付与装置を帯電開始位置と同レベ
ルになるように、帯電停止時それと同時又はその直前に
逆極性電荷付与装置を停止させると共に、複写工程終了
後少なくとも画像担持体１回転以上、除電装置及び全面
露光装置を作動させ、感光体表面電位を１００Ｖ以下ま
で除電することにより、トナー残留及び電位むらが解消
され、カセットの切り替わり時、コピーカウンターの切
り替わり時などのコピースタート時に数枚の間起こるコ
ピーの地汚れが解消し、１枚目より安定な画像品質が維
持可能となる。請求項４の発明によれば、画像形成時の
感光体への均一帯電に先立ちその帯電とは逆極性のの電
荷および感光体が有する最大感度近傍の波長の光を適切
な量与えることにより、感光層上に被覆した表面保護層
によって生じる残留電位の蓄積を有効に抑制することが
でき、さらに逆電荷を感光体特性に応じて間歇的に与え
ることにより、連続使用したさいに生じる帯電電位の低
下や残留電位の上昇をコントロール出来るようになるの
で、潜像電位が安定し、長期にわたって良好な画像品質
を維持に寄与することが可能となる。請求項５の発明に
よれば、画像担持体の保護層の比抵抗及び逆極性帯電付
与装置による電位を特定化することにより、画像担持体
の残留電位及びその蓄積性を抑制することができ、Ｓ／
Ｎ比のより安定した画像品質の提供が可能となる。ま
た、逆極性電荷付与装置による間歇付与法により、感光
体への逆帯電付与範囲を広くとれるので、従来残留電位
が高くて使用できなかった感光体でも使用出来る様にな
るので、感光体のロスがすくなくなるというメリットが
生じる。According to the first aspect of the present invention, a protective material coated on the photosensitive layer is provided by applying an appropriate amount of charge having a polarity opposite to that of the charge prior to uniform charging of the photoreceptor during image formation. Since the accumulation of residual potential caused by the layers can be effectively suppressed, the latent image potential becomes stable, and it becomes possible to contribute to maintaining good image quality for a long period of time. According to the invention of claim 2, by specifying the specific resistance of the protective layer of the image carrier and the charging potential by the reverse charging device, the residual potential of the image carrier and its accumulating property can be suppressed. It is possible to provide stable image quality. According to the third aspect of the present invention, by adding the opposite polarity charge applying device, the density of the leading end portion of the first copy of the copy may be reduced or the charge on the image carrier may be changed depending on the timing of starting and stopping the operation. A part of the toner remains, and the toner adheres to the developing portion in a solid state, the toner cannot be completely cleaned, and scumming occurs on the first copy of the copy. In order to prevent this, the opposite polarity charge applying device is stopped at the same time as or immediately before the charging is stopped so that the opposite polarity charge applying device is at the same level as the charging start position, and at least the image carrying is performed after the copying process is completed. By operating the static eliminator and the overall exposure device for more than one revolution of the body to eliminate the static electricity on the surface of the photoconductor to 100 V or less, residual toner and uneven potential are eliminated, and copying is performed when the cassette is switched or the copy counter is switched. The background stain of the copy that occurs for several sheets at the start is eliminated, and the image quality more stable than the first sheet can be maintained. According to the invention of claim 4, prior to the uniform charging of the photoconductor at the time of image formation, an appropriate amount of electric charges having a polarity opposite to that of the charge and light having a wavelength near the maximum sensitivity of the photoconductor are given, It is possible to effectively suppress the accumulation of residual potential caused by the surface protective layer coated on the photosensitive layer, and by intermittently applying the reverse charge according to the characteristics of the photosensitive member, the charging potential of the charging potential generated during continuous use can be reduced. Since it becomes possible to control the decrease and the increase in the residual potential, the latent image potential becomes stable, and it becomes possible to contribute to maintaining good image quality for a long period of time. According to the invention of claim 5, by specifying the specific resistance of the protective layer of the image carrier and the potential by the reverse polarity charging device, the residual potential of the image carrier and its accumulating property can be suppressed, S /
It is possible to provide more stable image quality with an N ratio. In addition, the intermittent charge method using the reverse polarity charge applying device allows a wide range of reverse charge application to the photoconductor, so that it can be used even for a photoconductor that could not be used because of a high residual potential. There is a merit that it will not be enough.

【図面の簡単な説明】[Brief description of drawings]

【図１】 （ａ）（ｂ）及び（ｃ）は本発明で用いられ
る感光体の三例の断面図である。1A, 1B, and 1C are cross-sectional views of three examples of photoreceptors used in the present invention.

【図２】 （ａ）（ｂ）及び（ｃ）は本発明の方法の実
施をするための装置の概略図である。2 (a) (b) and (c) are schematic views of an apparatus for carrying out the method of the present invention.

【図３】 逆極性電荷付与装置による表面電位に対する
効果を説明するための図である。FIG. 3 is a diagram for explaining an effect on a surface potential by a reverse polarity charge applying device.

【図４】 逆極性電荷付与及び全面露光の与え方を異に
した場合の画像部電位の低減化量比較を説明するための
図である。FIG. 4 is a diagram for explaining a comparison of reduction amounts of image part potentials when different methods of applying opposite polarity charges and applying whole surface exposure are used.

【図５】 本発明の第１の方法とその比較例のランニン
グ特性を表わした図である。FIG. 5 is a diagram showing running characteristics of the first method of the present invention and its comparative example.

【図６】 逆極性電荷付与装置のＯＮ／ＯＦＦ（間歇作
動）による表面電位推移例を表わした図である。FIG. 6 is a diagram showing an example of surface potential transition due to ON / OFF (intermittent operation) of a reverse polarity charge application device.

【図７】 逆極性電荷付与を連続した場合の表面電位推
移例を表わした図である。FIG. 7 is a diagram showing an example of surface potential transition in the case where application of opposite polarity charges is continued.

【図８】 逆極性電荷付与装置をＯＦＦした場合の表面
電位推移例を表わした図である。FIG. 8 is a diagram showing an example of surface potential transition when the reverse polarity charge applying device is turned off.

【図９】 表面電位を検知し逆極性電荷付与装置をＯＮ
／ＯＦＦした場合の表面電位推移例を表わした図であ
る。FIG. 9 Turns on the reverse polarity charge applying device by detecting the surface potential
It is a figure showing the example of surface potential change at the time of / OFF.

【符号の説明】[Explanation of symbols]

１ 導電性支持体 ２ 下引き層 ３ 感光層 ４ 電荷発生層（ＣＧＬ） ５ 電荷輸送層（ＣＴＬ） ６ 保護層 １０ 画像担持体（感光体） １１ 均一帯電装置 １２ 画像露光装置 １３ 現像装置 １４ 転写・分離装置 １５ 除電装置 １６ クリーニング装置 １７ 逆極性電荷付与装置 １８ 全面露光装置 １９ コピー用紙 DESCRIPTION OF SYMBOLS 1 Electroconductive support 2 Undercoat layer 3 Photosensitive layer 4 Charge generation layer (CGL) 5 Charge transport layer (CTL) 6 Protective layer 10 Image carrier (photosensitive member) 11 Uniform charging device 12 Image exposure device 13 Developing device 14 Transfer Separation device 15 Static eliminator 16 Cleaning device 17 Reverse polarity charge imparting device 18 Full surface exposure device 19 Copy paper

Claims (5)

【特許請求の範囲】[Claims] 【請求項１】 導電性支持体と有機感光層との間に下引
き層を有し、かつ、その感光層上に炭素または炭素を主
成分として構成された薄膜を表面保護層として有する有
機系感光体に均一帯電、画像露光、現像、転写、分離、
除電及びクリーニングを繰り返し行なって普通紙等に多
数枚のコピーを得る電子写真法において、該クリーニン
グと該均一帯電との間に該均一帯電とは逆極性の電荷付
与及びその逆極性電荷付与の直前あるいは直後、若しく
は同時に該感光体が有する最大感度近傍の波長の全面露
光を行なうことを特徴とする電子写真法。1. An organic system having an undercoat layer between a conductive support and an organic photosensitive layer, and having carbon or a thin film composed mainly of carbon as a surface protective layer on the photosensitive layer. Uniform charging, image exposure, development, transfer, separation on photoreceptor
In an electrophotographic method in which charge removal and cleaning are repeatedly performed to obtain a large number of copies on plain paper or the like, immediately before the application of a charge having a polarity opposite to that of the uniform charging and the application of a charge having the opposite polarity between the cleaning and the uniform charging. Alternatively, immediately after or at the same time, the entire surface exposure is performed at a wavelength near the maximum sensitivity of the photoconductor, which is an electrophotographic method. 【請求項２】 前記の表面保護層はその比抵抗が少なく
とも１０¹³〜１０¹⁵Ω・ｃｍの炭素又は炭素を主成分と
して構成される薄膜であり、この表面保護層を積層して
なる有機系感光体の使用に際して、前記逆極性電荷付与
での帯電電位を２００〜７００ボルトにして画像形成を
行なう請求項１記載の電子写真法。2. The surface protective layer is carbon having a specific resistance of at least 10 ¹³ to 10 ¹⁵ Ω · cm or a thin film composed mainly of carbon, and an organic system formed by laminating the surface protective layers. The electrophotographic method according to claim 1, wherein when a photosensitive member is used, an image is formed by setting a charging potential for applying the opposite polarity charge to 200 to 700 volts. 【請求項３】 画像形成の際、感光体が回転するのとほ
ぼ同時に、前記の逆極性電荷付与を帯電開始の位置と同
レベルになるように均一帯電に先だって行ない、均一帯
電の停止時それと同時又はその直前に逆極性電荷付与を
停止させるとともに、複写終了後、少なくとも感光体を
一回転させる間、逆極性電荷付与による除電及びその直
前、直後或いは同時に全面露光による露光を引き続き行
なう請求項１記載の電子写真法。3. At the time of image formation, almost simultaneously with the rotation of the photosensitive member, the opposite polarity charge is applied prior to the uniform charging so as to be at the same level as the charging start position, and when the uniform charging is stopped. At the same time or immediately before that, the application of the opposite polarity charge is stopped, and after the copying is completed, at least one rotation of the photosensitive member is performed, and then the neutralization by the application of the opposite polarity charge and the exposure by the whole surface exposure immediately before, immediately after, or simultaneously are continuously performed. Electrophotography as described. 【請求項４】 導電性支持体と有機感光層との間に下引
き層を有し、かつ、その感光層上に炭素または炭素を主
成分として構成された薄膜を表面保護層として有する有
機系感光体に均一帯電、画像露光、現像、転写、分離、
除電及びクリーニングを繰り返し行なって普通紙等に多
数枚のコピーを得る電子写真法において、該クリーニン
グと該均一帯電との間に該均一帯電とは逆極性の電荷付
与及びその逆極性電荷付与の直前あるいは直後、若しく
は同時に該感光体が有する最大感度近傍の波長の全面照
射を間歇的に行なうことを特徴とする電子写真法。4. An organic system having an undercoat layer between a conductive support and an organic photosensitive layer, and having carbon or a thin film composed mainly of carbon as a surface protective layer on the photosensitive layer. Uniform charging, image exposure, development, transfer, separation on photoreceptor
In an electrophotographic method in which charge removal and cleaning are repeatedly performed to obtain a large number of copies on plain paper or the like, immediately before the application of a charge having a polarity opposite to that of the uniform charging and the application of a charge having the opposite polarity between the cleaning and the uniform charging. Alternatively, immediately after or at the same time, the entire surface of the photosensitive member is intermittently irradiated with a wavelength in the vicinity of the maximum sensitivity, which is an electrophotographic method. 【請求項５】 前記の表面保護層はその比抵抗が少なく
とも１０¹³〜１０¹⁵Ω・ｃｍでヌープ硬度が４００ｋｇ
／ｍｍ²以上の炭素又は炭素を主成分として構成される
薄膜であり、この表面保護層を積層してなる有機感光体
の使用に際して、前記間歇的な逆極性電荷付与での帯電
電位を３００〜１０００ボルトにして画像形成を行なう
請求項４記載の電子写真法。5. The surface protective layer has a specific resistance of at least 10 ¹³ to 10 ¹⁵ Ω · cm and a Knoop hardness of 400 kg.
/ Mm ² or more of carbon or a thin film containing carbon as a main component, and when using the organic photoreceptor having the surface protective layer laminated, the charging potential in the intermittent application of the reverse polarity charge is 300 to The electrophotographic method according to claim 4, wherein an image is formed at 1000 volts.