JPH0455309B2 - - Google Patents
Info
- Publication number
- JPH0455309B2 JPH0455309B2 JP59011448A JP1144884A JPH0455309B2 JP H0455309 B2 JPH0455309 B2 JP H0455309B2 JP 59011448 A JP59011448 A JP 59011448A JP 1144884 A JP1144884 A JP 1144884A JP H0455309 B2 JPH0455309 B2 JP H0455309B2
- Authority
- JP
- Japan
- Prior art keywords
- photoreceptor
- charge
- bias voltage
- light
- image
- 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.)
- Expired - Lifetime
Links
- 108091008695 photoreceptors Proteins 0.000 claims description 32
- 229910021417 amorphous silicon Inorganic materials 0.000 claims description 19
- 238000007600 charging Methods 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 15
- 238000012546 transfer Methods 0.000 claims description 11
- 238000004140 cleaning Methods 0.000 claims description 7
- 238000011161 development Methods 0.000 claims description 5
- 230000006641 stabilisation Effects 0.000 claims description 4
- 238000011105 stabilization Methods 0.000 claims description 4
- 239000000758 substrate Substances 0.000 claims description 3
- 230000003287 optical effect Effects 0.000 description 21
- 238000010438 heat treatment Methods 0.000 description 12
- 230000007423 decrease Effects 0.000 description 11
- 206010047571 Visual impairment Diseases 0.000 description 7
- 230000000694 effects Effects 0.000 description 7
- 238000002474 experimental method Methods 0.000 description 7
- 238000010586 diagram Methods 0.000 description 6
- 230000005684 electric field Effects 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 230000003068 static effect Effects 0.000 description 5
- 238000001179 sorption measurement Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 238000012217 deletion Methods 0.000 description 2
- 230000037430 deletion Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000031700 light absorption Effects 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical group [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000009291 secondary effect Effects 0.000 description 1
- 229910052711 selenium Inorganic materials 0.000 description 1
- 239000011669 selenium Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- G03G21/00—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge
- G03G21/0094—Arrangements not provided for by groups G03G13/00 - G03G19/00, e.g. cleaning, elimination of residual charge fatigue treatment of the photoconductor
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Discharging, Photosensitive Material Shape In Electrophotography (AREA)
- Control Or Security For Electrophotography (AREA)
Description
産業上の利用分野
本発明は、帯電安定方法に関するもので、より
詳細には、非晶質シリコン系光導電体層を用いて
電子写真法により画像形成を行うに際し、該光導
電体層の表面電位を一定のレベルに安定させる方
法に関する。
発明の技術分野
非晶質シリコン系光導電体層は、表面硬度が高
く、長波長側の光に感度を有し、しかも感度どそ
のものも良好であるので、電子写真用の感光体と
して着目されている。
しかしながら、本発明者等の研究によると、非
晶質シリコンは上述した優れた特性を有するもの
の、高速複写に際して光疲労が比較的大であると
いう問題点を有している。例えば、通常の複写サ
イクル内で、帯電、露光、現像、転写及びクリー
ニングの諸動作を感光層に反復すると、セレン感
光層の場合、二回目以降の帯電量は一回目の帯電
量の0.5乃至３％程度の低下に過ぎず、光疲労に
よる影響は殆ど無視し得るものであるが、非晶質
シリコンの場合には、二回目以降の帯電量は一回
目の帯電量よりも５乃至20％も低下する傾向があ
る。このため、ドラムの外周長と複写物の長さが
一致している場合は一枚目の画像と比較して二枚
目以降の画像は目で識別できる程度の濃度低下を
生ずるという欠点がある。
また、ドラムの外周長よりも長い複写物を得る
場合には、同一複写物において濃度差が生じた
り、或いはメモリー残像現象が生じるという欠点
があつた。ここでメモリー残像現象とは、例えば
第１−ａ図の様な原稿を用いた場合に、文字部１
と黒ベタ部２までの距離ｌがドラムの外周長と一
致する時、第１−ｂ図の複写物では、黒ベタ部
２′中に文字部１′が重なつた画像として生じる現
像を言う。この現像が生じる原因としては、ドラ
ム１回転目において文字部１の潜像が感光体表面
に形成されると、文字部１の文字３の部分は露光
されないが背影４の部分は露光されるため文字３
と背影４の各部分において感光体の光疲労度に差
が生じ、その結果、ドラム２回転目において感光
体表面のこの位置に黒ベタ部２の潜像を形成する
ために帯電させようとしても、前回文字だつた部
分５の帯電量は初回と同程度の電位に維持される
が、前回背影だつた部分６は光疲労の影響で帯電
量が低下し、未疲労部５と疲労部６とに濃度差が
生じるためと考えられる。
最近になつてこの様な光疲労を防止する一手段
として例えば特開昭58−62659では光源として
600nm以下の光で露光、除電することが提案され
ている。この方法によれば、露光の繰り返しによ
り光疲労が生じ帯電量の低下を来すが、これが一
定のレベルに維持され、しかも600nm以下の光を
用いれば、光疲労が生じても高い帯電量のレベル
で安定するというものである。しかしながら、こ
の提案においても高いレベルでの安定化ができ、
実使用においては概ね良好ではあるものの安全に
光疲労を防止し得るまでには至つていないのが現
状である。このことから、完全に光疲労を防止し
得る方法が望まれている。
発明の目的及び概要
従つて、本発明の目的は、非晶質シリコン系光
導電体層の表面帯電電位を一回目の行程と二回目
以降の行程として、帯電量を何ら低下させること
なく実質上同一レベルに調節し、光疲労の差から
生じるメモリー残像現象を防止し得る方法を提供
するにある。
本発明によれば非晶質シリコン系光導電体層を
導電性基質上に有する電子写真感光体に主帯電、
画像露光、現像、転写及びクリーニングの行程を
反復することにより行う画像形成方法において、
前記クリーニング行程と帯電行程との間にバイア
ス電圧が印加された導電性可撓性部材を、加温状
態下にて前記感光体に接触させて行う脱トラツピ
ング行程を設けたことを特徴とする帯電安定方法
が提案される。
発明の構成
本発明の帯電安定方法を説明するための第２図
において、駆動回転される金属ドラムの表面に、
非晶質シリコン系光導電体層が設けられ感光体ド
ラム１１を構成している。このドラムの周囲に
は、主帯電用コロナチヤージヤ１３、ランプ１
４、原稿支持透明板１５及び光学系１６から成る
画像露光機構、トナー１７を有する現像機構１
８、トナー転写用コロナチヤージヤ１９、紙分離
用コロナチヤージヤ２０、除電ランプ２１、及び
クリーニング機構２２がこの順序に設けられてい
る。
先ず、感光体ドラム１１をコロナチヤージヤ１
３で一定極性の電荷で帯電させる。次いで、ラン
プ１４で複写すべき原稿２３を照明し、光学系１
６を経て原稿の光線像で感光体ドラム１１を露光
し、原稿画像に対応する静電潜像を形成させる。
この静電潜像を、現像機構１８によりトナー１７
で現像する。転写紙２４を、トナー転写用チヤー
ジヤ１９の位置でドラム表面と接触するように供
給し、転写紙２４の背面から静電像と同極性のコ
ロナ放電を行つて、トナー像を転写紙２４に転写
させる。トナー像が転写された転写紙２４は、分
離用コロナチヤージヤ２０の除電によつてドラム
から静電的に剥離され、定着域（図示せず）等の
処理域に送られる。
トナー転写後の感光体ドラム１１は、除電ラン
プ２１による全面露光で残留電荷が消去され、つ
いでクリーニング機構２２によつて残留トナーの
除去が行われる。
本発明で用いる非晶質シリコン感光層を表面に
設けた感光ドラム１１は、既に述べた通り、無視
し得ないオーダーの光疲労を示し、露光後の感光
層の帯電電位は、露光を受けていない感光層の帯
電電位に比して最大20％にも及ぶ低下を示し、形
成される複写物の画像濃度も一枚目と二枚目以降
のものとではかなり異なつたものとなる。
本発明者らは、非晶質シリコン系光導電体の光
疲労は、露光時に光導電体層中に生じたフオトキ
ヤリアが一部トラツプされて光導電体層中に残
り、これが次の帯電時に表面電荷が作る電界の作
用で放出され、表面電荷を中和することにより帯
電特性が劣化する現像であると推論している。そ
こで、露光或いは除電光を照射した後であつて、
次の主帯電前において、一方の電極が接地された
電源よりドラム基体が接地された感光体ドラム表
面にバイアス電圧を印加して、トラツプからフオ
トキヤリアを放出させるに十分な電界を付与した
場合には、光導電体層中のトラツプされたフオト
キヤリアは、この電界の作用を受け、脱トラツプ
し、トラツプされているフオトキヤリアが消失す
ることを見出したものである。
また第３図は28.0μW／cm2の光強度を有する単
色光を用いて測定した光疲労の波長依存性を示す
線図であつて、横軸は感光層露光時の波長、縦軸
は表面電位の低下量乃至は低下の度合い（光疲労
率％）を示している。この第３図を参照すると、
非晶質シリコンの光疲労は光線の波長に大きく依
存しており、波長725nm付近で最大の疲労を示
し、波長が600nm以下の光線に対しては殆ど疲労
を示さないことがわかる。それゆえ、前述した公
知の方法では露光及び除電光を600nm以下のもの
を用いていたのである。この理由は、波長が
600nm以下の光線では、光の吸収が感光体表面で
起こり、フオトキヤリアが主として感光層表面か
ら発生するためトラツプされる比率が少ないのに
対して、波長長光の場合光の吸収が感光層全体で
起こるため感光層の体積内（バルク内）でフオト
キヤリアが発生し、トラツプされる量が増大する
（バルク効果）ためである。
しかしながら、600nm以下の波長を用いた場
合、トラツプされるフオトキヤリアの量が少な
く、このまま次の帯電を行う場合、実用上問題と
ならないにしても帯電量の低下は免れず、完全に
光疲労を防止したこととはなつていない。
これに対し、本発明に従い主帯電前にバイアス
電圧を印加してあらかじめ脱トラツプさせておけ
ば、再帯電時に表面電荷が中和され得ない為、光
疲労は完全に防止し得るのである。
しかも本発明に従えば、印加電圧の電界強度に
より脱トラツプを行うため、バルク内にトラツプ
されているキヤリアよりも感光体表面にトラツプ
されているフオトキヤリアを脱トラツプさせるこ
との方が容易となる。この意味において使用する
光源を600nm以下のものを用いることの方が望ま
しい。ただ、本発明においては電界強度を大きく
することで感光層バルク内のフオトキヤリアも脱
キヤリアさせることも可能であるので長波長光を
も使用することができる。それゆえ半導体レーザ
ー等の使用を始め、より多くの光源に適用できる
利点を有している。
本発明において感光体表面にバイアス電圧を印
加する手段としては、感光体ドラムの長手方向に
亘つて均一にバイアス電圧を印加することが可能
なものであれば、それ自体公知の任意の手段が適
用できる。例えば、第２図においては一方の電極
が接地された電源３０の他方の電極に接続された
導電性ゴムローラ３１によりバイアス電圧が印加
される構成となつている。
このゴムローラ以外にも、感光体表面と摺擦さ
せた場合にも感光体に強い機械的応力を与えない
程度の部材、例えば導電性ゴムブレード、カーボ
ン或いは金属の繊維を用いた導電性ブラシ等の導
電性可撓性部材を用いることもできる。
感光体表面に印加するバイアス電圧の量は、用
いる光源の種類や、非晶質シリコン感光体の種類
によつても異なるが、一般に90乃至400V特に200
乃至400V印加するのがよい。
このバイアス電圧の種類は、非晶質シリコン系
感光体の帯電極性に応じて正または負いずれもが
使用できるが、一般には主帯電により発生するオ
ゾンの劣化等を考慮し感光体としては正帯電を用
いる場合が多く、この意味からすれば、バイアス
電圧の種類の正の直流バイアス或いは、交流バイ
アス電圧が好ましい。
更にバイアス電圧の印加手段に代わり得る手段
としてACコロナチヤージヤによる方法も考えら
れるが、放電に際しオゾン等を発生させることと
なり、感光体表面を劣化させ、画像流れつまり感
光体表面に形成された静電潜像の横方向のリーク
現象を発生させる原因ともなり好ましくない。
本発明においては、上述したバイアス電圧を印
加させる際に更に、一定温度に加温させながら行
うことが重要である。この加温の目的は、光半導
体の一種類である非晶質シリコン光導電体の暗中
の電気電導度を向上させ、バイアス電圧の通電効
果並びに脱トラツピング効果をより向上させるこ
とを目的とするものである。また、この加温処理
は、主帯電や転写或いは紙分離チヤージヤのコロ
ナの被爆により発生する画像流れ現象の発生をも
有効に防止し得るという副次的効果も有する。こ
の理由は、画像流れ現象がコロナ放電の際に発生
するオゾン等の攻撃を受け、感光体表面にSiとＯ
との結合を生じさせることに関連して、感光体表
面が親水性となり、この親水性化した感光体表面
が温度、湿度に依存した空気中の水分子の吸着脱
離現象により一定の温度以下では空気中の水分子
が露点以下の温度で感光体表面に吸着し表面電荷
のリークを生じることとなるため、加温によりこ
の吸着現象を防止し得るからである。
本発明においては、この加温は感光体表面を35
乃至45℃となるように行うことで上述した目的を
達成することができる。35℃未満では水分子の吸
着現象を防止することが困難であると共に脱トラ
ツピングを促進させる効果が少なく、逆に45℃を
超える場合には、脱トラツピングも、水分子の吸
着現象の防止に対しては上述した温度範囲と同様
程度である反面次の主帯電プロセスにおいて、帯
電電位の低下をもたらすこととなり、ひいては複
写物の画像濃度の低下を来すようになるためであ
る。
本発明において上述した条件下での加温手段と
しては、第２図に示したように導電性ゴムローラ
３１の中心にヒーター３２を設けて行う以外に、
この導電性ゴムローラ３１に印加するバイアス電
圧とは別に、この導電性ゴムローラ３１を付荷抵
抗とするように別の電圧を印加することでゴムロ
ーラ３１自体を加熱させることも勿論可能であ
る。またこのゴムローラ３１の温度制御は、脱ト
ラツピング行程域近傍且つ感光体表面近傍に設け
られた温度センサーまたはサーモスタツト等の手
段を用いて上述した温度範囲に適宜制御し得る。
非晶質シリコン系光導電体層としては、それ自
体公知の任意のものが使用され、例えばシランガ
スのプラズマ分解等で基板上に析出される非晶質
シリコンが使用され、このものは、水素やハロゲ
ン等でドーピングされ、更にボロンやリン等の周
期律表第族または第族元素でドーピングされ
たものであつてもよい。
代表的なアモルフアスシリコン感光体の物性値
は、暗導電率10-12Ω-1・cm-1、活性化エネルギ
ー＜0.85eV、光導電率＞10-7Ω-1・cm-1、光学的
バンドギヤツプ1.7〜1.9eVであり、また結合水素
量は10〜20原子％の量でその膜の誘電率は11.5〜
12.5の範囲にあるものである。
発明の実施例
本発明を次の例で説明する。
実施例 １
第２図に示した構成を備えた電子写真複写装置
を用いて、光源１４、除電光２１及び加温手段と
して中心部にヒーターを有し且つバイアス電圧印
加電源３０を有する導電性ゴムローラ３１を第１
表に示した関係にてNo.１〜No.４の実験を行つた。
尚、感光体ドラムとしては膜厚が20μmのａ−
Si：Ｈドラム（90φ）を装着した。
INDUSTRIAL APPLICATION FIELD The present invention relates to a charge stabilization method, and more specifically, when forming an image by electrophotography using an amorphous silicon-based photoconductor layer, the surface of the photoconductor layer is It relates to a method of stabilizing the potential at a constant level. Technical Field of the Invention Amorphous silicon-based photoconductor layers have high surface hardness, are sensitive to light on the long wavelength side, and have good sensitivity, so they have attracted attention as photoconductors for electrophotography. ing. However, according to research conducted by the present inventors, although amorphous silicon has the above-mentioned excellent properties, it has the problem of relatively high optical fatigue during high-speed copying. For example, when the various operations of charging, exposing, developing, transferring, and cleaning are repeated on a photosensitive layer in a normal copying cycle, in the case of a selenium photosensitive layer, the amount of charge after the second time is 0.5 to 3 of the amount of charge at the first time. %, and the effect of optical fatigue can be almost ignored. However, in the case of amorphous silicon, the amount of charge after the second charge is 5 to 20% more than the amount of charge after the first charge. There is a tendency to decrease. For this reason, if the outer circumference of the drum and the length of the copy match, there is a disadvantage that the density of the second and subsequent images will be lowered by an amount that can be discerned visually compared to the first image. . Further, when obtaining copies longer than the outer circumference of the drum, there is a drawback that differences in density occur in the same copy or a memory afterimage phenomenon occurs. Here, the memory afterimage phenomenon refers to, for example, when using a document like the one shown in Figure 1-a, the character part 1
When the distance l to the black solid area 2 matches the outer circumference of the drum, in the copy of Figure 1-b, development occurs as an image in which the character area 1' overlaps in the black solid area 2'. . The reason why this development occurs is that when the latent image of character part 1 is formed on the surface of the photoreceptor in the first rotation of the drum, the part of character 3 of character part 1 is not exposed, but the part of back shadow 4 is exposed. character 3
There is a difference in the degree of optical fatigue of the photoreceptor in each part of the back shadow 4, and as a result, even if an attempt is made to charge the surface of the photoreceptor in order to form a latent image of the black solid area 2 at this position on the surface of the photoreceptor during the second rotation of the drum, , the amount of charge on the part 5 where letters appeared last time is maintained at the same potential as the first time, but the amount of charge on the part 6 where there was a shadow last time decreases due to the influence of optical fatigue, and the amount of charge on the part 5 where letters appeared last time decreases due to the effect of optical fatigue. This is thought to be due to the difference in concentration between the two. Recently, as a means to prevent such optical fatigue, for example, in Japanese Patent Application Laid-Open No. 58-62659, as a light source,
It has been proposed to remove static electricity by exposing it to light of 600 nm or less. According to this method, photofatigue occurs due to repeated exposure, resulting in a decrease in the amount of charge. However, if this is maintained at a constant level, and if light of 600 nm or less is used, even if photofatigue occurs, a high amount of charge can be maintained. It is stable at a certain level. However, this proposal also achieves a high level of stability,
Although it is generally good in actual use, it is not yet possible to safely prevent optical fatigue. For this reason, a method that can completely prevent optical fatigue is desired. OBJECT AND SUMMARY OF THE INVENTION Therefore, an object of the present invention is to substantially increase the surface charging potential of an amorphous silicon-based photoconductor layer in the first and subsequent steps without reducing the amount of charge. The object of the present invention is to provide a method that can adjust to the same level and prevent memory afterimage phenomenon caused by differences in optical fatigue. According to the present invention, an electrophotographic photoreceptor having an amorphous silicon-based photoconductor layer on a conductive substrate is mainly charged;
In an image forming method performed by repeating the steps of image exposure, development, transfer and cleaning,
Charging characterized in that a detrapping step is provided between the cleaning step and the charging step in which a conductive flexible member to which a bias voltage is applied is brought into contact with the photoreceptor under a heated state. A stabilization method is proposed. Structure of the Invention In FIG. 2 for explaining the charging stabilization method of the present invention, on the surface of the metal drum that is driven and rotated,
A photoconductor drum 11 is provided with an amorphous silicon-based photoconductor layer. Around this drum, there is a main charging corona charger 13, a lamp 1
4. An image exposure mechanism consisting of a document support transparent plate 15 and an optical system 16, and a developing mechanism 1 having toner 17.
8, a toner transfer corona charger 19, a paper separation corona charger 20, a static elimination lamp 21, and a cleaning mechanism 22 are provided in this order. First, the photoreceptor drum 11 is moved through the corona charger 1.
Step 3: Charge with a constant polarity charge. Next, the lamp 14 illuminates the original 23 to be copied, and the optical system 1
6, the photoreceptor drum 11 is exposed to a light beam image of the original, thereby forming an electrostatic latent image corresponding to the original image.
This electrostatic latent image is transferred to a toner 17 by a developing mechanism 18.
Develop it with The transfer paper 24 is supplied so as to be in contact with the drum surface at the position of the toner transfer charger 19, and corona discharge with the same polarity as the electrostatic image is performed from the back side of the transfer paper 24 to transfer the toner image onto the transfer paper 24. let The transfer paper 24 on which the toner image has been transferred is electrostatically peeled off from the drum by the separation corona charger 20 and sent to a processing area such as a fixing area (not shown). After the toner has been transferred, the photoreceptor drum 11 is exposed to light from the entire surface by a discharge lamp 21 to erase residual charges, and then a cleaning mechanism 22 removes the residual toner. As already mentioned, the photosensitive drum 11 having the amorphous silicon photosensitive layer on its surface used in the present invention exhibits a non-negligible level of optical fatigue, and the charged potential of the photosensitive layer after exposure is different from that of the exposed photosensitive layer. The charge potential of the photosensitive layer is reduced by up to 20% compared to the charged potential of the photosensitive layer, and the image densities of the copies formed will be considerably different from those of the second and subsequent copies. The present inventors believe that photofatigue of amorphous silicon-based photoconductors is caused by photocarriers generated in the photoconductor layer during exposure to light being partially trapped and remaining in the photoconductor layer during the next charging. It is inferred that this is a development in which the surface charge is released due to the action of the electric field created by the surface charge, and the charging characteristics deteriorate by neutralizing the surface charge. Therefore, after exposure or irradiation with static eliminating light,
Before the next main charging, when a bias voltage is applied to the surface of the photoreceptor drum whose drum base is grounded from a power source whose one electrode is grounded, and an electric field sufficient to release photocarriers from the trap is applied. discovered that the photocarriers trapped in the photoconductor layer are untrapped by the action of this electric field, causing the trapped photocarriers to disappear. Figure 3 is a diagram showing the wavelength dependence of optical fatigue measured using monochromatic light with a light intensity of 28.0 μW/cm 2 , where the horizontal axis is the wavelength at the time of exposure of the photosensitive layer, and the vertical axis is the surface It shows the amount of decrease in potential or the degree of decrease (light fatigue rate %). Referring to this figure 3,
It can be seen that the optical fatigue of amorphous silicon is highly dependent on the wavelength of the light beam, with maximum fatigue occurring around a wavelength of 725 nm, and almost no fatigue occurring for light beams with a wavelength of 600 nm or less. Therefore, the above-mentioned known method uses exposure and neutralization light of 600 nm or less. The reason for this is that the wavelength
For light rays with a wavelength of 600 nm or less, absorption of light occurs on the surface of the photoreceptor, and photocarriers are generated mainly from the surface of the photosensitive layer, so the proportion of trapped light is small, whereas for light with longer wavelengths, absorption of light occurs throughout the entire photosensitive layer. This is because photocarriers are generated within the volume (bulk) of the photosensitive layer, and the amount of trapped information increases (bulk effect). However, when a wavelength of 600 nm or less is used, the amount of photocarriers trapped is small, and if the next charge is performed as it is, the charge amount will inevitably decrease, even if it is not a practical problem, and optical fatigue will not be completely avoided. This is not what was prevented. On the other hand, according to the present invention, if a bias voltage is applied before the main charging to remove the trap, the surface charge cannot be neutralized during recharging, so that optical fatigue can be completely prevented. Moreover, according to the present invention, since trapping is performed by the electric field strength of the applied voltage, it is easier to untrap photocarriers trapped on the surface of the photoreceptor than carriers trapped in the bulk. . In this sense, it is preferable to use a light source of 600 nm or less. However, in the present invention, photocarriers in the bulk of the photosensitive layer can also be removed by increasing the electric field strength, so long wavelength light can also be used. Therefore, it has the advantage of being applicable to more light sources, including the use of semiconductor lasers. In the present invention, any means known per se can be used as a means for applying a bias voltage to the surface of the photoreceptor as long as it is possible to apply a bias voltage uniformly over the longitudinal direction of the photoreceptor drum. can. For example, in FIG. 2, a bias voltage is applied by a conductive rubber roller 31 connected to the other electrode of a power source 30, one electrode of which is grounded. In addition to this rubber roller, there may be other materials that do not apply strong mechanical stress to the photoreceptor even when it rubs against the surface of the photoreceptor, such as a conductive rubber blade, a conductive brush made of carbon or metal fibers, etc. Conductive flexible members can also be used. The amount of bias voltage applied to the surface of the photoconductor varies depending on the type of light source used and the type of amorphous silicon photoconductor, but it is generally 90 to 400V, especially 200V.
It is preferable to apply 400V to 400V. Either positive or negative bias voltage can be used depending on the charging polarity of the amorphous silicon photoreceptor, but in general, taking into consideration the deterioration of ozone generated by main charging, the photoreceptor is positively charged. is often used, and from this point of view, positive DC bias or AC bias voltage is preferable as a bias voltage. Furthermore, a method using an AC corona charger can be considered as an alternative to applying a bias voltage, but it generates ozone etc. during discharge, which deteriorates the surface of the photoreceptor and causes image deletion, or electrostatic latent formed on the surface of the photoreceptor. This is undesirable as it also causes a leakage phenomenon in the lateral direction of the image. In the present invention, it is important to further apply the bias voltage described above while heating it to a constant temperature. The purpose of this heating is to improve the electrical conductivity in the dark of the amorphous silicon photoconductor, which is a type of optical semiconductor, and to further improve the conduction effect and detrapping effect of the bias voltage. It is. This heating treatment also has the secondary effect of effectively preventing the occurrence of image deletion caused by main charging, transfer, or exposure to corona in the paper separation charger. The reason for this is that the image blurring phenomenon occurs when the photoreceptor surface is attacked by ozone, etc. generated during corona discharge, and the surface of the photoreceptor is exposed to Si and O2.
The surface of the photoreceptor becomes hydrophilic due to the bonding with the surface of the photoreceptor, and the surface of the photoreceptor becomes hydrophilic when the temperature drops below a certain level due to adsorption and desorption of water molecules in the air, which is dependent on temperature and humidity. This is because water molecules in the air are adsorbed to the surface of the photoreceptor at a temperature below the dew point, causing surface charge leakage, and this adsorption phenomenon can be prevented by heating. In the present invention, this heating heats the surface of the photoreceptor by 35°C.
The above-mentioned purpose can be achieved by performing the heating at a temperature of 45°C to 45°C. At temperatures below 35°C, it is difficult to prevent the adsorption phenomenon of water molecules and there is little effect in promoting detrapping.On the other hand, when the temperature exceeds 45°C, detrapping has no effect on preventing the adsorption phenomenon of water molecules. This is because, although the temperature range is similar to the above-mentioned temperature range, the charging potential decreases in the next main charging process, which in turn causes a decrease in the image density of the copy. In the present invention, heating means under the above-mentioned conditions include, in addition to providing a heater 32 at the center of the conductive rubber roller 31 as shown in FIG.
In addition to the bias voltage applied to the conductive rubber roller 31, it is of course possible to heat the rubber roller 31 itself by applying another voltage so that the conductive rubber roller 31 acts as a resistance. Further, the temperature of the rubber roller 31 can be appropriately controlled within the above-mentioned temperature range using means such as a temperature sensor or a thermostat provided near the detrapping stroke area and near the surface of the photoreceptor. As the amorphous silicon-based photoconductor layer, any material known per se can be used. For example, amorphous silicon deposited on the substrate by plasma decomposition of silane gas is used, and this material is It may be doped with a halogen or the like, and further doped with a Group or Group element of the periodic table, such as boron or phosphorus. The physical properties of a typical amorphous silicon photoreceptor are: dark conductivity 10 -12 Ω -1 cm -1 , activation energy <0.85 eV, photoconductivity >10 -7 Ω -1 cm -1 , optical conductivity The band gap is 1.7 to 1.9 eV, the amount of bonded hydrogen is 10 to 20 at%, and the dielectric constant of the film is 11.5 to 1.9 eV.
12.5. EXAMPLES OF THE INVENTION The invention is illustrated by the following examples. Example 1 Using an electrophotographic copying apparatus having the configuration shown in FIG. 2, a conductive rubber roller having a light source 14, a static eliminating light 21, a heater in the center as a heating means, and a bias voltage applying power source 30 was prepared. 31 as the first
Experiments No. 1 to No. 4 were conducted using the relationships shown in the table.
The photoreceptor drum is a-
A Si:H drum (90φ) was installed.
【表】
この一連の実験において使用した原稿はA3判
の大きさのものであり、第１−ａ図に示したよう
に前半部分には反射濃度1.5の黒ベタ文字部３、
後半部分には反射濃度0.8の中間調黒ベタ部分２
を有する。この第１−ａ図に基ずく原稿における
ｌの値は90φのドラムの円周長に該当するように
約28cmとしている。
この原稿から、上記した電子写真複写装置によ
り作成した。コピー物の各部の反射濃度を
(A)：原稿の文字部３に対応
(B)：第１−ａ図中引照数字６に対応
(C)：第１−ａ図中引照数字５に対応
として、その結果を第２表に示す。[Table] The manuscript used in this series of experiments was A3 size, and as shown in Figure 1-a, the first half had a black solid character area 3 with a reflection density of 1.5,
In the second half, there is a halftone black solid part 2 with a reflection density of 0.8.
has. The value of l in the original document based on FIG. 1-a is approximately 28 cm, which corresponds to the circumferential length of a 90φ drum. A document was created from this manuscript using the electrophotographic copying apparatus described above. Reflection density of each part of the copy (A): Corresponds to character part 3 of the original (B): Corresponds to reference numeral 6 in Figure 1-a (C): Corresponds to reference numeral 5 in Figure 1-a , the results are shown in Table 2.
【表】
この結果から、実験No.１の態様において導電性
ゴムローラによる加熱及びバイアス電圧印加によ
りコピー物の(B)、(C)の部分の濃度が生じなくなり
メモリー残像現象は消失していることが明らかと
なる。
これに対して、導電性ゴムローラによる加熱を
行わなかつた場合（No.３）及びバイアス電圧を印
加しなかつた場合（No.４）はコピー物中の(B)、(C)
の部分における濃度に差が生じ、かなりのメモリ
ー残像現象が生じていた。
また導電性ゴムローラーによる加熱温度が高過
ぎる場合（No.２）、画像濃度は全体に低下してい
ることがわかつた。この温度と画像濃度との関係
は次の実験で検討する。
実施例 ２
導電性ゴムローラーの温度Ｔ（℃）とコピー物
中の(B)及び(C)の部分の濃度差ΔI.D.との関係を調
べるためにローラ温度条件以外前記実施例No.１と
同一条件で実験を行つた。この結果を該４図のグ
ラフに示した。
この結果から、目視にて温度差を識別すること
ができない限界の濃度つまり0.05を考慮すれば35
℃以上が有効温度となることがわかつた。この場
合、45℃以上のローラ温度ではΔI.D.は小さくな
るが、半導体の性質上熱キヤリアの発生により暗
導電率が上昇し、表面電位を下げるため全体のI.
D.低下をもたらす。このことから、45℃付近を
上限と考えることができる。
実施例 ３
導電性ゴムローラに印加する電圧Ｖとコピー物
中の(B)および(C)の部分の濃度差ΔI.D.との関係を
調べるために印加電圧を変化させる以外前記実施
例No.１の条件に従い実験を行つた。この結果をグ
ラフに表したものが第５図である。
この結果から前記した実施例３と同様、ΔI.
D.0.05を臨界条件とすれば90V以上が有効となる
ことがわかつた。この場合200℃以上の印加電圧
ではΔI.D.はほぼ一定となりこれ以上印加電圧を
高くする必要性はうすく、ａ−Si：Ｈの主帯電に
よる帯電量を考慮すれば400V付近が上限である
と考えることができる。
実施例 ４
実施例１のNo.１の実験において直流バイアスの
代わりに周波数50Hz200Vの交流バイアス及び−
200Vの負バイアスを印加してコピーしたところ
ΔI.D.は各々0.02及び0.01であり、いずれの形態の
バイアス電圧印加も有効であることがわかつた。[Table] From this result, in the embodiment of Experiment No. 1, the density of parts (B) and (C) of the copy no longer occurs due to heating by the conductive rubber roller and application of bias voltage, and the memory afterimage phenomenon disappears. becomes clear. On the other hand, when heating with the conductive rubber roller was not performed (No. 3) and when the bias voltage was not applied (No. 4), (B) and (C) in the copy were
There was a difference in the density in the area, and a considerable memory afterimage phenomenon occurred. It was also found that when the heating temperature using the conductive rubber roller was too high (No. 2), the image density decreased overall. The relationship between this temperature and image density will be studied in the next experiment. Example 2 In order to investigate the relationship between the temperature T (°C) of the conductive rubber roller and the density difference ΔI.D. between portions (B) and (C) in the copy, the above Example No. was used except for the roller temperature condition. The experiment was conducted under the same conditions as 1. The results are shown in the graph of FIG. From this result, considering the limit concentration at which temperature differences cannot be visually discerned, that is, 0.05, 35
It was found that the effective temperature is ℃ or higher. In this case, when the roller temperature is 45°C or higher, the ΔI.D. becomes small, but due to the nature of semiconductors, the dark conductivity increases due to the generation of heat carriers and the surface potential decreases, so the overall I.D.
D. cause a decline. From this, it can be considered that around 45°C is the upper limit. Example 3 Example No. 3 was performed as described above except that the applied voltage was varied in order to examine the relationship between the voltage V applied to the conductive rubber roller and the density difference ΔI.D. between parts (B) and (C) in the copy. The experiment was conducted according to the conditions of 1. FIG. 5 shows a graph of this result. From this result, as in Example 3 described above, ΔI.
It was found that if D.0.05 is the critical condition, 90V or more is effective. In this case, at an applied voltage of 200°C or higher, ΔI.D. is almost constant, and there is little need to increase the applied voltage any higher; considering the amount of charge due to the main charge of a-Si:H, the upper limit is around 400V. You can think about it. Example 4 In the experiment No. 1 of Example 1, an AC bias with a frequency of 50Hz 200V and -
When a negative bias of 200V was applied and copies were made, ΔI.D. was 0.02 and 0.01, respectively, indicating that any form of bias voltage application is effective.
第１図−ａはメモリー残像現象を調べるために
使用する原稿を表した図であり、第１図−ｂはそ
のコピー物を表した図である、第２図は本発明の
方法を実施するための複写装置を表した概略図、
第３図は光疲労の波長依存性を示すグラフ図、第
４図はローラー温度と光疲労により生じるコピー
物の濃度差の関係を示すグラフ図、及び第５図は
バイアス印加電圧と光疲労により生じるコピー物
の濃度差との関係を示すグラフ図である。
図中、引照数字１１はａ−Si：Ｈドラム、１３
は主帯電器、１４は光源ランプ、１９は転写帯電
器、２１は除電光、３０はバイアス電圧印加電
源、３１は導電性ゴムローラ及び３２はローラー
加熱用熱源を夫々表す。
FIG. 1-a is a diagram showing an original used to investigate the memory afterimage phenomenon, FIG. 1-b is a diagram showing a copy thereof, and FIG. 2 is a diagram showing a copy of the original used to investigate the memory afterimage phenomenon. a schematic diagram representing a copying device for;
Figure 3 is a graph showing the wavelength dependence of optical fatigue, Figure 4 is a graph showing the relationship between the density difference of a copy caused by roller temperature and optical fatigue, and Figure 5 is a graph showing the relationship between applied bias voltage and optical fatigue. FIG. 3 is a graph diagram showing the relationship between the difference in density of a copy and the difference in density that occurs. In the figure, reference number 11 is a-Si:H drum, 13
14 is a main charger, 14 is a light source lamp, 19 is a transfer charger, 21 is a static eliminating light, 30 is a bias voltage application power source, 31 is a conductive rubber roller, and 32 is a heat source for heating the roller.
Claims (1)
に有する電子写真感光体に主帯電、画像露光、現
像、転写及びクリーニングの行程を反復すること
により行う画像形成方法において、前記クリーニ
ング行程と主帯電行程のとの間にバイアス電圧が
印加された導電性可撓性部材を、加温状態下にて
前記感光体に接触させて行う脱トラツピング行程
を設けたことを特徴とする帯電安定方法。 ２ 導電性可撓性部材の加温を35乃至45度で行う
ことを特徴とする特許請求の範囲第１項記載の方
法。 ３ 導電性可撓性部材がゴムローラである特許請
求の範囲第１項又は第２項記載の方法。[Scope of Claims] 1. An image forming method carried out by repeating the steps of main charging, image exposure, development, transfer, and cleaning on an electrophotographic photoreceptor having an amorphous silicon-based photoconductor layer on a conductive substrate. In the above, a detrapping step is provided between the cleaning step and the main charging step in which a conductive flexible member to which a bias voltage is applied is brought into contact with the photoreceptor under a heated state. Characteristic charging stabilization method. 2. The method according to claim 1, characterized in that the conductive flexible member is heated at 35 to 45 degrees. 3. The method according to claim 1 or 2, wherein the conductive flexible member is a rubber roller.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59011448A JPS60156068A (en) | 1984-01-25 | 1984-01-25 | Electrostatic charge stabilizing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP59011448A JPS60156068A (en) | 1984-01-25 | 1984-01-25 | Electrostatic charge stabilizing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60156068A JPS60156068A (en) | 1985-08-16 |
| JPH0455309B2 true JPH0455309B2 (en) | 1992-09-02 |
Family
ID=11778372
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP59011448A Granted JPS60156068A (en) | 1984-01-25 | 1984-01-25 | Electrostatic charge stabilizing method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60156068A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07111592B2 (en) * | 1986-05-27 | 1995-11-29 | 富士ゼロックス株式会社 | Electrophotographic copying machine |
| JP4539704B2 (en) * | 2007-09-28 | 2010-09-08 | 富士ゼロックス株式会社 | Image forming apparatus |
| JP5836302B2 (en) * | 2013-03-26 | 2015-12-24 | 京セラドキュメントソリューションズ株式会社 | Image forming apparatus |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5654458A (en) * | 1979-10-09 | 1981-05-14 | Canon Inc | Image formation method |
| JPS5924876A (en) * | 1982-08-03 | 1984-02-08 | Ricoh Co Ltd | Electrostatic recording method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5888646U (en) * | 1981-12-10 | 1983-06-16 | 株式会社東芝 | charging device |
-
1984
- 1984-01-25 JP JP59011448A patent/JPS60156068A/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5654458A (en) * | 1979-10-09 | 1981-05-14 | Canon Inc | Image formation method |
| JPS5924876A (en) * | 1982-08-03 | 1984-02-08 | Ricoh Co Ltd | Electrostatic recording method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60156068A (en) | 1985-08-16 |
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