JPH0466032B2 - - Google Patents

Info

Publication number
JPH0466032B2
JPH0466032B2 JP58035770A JP3577083A JPH0466032B2 JP H0466032 B2 JPH0466032 B2 JP H0466032B2 JP 58035770 A JP58035770 A JP 58035770A JP 3577083 A JP3577083 A JP 3577083A JP H0466032 B2 JPH0466032 B2 JP H0466032B2
Authority
JP
Japan
Prior art keywords
color
image
potential
toner
latent 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
Application number
JP58035770A
Other languages
Japanese (ja)
Other versions
JPS59162572A (en
Inventor
Masayuki Kaneda
Norio Hokari
Hiroshi Hirata
Kazue Takeuchi
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Fujifilm Business Innovation Corp
Original Assignee
Fuji Xerox Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Fuji Xerox Co Ltd filed Critical Fuji Xerox Co Ltd
Priority to JP58035770A priority Critical patent/JPS59162572A/en
Publication of JPS59162572A publication Critical patent/JPS59162572A/en
Publication of JPH0466032B2 publication Critical patent/JPH0466032B2/ja
Granted legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • G03G15/0147—Structure of complete machines using a single reusable electrographic recording member
    • G03G15/0152—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member
    • G03G15/0163—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member primary transfer to the final recording medium

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Developing For Electrophotography (AREA)

Description

【発明の詳細な説明】 産業上の利用分野 この発明は多色電子写真法における潜像形成方
法、更に詳しく言えば、カラー原稿画像濃度の低
い領域での微細なコントラスト変化を忠実に再現
することのできる潜像形成方法に関する。[Detailed Description of the Invention] Industrial Application Field The present invention relates to a latent image forming method in multicolor electrophotography, and more specifically, to faithfully reproducing minute contrast changes in areas of low density of a color original image. The present invention relates to a latent image forming method capable of forming a latent image.

従来技術 多色電子写真法は種々提案されているが、その
一つとしてレツド、グリーン、ブルーの三種の色
分解フイルターを用いて感光体に原稿像を分光露
光し、各色の色像電荷潜像を前記の色分解フイル
ターの色に対して補色の関係にあるシアン、マゼ
ンタ及びイエローの三種の色トナーで現像するプ
ロセスを三種の色分解フイルターについて逐次繰
返して色トナー像を転写紙に重ね合わせ、定着し
て多色画像を形成するカラー電子写真法がある。
この電子写真法において特に低濃度領域に微細な
コントラスト変化がある場合、フイルターを介し
た画像露光により感光体の表面電位はそのフイル
ター色の原稿濃度に対応した電位分布を示すが、
この潜像を前記フイルター色の補色トナーで現像
すると、原稿濃度の微細なコントラスト変化に対
応して発生するフリンジ電場の影響によりコント
ラスト変化が強調されてしまい、原稿濃度の比較
的高い部分はトナー濃度が高くなり、一方原稿濃
度の比較的低い部分はトナーが付着せずに色抜け
したり、粒状性の悪い画像となつてしまう。PRIOR TECHNOLOGY Various multicolor electrophotographic methods have been proposed, one of which is to expose an original image on a photoreceptor spectrally using three types of color separation filters: red, green, and blue, to create a latent image of each color. The process of developing with three types of color toners, cyan, magenta, and yellow, which are complementary colors to the color of the color separation filter, is sequentially repeated for the three color separation filters, and the color toner images are superimposed on the transfer paper, There is a color electrophotographic method in which a multicolor image is formed by fixing.
In this electrophotographic method, when there is a minute contrast change especially in a low density area, the surface potential of the photoreceptor due to image exposure through a filter shows a potential distribution corresponding to the original density of the filter color.
When this latent image is developed with toner of a complementary color to the filter color, the contrast change is emphasized due to the influence of the fringe electric field that occurs in response to minute contrast changes in the original density, and the toner density is On the other hand, toner does not adhere to portions of the document where the density is relatively low, resulting in color loss and images with poor graininess.

第１図ａ及びｂに低濃度部に微細なコントラス
ト変化を有する原稿の画像露光によつて得られる
感光体の表面電位（第１図ａ）と、この静電潜像
による電位に対応する電場パターン（第１図ｂ）
の例を示す。感光体の表面電位に対応する電場パ
ターンは、いわゆるエツジ効果によりその周縁部
において強くなり、中央部で弱くなる。そしてこ
の反作用でコントラストの弱い部分の周縁部の電
界がコントラストの強い部分の電界と逆極性すな
わち負の電界になる。このような静電潜像をトナ
ーＴで現像するとトナーは本来現像が行われるべ
き現像バイアスVBIより高電位の領域に、原稿濃
度に対応したようには付着せず、エツジ効果によ
るフリンジ電場の影響でコントラストに差のある
境界部は現像されず粒状性の悪い画像となる。 Figures 1a and b show the surface potential of the photoreceptor (Figure 1a) obtained by image exposure of a document with minute contrast changes in low-density areas, and the electric field corresponding to the potential due to this electrostatic latent image. Pattern (Figure 1b)
Here is an example. The electric field pattern corresponding to the surface potential of the photoreceptor becomes stronger at its periphery and weaker at its center due to the so-called edge effect. As a result of this reaction, the electric field at the periphery of the weakly contrasted portion becomes a negative electric field with a polarity opposite to that of the strong contrasted portion. When such an electrostatic latent image is developed with toner T, the toner does not adhere to an area with a higher potential than the development bias V BI where development should normally take place in a manner corresponding to the original density, and the fringe electric field due to the edge effect is Boundary areas where there is a difference in contrast due to this effect are not developed, resulting in an image with poor graininess.

このような現像は原稿濃度の高い側でも当然発
生するが、感光体の明減衰特性及び現像特性のγ
−値が小さいため低濃度側ほどは顕著には現れな
い。そして多色電子写真法では、再現したい色に
対して不要の色成分の場合に、この現象は顕著で
あり、例えば肌色の画像についてのシアン成分、
薄い黄緑色の場合のマゼンタ成分等（これらはオ
リジナルを色分解すると多少含まれている）のコ
ントラスト変化が強調され、粒状性が悪くなると
各色像を重ね合せた最終多色画像上においてその
粒状性の悪さが目立ち、ざらついた色再現性の悪
い汚れた感じの多色画像となつてしまう。この対
策として不要成分トナーによる現像を行わない方
法があるが、これによれば多色原稿の忠実な再現
は不可能である。 Such development naturally occurs even on the high-density side of the original, but the brightness decay characteristics of the photoreceptor and the development characteristics γ
-Since the value is small, it is not as noticeable as it is on the lower concentration side. In multicolor electrophotography, this phenomenon is noticeable when color components are unnecessary for the color you want to reproduce.For example, cyan components for skin-tone images,
Contrast changes in magenta components (these are included to some extent when the original is color separated) in the case of pale yellow-green are emphasized, and when the graininess worsens, the graininess becomes worse on the final multicolor image in which each color image is superimposed. The poor quality is noticeable, resulting in a multicolor image that looks grainy and has poor color reproducibility. As a countermeasure to this problem, there is a method of not performing development with unnecessary component toner, but this method makes it impossible to faithfully reproduce a multicolor original.

発明の目的 従つて、本発明は低濃度側に微細なコントラス
ト変化のあるカラー原稿について画像に対応した
複写物を得ることのできる潜像形成方法を提供す
ることを目的とする。OBJECTS OF THE INVENTION Accordingly, an object of the present invention is to provide a latent image forming method capable of obtaining a copy corresponding to an image of a color original having a minute contrast change on the low density side.

発明の構成 本発明は感光体の帯電工程後多色原稿像を複数
の色分解又はNDフイルター（レツド、グリー
ン、ブルー、イエロー又はNDフイルター）を用
いて感光体に分光又は減光露光し、各色の色像電
荷潜像を前記の色分解又はNDフイルターの色に
対して補色の関係にあるシアン、マゼンタ、イエ
ロー及び黒色の四種の色トナーで現像するプロセ
スを少なくとも二種のフイルターについて繰返し
て色トナー像を転写紙に重ね合せ定着して多色画
像を再現する電子写真法において、画像露光工程
後、現像工程の前に第二の帯電工程を設け、レベ
リング電位が白地部（背景部）電位と再現する濃
度部画像電位との間になるよう各色ごとに放電を
施すことを特徴とする。Structure of the Invention The present invention involves exposing a multicolor original image to a photoconductor using a plurality of color separations or ND filters (red, green, blue, yellow, or ND filters) after the process of charging the photoconductor, and exposing the photoconductor to spectral or attenuated light. The process of developing the color charge latent image with four color toners, cyan, magenta, yellow, and black, which are complementary colors to the color of the color separation or ND filter, is repeated for at least two types of filters. In electrophotography, in which color toner images are overlaid and fixed on transfer paper to reproduce a multicolor image, a second charging process is provided after the image exposure process and before the development process, and the leveling potential is applied to the white area (background area). It is characterized in that a discharge is applied for each color so that the potential is between the potential and the density image potential to be reproduced.

すなわち、本発明の方法では各色ごとに前記の
第１図ａに示した表面電位パターンの凹凸を第２
図ａの実線に示すようになうすことによつてフリ
ンジ電場の大きさを減少させ、エツジ効果の影響
を少なくして粒状性を改善するものである。第２
図ａに示す表面電位パターンに対応して電場パタ
ーンは第２図ｂに示すようになり、トナーＴは画
像濃度に比例して均一に静電潜像を顕像化する。
つまり、再現したい画像に必要な色成分について
表面電位の凹凸を適度にならし、現像バイアスを
も適度に上げてあまり必要のない色成分について
は凹凸をつぶしぎみにしてその色トナーが薄くの
るようにする。この場合各色共つぶしぎみにする
と細部の再現が悪くなるので、適度にレベリング
電圧を設定する。 That is, in the method of the present invention, for each color, the unevenness of the surface potential pattern shown in FIG.
By reducing the thickness as shown by the solid line in Figure a, the magnitude of the fringe electric field is reduced, the influence of the edge effect is reduced, and the graininess is improved. Second
Corresponding to the surface potential pattern shown in Figure a, the electric field pattern becomes as shown in Figure 2b, and the toner T uniformly visualizes the electrostatic latent image in proportion to the image density.
In other words, the unevenness of the surface potential of the color components necessary for the image to be reproduced is moderately smoothed out, and the development bias is increased appropriately, and the unevenness of the color components that are not so necessary is crushed to the extent that the toner of that color is applied thinly. Do it like this. In this case, if each color is squeezed too much, the reproduction of details will deteriorate, so the leveling voltage should be set appropriately.

以下に更に詳しく本発明の潜電潜像形成方法を
説明する。 The latent image forming method of the present invention will be explained in more detail below.

第３図は本発明の潜像形成法を適用した電子写
真複写装置例の概要図である。この装置では第１
帯電器１、像露光ステーシヨン２、第２帯電器
３、三種トナー用現像機４ａ，４ｂ，４ｃ、転写
前コロトロン５、転写コロトロン６、剥離コロト
ロン７、クリーニング前コロトロン８、クリーニ
ング装置９がこの順に設けられている。ここで第
２帯電器３としては第４図にＡまたはＢで示す特
性を有するものを使用する。 FIG. 3 is a schematic diagram of an example of an electrophotographic copying apparatus to which the latent image forming method of the present invention is applied. In this device, the first
Charger 1, image exposure station 2, second charger 3, three types of toner developing devices 4a, 4b, 4c, pre-transfer corotron 5, transfer corotron 6, stripping corotron 7, pre-cleaning corotron 8, and cleaning device 9 in this order. It is provided. Here, as the second charger 3, one having characteristics shown by A or B in FIG. 4 is used.

第４図において縦軸は帯電器３による感光体へ
の流入電流を表わし、横軸は感光体の表面電位を
表わす。VWは白地部電位、VLはレベリング電位
であり、Ａの場合には感光体の流入電流が零とな
る電位であり、Ｂの場合にはVLの値より低い電
位に対しては流入電流が正となり、VLの値より
高い電位に対しては流入電流が負となる電位であ
り、Voは再現したい濃度部電位である。 In FIG. 4, the vertical axis represents the current flowing into the photoreceptor by the charger 3, and the horizontal axis represents the surface potential of the photoreceptor. V W is the white background potential, and V L is the leveling potential. This is the potential at which the current becomes positive and the inflow current becomes negative for potentials higher than the value of V L , and V o is the concentration potential that is desired to be reproduced.

Ａの特性を有する帯電器は直流定電圧コロトロ
ンであり、Ｂの特性を有する帯電器は交流重畳直
流コロトロンである。勿論スコトロンを用いるこ
ともできる。 The charger having characteristics A is a DC constant voltage corotron, and the charger having characteristics B is an AC superimposed DC corotron. Of course, Scotron can also be used.

直流定電圧コロトロンを用いるＡの場合につい
て説明すると、レベリング電位VLを白地部電位
VBGと再現したい濃度部電位Voとの間に設定す
る。 To explain case A using a DC constant voltage corotron, the leveling potential V L is the white background potential.
Set between V BG and the concentration potential V o that you want to reproduce.

これにより、白地部電位はVLまで上昇し、濃
度部電位Voは先の第２図ａのVo′まで上昇する。
この場合Vo＜VLをした場合でも、Voの領域にコ
ロナ放電により電流が流れるのは、第１図に示し
た電場パターンに於て、Voのエツジ部が負方向
のフリンジ電場を有するためである。本発明では
再現したい画像に必要な色成分については、レベ
リング電位VLを適当に設定し、不要な色成分に
ついてはVLを極端に上げ、第４図における傾き
を大きくして、これに応じて現像バイアスを上げ
エツジ効果の影響を緩和させるものである。 As a result, the white background potential rises to V L and the density potential V o rises to V o ' in FIG. 2a.
In this case, even if V o <V L , current flows in the region of V o due to corona discharge because, in the electric field pattern shown in Fig. 1, the edge of V o receives a fringe electric field in the negative direction. This is to have. In the present invention, the leveling potential V L is appropriately set for color components necessary for the image to be reproduced, and V L is extremely raised for unnecessary color components, and the slope shown in FIG. This increases the developing bias to alleviate the influence of edge effects.

次に本発明を実施例により説明する。 Next, the present invention will be explained by examples.

実施例 この例は原稿のうち、特に人間の肌部に注目
し、その忠実な再現を狙つたものである。Example This example focuses on the human skin part of the manuscript and aims to faithfully reproduce it.

第３図において、像露光ステーシヨン２と現像
機４ａ，４ｂ，４ｃの間にスコロトロンを取り付
け（ドラムとワイヤーの距離DWS＝15mm、ドラ
ムとグリツドの距離DGS＝４mm）、マゼンタ及び
イエローの現像に対する潜像についてはワイヤー
印加電圧VWを約4KV、グリツド印加電圧VGを約
300Vとし、現像バイアスを通常の約400Vから
450〜500Vに上げ、シアンの現像に対する潜像に
ついてはVWを約5KV、VGを約400Vとし、現像
バイアスを通常の約400Vから約550Vに上げたと
ころ、粒状性のグレードが６段階法による測定で
Ｖからに改善されると共に良好に肌色を再現す
ることができた。なお、この特のスコロトロンの
放電特性を第５図に示す。 In Fig. 3, a scorotron is installed between the image exposure station 2 and the developing machines 4a, 4b, and 4c (drum-to-wire distance DWS = 15 mm, drum-to-grid distance DGS = 4 mm), and a latent for magenta and yellow development is installed. For the image, the wire applied voltage V W is about 4KV, and the grid applied voltage V G is about 4KV.
300V and the developing bias from the usual approximately 400V.
When increasing the voltage to 450 to 500V, and setting V W to approximately 5 KV and V G to approximately 400 V for the latent image for cyan development, and increasing the developing bias from the normal approximately 400 V to approximately 550 V, the graininess grade was determined by the 6-step method. As measured by , it was improved from V and was able to reproduce the skin color satisfactorily. The discharge characteristics of this particular scorotron are shown in FIG.

発明の効果 以上説明したように、本発明は像露光後現像工
程の前に第二の帯電工程を設けて、各色ごとにレ
ベリング電位が原稿の白地部電位と再現する濃度
画像電位との間で適度な値となるように処理する
ものであり、これによつて特に低濃度部に微細な
コントラスト変化のある原稿におけるフリンジ電
場による画像の荒れ、粒状性の悪さ、不要な色成
が強調されることによつて起る画像の汚れた感じ
を抑え、多色原稿に忠実なカラー複色物を得るこ
とを可能にしたものである。Effects of the Invention As explained above, the present invention provides a second charging process after image exposure and before the development process, so that the leveling potential for each color is set between the white background potential of the original and the density image potential to be reproduced. This process emphasizes image roughness, poor graininess, and unnecessary color formation due to fringe electric fields, especially in originals with minute contrast changes in low-density areas. This suppresses the smudged appearance of images caused by this phenomenon, and makes it possible to obtain multicolor objects that are faithful to multicolor originals.

【図面の簡単な説明】[Brief explanation of the drawing]

第１図ａ及びｂは、従来の電子写真法により低
濃度部に微細コントラストを有する画像の露光に
よる感光体の表面電位及び電場パターンを示すグ
ラフ、第２図ａは本発明の方法による処理を施し
た場合の感光体の表面電位を示すグラフ、第２図
ｂは第２図ａに対応する電場パターンを示し、第
３図は本発明の潜像形成法を適用した電子写真複
写装置例の概要図、第４図は本発明に用いる帯電
器の特性を示すグラフ、第５図は本発明の実施例
で用いた帯電器の特性を示すグラフである。 図中符号、１……第１帯電器、２……像露光ス
テーシヨン、３……第２帯電器、４ａ，４ｂ，４
ｃ……現像装置、５……転写前コロトロン、６…
…転写コロトロン、７……剥離コロトロン、８…
…クリーニング前コロトロン、９……クリーニン
グ装置、１０……転写用紙、１１……感光体ドラ
ム、１２……転写ドラム、Ｖ……感光体表面電
位、Ｉ……感光体への流入電流、VW，VBG……白
地部電圧、Vo……再現する濃度電位、VL……レ
ベリング電位、Ａ……直流定電圧コロトロンの特
性、Ｂ……交流重畳直流コロトロンの特性。 FIGS. 1a and 1b are graphs showing the surface potential and electric field pattern of the photoreceptor after exposure of an image with fine contrast in low density areas by conventional electrophotography, and FIG. FIG. 2b shows an electric field pattern corresponding to FIG. 2a, and FIG. 3 shows an example of an electrophotographic copying apparatus to which the latent image forming method of the present invention is applied. FIG. 4 is a graph showing the characteristics of the charger used in the present invention, and FIG. 5 is a graph showing the characteristics of the charger used in the embodiment of the present invention. Symbols in the figure: 1...First charger, 2...Image exposure station, 3...Second charger, 4a, 4b, 4
c...Developing device, 5...Pre-transfer corotron, 6...
...Transfer corotron, 7...Peeling corotron, 8...
...Corotron before cleaning, 9...Cleaning device, 10...Transfer paper, 11...Photoconductor drum, 12...Transfer drum, V...Surface potential of photoconductor, I...Current flowing into photoconductor, VW , V BG ...White background voltage, V o ...Concentration potential to be reproduced, V L ...Leveling potential, A ...Characteristics of DC constant voltage corotron, B ...Characteristics of AC superimposed DC corotron.

Claims (1)

【特許請求の範囲】[Claims] １ 帯電、像露光、現像、転写及び定着工程から
なり、複数の色分解又はNDフイルターを用いて
感光体に原稿像を分光又は減光露光し、各色の色
像電荷潜像を前記の色分解又はNDフイルターの
色に対して補色の関係にある三種のカラートナー
又は黒色トナーで現像するプロセスを各フイルタ
ー毎に繰返して色トナー像を重ね合せ定着する電
子写真法において、像露光工程後現像工程前に第
二の帯電工程を設け各色ごとに原稿の白地部電位
と再現する画像濃度電位との間で前記第二の帯電
レベリング電位を変化させることを特徴とする潜
像形成方法。1 Consists of charging, image exposure, development, transfer, and fixing steps, the original image is exposed to light spectrally or attenuatedly on a photoreceptor using multiple color separations or ND filters, and the color image charge latent image of each color is separated into the color separations described above. Or, in an electrophotographic method in which the process of developing with three types of color toner or black toner that are complementary colors to the color of the ND filter is repeated for each filter to superimpose and fix color toner images, the development process is performed after the image exposure process. A method for forming a latent image, characterized in that a second charging step is provided beforehand, and the second charging leveling potential is varied between the white background potential of the document and the image density potential to be reproduced for each color.
JP58035770A 1983-03-07 1983-03-07 Formation of latent image by polychromatic electrophotography Granted JPS59162572A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP58035770A JPS59162572A (en) 1983-03-07 1983-03-07 Formation of latent image by polychromatic electrophotography

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP58035770A JPS59162572A (en) 1983-03-07 1983-03-07 Formation of latent image by polychromatic electrophotography

Publications (2)

Publication Number Publication Date
JPS59162572A JPS59162572A (en) 1984-09-13
JPH0466032B2 true JPH0466032B2 (en) 1992-10-21

Family

ID=12451100

Family Applications (1)

Application Number Title Priority Date Filing Date
JP58035770A Granted JPS59162572A (en) 1983-03-07 1983-03-07 Formation of latent image by polychromatic electrophotography

Country Status (1)

Country Link
JP (1) JPS59162572A (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3236183B2 (en) * 1995-01-19 2001-12-10 キヤノン株式会社 Image forming device

Also Published As

Publication number Publication date
JPS59162572A (en) 1984-09-13

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