EP0226750A1 - Procédé de la formation d'images à couleurs électrostatique par inversion d'images - Google Patents

Procédé de la formation d'images à couleurs électrostatique par inversion d'images Download PDF

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Publication number
EP0226750A1
EP0226750A1 EP86114668A EP86114668A EP0226750A1 EP 0226750 A1 EP0226750 A1 EP 0226750A1 EP 86114668 A EP86114668 A EP 86114668A EP 86114668 A EP86114668 A EP 86114668A EP 0226750 A1 EP0226750 A1 EP 0226750A1
Authority
EP
European Patent Office
Prior art keywords
color toner
photoconductor
image
donor member
areas
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP86114668A
Other languages
German (de)
English (en)
Other versions
EP0226750B1 (fr
Inventor
Josef Matkan
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.)
Stork Colorproofing BV
Original Assignee
Stork Colorproofing BV
Coulter Systems Corp
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 Stork Colorproofing BV, Coulter Systems Corp filed Critical Stork Colorproofing BV
Priority to AT86114668T priority Critical patent/ATE54377T1/de
Publication of EP0226750A1 publication Critical patent/EP0226750A1/fr
Application granted granted Critical
Publication of EP0226750B1 publication Critical patent/EP0226750B1/fr
Expired legal-status Critical Current

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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
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • G03G15/101—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer for wetting the recording material
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/01—Electrographic processes using a charge pattern for multicoloured copies

Definitions

  • This invention relates to electrophotography and in particular to a novel method of preparing by an elec­trophotographic process multicolor pre-press proofs from negative color separation films.
  • pre-press proofs as is well known in the art is to assess color balance and strength which can be expected from the final press run and according­ly to correct the separation transparencies before the printing plates are made therefrom. In many instances it is also required to produce so-called customer proofs for approval of subject, composition and general appearance of the print prior to press run. Thus it is essential that the pre-press proof should have the same appearance as the press print, that is to say in addi­tion to matching the colors of the press print, the pre-press proof shouId be on the same paper as the press print.
  • a positive working printing plate is ex­posed to a positive transparency or film positive wherein the information to be printed corresponds directly to opaque areas whereas the non-printing back­ground areas correspond to transparent areas contained on such film positive.
  • the exposed areas become photo­hardened and form the ink receptive printing areas whereas the unexposed areas are removed by chemical treatment and the underlying water receptive usually grained aluminium plate surface forms the non-printing or non-image areas during subsequent lithographic or offset printing.
  • Prior art electrophotographic pre-press proofing processes are not suitable for the proofing of film negatives used for the preparation of negative working printing plates that is to say such processes are not suitable for the reversal reproduction of imagery wherein the transparent areas contained on a film nega­tive are to be reproduced as the image areas on the pre-press proof.
  • Reversal reproduction per se by elec­trophotography is well known in the art but the proc­esses employed for this purpose are not suitable for multicolor pre-press proofing.
  • Reversal image reproduction in electrophotography is normally carried out according to prior art prac­tices by means of so-called repulsion toning.
  • This process comprises the steps of electrostatically charg­ing the surface of a photoconductor to a polarity, typically charging an n-type photoconductor such as zinc oxide to negative polarity, exposing said surface to a film negative containing the image to be reproduced in the form of transparent areas and the non-image part in the form of opaque areas whereby the photoconductor surface becomes discharged in the ex­posed image areas while retaining the charge in the un­exposed non-image areas and applying to said surface toner materiaI having the same polarity as that of the charges contained on said surface, typically applying negative toner material to a negatively charged n-type photoconductor surface, whereby such toner material is repelled from the charged non-image areas onto the dis­charged image areas forming toner deposits thereon cor­responding to the image to be reproduced.
  • the invention provides a method of electrostatographic image reversal wherein a positive print comprising a receptor sheet having image-free areas and image areas formed by color toner deposits is produced from a negative film having opaque areas cor­responding to the image-free areas on said print and transparent areas corresponding to the image areas on said print, said method characterized by the steps of electrostatically charging a photoconductor to deposit thereon uniformly charges of a first polarity, exposing said photoconductor to light through a negative film thereby to discharge said photoconductor in the areas corresponding to said transparent areas of said nega­tive film while retaining said charges theron in areas corresponding to said opaque areas of said negative film forming a uniform color toner layer of a second polarity on a donor member, effecting a virtual contact between said photoconductor and said color toner layer on said donor member to thereby transfer portions of said color toner layer to said photoconductor by at­traction to said retained charges thereon while pre­serving said color toner layer on said
  • FIG. 1 is shown a photoconductive recording member 1 comprising a photoconductive layer 2 on a con­ductive support 3, uniformly charged to negative polarity as indicated by the negative charges 4.
  • a film negative separation of the first color 5 contain­ing opaque final background or non-image areas 6 and transparent final image areas 7 is placed in contact with photoconductive recording member 1 for contact ex­posure through light source 8.
  • FIG 3 is illustrated a donor member 9 com­prising for instance a metal cylinder, partially im­mersed in liquid toner of the first color 10 containing therein suspended positive toner particles 11.
  • the liquid toner 10 is contained within tank 12.
  • Donor member 9 is also grounded, whereby an electrophoretic cell is formed wherein donor member 9 and electrode 13 con­stitute the two electrodes of opposite polarity.
  • Photoconductive recording member 1 is caused to traverse in the direction shown at the same linear speed as the circumferential speed of donor member 9, its photoconductive surface 2 containing after exposure residual negative charges 4 thereon being in virtual contact with rotating donor member 9, its conductive support 3 being grounded.
  • toner layer 15 is split, in that portion of toner layer 15 contacting the photoconductive surface 2 where electrostatic charges 4 are contained thereon are at­tracted and transferred thereto whereas those portions of toner layer 15 contacting areas on photoconductive layer 2 which, due to preceding exposure are free of electrostatic charges, remain thereon.
  • the remaining portion 16 of toner layer 15 on donor member 9 corresponds to the transparent final image areas 7 of film negative 5 in Figure 1.
  • the toner deposits forming said remaining portion 16 are electrostatically transferred onto receptor member such as printing stock 17 and the circumferential speed of transfer roll 19 being the same as the circumferential speed of donor member 9.
  • Electrostatic transfer is ef­fected by connecting transfer roll 19 to the negative terminal of power supply 20, the positive terminal of which is grounded. It will be seen that transferred first color toner deposits 18 on printing stock 17 are contained thereon in areas corresponding to the final transparent image areas 7 of first color separation film negative 5 as shown in Figure 1 and thus a rever­sal reproduction, that is to say a positive print from a negative film has been produced by toner transfer based on attraction throughout.
  • the above disclosed steps are repeated in succession with negative film separations of subsequent colors and corresponding color toners.
  • the receptor member or printing stock carrying thereon the preceding color toner deposits is moved around the transfer roll in register with the donor member to ensure that all color images are transferred to the printing stock in exact register with each other.
  • the color separation film negatives are placed in register with the photoconductive recording member during con­tact exposure, and as the photoconductive member tra­verses the donor member for transfer toning, registra­ tion means are provided to ensure exact coincidence be­tween corresponding image areas on the photoconductive surface and the donor member surface.
  • electrostatic transfer from the donor member onto the printing stock has been illustrated by means of a roll comprising for instance a conductive core connected to the terminal of the power supply and a cover layer of semi-conductive elastomer, as is well known in the art, however other well known means for eleotrostatic trans­fer such as a corona generator can be employed equally well to serve the same purpose.
  • transfer of color toner deposits from the donor member onto the receiving member may be effected by methods other than electrostatic, such as for instance by pressure, adhe­sion, heat and/or embedment in a receptor coating on the receiving member.
  • the photoconductive member has been illustrated as a flat plate and the donor mem­ ber as a cylinder, it should be realized that the photoconductive member may be cylindrical and the donor member flat, or both members can be flat or cylindri­cal, or either or both members can be in the form of belts, if so desired.
  • the receptor mem­ber instead of being a flexible paper sheet as il­lustrated can comprise a rigid material such as cardboard or metal plate, in which case of course ap­propriate re-arrangement of the transfer from the donor to the receptor member will be required, as would be obvious to those skilled in the art.
  • FIG. 3 comprises only the essential elements of the present invention, and it should be realized that in practice it may be desirable to incorporate other elements as are commonly used in electrostatographic equipment for improving performance and/or image quality, such as for instance a doctor blade or corona generator means to control the quantity of carrier liquid over the toner layer formed on the donor member, means to wet the photoconductor surface with carrier liquid type solvent before and/or after transfer toning, cleaning means to remove toner layer portions from the photoconductive surface preparatory to oharging for a following color, means to wet with carrier liquid type solvent the donor member and/or the receptor member prior to toner deposit transfer, and the like.
  • a doctor blade or corona generator to control the quantity of carrier liquid over the toner layer formed on the donor member, means to wet the photoconductor surface with carrier liquid type solvent before and/or after transfer toning, cleaning means to remove toner layer portions from the photoconductive surface preparatory to oharging for a following color, means to wet with carrier liquid type solvent the donor member and
  • An important feature of this invention consists in the capability to precisely predetermine the thickness of the toner layer formed on the donor member as a function of the electrophoretic mobility of specific toners, toner concentration, the gap between electrode and donor member, electrode voltage and speed of rota­tion of donor member.
  • Color toners usable in the process of the present invetion may be for example as disclosed in U.S. Patent No. 3,998,746 of Tsuneda, U.S. Patent 3,820,986 of Fukashima et aI., and U.S. Patent 3,419,411 of Wright.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Color Electrophotography (AREA)
EP19860114668 1985-10-31 1986-10-22 Procédé de la formation d'images à couleurs électrostatique par inversion d'images Expired EP0226750B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT86114668T ATE54377T1 (de) 1985-10-31 1986-10-22 Verfahren zur elektrostatischen farbbildherstellung durch bildumkehr.

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
AU3192/85 1985-10-31
AUPH319285 1985-10-31
AU64346/86A AU581790B2 (en) 1985-10-31 1986-10-31 Method of electrostatic colour proofing by image reversal

Publications (2)

Publication Number Publication Date
EP0226750A1 true EP0226750A1 (fr) 1987-07-01
EP0226750B1 EP0226750B1 (fr) 1990-07-04

Family

ID=25634305

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19860114668 Expired EP0226750B1 (fr) 1985-10-31 1986-10-22 Procédé de la formation d'images à couleurs électrostatique par inversion d'images

Country Status (2)

Country Link
EP (1) EP0226750B1 (fr)
AU (1) AU581790B2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0343167A1 (fr) * 1987-01-15 1989-11-29 Stork Colorproofing B.V. Procede d'inversion d'image
WO1993001531A1 (fr) * 1991-07-09 1993-01-21 Spectrum Sciences B.V. Appareil revelateur d'images latentes
USRE37859E1 (en) 1991-07-09 2002-09-24 Indigo N.V. Development control system

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
AU598702B2 (en) * 1987-12-01 1990-06-28 Stork Colorproofing B.V. Electrostatic proofing of negative color separations

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2149889B2 (fr) * 1970-10-08 1974-10-24 Canon K.K., Tokio
US3862848A (en) * 1971-12-24 1975-01-28 Australia Res Lab Transfer of color images
DE2525676A1 (de) * 1974-06-07 1975-12-18 Australia Res Lab Verfahren zur druckinduzierten entwicklung elektrostatischer latenter bilder
DE2810704A1 (de) * 1977-03-15 1978-09-21 Fuji Photo Film Co Ltd Vorrichtung zum entwickeln elektrostatischer, latenter bilder
EP0038050A2 (fr) * 1980-04-11 1981-10-21 Coulter Systems Corporation Machine électrophotographique à copie par contact en couleur
DD215879A1 (de) * 1983-05-31 1984-11-21 Univ Magdeburg Tech Einrichtung und verfahren zur bildmaessigen elektrofotografischen entwicklung

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4021586A (en) * 1970-10-08 1977-05-03 Canon Kabushiki Kaisha Method of and means for the development of electrostatic images
AU3987785A (en) * 1984-02-14 1985-09-12 Coulter Systems Corp. Multicolour electrostatic duplicator

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2149889B2 (fr) * 1970-10-08 1974-10-24 Canon K.K., Tokio
US3862848A (en) * 1971-12-24 1975-01-28 Australia Res Lab Transfer of color images
DE2525676A1 (de) * 1974-06-07 1975-12-18 Australia Res Lab Verfahren zur druckinduzierten entwicklung elektrostatischer latenter bilder
DE2810704A1 (de) * 1977-03-15 1978-09-21 Fuji Photo Film Co Ltd Vorrichtung zum entwickeln elektrostatischer, latenter bilder
EP0038050A2 (fr) * 1980-04-11 1981-10-21 Coulter Systems Corporation Machine électrophotographique à copie par contact en couleur
DD215879A1 (de) * 1983-05-31 1984-11-21 Univ Magdeburg Tech Einrichtung und verfahren zur bildmaessigen elektrofotografischen entwicklung

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0343167A1 (fr) * 1987-01-15 1989-11-29 Stork Colorproofing B.V. Procede d'inversion d'image
EP0343167A4 (en) * 1987-01-15 1990-12-05 Stork Colorproofing B.V. Image reversal process
WO1993001531A1 (fr) * 1991-07-09 1993-01-21 Spectrum Sciences B.V. Appareil revelateur d'images latentes
US5596396A (en) * 1991-07-09 1997-01-21 Indigo N.V. Latent image development apparatus
USRE37859E1 (en) 1991-07-09 2002-09-24 Indigo N.V. Development control system

Also Published As

Publication number Publication date
EP0226750B1 (fr) 1990-07-04
AU6434686A (en) 1987-05-07
AU581790B2 (en) 1989-03-02

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