EP0963852B1 - Méthode d'impression et contrôle pour une tête d'impression avec électrodes de déviation pour l'impression électrostatique directe - Google Patents

Méthode d'impression et contrôle pour une tête d'impression avec électrodes de déviation pour l'impression électrostatique directe Download PDF

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Publication number
EP0963852B1
EP0963852B1 EP99200479A EP99200479A EP0963852B1 EP 0963852 B1 EP0963852 B1 EP 0963852B1 EP 99200479 A EP99200479 A EP 99200479A EP 99200479 A EP99200479 A EP 99200479A EP 0963852 B1 EP0963852 B1 EP 0963852B1
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EP
European Patent Office
Prior art keywords
printing
printhead structure
deflection electrodes
voltage
deflection
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
Application number
EP99200479A
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German (de)
English (en)
Other versions
EP0963852A1 (fr
Inventor
Guido Desie
Hilbrand Van Den Wijngaert
François Backeljauw
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Agfa Gevaert NV
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Agfa Gevaert NV
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Publication date
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Priority to EP99200479A priority Critical patent/EP0963852B1/fr
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Publication of EP0963852B1 publication Critical patent/EP0963852B1/fr
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/385—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material
    • B41J2/41—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material for electrostatic printing
    • B41J2/415—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material for electrostatic printing by passing charged particles through a hole or a slit
    • B41J2/4155—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by selective supply of electric current or selective application of magnetism to a printing or impression-transfer material for electrostatic printing by passing charged particles through a hole or a slit for direct electrostatic printing [DEP]
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2217/00—Details of electrographic processes using patterns other than charge patterns
    • G03G2217/0008—Process where toner image is produced by controlling which part of the toner should move to the image- carrying member
    • G03G2217/0025—Process where toner image is produced by controlling which part of the toner should move to the image- carrying member where the toner starts moving from behind the electrode array, e.g. a mask of holes

Definitions

  • This invention relates to a recording method and an apparatus for use in the process of Direct Electrostatic Printing (DEP), in which an image is created upon a receiving substrate by creating a flow of toner particles from a toner bearing surface to the image receiving substrate and image-wise modulating the flow of toner particles by means of an electronically addressable printhead structure.
  • DEP Direct Electrostatic Printing
  • toner particles are deposited directly in an image-wise way on a receiving substrate, the latter not bearing any image-wise latent electrostatic image.
  • a DEP device is disclosed in e.g. US-A-3 689 935.
  • This document discloses an electrostatic line printer having a multi-layered particle modulator or printhead structure comprising :
  • Each control electrode is formed around one aperture and is isolated from each other control electrode.
  • Selected electric potentials are applied to each of the control electrodes while a fixed potential is applied to the shield electrode.
  • An overall applied propulsion field between a toner delivery means and a support for a toner receiving substrate projects charged toner particles through a row of apertures of the printhead structure.
  • the intensity of the particle stream is modulated according to the pattern of potentials applied to the control electrodes.
  • the modulated stream of charged particles impinges upon a receiving substrate, interposed in the modulated particle stream.
  • the receiving substrate is transported in a direction perpendicular to the printhead structure, to provide a line-by-line scan printing.
  • the shield electrode may face the toner delivery means and the control electrodes may face the receiving substrate.
  • a DC-field is applied between the printhead structure and a single back electrode on the receiving substrate. This propulsion field is responsible for the attraction of toner to the receiving substrate that is placed between the printhead structure and the back electrode.
  • US-A-4 860 036 e.g. a printhead structure with at least 3 rows of printing apertures is disclosed in order to diminish the white zone between neighbouring printing apertures.
  • a DEP device having a printhead structure that comprises an insulating material with apertures and control electrodes, and extra apertures in between two of said neighbouring control electrodes.
  • a printhead structure lower density banding in the print direction is impossible.
  • the construction of said slit-printhead structure is not that easy.
  • DE-A-195 34 705 a DEP device is described in which the problem of lower density banding is tackled by the introduction of two different printhead structures and two toner application devices. This is of course an easy but costly solution to said banding problem.
  • a DEP device comprising a printhead structure, an ultrasonic vibration means, an image information generating means and a toner deflecting means.
  • Said toner deflecting means is a set of deflection electrodes (isolated from said control electrodes) positioned in between said image receptive member and said printhead structure. Between said two sets of deflection electrodes a varying electrical field is applied resulting to deformation of said toner flux towards said image receptive member.
  • said varying electrical field can be a pulsed voltage, a stepwise voltage as well as a saw-tooth voltage.
  • the printhead structure is rather complex since it comprises (if it is formed in a PCB-layout) three different conductor layers that have to be isolated from each other. If a simple printhead structure is used with only two planes with electrodes, a further set of deflection electrodes is placed between the printhead structure and the substrate to be printed.
  • a DEP device which comprises a layer of control electrodes in a control grid, a toner flying stabilisation grid and a set of deflection electrodes that can position a dot on the final receiver on one of different possible positions.
  • a DEP device and a method of printing comprising at least a set of deflection electrodes and a controller for said deflection electrodes so that through one printing aperture three dots can be printed, in a straight, a left and a right position.
  • the number of control electrodes is lower than the addressability of the device, i.e. there are less control electrodes than dots printed.
  • This implementation can enhance the resolution of the printhead structure or diminish the complexity by reducing the number of control IC's that are essential for providing the image variation, but by using said deflection electrodes on a time-based scale to print three different dots on the receiving material in consecutive order, the maximum attainable printing speed is diminished by a factor of at least 3.
  • DEP device and a method of printing comprising at least a set of deflection electrodes and a controller for said deflection electrodes.
  • On the control electrodes a changing voltage is applied with a period equal to the line time.
  • the toner flow trough a printing aperture is continuously moved from one side to another so that a circular dot is printed as an ellipse.
  • white banding in the print direction is avoided.
  • the white banding is avoided in the higher density, but is not totally avoided in the lower densities.
  • the prior art disclosures concentrate on the construction of the printhead structure, the deflection electrodes and the voltage applied to the deflection electrodes.
  • It is an object of the invention is to provide a DEP device, i.e. a device for direct electrostatic printing that can print at high speed with low clogging of the printing apertures and with high and constant maximum density with almost no white banding parallel to the printing direction.
  • the object of the invention is realised by providing a device for direct electrostatic printing with an addressability, AD, in dots per cm, comprising
  • Figure 3 shows schematically a third possible embodiment of a printhead structure useful in a DEP device according to the present invention.
  • Figure 4 shows a DEP device comprising a printhead structure according to the first possible embodiment of a printhead structure useful in a method for Direct Electrostatic Printing and in a DEP device according to of the present invention.
  • WRT Write time
  • Addressability the number of dots printed per unit of length (2.54 dots per inch (dpi) equal 1 dot per cm) that are addressed.
  • a DEP device having a number of control electrodes equal to the addressability have one control electrode for each dot to be addressed.
  • One dot can be written via one printing aperture controlled by one control electrode or by more than one printing aperture when these printing apertures are controlled by one control electrode. The latter system has been described in detail in e.g. EP-A-754 557.
  • deflection electrodes in different layers (multilayer structure) and enhancing the deflection voltage in ratio proportional to the isolation power. It is also possible to combine the concept of deflection electrodes with other concepts for elimination of lower density stripes as multiple printhead structures, multiple apertures per control electrode, multipass printing, sliding contact between the toner particle source and the printhead structure, etc..

Claims (5)

  1. Dispositif d'impression électrostatique directe ayant une adressabilité, AD, en points par cm, comprenant
    un moyen pour distribuer des particules de toner chargées, ledit moyen ayant une surface porteuse de particules de toner chargées (112) couplée à un moyen pour appliquer un premier potentiel électrique (DC1) à ladite surface,
    une électrode arrière (105) pour coupler un substrat récepteur d'image (108) à un deuxième potentiel électrique (DC4) différent dudit premier, ladite différence (|DC4-DC1|) créant un champ électrique entre ladite surface et ledit substrat, dans lequel un flux desdites particules de toner chargées (104) est créé vers ledit substrat,
    un moyen (115) pour déplacer ledit substrat dans un sens d'impression (flèche A) de manière à avoir un temps de ligne, LT, ledit temps de ligne étant le temps nécessaire pour imprimer un point à la pleine densité,
    une structure de tête d'impression (106), placée entre ladite surface porteuse de toner (112) et ledit substrat récepteur d'image (108), laissant un écart, d, entre ladite surface porteuse de toner et ladite structure de tête d'impression et laissant un écart, dB, entre ladite structure de tête d'impression et ladite électrode arrière,
       ladite structure de tête d'impression ayant
    une feuille de matière isolante (106c) avec une première et une deuxième face, un certain nombre d'éléments d'impression (116) formant au moins une rangée sur ladite feuille de matière isolante, chacun desdits éléments d'impression comportant au moins une ouverture d'impression (107) à travers ladite feuille de matière isolante,
    au moins deux ensembles d'électrodes de déviation (106b1, 106b2), disposés dans ladite structure de tête d'impression de manière à avoir, près de deux éléments d'impression adjacents, au moins une électrode de déviation,
    une source de tension, DC3, couplée auxdits éléments d'impression pour appliquer selon l'image des potentiels électriques (V3) auxdits éléments d'impression pour ouvrir et fermer sélectivement lesdites ouvertures d'impression conformément à des données d'image
    une source de tension, couplée à chacun desdits au moins deux ensembles d'électrodes de déviation, pour appliquer une tension variable (AC5, AC6) auxdites électrodes de déviation,
    caractérisé en ce que
    ledit écart, dB, entre ladite structure de tête d'impression et ladite électrode arrière, se rapporte à ladite différence entre DC4 et DC1 de telle sorte que R1 = (|DC4-DC1|/dB) ≤ 1,5 V/µm et que ladite source de tension couplée à ladite électrode de déviation est équipée pour fournir une tension variable auxdites électrodes de déviation avec une tension crête à crête, Vp de telle sorte que Vp/R1 > 250 µm.
  2. Dispositif selon la revendication 1, dans lequel ladite source de tension couplée auxdites électrodes de déviation est équipée pour fournir une tension variable auxdites électrodes de déviation avec une tension crête à crête, Vp, de telle sorte que Vp/R1 > 400 µm.
  3. Dispositif selon la revendication 1 ou 2, dans lequel ledit écart, dB, entre ladite structure de tête d'impression et ladite électrode arrière, se rapporte à ladite différence entre DC4 et DC1 de telle sorte que R1 = (|DC4-DC1|/dB) ≤ 1,0 V/µm.
  4. Dispositif selon l'une quelconque des revendications 1 à 3, dans lequel ladite tension variable varie par pas discrets.
  5. Dispositif selon l'une quelconque des revendications 1 à 4, dans lequel ladite tension variable varie continuellement et a une fréquence, f, se rapportant audit temps de ligne LT de telle sorte que f x LT = 1,00.
EP99200479A 1998-06-09 1999-02-18 Méthode d'impression et contrôle pour une tête d'impression avec électrodes de déviation pour l'impression électrostatique directe Expired - Lifetime EP0963852B1 (fr)

Priority Applications (1)

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EP99200479A EP0963852B1 (fr) 1998-06-09 1999-02-18 Méthode d'impression et contrôle pour une tête d'impression avec électrodes de déviation pour l'impression électrostatique directe

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP98201965 1998-06-09
EP98201965 1998-06-09
EP99200479A EP0963852B1 (fr) 1998-06-09 1999-02-18 Méthode d'impression et contrôle pour une tête d'impression avec électrodes de déviation pour l'impression électrostatique directe

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EP0963852A1 EP0963852A1 (fr) 1999-12-15
EP0963852B1 true EP0963852B1 (fr) 2001-05-16

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Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2001045955A1 (fr) * 1999-12-21 2001-06-28 Array Printers Ab Procede et appareil d'impression electrostatique directe
WO2001045953A1 (fr) * 1999-12-21 2001-06-28 Array Ab Publ. Procede et appareil d'impression electrostatique directe
AU2835700A (en) * 1999-12-21 2001-07-03 Array Ab Direct electrostatic printing method and apparatus
AU2000279759A1 (en) * 2000-09-20 2002-04-02 Array Ab Printhead structure and image recording device including such printhead structure

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0945275A2 (fr) * 1998-03-24 1999-09-29 Matsushita Electric Industrial Co., Ltd. Appareil et procédé de formation d'images

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3689935A (en) 1969-10-06 1972-09-05 Electroprint Inc Electrostatic line printer
US4860036A (en) 1988-07-29 1989-08-22 Xerox Corporation Direct electrostatic printer (DEP) and printhead structure therefor
JP3271816B2 (ja) 1993-03-09 2002-04-08 ブラザー工業株式会社 画像形成装置
JPH0740579A (ja) 1993-07-28 1995-02-10 Brother Ind Ltd 画像形成装置
JPH07304206A (ja) 1994-05-16 1995-11-21 Brother Ind Ltd 画像形成装置
SE503634C2 (sv) 1994-09-19 1996-07-22 Array Printers Ab Metod och anordning i en skrivare
EP0754557B1 (fr) 1995-07-18 1998-10-14 Agfa-Gevaert N.V. Structure de tête d'impression pour son utilisation dans une imprimante électrostatique direct (DEP)
DE69522948T2 (de) 1995-12-18 2002-04-25 Agfa Gevaert Nv Vorrichtung zum direkten elektrostatischen Drucken mit einer Druckkopfstruktur mit Schlitzöffnungen
US5847733A (en) * 1996-03-22 1998-12-08 Array Printers Ab Publ. Apparatus and method for increasing the coverage area of a control electrode during direct electrostatic printing
US5774159A (en) * 1996-09-13 1998-06-30 Array Printers Ab Direct printing method utilizing continuous deflection and a device for accomplishing the method

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0945275A2 (fr) * 1998-03-24 1999-09-29 Matsushita Electric Industrial Co., Ltd. Appareil et procédé de formation d'images

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