EP0221452B1 - Elektrostatischer Bilddruckkopf - Google Patents

Elektrostatischer Bilddruckkopf Download PDF

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Publication number
EP0221452B1
EP0221452B1 EP86114690A EP86114690A EP0221452B1 EP 0221452 B1 EP0221452 B1 EP 0221452B1 EP 86114690 A EP86114690 A EP 86114690A EP 86114690 A EP86114690 A EP 86114690A EP 0221452 B1 EP0221452 B1 EP 0221452B1
Authority
EP
European Patent Office
Prior art keywords
electrodes
counterelectrodes
recording medium
counter
coupling electrode
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
EP86114690A
Other languages
English (en)
French (fr)
Other versions
EP0221452A1 (de
Inventor
Patrice Playe
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.)
ALCATEL BUSINESS SYSTEMS
Original Assignee
Telic Alcatel SA
Alcatel Business Systemes SA
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 Telic Alcatel SA, Alcatel Business Systemes SA filed Critical Telic Alcatel SA
Publication of EP0221452A1 publication Critical patent/EP0221452A1/de
Application granted granted Critical
Publication of EP0221452B1 publication Critical patent/EP0221452B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • B41J2/39—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 using multi-stylus heads
    • B41J2/395—Structure of multi-stylus heads

Definitions

  • the present invention relates to an electrostatic image printing head.
  • Such electrostatic printheads make it possible to gradually create a latent electrostatic image on a moving dielectric recording medium by means of ionic discharges.
  • direct electrostatic printing requires a special paper consisting of a conductive base covered by a thin dielectric film.
  • a latent electrostatic image is created on the special paper by ionic discharge in the air by means of a row of small electrodes brought to high voltage.
  • the latent image is inked, for example using a magnetic brush carrying powdered ink, then fixed on the special paper by pressure and / or by cooking.
  • a high voltage is created between at least one of the electrodes and at least one counter-electrode placed nearby so that the resulting electric field at the electrode is perpendicular to the surface of the special paper.
  • the counter-electrodes are placed on the same side of the special paper as the electrodes and the discharge takes place by the capacitive effect of the counter-electrodes through the dielectric film with which the special paper is provided and due to conduction of the conductive base of this special paper.
  • the individual electrodes used in the print head are of very small dimensions and in large number, for an image line of given length, so as to allow for example the printing of eight dots per millimeter.
  • the high voltage necessary for ionic discharges is preferably shared between electrodes and counter-electrodes, as the discharges occur only from a threshold value of the high voltage, it is arranged so that the voltage applied separately to a electrode or counter electrode is insufficient to cause a discharge alone and therefore an impression.
  • the electrodes are aligned in bundles on at least one row, the electrodes of the same row of the bundles of the same row being interconnected.
  • the counter electrodes are distributed along the bundles.
  • a relatively large separation for example from 0.2 to 0.5 millimeter, is necessary between neighboring counter-electrodes because of the voltage values to be switched. This adversely affects printing when the requested resolution is high.
  • the conductivity of the conductive base formed by the special paper there is a decrease in the electric field in the areas where the electrodes are in front of a space between counter-electrodes.
  • the latent image is created on a thin insulating film, then revealed by inking according to a process identical to that mentioned above.
  • the revealed image is then transferred and fixed on a sheet of plain paper, for example by pressing the sheet on the inked insulating film.
  • the arrangement of the electrodes used for direct electrostatic writing is also suitable for indirect electrostatic writing, it is generally not the same with regard to the arrangement of the counter-electrodes since in this case neither the insulating film nor the paper are conductive.
  • the conventional solution in indirect electrostatic writing consists in passing the insulating film, where the latent image is created, between the electrodes and the counter-electrodes which face each other.
  • this solution has drawbacks, linked in particular to the complexity of the voltage control system of the assembly and to the need for precise positioning of the counter-electrodes relative to the electrodes, whereas it is advantageous with this power solution. spread the electrodes of the counter-electrodes to place the insulating film or remove it during regular film replacements that the user must carry out.
  • the present invention therefore provides an electrostatic image printing head on a recording medium, in particular of the plain paper type, in which the electrodes and counter-electrodes necessary for ionic discharge are arranged on the same side of the recording medium. .
  • the printhead conventionally comprises, firstly, at least one row of individual electrodes arranged in regular pitch and organized in n groups distributed in two networks, the electrodes having the same positions in the groups of a network being interconnected between they.
  • the recording head conventionally comprises, secondly, at least one set of counter-electrodes aligned in parallel with the individual electrodes and each assigned to at least one group of electrodes which it runs along, so as to create a latent image on a insulating recording medium, scrolling flush with these electrodes and counter-electrodes, by ionic discharge between at least one electrode and at least one counter-electrode brought respectively to high-voltage potentials of opposite polarities by high-voltage pulses of ordered.
  • the electrostatic print head comprises a rotary coupling electrode which is made of conductive material and brought to a medium-voltage direct potential, of the same polarity as the high pulses. te-tension applied to the counter electrodes, said coupling electrode being pressed against the recording medium in line with the electrodes and counter electrodes, on the other side of these relative to the recording medium.
  • an electrostatic printing head usually comprises a plurality of electrodes E aligned in at least one row along which are arranged at least one and here two rows of CE counter-electrodes which border the row or rows of electrodes seen here at the end and by their active end, as well as the counter-electrodes.
  • the electrodes and counter-electrodes are intended to be flush with the support for recording latent images on the same side of the strip that this support forms.
  • the electrodes E which are in large number, for example 1728, are divided into n groups distributed in two networks and preferably comprising the same number r of electrodes, for example 36 groups of 48 electrodes, the number r being chosen equal to four in Figure 1 for reasons of simplification of the figure.
  • the electrodes E of the same rank, in the different groups of a network are interconnected with one another, such as for example the electrodes E13, E33 or E23, En3.
  • the electrodes of each network are powered up by 1 D or 2D switches which each serve a group of interconnected electrodes, such as switch 1 D3 for the electrodes E13, E33 given above as an example.
  • a zero voltage OV is normally applied by each switch D to the electrodes to which it is connected, in the absence of individual control concerning them for a printing need.
  • the latter is actuated so as to bring this electrode and those which are interconnected with it to a high voltage potential -V / 2, of lower value and here half of the high threshold voltage V necessary for an ionic discharge of printing.
  • the counter electrodes CE other than those at the end CE1, CE1 'and CEP, CEP', are arranged along electrodes belonging to two successive groups, such as the counter electrodes CE2, CE2 'along the electrodes E13, E14 from group 1 and E21, E22 from group 2.
  • the counter-electrodes are energized by switches C, here referenced from C1 to Cp, which are shown each connected to a pair of interconnected counter-electrodes of the same rank, such as C1 to the CE1 counter-electrodes. , CE1 '.
  • a zero voltage OV is normally applied by each switch C to the counter-electrodes to which it is connected, in the absence of individual control concerning them for printing.
  • a print command actuates the switch C, concerned, so as to bring the counter-electrodes which it serves to a high voltage potential + V / 2.
  • the ionic impression discharge is therefore obtained by setting the potential -V / 2 of an electrode and the potential + V / 2 of the counter-electrodes which runs along it.
  • the recording medium 1 is of the conductive layer 1 C type covered with a dielectric layer 1 D intended to be pressed against the electrode / counter-electrode assembly to store point charges, the conductive layer serving least resistive path between an electrode E and the neighboring counter-electrodes CE and CE ', for ionic discharge, via the dielectric layer (FIG. 2).
  • the recording medium 1 is a thin insulating film used as an intermediate for the formation of latent images, subsequently transferred to a final medium generally made of plain paper.
  • a rotary EC coupling electrode such as EC1 in FIG. 2, which is brought to a direct potential V1 of the same polarity as the control pulses applied to the counter-electrodes, so as to associate its action with their in case of order.
  • the continuous potential + V1 is chosen to have a value much lower than the value + V / 2 so as not to allow the triggering of an ionic discharge between an electrode E and the coupling electrode, it is for example of the order from one hundred to two hundred and fifty volts for a voltage V of the order of five hundred to six hundred volts.
  • the coupling electrode EC is arranged transversely to the direction of movement of the recording medium and covers all of the electrodes E and counter electrodes CE, of which it extends beyond the rows of electrodes and counter electrodes, these these being of course also arranged transversely with respect to the direction of movement of the recording medium, in a block of insulating material 2 which keeps them in position relative to each other.
  • the recording medium is generally constituted by a very smooth thin film, a small air gap 3 is provided under the electrodes between them and the recording medium, this interval is usually obtained by grooving the block 2 to the right of the electrodes E.
  • the coupling electrode EC1 consists of an endless band of flexible resistive material, of the charged elastomer type, the resistivity of which is for example of the order of 10 6 to 10 7 ohm. .
  • This strip electrode is wound freely around carrier rollers 4 here three in number which allow its tension and for two of them its pressing against the recording medium 1 on and around the ends of the electrodes and counter-electrodes.
  • the coupling electrode EC1 is brought to potential + V1, for example at one of its carrier rollers by contact using means known per se, of the trotter type or connection by ring and wiper.
  • the support assembly 2 rollers 4 and CE1 counter electrode is mechanically positioned in a usual support frame, not shown, which will not be specified here insofar as this structure has only an indirect relationship with the invention.
  • a cylindrical EC2 coupling electrode is replaced by the endless belt provided in FIG. 2.
  • This coupling electrode EC2, arranged transversely or direction of movement of the recording medium 1 is produced by a tube made of flexible material having for example a hardness less than thirty shores and a diameter of the order of six centimeters.
  • the flexible tube obtained is for example made of an elastomeric material having a resistivity of the order of 10 6 to 10 7 ohm-centimeters; in the alternative embodiment presented here the flexible tube 5, mounted idly on an axis 6, is covered by an outer layer of constant thickness with a value for example between 0.1 and several millimeters which has the required resistivity and which is connected to the potential + V1, for example by a ring system associated with the tube and fixed trotter which is not reproduced here because of its classicism.
  • the coupling electrode EC2 is mechanically pressed for example by a spring system against the recording medium itself applied against the assembly formed by the electrodes, the counter-electrodes and the block part which contains them, it deforms under pressure so as to cover said electrodes and counter electrodes.
  • a print head as defined above which allows printing on any support, after inking the latent electrostatic image, by transferring this inked image to the final support which is to carry it, allows also printing on special composite paper comprising a dielectric layer and a conductive layer joined together.

Landscapes

  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)

Claims (4)

1. Elektrostatischer Druckkopf, der erstens mindestens eine Reihe von Einzelelektroden (E) aufweist, die in regelmäßigem Abstand und in n Gruppen auf zwei Netze aufgeteilt angeordnet sind, wobei die Elektroden mit der gleichen Position in den Gruppen desselben Netzes miteinander verbunden sind, und der zweitens mindestens eine Reihe von Gegenelektroden (CE, CE') aufweist, die parallel zu den Einzelelektroden angeordnet sind und von denen jede mindestens einer der Gruppen von Elektroden zugeordnet ist, längs derer sie sich befindet, derart, daß auf einem dielektrischen Aufzeichnungsträger (1), der dicht an den Elektroden (E) und den Gegenelektroden (CE, CE') vorbeigeführt wird, durch lonenentladung zwischen mindestens einer Elektrode und mindestens einer Gegenelektrode ein latentes Bild erzeugt wird, wobei diese Elektroden jeweils durch Hochspannungssteuerimpulse auf Hochspannungspotentiale (V/2) gebracht werden, dadurch gekennzeichnet, daß der Druckkopf eine drehbare Koppelelektrode (EC) aufweist, die aus leitendem Material besteht und auf ein Gleichpotential mittlerer Spannung (V1) der gleichen Polarität gebracht wird, wie diejenige der an die Gegenelektroden (CE, CE') angelegten Hochspannungsimpulse, wobei die Koppelelektrode (EC) in Höhe der Elektroden (E) und der Gegenelektroden (CE, CE') gegen den Aufzeichnungsträger (1) drückt, und zwar von der den Elektroden und Gegenelektroden abgewandten Seite aus.
2. Elektrostatischer Druckkopf nach Anspruch 1, dadurch gekennzeichnet, daß die drehbare Kopplungselektrode (EC1) aus einem Endlosband aus weichem und elektrisch leitendem Material besteht, das über drehbare, quer zum Aufzeichnungsträger (1) angeordnete Wellen verläuft, derart, daß es sich gegen den Träger in einer Zone anlegt, die sich über den Bereich der Elektroden (E) und der Gegenelektroden (CE, CE') sowie zu beiden Seiten davon erstreckt.
3. Elektrostatischer Druckkopf nach Anspruch 1, dadurch gekennzeichnet, daß die drehbare Kopplungselektrode (EC2) von einem Zylinder aus Elastomerwiderstandsmaterial gebildet wird, der aus einer quer zum Aufzeichnungsträger angeordneten drehbaren Welle gelagert ist, derart, daß es sich gegen den Träger in einer Zone anlegt, die sich über den Bereich der Elektroden (E) und der Gegenelektroden (CE, CE') sowie zu beiden Seiten davon erstreckt
4. Elektrostatischer Druckkopf nach Anspruch 1, dadurch gekennzeichnet, daß die drehbare Kopplungselektrode aus einem Elastomerwiderstandsmaterial besteht, mit dem ein Zylinder (5) aus isolierendem, weichem Material überzogen ist, welcher aus einer quer zum Aufzeichnungsträger angeordneten drehbaren Welle (6) gelagert ist, derart, daß es sich gegen den Träger in einer Zone anlegt, die sich über den Bereich der Elektroden (E) und der Gegenelektroden (CE, CE') sowie zu beiden Seiten davon erstreckt.
EP86114690A 1985-10-28 1986-10-23 Elektrostatischer Bilddruckkopf Expired - Lifetime EP0221452B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8515978 1985-10-28
FR8515978A FR2589273B1 (fr) 1985-10-28 1985-10-28 Tete d'impression electrostatique d'image

Publications (2)

Publication Number Publication Date
EP0221452A1 EP0221452A1 (de) 1987-05-13
EP0221452B1 true EP0221452B1 (de) 1990-05-02

Family

ID=9324262

Family Applications (1)

Application Number Title Priority Date Filing Date
EP86114690A Expired - Lifetime EP0221452B1 (de) 1985-10-28 1986-10-23 Elektrostatischer Bilddruckkopf

Country Status (4)

Country Link
US (1) US4727386A (de)
EP (1) EP0221452B1 (de)
DE (1) DE3670792D1 (de)
FR (1) FR2589273B1 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0329965A (ja) * 1989-06-28 1991-02-07 Matsushita Graphic Commun Syst Inc 静電潜像形成装置
US4977416A (en) * 1989-09-21 1990-12-11 Rastergraphics, Inc. Integrated thick film electrostatic writing head

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5814160A (ja) * 1981-07-17 1983-01-26 Ricoh Co Ltd 静電記録方法
FR2545759A1 (fr) * 1983-05-09 1984-11-16 Cit Alcatel Tete d'impression electrostatique

Also Published As

Publication number Publication date
EP0221452A1 (de) 1987-05-13
US4727386A (en) 1988-02-23
DE3670792D1 (de) 1990-06-07
FR2589273A1 (fr) 1987-04-30
FR2589273B1 (fr) 1987-12-11

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