EP0124856B1 - Tête d'impression électrostatique - Google Patents

Tête d'impression électrostatique Download PDF

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Publication number
EP0124856B1
EP0124856B1 EP84104892A EP84104892A EP0124856B1 EP 0124856 B1 EP0124856 B1 EP 0124856B1 EP 84104892 A EP84104892 A EP 84104892A EP 84104892 A EP84104892 A EP 84104892A EP 0124856 B1 EP0124856 B1 EP 0124856B1
Authority
EP
European Patent Office
Prior art keywords
electrodes
groups
counter
print head
row
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
EP84104892A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0124856A1 (fr
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.)
ALE International SAS
Original Assignee
Telic Alcatel 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 filed Critical Telic Alcatel SA
Publication of EP0124856A1 publication Critical patent/EP0124856A1/fr
Application granted granted Critical
Publication of EP0124856B1 publication Critical patent/EP0124856B1/fr
Expired 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 printing devices using a plurality of aligned individual electrodes for printing a recording medium displaced in front of these electrodes.
  • It relates more particularly to an electrostatic printing head by means of which a latent electrostatic image is gradually created on the recording medium, by ionic discharge obtained by carrying the high voltage electrodes while the recording medium is moved in front the head.
  • the individual electrodes used in the print head are of very small dimensions and are in high number for a line of given length, for a good resolution desired. There will be, for example, 1,728 of them for printing a recording medium of A format 4 to 8 points per millimeter.
  • the electrodes are associated with a counter-electrode also brought to high voltage. Under these conditions, the high voltage necessary for ionic discharge will be applied to each counter-electrode electrode pair, the high voltage applied to the electrode alone, or to the counter-electrode alone, being less than the threshold value causing this discharge. ionic and therefore unable to allow printing.
  • dielectric paper In direct electrostatic printing, special paper is used, consisting of a base of conductive paper covered by a dielectric deposit a few micrometers thick, called dielectric paper, on which the latent electrostatic image is directly printed.
  • the latent image is then inked or developed, using a magnetic brush or any other development means, then the developed image is fixed by pressure or in an oven.
  • An optimal arrangement is defined by adopting, for a print head of 1,728 electrodes, 36 groups of 48 electrodes each and therefore 36 counter-electrodes; to this arrangement correspond 84 power switches.
  • This special support is further improved to avoid possible breakdowns between the electrodes and the conductive segments, these breakdowns being able to result from defects in the thin dielectric layer.
  • This improvement consists of a resistive layer interposed between the conductive segments and the dielectric layer; the resistive layer covers the segments and fills the inter-segment intervals to reinforce their insulation.
  • each counter electrode is placed, which is made of metal and whose length is substantially equal to the length of each of the groups of electrodes, facing electrodes belonging to two successive groups.
  • the demultiplexing circuit then used connects between them the electrodes of the same rank belonging to the even groups in a first network and between them the electrodes of the same rank belonging to the odd groups in a second independent network, these networks being each connected to as many individual switches there are electrodes in each group and the counter electrodes connected to individual power switches.
  • Printing is then carried out by applying, alternately on one network and the other, the printing voltage, -V / 2 or 0 volts, to the electrodes of successive rows interconnected with each other in their network and by applying the voltage V / 2 simultaneously with the two successive counter-electrodes arranged facing each of the groups of electrodes, so as to minimize the edge effect due to the inter-counter-electrode space.
  • the electrodes are arranged in two identical and independent rows, on each of which they are associated in groups, these two rows being offset one from the other by half the pitch of the electrodes on each of the rows.
  • the counter electrodes are then associated with the electrodes of the two rows, projecting on either side of these rows.
  • the electrodes and the associated counter-electrodes which are placed close to their electrodes, can be placed either on either side of the dielectric paper or on the same side of the dielectric paper, opposite the face carrying the dielectric deposit, two identical rows of counter-electrodes being used in the latter case that there are one or two rows of electrodes, these two rows of counter-electrodes being arranged on either side other of the row or of the set of two rows of electrodes and two opposite counter-electrodes being always brought to the same potential.
  • a set of electrodes is used, also called an electrode comb, identical or analogous to that of direct electrostatic printing systems, applied to one face of the dielectric film constituting the recording medium.
  • an electrode comb identical or analogous to that of direct electrostatic printing systems, applied to one face of the dielectric film constituting the recording medium.
  • the absence of a conductive layer in this intermediate support makes it impossible to associate independent counter-electrodes with the comb electrodes, printing cannot be carried out between the counter-electrodes, and consequently makes it impossible to use a demultiplexing circuit.
  • the present invention aims to allow the use of a demultiplexing circuit in an electrostatic printing head, so that said head can provide direct or indirect electrostatic printing on a conventional recording medium.
  • said conductive tracks each have a width greater than the pitch of said electrodes along their row.
  • the counter-electrode according to the invention intended to be associated with a row of electrodes in an electrostatic print head, is. consisting of a resistive material in which are implanted, by being in good electrical contact with the resistive material, a plurality of conductive tracks. These conductive tracks are arranged at regular intervals from one another.
  • the counter electrode has been designated under the general reference 1.
  • This counter electrode comprises an insulating substrate 2, such as a rigid or flexible printed circuit substrate, bearing on one of its faces and in the vicinity of one of its longitudinal edges a layer of resistive material 3, for example such as those used for the manufacture of resistors of hybrid circuits and for which the drying takes place at low temperature, in which are embedded, at not regular, the ends of conductive tracks 4 running, moreover, over the width of the substrate 2.
  • the conductive tracks 4 are of thickness less than that of the resistive layer 3.
  • the counter-electrode designated by the general reference 10 is constituted by a resistive substrate 13, rigid or flexible, carrying on one of its faces conductive tracks 14.
  • These conductive tracks 14 run over the width of the substrate, between its two edges longitudinal. They are in good electrical contact with the resistive substrate 13, at least in a longitudinal portion of the substrate 13, for example that along one of its longitudinal edges, in which they are with regular pitch and constitute with the substrate the counter-electrode 10, the conductive tracks 14, outside this portion, which can be isolated from the substrate 13 which carry them by an insulating layer.
  • the substrate carrying the counter-electrode or constituting with the conductive tracks the counter-electrode will thus advantageously allow the connection of the conductive tracks to a printed circuit board connector (not shown).
  • the counter-electrode according to the invention has been shown independently of a row of electrodes with which it will be associated in an electrostatic print head. It will however be readily understood, in particular in view of FIG. 5, that in the resulting print head, the resistive material will face the row of electrodes. It will also be understood that the pitch of the conductive tracks in contact with this resistive material will be chosen to be substantially equal to the length of each of the groups of electrodes which will be defined on the row of electrodes with which the counter-electrode is associated.
  • the counter-electrode will then preferably be mounted, so that each portion of resistive material between two conductive tracks faces a group of electrodes, the conductive tracks preferably being made of width greater than the pitch of the electrodes in the row, for example 4 or 8 times this pitch, and coming to be positioned, in the head, facing electrodes belonging to two consecutive groups.
  • the counter electrode according to the invention can be obtained by implementing methods as such known.
  • the conductive tracks will be deposited on the substrate, either according to the technology for obtaining printed circuits, or by screen printing, while the resistive material used in the embodiments of FIGS. 1 to 3 will be deposited on the substrate and its conductive tracks by screen printing.
  • the individual electrodes 21 are arranged in regular pitch and organized into n identical groups denoted G, to G n in each of which they occupy successive rows denoted P 1 to P m .
  • the electrodes of the same rank belonging to the odd groups G 1 , G 3 ... are interconnected with one another.
  • the electrodes of the same rank belonging to the even groups G 2 , G 4 ... are also interconnected with one another.
  • Electrodes of rows P l to P m are set to a potential - V / 2 or 0 volts, for the odd groups, by means of a first set of m individual switches E 11 to E 1m and, for the groups peers, via a second set of m individual switches E 21 , at E 2m , independent of the first set.
  • the counter-electrode 1 made of resistive material has n + 1 regular conductive tracks associating each portion of the counter-electrode comprised between two successive tracks with one of the different groups of electrodes facing which it is placed.
  • the n + 1 tracks define a set of n resistors in series R, to R n assigned individually to the groups of electrodes G, to G n and arranged opposite these groups, provided with intermediate connections C 2 to C n and two terminal connections C 1 and C n + 1 connected respectively to the common terminals of the series resistors and to the two other terminals of the terminal resistors R, and R n .
  • These connections C 1 to C n + are set to a potential V / 2 or 0 volts by means of n + 1 individual switches CE 1 to CE n + 1 .
  • each of the resistors R 1 to R n will be chosen to be high, of the order of a few megohms, in order to limit the current consumption.
  • the printing operation of the electrodes of the first group G, of the row of electrodes is obtained by switching the potential V / 2 on the connections Ci and C 2 , ie at the two terminals of the resistor R 1 , while all the other connections are set to 0 volts, and by applying the printing signal, of value - V / 2 or 0 volts depending on whether there must be real printing or not, successively at the electrodes of rows P l to P m of the odd groups then that all the electrodes of the even groups are set to 0 volts.
  • the only connections C 2 and C 3 are set to V / 2 while the printing signal will be applied successively to the row electrodes P, at P m of the even groups, those of the odd groups being set to 0 volts.
  • Printing by the full row electrodes will continue in a similar fashion. It will be systematically obtained by successively applying the printing signal, at - V / 2 or 0 volts, to the electrodes of rows P, to P m of, simultaneously, all the odd groups or all the even groups considered alternately, the electrodes of the groups of the other parity being at 0 volts, and the potential V / 2 to the only two connections directly connected to the resistance assigned to each of the groups of successive electrodes. Under these conditions, it is the resistances assigned to the different groups and, consequently, their two connections “directly framing each of the groups which carry out the selection of the only group of electrodes ensuring instant printing.
  • the print head may have several rows of electrodes.
  • the print head may in particular comprise two rows along each of which the electrodes will be distributed in identical odd and even groups and in which the electrodes will be from one row to the other offset by half a pitch of electrodes of one of the rows, with a single counter-electrode, similar to that illustrated, associated with the assembly of one and the other of the two rows of electrodes intended to be arranged on the other side of a recording medium with respect to this counter electrode.
  • the choice of the width of the conductive tracks is not critical. In practice, however, in order to benefit from mechanical positioning tolerances between the counter-electrode and the row of electrodes on the one hand and allow easy production of resistors R 1 to R n of high value on the other hand, it is preferable to adopt an arrangement where the connections C, to C n + 1 (FIG. 5) constituted by the conductive tracks are of width much greater than the pitch of the electrodes in their row but much less than the pitch of the groups of electrodes, for example from 4 to 8 times the pitch of the electrodes or even a little higher.
  • This counter-electrode which allows the use of a demultiplexing circuit for the supply of the individual electrodes can equally equip a direct or indirect electrostatic print head. It will be noted that it will be possible to adopt known demultiplexing arrangements between electrodes and to organize accordingly the counter-electrode associated with the different groups of defined electrodes which allows the selection of the electrodes of the successive groups on the row.

Landscapes

  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
  • Dot-Matrix Printers And Others (AREA)
EP84104892A 1983-05-09 1984-05-02 Tête d'impression électrostatique Expired EP0124856B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8307685A FR2545759A1 (fr) 1983-05-09 1983-05-09 Tete d'impression electrostatique
FR8307685 1983-05-09

Publications (2)

Publication Number Publication Date
EP0124856A1 EP0124856A1 (fr) 1984-11-14
EP0124856B1 true EP0124856B1 (fr) 1988-07-06

Family

ID=9288700

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84104892A Expired EP0124856B1 (fr) 1983-05-09 1984-05-02 Tête d'impression électrostatique

Country Status (8)

Country Link
US (1) US4636816A (enrdf_load_stackoverflow)
EP (1) EP0124856B1 (enrdf_load_stackoverflow)
JP (1) JPS6011372A (enrdf_load_stackoverflow)
CA (1) CA1210050A (enrdf_load_stackoverflow)
DE (1) DE3472546D1 (enrdf_load_stackoverflow)
DK (1) DK161126C (enrdf_load_stackoverflow)
ES (1) ES532296A0 (enrdf_load_stackoverflow)
FR (1) FR2545759A1 (enrdf_load_stackoverflow)

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2589273B1 (fr) * 1985-10-28 1987-12-11 Telephonie Ind Commerciale Tete d'impression electrostatique d'image
US5218382A (en) * 1989-04-28 1993-06-08 Synergy Computer Graphics Corporation Electrostatic printer head structure and styli geometry
SE8902090D0 (sv) * 1989-06-07 1989-06-07 Array Printers Ab Saett att foerbaettra utskriftsprestanda foer skrivare samt anordningar foer genomfoerande av saettet
US4977416A (en) * 1989-09-21 1990-12-11 Rastergraphics, Inc. Integrated thick film electrostatic writing head
US5150134A (en) * 1991-05-29 1992-09-22 Xerox Corporation Counter electrode for an electrostatic recorder

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1946815C3 (de) * 1969-09-16 1973-12-06 Philips Patentverwaltung Gmbh, 2000 Hamburg Anordnung zur elektrostatischen Aufzeichnung
US3653065A (en) * 1969-10-22 1972-03-28 Clevite Corp Electrographic recording system with interleaved electrode groups
US4183032A (en) * 1977-01-12 1980-01-08 Ricoh Co., Ltd. Electrostatic recording medium with elongated conductive segments
JPS5387224A (en) * 1977-01-12 1978-08-01 Ricoh Co Ltd Electrostatic recording body
FR2394945A1 (fr) * 1977-06-13 1979-01-12 Cit Alcatel Barrette d'impression d'une image
FR2394399A1 (fr) * 1977-06-13 1979-01-12 Cit Alcatel Barrette d'impression d'une image
JPS5439633A (en) * 1977-09-02 1979-03-27 Hitachi Chemical Co Ltd Multiistylus head and method of making same
US4315270A (en) * 1978-06-01 1982-02-09 Xerox Corporation Backup electrode for an electrostatic recorder
US4271417A (en) * 1978-11-24 1981-06-02 Gould Inc. Electrographic imaging with non-sequential electrode actuation
GB2100196B (en) * 1981-04-15 1986-03-12 Tokyo Shibaura Electric Co Electrostatic recording head a method for manufacturing the same and an apparatus for practising this method

Also Published As

Publication number Publication date
US4636816A (en) 1987-01-13
EP0124856A1 (fr) 1984-11-14
FR2545759A1 (fr) 1984-11-16
DK161126B (da) 1991-06-03
DK228284D0 (da) 1984-05-08
DK161126C (da) 1991-11-18
CA1210050A (fr) 1986-08-19
ES8502383A1 (es) 1985-01-01
ES532296A0 (es) 1985-01-01
DK228284A (da) 1984-11-10
DE3472546D1 (en) 1988-08-11
JPS6011372A (ja) 1985-01-21
JPH0343991B2 (enrdf_load_stackoverflow) 1991-07-04

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