EP0813966B1 - Aufzeichnungskopfe für eine elektrostatische Tintenstrahlaufzeichnungsvorrichtung - Google Patents

Aufzeichnungskopfe für eine elektrostatische Tintenstrahlaufzeichnungsvorrichtung Download PDF

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Publication number
EP0813966B1
EP0813966B1 EP19970250184 EP97250184A EP0813966B1 EP 0813966 B1 EP0813966 B1 EP 0813966B1 EP 19970250184 EP19970250184 EP 19970250184 EP 97250184 A EP97250184 A EP 97250184A EP 0813966 B1 EP0813966 B1 EP 0813966B1
Authority
EP
European Patent Office
Prior art keywords
ink
ridges
ejection
head
record head
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
EP19970250184
Other languages
English (en)
French (fr)
Other versions
EP0813966A3 (de
EP0813966A2 (de
Inventor
Shima Kazuo
Suetsugu Junichi
Uematsu Ryosuke
Mizoguchi Tadashi
Minemoto Hitoshi
Takemoto Hitoshi
Hagiwara Yoshihiro
Yakushiji Toru
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.)
NEC Corp
Original Assignee
NEC 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 NEC Corp filed Critical NEC Corp
Publication of EP0813966A2 publication Critical patent/EP0813966A2/de
Publication of EP0813966A3 publication Critical patent/EP0813966A3/de
Application granted granted Critical
Publication of EP0813966B1 publication Critical patent/EP0813966B1/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
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/06—Ink jet characterised by the jet generation process generating single droplets or particles on demand by electric or magnetic field
    • 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
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
    • B41J2/06—Ink jet characterised by the jet generation process generating single droplets or particles on demand by electric or magnetic field
    • B41J2002/061—Ejection by electric field of ink or of toner particles contained in ink

Definitions

  • the present invention relates to a recorder of the type recording an image on a medium by depositing toner on the medium and, more particularly, to a record head for an electrostatic ink jet recorder.
  • Non-impact recording schemes are attracting increasing attention because they produce only a negligible degree of noise during operation.
  • an ink jet recording scheme is capable of recording an image directly on a medium at a high speed despite its simple configuration, and practicable even with plain papers.
  • Various kinds of ink jet recording systems heretofore proposed include one using ink consisting of a carrier liquid and toner particles dispersed in the liquid.
  • a voltage is selectively applied between needle-like ejection electrodes and a counter electrode facing the ejection electrodes and located behind a sheet or recording medium.
  • the resulting electric field causes a coloring material contained in the ink to electrostatically fly toward the sheet, forming an image on the sheet.
  • a record head for such a system includes a substrate on which ejection electrodes are formed independently of each other. Meniscus forming members each overlies one of the ejection electrodes. A cover covers the meniscus forming members and has an ink inlet port and an ink outlet port. Fine ejection openings or slits are formed by the substrate, meniscus forming members, and cover. Ink introduced into the head via the ink inlet port forms meniscuses at the front ends or tips of the meniscus forming members.
  • the above conventional record head has the following problems left unsolved. Because the meniscus forming members are implemented by a photoconductive resist, their thickness is limited to several tens of microns. Further, because the meniscus forming members are formed by photolithographic exposure and development, their front corner portions or ejection points are not sharp. These in combination prevent meniscus from having a stable shape. Moreover, the ink is not circulated around the ejection points of the meniscus forming members. This causes the toner density of the ink to differ from one ejection point to another ejection point and causes the toner particles to excessively concentrate around the points where ink is not ejected, resulting in defective ink ejection.
  • a record head for an electrostatic ink jet recorder of the present invention includes a head base formed of an insulating material and so undulated as to form ridges at intervals.
  • Independent ejection electrodes are formed of a conductive material and formed on the tops of the ridges or on at least one of the walls of the ridges facing each other and the bottoms of channels defined between the ridges.
  • An ink collecting member covers the front end of the head base with respect to the direction of ink ejection and the bottoms of the channels, and collects ink overflown the head base.
  • a cover covers the top of the head base except for a front portion thereof.
  • FIGS. 1A-1C a conventional record head of an electrostatic ink jet recorder, shown in FIGS. 1A-1C.
  • the recorder to be described uses ink consisting of a carrier liquid and toner particles dispersed in the liquid.
  • a voltage is selectively applied between needle-like ejection electrodes and a counter electrode facing the ejection electrodes and located behind a sheet or recording medium.
  • the resulting electric field causes a coloring material contained in the ink to electrostatically fly toward the sheet, forming an image on the sheet.
  • the record head includes a flat substrate 101 formed of an insulating material.
  • a plurality of ejection electrodes 102 are formed on the surface of the substrate 101 at intervals corresponding to a desired resolution.
  • the entire surface of the substrate 101 is covered with Cu, Ni or similar conductive substance by sputtering, and then the conductive material is exposed and developed via a mask formed with a pattern representative of the electrodes 102.
  • the electrodes 102 are independent of each other and connected to a driver, not shown, at one end thereof.
  • a high pulse voltage is selectively applied to the electrodes 102.
  • the surface of the substrate formed with the electrodes 102 is coated with an insulative coating material by spin coating, so that the electrodes 102 and ink are insulated from each other.
  • Meniscus forming members 103 each overlies the respective ejection electrode 102 on the substrate 101.
  • an insulative photoconductive resist is laminated or spin-coated on the substrate 101 over the electrodes 102, and then the resist is exposed and developed via a mask formed with a pattern representative of the members 103.
  • a cover 104 is formed of an insulating material and mounted on the meniscus forming members 103 at a position recessed from the front ends of the members 103.
  • An ink inlet port 105 and an ink outlet port 106 are formed in the cover 104, as illustrated.
  • the substrate 101, cover 104 and nearby meniscus forming members 103 form a fine opening or slit 107.
  • Ink fed via the inlet port 105 is routed through the slit 107 to the front ends of the meniscus forming members 103.
  • the members 103 each forms an ink meniscus 108 at the front end or tip thereof.
  • the reference numeral 109 designates a drop ejected from the head.
  • the conventional record head described above has some problems left unsolved, as follows. Because the meniscus forming members 103 are implemented by a photoconductive resist, their thickness is limited to several tens of microns. Further, because the members 103 are formed by photolithographic exposure and development, their front corner portions or ejection points are not sharp. These in combination prevent the meniscus from having a stable shape. Moreover, the ink is not circulated around the tips or ejection points of the members 103. This causes the toner density of the ink to differ from one ejection point to another ejection point and causes the toner particles to excessively concentrate around the points where the ink is not ejected, resulting in defective ink ejection.
  • the record head 1 includes a head base 4 formed with ejection electrodes 3 to which drive pulses are selectively applied.
  • An ink collecting member 5 receives ink 2 overflown the head base 4.
  • a base plate 6 is formed of an insulating material and allows the head base 4 to be mounted thereon at a desired position.
  • a cover 8 is positioned above the base plate 6 and cooperates with the base plate 6 to form an ink chamber 7. The ink chamber 7 is filled with the ink 2.
  • the head base 4 is made up of a substrate 9 formed of glass, ceramic or similar insulating material, and ejection electrodes 3 formed of Ni, Cu or similar conductive material.
  • the surface of the substrate 9 is so undulated as to form a plurality of projections or ridges 10 at intervals corresponding to a desired resolution.
  • the ejection electrodes 3 are independent of each other, and each is formed on the top of the respective ridge 10.
  • the ridges 10 are formed by dicing, laser machining, isotropic etching or similar technology and provided with a high aspect ratio.
  • a channel formed by nearby ridges 10 has a bottom 11 whose width is small enough to generate capillarity.
  • Each ridge 10 has a height greater than the width of the bottom 11.
  • the ink collecting member 5 is implemented as a molding of plastics or similar insulating material.
  • the member 5 is so positioned as to cover the end faces, or front end faces, 4a of the head base 4 and the bottoms 11 of the channels.
  • the member 5 includes a wall 5A facing the front end faces 4a and rising to a higher level than the bottoms 11.
  • a gutter 12 is formed in the inner periphery of the member 5 in order to collect the ink 2 overflown the head base 4 in cooperation with the base 4.
  • An ink outlet 13 is formed in the bottom of the member 5, so that the ink 2 collected by the gutter 12 can flow out.
  • the ink outlet 13 is communicated to an ink tank by a tubing, although not shown specifically.
  • Electrode pads 14 and a pattern of conductors 15 are formed on the surface of the base plate 6.
  • the electrode pads 14 are connected to a driver not shown.
  • the conductors 15 each receives a drive voltage from associated one of the electrode pads 14 and applies it to associated one of the ejection electrodes 3.
  • the head base 4 is mounted on the base plate 6 such that its front end faces 4a protrude outward from the base plate 6.
  • the ejection electrodes 3 and conductors 15 are electrically connected together by wire bonding or similar technology.
  • the portions connecting the ejection electrodes 3 and conductors 15 and the individual conductor 15 are covered and sealed by use of an insulating resin.
  • the base plate 6 may be implemented as a printed circuit board or a flexible printed circuit board adhered to an insulating plate.
  • the cover 8 is implemented as a molding of plastics or similar insulating material and forms the previously mentioned ink chamber 7.
  • An ink inlet 16 is formed in the top of the cover 8 in order to feed the ink 2 into the ink chamber 7.
  • the ink inlet 16 is connected to an ink circulation pump and the ink tank by a tubing, although not shown specifically.
  • a part of the cover 8 is disposed above the head base 4 and covers the tops of the ridges 10 at a position recessed from the front end faces 4a.
  • the ink 2 introduced into the ink chamber 7 via the inlet 16 is fed to the front ends or tips of the ejection electrodes 3 via the channels between the ridges 10.
  • the ink 2 overflown the head base 4 via the front end faces 4a is collected in the gutter 12 and returned to the ink tank via the outlet 13.
  • the ink 2 returned to the ink tank is again fed under pressure to the inlet 16 by the pump.
  • a counter electrode 18 is located in front of the front end of the head base 4 and plays the role of a platen at the same time.
  • the head 1 is positioned such that at the front end of the head base 4, the corner portions 10a of the ridges 10 are closest to the counter electrode 18.
  • a fine gap for ejection is defined between the corners 10a of the ridges 10 and the counter electrode 18.
  • a sheet 17 is conveyed along the counter electrode 18 in the gap between the head 1 and the electrode 18.
  • the counter electrode 18 is constantly connected to ground or to a preselected negative bias source.
  • a drive pulse voltage is selectively applied to the ejection electrodes 3 in order to generate electric fields between them and the counter electrode 18.
  • a Coulomb force based on the concentration of the electric field is generated in the toner particles of the ink 2 forming a convex meniscus at the corner portion 10a of each ridge 10 where the driven electrode 3 is present.
  • an ink drop 19 containing the toner particles is ejected from the corner portion or ejection point 10a toward the counter electrode 18.
  • the ink drop 19 forms a dot on the sheet 17 on arriving at the sheet 17.
  • the surface of the head base 4 is undulated with a high aspect radio, forming the channels between the ridges 10.
  • the channels as ink passageways, it is possible to form convex ink meniscuses stably at the corner portions 10a of the ridges 10. This insures the stable ejection of the ink drops 19.
  • the ink 2 fed to the corner portions or ejection points 10a is constantly circulated by way of the ink collecting member 5. Such circulation of the ink 2 maintains the toner content of the ink 2 uniform throughout the ejection points, and prevents the toner particles from excessively concentrating on the ejection points where ink ejection does not occur.
  • FIG. 5 shows an alternative embodiment of the present invention.
  • the head base shown in FIG. 5 differs in configuration from the head bases 4 shown in FIG. 2B.
  • the head base 4 is made up of the substrate 9 and election electrodes 3, as in the configuration of FIG. 2B.
  • the ridges 10 are also formed on the substrate 9 at intervals corresponding to a desired resolution.
  • the ejection electrodes 3 are formed of metal and formed on at least one of the walls 10b and 10c of the ridges 10 facing each other and the bottoms 11 of the channels.
  • a record head for an electrostatic ink jet recorder is formed with undulation having a high aspect ratio thereon.
  • Channels between nearby ridges are used as ink passageways. This allows the ridges to form convex ink meniscuses stably at all times at their front ends or ejection points, and thereby insures stable ejection of ink drops.
  • ink fed to the front ends of the ridges is constantly circulated by way of an ink collecting member. The circulation of the ink maintains the toner content of the ink uniform throughout the ejection points, and prevents the toner particles from excessively concentrating on the ejection points where ink ejection does not occur.

Landscapes

  • Particle Formation And Scattering Control In Inkjet Printers (AREA)

Claims (5)

  1. Aufzeichnungskopf für elektrostatische Tintenstrahlaufzeichnungsvorrichtung umfassend:
    eine Kopfbasis, die aus einem isolierenden Material gebildet und so gewellt ist, daß sie in Intervallen Erhöhungen bildet, unabhängige Ausstoßelektroden, die aus einem leitenden Material gebildet sind, das oben auf den Erhöhungen oder auf mindestens einer der Wände der einander gegenüberliegenden Erhöhungen ausgebildet ist, und Böden und Kanäle, die zwischen den Erhöhungen definiert sind;
    ein Tintensammelelement (5, 12), das ein in bezug auf eine Richtung des Tintenausstoßes vorderes Ende der Kopfbasis und die Böden der Kanäle zum Sammeln von die Kopfbasis überflutender Tinte abdeckt; und
    eine Abdeckung (8), die ein oberes Ende der Kopfbasis, ausgenommen einen vorderen Teil der Kopfbasis, abdeckt.
  2. Aufzeichnungskopf nach Anspruch 1, wobei die Ausstoßelektroden mit einem isolierenden Überzugsmaterial überzogen sind.
  3. Aufzeichnungskopf nach Anspruch 1, wobei die Ausstoßelektroden oben auf den Erhöhungen gebildet sind und wobei die Erhöhungen regelmäßig in Intervallen korrespondierend zu einer erwünschten Auflösung positioniert sind.
  4. Aufzeichnungskopf nach Anspruch 3, wobei die Ausstoßelektroden mit einem isolierenden Überzugsmaterial überzogen sind.
  5. Aufzeichnungskopf nach einem der Ansprüche 1, 2, 3, wobei jeder der Kanäle zwischen den Erhöhungen eine Breite aufweist, die Klein genug ist, einen Kapillareffekt zu erzeugen, und wobei die Erhöhungen eine Höhe aufweisen, die größer als die Breite der Kanäle ist.
EP19970250184 1996-06-17 1997-06-14 Aufzeichnungskopfe für eine elektrostatische Tintenstrahlaufzeichnungsvorrichtung Expired - Lifetime EP0813966B1 (de)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP15589596 1996-06-17
JP155895/96 1996-06-17
JP15589596A JP2845812B2 (ja) 1996-06-17 1996-06-17 静電式インクジェット記録ヘッド

Publications (3)

Publication Number Publication Date
EP0813966A2 EP0813966A2 (de) 1997-12-29
EP0813966A3 EP0813966A3 (de) 1998-08-19
EP0813966B1 true EP0813966B1 (de) 1999-10-27

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ID=15615862

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EP19970250184 Expired - Lifetime EP0813966B1 (de) 1996-06-17 1997-06-14 Aufzeichnungskopfe für eine elektrostatische Tintenstrahlaufzeichnungsvorrichtung

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EP (1) EP0813966B1 (de)
JP (1) JP2845812B2 (de)
DE (1) DE69700679T2 (de)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4728262A (en) * 1986-01-22 1988-03-01 Textron Inc. Erosion resistant propellers
DE69707988T2 (de) * 1996-07-31 2002-04-04 Nec Corp Elektrostatischer Tintenstrahlaufzeichnungskopf

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1993011866A1 (en) * 1991-12-18 1993-06-24 Research Laboratories Of Australia Pty. Ltd. Method and apparatus for the production of discrete agglomerations of particulate matter
US5835113A (en) * 1994-09-22 1998-11-10 Kabushiki Kaisha Toshiba Ink jet printing apparatus with controlled compression and ejection of colorants in liquid ink
JP3315268B2 (ja) * 1994-09-22 2002-08-19 株式会社東芝 画像形成装置

Also Published As

Publication number Publication date
EP0813966A3 (de) 1998-08-19
DE69700679D1 (de) 1999-12-02
DE69700679T2 (de) 2000-07-06
JPH10806A (ja) 1998-01-06
JP2845812B2 (ja) 1999-01-13
EP0813966A2 (de) 1997-12-29

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