EP0107743A1 - Flüssigkeitsstrahldrucker - Google Patents

Flüssigkeitsstrahldrucker Download PDF

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Publication number
EP0107743A1
EP0107743A1 EP82305268A EP82305268A EP0107743A1 EP 0107743 A1 EP0107743 A1 EP 0107743A1 EP 82305268 A EP82305268 A EP 82305268A EP 82305268 A EP82305268 A EP 82305268A EP 0107743 A1 EP0107743 A1 EP 0107743A1
Authority
EP
European Patent Office
Prior art keywords
fluid
ink
charge
ink fluid
orifice
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.)
Withdrawn
Application number
EP82305268A
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English (en)
French (fr)
Inventor
Arnold James Kelly
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.)
ExxonMobil Technology and Engineering Co
Original Assignee
Exxon Research and Engineering Co
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 Exxon Research and Engineering Co filed Critical Exxon Research and Engineering Co
Priority to EP82305268A priority Critical patent/EP0107743A1/de
Publication of EP0107743A1 publication Critical patent/EP0107743A1/de
Withdrawn legal-status Critical Current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
    • B41J2/02—Ink jet characterised by the jet generation process generating a continuous ink jet
    • B41J2/035—Ink jet characterised by the jet generation process generating a continuous ink jet by electric or magnetic field

Definitions

  • This invention pertains to ink jet printing, and more particularly, to a new approach to ink jet printing which is fluid independent when electrically charging the fluid.
  • ink jet systems have, relied upon inductive charging of electrically conductive ink fluids in order to project charged ink droplets upon a printing target.
  • Such systems are well known in the art, and all are fluid dependent, i.e. they require an ink fluid having a minimum electrical conductivity in order to adequately charge and project the ink fluid.
  • These systems generally comprise a two electrode, diode type- structured inductive charging system.
  • the conductive ink flows through an orifice which is usually grounded. After exiting the orifice and while still a continuous columnar jet, the stream passes coaxially without physical contact through a second, usually cylindrical, electrode. This electrode is at a different potential from the orifice and the conductive ink liquid. As a result, an induced current flows through the ink to the protruding liquid column, and excess charge (of sign opposite to the cylindrical electrode) is in the fluid.
  • the exiting column breaks into droplets by electrohydro-dynamic, fluid-dynamic, mechanical or other means, thereby isolating the charge on the droplets.
  • the fluid in order for the inductive charging process to work, it is essential that the fluid (ink) have sufficient electrical conductivity to permit adequate current to flow in the exiting jet and appropriate levels of charge to accumulate. Therefore, these systems are critically dependent upon the innate electrical conductivity of the ink for their operation.
  • the present invention features an entirely new approach to ink jet printing.
  • the subject invention has its roots in research involving the atomization of fluids, and the developed theory supporting the electrostatic spraying of these fluids.
  • the invention relates to a method and apparatus for fluid jet printing.
  • the method comprises the steps of :
  • the phrase of "injecting an electrical.charge into the ink fluid” shall mean: forceably injecting charge by means of an emitter electrode or electronic gun or other appropriate apparatus, into the ink fluid other than by way of induction, for creating excess free charge in the fluid.
  • the apparatus of the invention comprises :
  • the charge injection process proposed by this invention can charge non-conductive and poorly conductive liquids as well as conductive liquids.
  • two electrodes are in contact with the liquid and are submerged by the liquid.
  • One electrode is an emitter and serves to field emit charge into the liquid in response to a voltage difference imposed between it and the other (blunt) submerged electrode.
  • the injected charge will be more or less trapped in the fluid and swept to the outside by the bulk motion of the fluid (ink).
  • the exiting stream can be made to undergo breakup in a similar manner to that described for the aforementioned inductive system.
  • the charge is thereby trapped on individual droplets.
  • the paper or target upon which the droplets impinge functions as the third electrode, returning the charge and completing the circuit.
  • the system as described, represents a triode-structured system.
  • additional mechanical or vibrational pulsing of the ink fluid may be used to project ink droplets from an orifice in a traditional droplet formation scheme, with the charge injection functioning as a means to control droplet formation and direction.
  • the charge injection process is of particular interest because it is : (a) essentially independent of fluid conductivity; and (b) compact and capable of modest voltage operation.
  • the field emitter, dual submerged electrode geometry described is but one of a very broad class of possible devices that can be used to charge inject liquids.
  • a conventional thermionic vacuum electron gun firing through an appropriate window can be used to charge the flowing ink stream prior to exiting the head. Therefore, the invention is not to be limited by any specific exposition, description of which is exemplary and meant only to convey an understanding of the invention.
  • the ink fluids for use with the invention will generally be electrically poor or nonconductive, but not necessarily limited thereto.
  • the ink fluid can be selected from a wide variety of printing fluid materials consisting of at least one of the following : oleic acid, castor oil, a hydrocarbon fluid, an aliphatic fluid, an alkyl fluid, an aromatic fluid, and a fluorocarbon fluid.
  • the ink fluid is injected with a charge generally below a level of 10 Coulombs/m 3 .
  • the fluid is continuously jetted from the orifice having a laminar flow rate.
  • the ink is projected at a grounded platen.
  • the diameter of the orifice, which can be coated with a non-wetting material such as Teflon® is generally about .005 to .0005 inches and the ink fluid may be generally jetted at a flow rate of approximatgely 20 to 30 metres/sec.
  • the charge injected into the ink fluid may have a voltage of approximately 1 KV.
  • the ink fluid can be injected with an alternating, pulsed, time transient or wave-shaped charge if so desired.
  • Embodiments of this invention provide the following:-
  • Figure 1 is a schematic view of a charge induced ink fluid device for ink jet printing, as generally described by prior art
  • Figure 2 is a schematic view of one form of charge injected ink fluid device for ink jet printing in accordance with the teachings of this invention.
  • Figures 3 and 4 are graphical representations of ink jet formation parameters for the ink fluid device shown in Figure 2.
  • embodiments of the invention feature a new triode-structured device for charge injecting an ink fluid for the purposes of ink jet printing.
  • a charge induced ink fluid device shown in Figure 1 is a diode-structured system consisting of two annular electrodes 10 and 11, respectively. Ink 9 from a reservoir 12 is supplied to the electrode 10, which may also serve as a capillary tube for holding and emitting the ink fluid 9, as shown. The electrode charges the electrically conductive ink 9 with a negative charge so that the ink is attracted to the positively charged electrode 11. In this way, the ink fluid 9 is projected towards a printing target (not shown).
  • triode-structured device is generally illustrated by the schematic view of Figure 2.
  • Ink 12 is held in reservoir 13 by capillary forces.
  • the capillary restraining force is produced by the small diameter ( ⁇ 100 fm) orifice 18 of tube 14, the walls of which are coated with non-wetting material 15, e.g. Teflon ®.
  • an emitting electrode or electron gun 16 Upon command, an emitting electrode or electron gun 16 is energised. Under action of the field between this electrode 16 and the submersed electrode 15, sufficient electric field is produced to cause injection of charge into the ink 12 in tube 14. Just sufficient charge is injected to overcome the restraining surface tension forces and to provide a positive body force ejecting the ink from tube 24 and establishing a continuous flow. It should be noted that charge injection can perform a three-fold purpose: (1) it acts as a fast-acting valve to start the ink flow and ultimately to stop it; (2) it assists in ejecting ink from the tube; and (3) it charges the ink to permit further manipulation by an exogenous electric field.
  • Ink charge levels are restricted below the level that would lead to jet atomisation, i.e., 10 Coulombs/m 3 .
  • the device may be operated in a laminar flow regime.
  • a grounded platen 19 behind the surface to be printed 20 assists in developing an electric field attracting the ink jet to the surface 20.
  • control electrode 17 By radially segmenting control electrode 17 and applying voltage preferentially to one or more of the segments, it will be possible to laterally deflect the charged ink stream.
  • the amount of deflection will be a function of orifice/paper spacing and the overall spacing of the contiguous injector units necessary for character formation. By optimising the configuration of these units, it should be possible to provide sufficient deflection capability to produce characters having quality rivalling that from impact printing.
  • the triode-structured system can charge poorly conductive liquids.
  • the emitter electrode 16 serves to field emit charge into the liquid 12 in response to a voltage difference imposed between it and another (blunt) submerged electrode (15).
  • the injected charge will be more or less trapped in the fluid and swept to the outside by the bulk motion of the ink fluid 12.
  • the exiting stream can be made to undergo breakup in the manner described for the inductive system and thereby trap the charge on individual droplets.
  • the platen or target 20 to which the droplets are projected functions as the third electrode, returning the charge and completing the circuit.
  • the system as described represents a triode-structured system.
  • Appropriate voltage generating circuitry 21 and control circuitry 22 are within the state of the art.
  • Specific droplet sizes can be produced by the proper application of voltage wave forms to the inductive electrode 10 of the device of Figure 1. Such a configuration is capable of inducing a varying electrohydrodynamic force on the coaxially flowing column and hence to produce a prescribed disruption in the columm so as to produce droplets of a desired size.
  • the same effect can also be obtained by appropriate periodic charge injection into the flowing ink of this invention. As the ink fluid emerges from orifice 18, the excess charge in the fluid 12 now distributed in a spatially periodic fashion, will produce jet instability and the development of droplets of a preselected size.
  • the charge injection process is of particular interest because it is: (a) essentially independent of fluid conductivity; (b) compact and capable of low voltage operation.
  • the field emitter electron gun (dual submerged electrode 15, 16 geometry) is but one of a very broad class of possible devices that can be used to charge inject liquids.
  • a conventional thermionic vacuum electron gun firing through an appropriate window can be used to charge the flowing ink stream prior to exiting the orifice 18.
  • the ink jet Triode system shown in Figure 2 is typically operated below the maximum voltage, charge injection level, and charge density value, all of which are defined by the limiting electrical breakdown strength of the ink fluid column exiting the orifice 18.
  • the electrically unenergized flow from the ink jet Triode is usually in the form of a smooth uniform column.
  • the orifice and the ink fluid column are assumed to have a circular cross section.
  • the flow exiting from orifices that have other geometries will exhibit more involved fluid mechanical behavior (when unenergized) as compared to flows from circular orifices. This added variation complicates the detailed description of the jet behavior during charge injection but does not alter the general behavior pattern. All jets undergo the same overall modification in response to variation in injected charge density levels.
  • An initially unenergized ink stream or ink column will remain columnar for a protracted distance until disruption into a colinear droplet train occurs by random aerodynamic and mechanical vibratory forces.
  • the stream will usually break into droplets at about 20 cm from the orifice exit plane in a vertical mode (orifice directed downward) for the case to be discussed.
  • the ink jet system of Figure 2 can be operated in a columnar mode, wherein an ink fluid column is directed onto a paper target by an external electric field, or in a droplet mode, wherein the injected charge levels and system dimensions are chosen to produce a droplet stream. Additional mechanical or vibrational pulsing of the ink fluid may be used to project ink droplets from the orifice in a traditional droplet formation scheme, wherein the charge injection functions to charge the ink fluid for purposes of controlling formation and direction of the droplets.
EP82305268A 1982-10-04 1982-10-04 Flüssigkeitsstrahldrucker Withdrawn EP0107743A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP82305268A EP0107743A1 (de) 1982-10-04 1982-10-04 Flüssigkeitsstrahldrucker

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP82305268A EP0107743A1 (de) 1982-10-04 1982-10-04 Flüssigkeitsstrahldrucker

Publications (1)

Publication Number Publication Date
EP0107743A1 true EP0107743A1 (de) 1984-05-09

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EP82305268A Withdrawn EP0107743A1 (de) 1982-10-04 1982-10-04 Flüssigkeitsstrahldrucker

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3177800A (en) * 1962-06-28 1965-04-13 Sperry Rand Corp Immersed spark gap printer
US3693179A (en) * 1970-09-03 1972-09-19 Stephen F Skala Printing by selective ink ejection from capillaries
FR2256034A1 (en) * 1973-12-28 1975-07-25 Xerox Corp On demand type data ink printer(spitter) - avoids escape or dripping of ink from coated capillary tubes
US4166277A (en) * 1977-10-25 1979-08-28 Northern Telecom Limited Electrostatic ink ejection printing head
GB2031344A (en) * 1978-10-18 1980-04-23 Nippon Telegraph & Telephone Ink recording apparatus
US4333086A (en) * 1979-06-30 1982-06-01 Ricoh Company, Ltd. Ink jet printing apparatus

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3177800A (en) * 1962-06-28 1965-04-13 Sperry Rand Corp Immersed spark gap printer
US3693179A (en) * 1970-09-03 1972-09-19 Stephen F Skala Printing by selective ink ejection from capillaries
FR2256034A1 (en) * 1973-12-28 1975-07-25 Xerox Corp On demand type data ink printer(spitter) - avoids escape or dripping of ink from coated capillary tubes
US4166277A (en) * 1977-10-25 1979-08-28 Northern Telecom Limited Electrostatic ink ejection printing head
GB2031344A (en) * 1978-10-18 1980-04-23 Nippon Telegraph & Telephone Ink recording apparatus
US4333086A (en) * 1979-06-30 1982-06-01 Ricoh Company, Ltd. Ink jet printing apparatus

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
L'INDUSTRIE TEXTILE, no. 1090, June 1979, pages 535-541, Paris, FR. *

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Inventor name: KELLY, ARNOLD JAMES