EP0771655A2 - Kurzschlussnachweisschaltung für Tintenstrahldrucker - Google Patents

Kurzschlussnachweisschaltung für Tintenstrahldrucker Download PDF

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Publication number
EP0771655A2
EP0771655A2 EP96307865A EP96307865A EP0771655A2 EP 0771655 A2 EP0771655 A2 EP 0771655A2 EP 96307865 A EP96307865 A EP 96307865A EP 96307865 A EP96307865 A EP 96307865A EP 0771655 A2 EP0771655 A2 EP 0771655A2
Authority
EP
European Patent Office
Prior art keywords
circuit
ink
detection
electrodes
charge
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.)
Granted
Application number
EP96307865A
Other languages
English (en)
French (fr)
Other versions
EP0771655B1 (de
EP0771655A3 (de
Inventor
Randy L. Fagerquist
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.)
Kodak Versamark Inc
Original Assignee
Kodak Versamark Inc
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 Kodak Versamark Inc filed Critical Kodak Versamark Inc
Publication of EP0771655A2 publication Critical patent/EP0771655A2/de
Publication of EP0771655A3 publication Critical patent/EP0771655A3/de
Application granted granted Critical
Publication of EP0771655B1 publication Critical patent/EP0771655B1/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
    • B41J2/07—Ink jet characterised by jet control
    • 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
    • B41J2/07—Ink jet characterised by jet control
    • B41J2/125—Sensors, e.g. deflection sensors
    • 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
    • B41J2/17—Ink jet characterised by ink handling
    • B41J2/18—Ink recirculation systems
    • B41J2/185—Ink-collectors; Ink-catchers
    • 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
    • B41J2/17—Ink jet characterised by ink handling
    • B41J2/18—Ink recirculation systems
    • B41J2/185—Ink-collectors; Ink-catchers
    • B41J2002/1853—Ink-collectors; Ink-catchers ink collectors for continuous Inkjet printers, e.g. gutters, mist suction means

Definitions

  • the present invention relates to planar charging and deflection print heads that require a means of detecting unwanted ink on a charge plate during start-up and printing and, more particularly, to improved detection of misplaced ink in the charge plate region of such printing systems.
  • ink is supplied under pressure to a manifold region that distributes the ink to a plurality of orifices, typically arranged in a linear array(s).
  • the ink discharges from the orifices in filaments which break into droplet streams.
  • the approach for printing with these droplet streams is to selectively charge and deflect certain drops from their normal trajectories.
  • the unwanted ink may be a mist build-up on or near the charge leads, but is usually an accumulation of ink on or near the charge leads caused by a crooked jet or improper start-up.
  • the unwanted ink on the charge plate causes an electrical short between the charge leads and ground, causing print defects and physical damage to the charge plate due to unwanted current flow.
  • a detection means comprises a set of closely spaced, continuous parallel conductors placed immediately below and along the length of the charge plate, as short detection electrodes. Additionally, a circuit is provided for monitoring the conductivity between the electrodes. The electrodes are electrically isolated from one another when properly placed on the catcher surface. If the conductivity, as measured by the circuit, rises above a predetermined threshold level it is very likely that some amount of ink is present at the location of the conductors. This is an indication of improper print head operation and should signal a print head shut-down and/or clean cycle.
  • the present invention continuously monitors for ink accumulation in the charge plate area. It is a further advantage of the present invention that the electrically isolated monitoring circuit does not depend on current being drawn by the charge lead potential for detection. The circuit can also be made very sensitive to the presence of ink without being greatly affected by the electrical noise produced during printing. It is an object of the present invention that a jet impacting on the charge plate below the charge leads is as readily detected as a jet impacting on the charge leads.
  • Detection electrodes 10 as illustrated in Fig. 1, detect the presence of ink on or close to charge leads 16. If ink is present on or very close to the leads, there is a problem with the printhead which needs to be corrected.
  • the detection electrodes 10 are situated inside box 12. Outside box 12 is illustrated a detection circuit 14 used for monitoring conductivity between charge leads 16. Voltage source V s and associated internal impedance Z i provide an oscillating potential between leads 10. The conductivity between the leads is monitored by measuring the voltage drop across resistor R s with voltmeter circuit V ac . When the conductivity decreases between the detection leads due to the presence of a conductive fluid, such as ink, an increase in the current through R s is produced, yielding an increase in the voltage measured by V ac ⁇
  • the present invention relates to the type of continuous ink jet system illustrated in Fig. 2.
  • a plurality of jets is created at high spatial resolution by a drop generator, which stimulates the natural break-up of jets into uniform streams of droplets.
  • a plurality of conducting elements, or charge leads 16, are located on a planar charge plate 18.
  • a plurality of streams of drops 20 are supplied by drop generator 22.
  • a plurality of independently switchable sources 24 of electrostatic potential are supplied to the plurality of charge leads 16.
  • a catcher 26 intercepts the slightly deflected streams of drops.
  • the plurality of streams of drops impacting on the catcher forms a film of ink 30, which in turn forms a flow of ink 28, sucked away from the face of the catcher by a vacuum.
  • Reference number 32 represents the area on the catcher at which the deflected drops impact the catcher and merge together to form a film of ink on the catcher face.
  • the undeflected ink drops then print the image on substrate 34.
  • the present invention comprises a set of closely spaced, continuous parallel conductors placed immediately below and along the length of the charge plate 18, to operate as short detection electrodes 10.
  • Fig. 3 shows the location of short detection electrodes 10, situated just below and along the entire length of charge plate 18.
  • the electrodes can be any suitable electrodes, such as 2 mil diameter copper wires.
  • the electrodes may be secured by any suitable means, such as epoxy, at each end of the array.
  • the electrodes can be fabricated as a flex circuit 36 that is attached as a separate component to the catcher/charge plate assembly with an appropriate attachment means 38, such as epoxy, as in Fig. 4.
  • the flex circuit 36 of Fig. 4 comprises detection electrodes 10 as two flat conductive elements fixed on a thin dielectric substrate, with connections for the external sensing circuit.
  • Fig. 5 shows an alternative fabrication method comprising a dielectric 40 sandwiched between electrodes 10, which comprise two thin conductive plates. The edges of the plates form the sensing electrodes.
  • This structure is inserted between the catcher 26 and the charge plate 18 during charge plate bonding, with connection electrodes provided at any point convenient for the subsequent electronics to access.
  • the flex circuit sandwiched dielectric-type configurations allow a relatively small potential difference to be used between the sensing electrodes by the sensing circuit, producing a greatly reduced electrochemical reaction between the ink and the electrodes (when ink is present) as compared with that obtained by currently used short detect circuits.
  • FIG. 6 Another embodiment of the detection circuit 14, illustrated in Fig. 6, has the electrodes 10 connected to either terminal of one set of windings of a transformer 42.
  • This embodiment is novel in that the conductivity sensing circuit eliminates a direct electrical connection of the detection leads 10 to conductivity measuring circuitry.
  • the winding of transformer 42 would be an open circuit.
  • an impedance measuring circuit 44 connected to the second set of windings.
  • any suitable impedance measuring means such as an impedance bridge circuit comprised of inductors, capacitors, and resistors, could be used, as well as various known sophisticated integrated circuit versions of the impedance bridge.
  • Fig. 7 shows another embodiment of circuit 14 wherein the detection relies on a battery-like response caused by ink 46 bridging dissimilar metals, referenced as detection leads 10' and 10".
  • detection leads 10' and 10 When ink joins the detection electrodes 10' and 10", a voltage is produced which can be detected.
  • the detector electrodes 10' and 10" are dissimilar metals which, when bridged by an alkali or acidic ink 46, would produce an emf in a battery-type chemical reaction. This emf is then detected by a voltage sensing circuit 48.
  • any suitable voltage sensing means could be used, such as a standard operational amplifier circuit configured with resistors and capacitors as a high input impedance voltage measuring device.
  • the emf sensing device could be a single integrated circuit chosen for the specific purpose of measuring small voltages.
  • the advantage of the circuit embodiment illustrated in Fig. 7 is that it does not require a test voltage to be placed on the detector electrodes, allowing a completely passive input circuit design.
  • FIGs. 8A and 8B Yet another embodiment of the short detect circuit 14, according to the present invention, is illustrated in Figs. 8A and 8B.
  • the circuit 14 of Figs. 8A and 8B utilizes a single electrode 10 in place of the pair of electrodes illustrated in Figs. 1, 6 and 7.
  • This single electrode 10 is placed, by means of a voltage divider or equivalent circuit, at a potential between ground (catcher face potential) and the charge plate lead 16 potential.
  • ground catcher face potential
  • the charge plate lead 16 potential By noting the polarity of the current generated in the circuit connected to the lead, it can be ascertained whether the misplaced ink is bridging the electrode and charge plate or electrode and catcher. This is in addition to the somewhat simplified implementation obtained from using only a single lead.
  • Fig. 9 shows the voltage produced (Vac) across sensing resistor Rs of Fig. 1 during a print head start-up simulation on a print head test stand.
  • the sequence of events recorded in Fig. 9 are as follows. Initially, there was cross flush of the print head where ink is flowing from the orifice plate, over the charge plate and down the face of the catcher. In this state, ink is also flowing over the short detect electrodes, resulting in a relatively high conductivity between the wires. This produces a relatively high voltage across Rs, as indicated by the signal in region A of Fig. 9.
  • Region B of Fig. 9 shows the signal voltage across Rs produced when the print head has been taken out of the cross flush state and into the jetting and charge plate drying state.
  • jets have been started by closing the outlet valve and the catcher heater has been turned on.
  • the print head alignment is changed to eliminate the crashing jet condition.
  • Vac decreased to near zero. This obtains from the runoff/drying of the ink which accumulated during C. Therefore, the circuit recovers when an abnormal condition is removed.
  • the present invention comprises detection lead or leads positioned immediately below the charge plate on which a portion of any unwanted ink will likely be deposited; and an electrical circuit which monitors the conductivity of the area between the detection electrodes.
  • the circuit monitors the conductivity between the electrodes 10.
  • the electrodes are electrically isolated from one another when properly placed on the catcher surface. If the conductivity, as measured by the circuit, rises above a predetermined threshold level, it is very likely that some amount of ink is present at the location of the conductors. This is an indication of improper print head operation and should signal a print head shut-down and/or clean cycle.
  • the circuit for monitoring the conductivity between the electrodes is isolated (floating) from the charge driver potential so that in the case of a large mass of ink bridging the charge leads and short detect electrodes, no large currents are produced in either the charge lead(s) or the sensing electrodes.
  • the sensing circuit of the present invention can be, but is not restricted to, an ac signal with a frequency and amplitude chosen to provide maximum short detect sensitivity with high noise rejection.
  • a circuit functioning in a manner similar to a lock-in amplifier would reject all signals at frequencies other than that used for monitoring the conductivity between the sensing electrodes.
  • Various embodiments of the circuit are illustrated in Figs. 1, 6, 7, 8A and 8B. However, it will be obvious to those skilled in the art that various other circuit configurations may be used without departing from the scope of the invention.
  • the specific circuit selected for any given application typically depends on the electrical conductivity of the fluid.
  • the present invention is useful in the field of ink jet printing, and has the advantage of continuously monitoring for ink accumulation in the charge plate area.
  • the present invention has the further advantage of providing an electrically isolated monitoring circuit which is not dependent on current being drawn by the charge lead potential for detection. It is a further advantage that the circuit can be made very sensitive to the presence of ink, without being greatly affected by the electrical noise produced during printing. Finally, it is an advantage of the present invention that a jet impacting on the charge plate below the charge leads is detected as readily as a jet impacting on the charge leads.

Landscapes

  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
  • Ink Jet (AREA)
EP19960307865 1995-10-31 1996-10-30 Kurzschlussnachweisschaltung für Tintenstrahldrucker Expired - Lifetime EP0771655B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US55095895A 1995-10-31 1995-10-31
US550958 2006-10-19

Publications (3)

Publication Number Publication Date
EP0771655A2 true EP0771655A2 (de) 1997-05-07
EP0771655A3 EP0771655A3 (de) 1998-09-16
EP0771655B1 EP0771655B1 (de) 2002-09-25

Family

ID=24199263

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19960307865 Expired - Lifetime EP0771655B1 (de) 1995-10-31 1996-10-30 Kurzschlussnachweisschaltung für Tintenstrahldrucker

Country Status (4)

Country Link
EP (1) EP0771655B1 (de)
JP (1) JP3946800B2 (de)
CA (1) CA2189284A1 (de)
DE (1) DE69623907T2 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1129854A1 (de) * 2000-03-03 2001-09-05 Domino Printing Sciences Plc Durchschlagdetektor
EP1013426A3 (de) * 1998-12-14 2002-03-20 SCITEX DIGITAL PRINTING, Inc. Kurzschlussnachweis für einen Tintenstrahldruckkopf
WO2005108091A1 (en) * 2004-05-05 2005-11-17 Eastman Kodak Company Bevelled charge structure with short circuit sensing electrode
US8777364B2 (en) 2010-07-30 2014-07-15 Hewlett-Packard Development Company, L.P. Short circuit detection in an inkjet printhead
EP4552849A1 (de) * 2023-11-13 2025-05-14 Dover Europe Sàrl Industrieller tintenstrahldrucker mit stromverbrauchsmessung zur tintenverschmutzungsdetektion

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6733116B1 (en) 1998-10-16 2004-05-11 Silverbrook Research Pty Ltd Ink jet printer with print roll and printhead assemblies

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4631550A (en) * 1985-08-15 1986-12-23 Eastman Kodak Company Device and method for sensing the impact position of an ink jet on a surface of an ink catcher, in a continuous ink jet printer
JP2724998B2 (ja) * 1985-10-14 1998-03-09 セイコーエプソン株式会社 インク滴検出装置
US4928113A (en) * 1988-10-31 1990-05-22 Eastman Kodak Company Constructions and fabrication methods for drop charge/deflection in continuous ink jet printer
US4994821A (en) * 1989-09-18 1991-02-19 Eastman Kodak Company Continuous ink jet printer apparatus having improved short detection construction
US5381099A (en) * 1993-03-02 1995-01-10 Unisys Corporation Streak detection for ink-jet printer with obnically connected segment pairs
EP0744291B1 (de) * 1995-05-26 2000-07-12 SCITEX DIGITAL PRINTING, Inc. Verfahren zur Herstellung von Ladungselektroden

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
None

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1013426A3 (de) * 1998-12-14 2002-03-20 SCITEX DIGITAL PRINTING, Inc. Kurzschlussnachweis für einen Tintenstrahldruckkopf
EP1129854A1 (de) * 2000-03-03 2001-09-05 Domino Printing Sciences Plc Durchschlagdetektor
WO2005108091A1 (en) * 2004-05-05 2005-11-17 Eastman Kodak Company Bevelled charge structure with short circuit sensing electrode
US7144103B2 (en) 2004-05-05 2006-12-05 Eastman Kodak Company Beveled charge structure
US7506443B2 (en) 2004-05-05 2009-03-24 Eastman Kodak Company Beveled charge structure
US8777364B2 (en) 2010-07-30 2014-07-15 Hewlett-Packard Development Company, L.P. Short circuit detection in an inkjet printhead
EP4552849A1 (de) * 2023-11-13 2025-05-14 Dover Europe Sàrl Industrieller tintenstrahldrucker mit stromverbrauchsmessung zur tintenverschmutzungsdetektion
WO2025104113A1 (en) * 2023-11-13 2025-05-22 Dover Europe Sarl Industrial inkjet printer with current consumption measurement for ink pollution detection

Also Published As

Publication number Publication date
EP0771655B1 (de) 2002-09-25
EP0771655A3 (de) 1998-09-16
DE69623907D1 (de) 2002-10-31
DE69623907T2 (de) 2003-08-07
JP3946800B2 (ja) 2007-07-18
CA2189284A1 (en) 1997-05-01
JPH09201974A (ja) 1997-08-05

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