EP4303008A1 - Elektrische schaltung zur detektion des ausfalls eines parallelen auswurfelements - Google Patents

Elektrische schaltung zur detektion des ausfalls eines parallelen auswurfelements Download PDF

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Publication number
EP4303008A1
EP4303008A1 EP22183845.1A EP22183845A EP4303008A1 EP 4303008 A1 EP4303008 A1 EP 4303008A1 EP 22183845 A EP22183845 A EP 22183845A EP 4303008 A1 EP4303008 A1 EP 4303008A1
Authority
EP
European Patent Office
Prior art keywords
electric
piezo
ink
signal
reference signal
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.)
Pending
Application number
EP22183845.1A
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English (en)
French (fr)
Inventor
Aart Nijkamp
Vincent BREUKELS
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.)
Canon Production Printing Holding BV
Original Assignee
Canon Production Printing Holding BV
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 Canon Production Printing Holding BV filed Critical Canon Production Printing Holding BV
Priority to EP22183845.1A priority Critical patent/EP4303008A1/de
Publication of EP4303008A1 publication Critical patent/EP4303008A1/de
Pending 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
    • B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
    • B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
    • B41J2/0451—Control methods or devices therefor, e.g. driver circuits, control circuits for detecting failure, e.g. clogging, malfunctioning actuator

Definitions

  • the present invention generally pertains to an electric circuit that is used in determining an operating state of a piezo-actuated ejection element of an inkjet print head.
  • a known inkjet print head comprises an array of ejection elements, wherein each ejection element comprises a liquid chamber for holding an amount of liquid.
  • the liquid is an ink, such as a solvent-based or water-based ink, a hot-melt ink at an elevated temperature or a UV-curable ink.
  • the liquid may be any other kind of liquid, such as a liquid that needs to be dosed accurately.
  • the word "ink” is used for any liquid that may be ejected from a print head, either or not at elevated temperatures, in the form of small droplets.
  • the term "print head", “print” and derivatives thereof are to be understood to include any device or technique that deposits or creates material on a surface in a controlled manner.
  • Each ejection unit of the known inkjet print head further comprises an electromechanical transducer, usually a piezo-electric actuator, operatively coupled to the liquid chamber, for generating a pressure wave in the liquid held in the liquid chamber.
  • This actuator comprises two electrodes and a layer of piezo-electric material arranged therebetween. When an electric field is applied by application of a voltage over the electrodes, the piezo-material mechanically deforms and the deformation of the piezo-actuator generates the pressure wave in the liquid.
  • electromechanical transducer may also be referred to as the actuator or piezo-electric element.
  • the liquid chamber terminates at one end in a nozzle. If a suitable pressure wave is generated in the liquid in the liquid chamber, a droplet of the liquid is expelled through the nozzle. In this way an ink droplet may be ejected towards a recording medium to form an image dot on the recording medium. A pattern of such image dots thus forms a printed image on the recording medium as is well-known in the art.
  • a known disadvantage of the above-described inkjet print head is the susceptibility to malfunctioning of the ejection units.
  • an air bubble may be entrained in the nozzle or in the liquid chamber.
  • Such an air bubble changes the acoustics of the ejection unit and as a consequence a droplet may not be formed when the pressure wave is generated.
  • Another known cause for malfunctioning is the occurrence of dirt or dust particles (partly) blocking the nozzle. The presence of dirt does not only block the liquid flow, but also changes the acoustics of the liquid chamber.
  • a disadvantage of the known measurement circuits that are used to detect an operating state is the time needed for sensing the residual pressure wave and the time needed for analysis of the residual pressure wave. Due to this relatively long period needed for sensing and analyzing, it is not possible to perform the analysis for each ejection unit after each droplet ejection. Moreover, even if there would be sufficient time between consecutive droplet ejections, the computational power needed to analyze each ejection unit after each droplet ejection would be so high, that this would not be commercially feasible. In particular, a parallel operation for all ejection units is desired.
  • a circuit according to claim 1 is provided.
  • a reference signal is provided that is specific for the ejection unit that is monitored or for a group of ejection units that show similar behavior and/or acoustics. Because there are differences between the efficiency of the various piezo-electric elements, the electric signals that result from the residual pressure waves in the various ink channels vary in strength. Thus, for a correct assessment of the functioning of an ejection unit, the reference signal needs to be as close as possible to the signal that is associated with a correctly working element. This is achieved by associating each ejection unit with a specific part of a digital memory for saving the digital reference signals. If ejection elements show sufficiently similar behavior, they may of course share the same memory and use the same reference signals.
  • a circuit is exclusively connectable to a single ejection unit. This means that there are as many monitoring circuits as there are ejection units, which can be monitored all at the same time. This satisfies the desire to enable a parallel operation for all ejection units.
  • the invention also pertains to an inkjet printer that comprises a circuit for monitoring a condition of the inkjet elements that are used in printing an image.
  • This monitoring may even be scheduled during the print process, wherein an appropriate timing may be selected.
  • this monitoring may be scheduled after each droplet ejection to make sure a droplet is excreted from the inkjet element.
  • the condition of an inkjet element is determined based on an output of the comparator using both the electric signal from the residual pressure wave and the analog version of the reference signal as input signals.
  • After determining a deviating ejection element, also known as a failing nozzle it may be decided not to use this element for generating an ink drop, but to amend the print data in such a way that the original image is printed without the use of this element.
  • Another way of coping with this situation is to have another ejection element fulfil the task the deviating element is not capable to do.
  • Figure 1 shows a circuit that can be easily implemented in an integrated circuit. It comprises a print data module 1 that generates waveforms in accordance with the print data of an image.
  • the waveforms are amplified by the driver 2 for driving the ink ejection element 3, wherein the electric voltage across a piezo-electric element or, equivalently, the current in the element generates an acoustic wave in the ink in the ink chamber, resulting in the ejection of an ink droplet.
  • the switch 4 is open during the application of the waveforms and is closed after a waveform is finished to monitor the voltage across the ejection element 3 as a result of a residual acoustic wave in the ink chamber. Switch 4 is controlled by trigger element 5.
  • Each ejection element is associated with a memory 6 that comprises a digital reference signal. This signal has been saved in a procedure wherein the functioning of an ejection element is associated with a determination of a residual acoustic wave signal.
  • Trigger element 5 indicates the timing of sending this digital signal to the digital-analog converter (DAC) 7.
  • the comparator 8 subtracts the reference signal from the residual acoustic wave signal, thus obtaining an output signal 9 that indicates whether these signals cancel or not. If they cancel, the ejection element 3 functions as required. If they do not, the ejection element may need maintenance or some other action is necessary.
  • the output signal 9 may be analyzed to suggest the various actions.
  • Trigger element 5 is connected to the print data module 1, the switch 4 and the digital memory 6 by the various control lines 10,11, and 12 in order to obtain a proper timing of the signals.
  • Figure 2 shows the outline of an inkjet printer wherein the circuit of Figure 1 is applied.
  • a substrate 50 is conveyed in direction 51 by a belt that moves over rollers 21 and 22.
  • Several processes are performed on the substrate, which may be a sheet of paper or other material. All processes are performed over the full width 52 of the substrate.
  • a first process 13 involves a pretreatment, such as a preheater, for example a heater by infrared radiation, or a corona or plasma treatment. This is not necessary for all kind of substrates, but its presence makes the printer more versatile.
  • a roller coating 14 comprising an auxiliary roll 16 and a main roll 17 for coating the substrate with a pre-treatment liquid, such as a primer material. This is used to affect the way the ink spreads on some substrate materials.
  • a pre-treatment liquid such as a primer material.
  • Each surface of the double rolls may be covered with a porous resin material such as sponge.
  • the coated substrate, on which the aqueous pretreatment liquid was supplied may optionally be heated and dried by drying member 18.
  • This element is composed of a drying heater installed at the downstream position of the aqueous pretreatment liquid applying member 14 in order to decrease the quantity of the water content in the aqueous pretreatment liquid to a predetermined range.
  • 110 represents an inkjet marking module comprising four inkjet marking devices, indicated with 111, 112, 113 and 114, each arranged to eject an ink of a different color, usually cyan, magenta, yellow and black, or CMYK.
  • Each inkjet marking device is as wide as the substrate that passes underneath. The number of ejection units is so high that only one pass is needed to completely print an image on the substrate. If one of the ejection units fails to eject ink drops or ejects droplets in a skew direction, a streaklike defect may occur in the print. This may be remedied by enhancing the ink density in neighboring ejection units.
  • each of the ejection units in the inkjet printer in Figure 2 is actuated by a circuit as indicated in Figure 1 .
  • This has the advantage that during printing the condition of the ejection unit is monitored and immediate intervention is possible. Thereby the amount of streaklike defects in the print is reduced considerably.
  • a temperature control device 19 is arranged to control the temperature of the substrate during the ink application, for example in the range of 30°C to 60°C. It may comprise heaters, such as radiation heaters, and a cooling means, for example a cold blast, in order to control the surface temperature of the receiving medium within a predetermined range.
  • the final process is a drying process.
  • a drying and fixing unit 20 is schematically shown. This unit may comprise a heater, for example a radiation heater.
  • the print is conveyed to and passed through the drying and fixing unit 20.
  • the print is heated such that solvents present in the printed image, which is to a large extent water, evaporate.
  • the speed of evaporation and hence drying may be enhanced by increasing the air refresh rate in the drying and fixing unit 20.
  • film formation of the ink occurs, because the prints are heated to a temperature above the minimum film formation temperature.
  • the residence time of the print in the drying and fixing unit 20 and the temperature at which the unit operates are optimized, such that when the print leaves the unit a dry and robust print has been obtained.
  • Figure 3 shows three signals as obtained from a residual pressure wave in the ejection element 3 in Figure 1 .
  • the signals are given as a voltage 60 as a function of time 61.
  • Signal 62 is obtained during a start-up procedure wherein the functioning of ejection elements is determined.
  • This signal is digitized and stored in the digital memory 6 as a reference signal.
  • Signal 63 is obtained during the printing process and is sent to comparator 8 after closing switch 4. Since the reference signal, coming from the memory 6 is also led to the comparator, the output signal 9 will be substantially zero. However, if the ejection element 3 is not functioning properly, a signal like signal 64 will be obtained and after comparing this to signal 62, the output signal 9 will not be zero and immediate action may be taken. Thus the amount of streaklike defects in the print will be greatly reduced.

Landscapes

  • Particle Formation And Scattering Control In Inkjet Printers (AREA)
EP22183845.1A 2022-07-08 2022-07-08 Elektrische schaltung zur detektion des ausfalls eines parallelen auswurfelements Pending EP4303008A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP22183845.1A EP4303008A1 (de) 2022-07-08 2022-07-08 Elektrische schaltung zur detektion des ausfalls eines parallelen auswurfelements

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22183845.1A EP4303008A1 (de) 2022-07-08 2022-07-08 Elektrische schaltung zur detektion des ausfalls eines parallelen auswurfelements

Publications (1)

Publication Number Publication Date
EP4303008A1 true EP4303008A1 (de) 2024-01-10

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP22183845.1A Pending EP4303008A1 (de) 2022-07-08 2022-07-08 Elektrische schaltung zur detektion des ausfalls eines parallelen auswurfelements

Country Status (1)

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EP (1) EP4303008A1 (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110285773A1 (en) * 2010-05-18 2011-11-24 Seiko Epson Corporation Liquid ejection device and liquid testing method
US20120293577A1 (en) * 2011-05-19 2012-11-22 Fuji Xerox Co., Ltd. Liquid ejection apparatus and ejection control method for same, and inkjet apparatus
US20150367633A1 (en) * 2014-06-19 2015-12-24 Ricoh Company, Ltd. Liquid droplet ejecting device, inkjet recording apparatus, liquid droplet ejecting method, and storage medium for liquid droplet ejecting method

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110285773A1 (en) * 2010-05-18 2011-11-24 Seiko Epson Corporation Liquid ejection device and liquid testing method
US20120293577A1 (en) * 2011-05-19 2012-11-22 Fuji Xerox Co., Ltd. Liquid ejection apparatus and ejection control method for same, and inkjet apparatus
US20150367633A1 (en) * 2014-06-19 2015-12-24 Ricoh Company, Ltd. Liquid droplet ejecting device, inkjet recording apparatus, liquid droplet ejecting method, and storage medium for liquid droplet ejecting method

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