EP2939834B1 - Method for cleaning a printer head - Google Patents

Method for cleaning a printer head Download PDF

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Publication number
EP2939834B1
EP2939834B1 EP15000693.0A EP15000693A EP2939834B1 EP 2939834 B1 EP2939834 B1 EP 2939834B1 EP 15000693 A EP15000693 A EP 15000693A EP 2939834 B1 EP2939834 B1 EP 2939834B1
Authority
EP
European Patent Office
Prior art keywords
nozzle plate
ink
cleaning
nozzle
surface
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.)
Active
Application number
EP15000693.0A
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German (de)
French (fr)
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EP2939834A1 (en
Inventor
Klaus Delueg
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.)
Durst Phototechnik AG
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Durst Phototechnik AG
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Publication date
Priority to ITBZ20140011 priority Critical
Application filed by Durst Phototechnik AG filed Critical Durst Phototechnik AG
Publication of EP2939834A1 publication Critical patent/EP2939834A1/en
Application granted granted Critical
Publication of EP2939834B1 publication Critical patent/EP2939834B1/en
Application status is Active legal-status Critical
Anticipated expiration legal-status Critical

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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, e.g. INK-JET PRINTERS, THERMAL PRINTERS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters 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
    • B41J2/01Ink jet
    • B41J2/135Nozzles
    • B41J2/165Preventing or detecting of nozzle clogging, e.g. cleaning, capping or moistening for nozzles
    • B41J2/16517Cleaning of print head nozzles
    • B41J2/16552Cleaning of print head nozzles using cleaning fluids
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, e.g. INK-JET PRINTERS, THERMAL PRINTERS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters 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
    • B41J2/01Ink jet
    • B41J2/135Nozzles
    • B41J2/165Preventing or detecting of nozzle clogging, e.g. cleaning, capping or moistening for nozzles
    • B41J2/16517Cleaning of print head nozzles
    • B41J2/1652Cleaning of print head nozzles by driving a fluid through the nozzles to the outside thereof, e.g. by applying pressure to the inside or vacuum at the outside of the print head

Description

  • The present invention relates to a method of cleaning a printhead of an ink jet printing apparatus.
  • A printhead generally comprises a nozzle plate having nozzles which are each connected via a nozzle channel to an ink chamber and via which ink droplets can be applied to a substrate surface to be printed by ejecting drops from the nozzles. During the ejection of the ink droplets, it is known that an undesirable, but unavoidable wetting of the nozzle opening environment, including the surface of the nozzle plate, with ink. This ink dries especially in longer life, so with longer-lasting pressure interruptions, a. This phenomenon, though to a lesser extent, also occurs during continuous printing and may occur more intensively at positions further from the nozzle orifices. Depending on where and to what extent the nozzle opening environment, including the surface of the nozzle plate, by this liquid and / or dried ink - hereinafter also referred to as ink residues - contaminated, different problems arise.
  • If there are dried or liquid ink residues in the nozzle orifice environment, so that the affected nozzle orifice is at least partially closed, these ink residues may be in the way of the trajectory of the ink drops, causing the ejection process to be disrupted. As a result, for example, the ink drops can no longer impinge on the desired positions of the substrate to be printed. If there are dried ink residues in the nozzle opening environment, the affected nozzle may become a skew. In the worst case, the nozzle may even fail due to a congestion that has occurred. Printing an image with a single-pass printer is particularly noticeable because the background color appears in solid lines instead of the intended colors of the image to be printed for the viewer. This has a negative effect on the print quality and can lead to production losses. Lie on the other hand, if dried ink residues are present on the nozzle plate itself, there is a risk that it will occasionally peel off due to vibrations and get onto the medium to be printed, so that quality losses must also be expected.
  • If inkjet printers are exposed to a relatively dusty environment, for example in halls in which press devices for the production of ceramic tile blanks are operated in addition to the printers, contamination of the nozzle plate with dust particles occurs in addition to contamination by ink residues. This can lead to the reinforcement of the above-mentioned problem.
  • Cleaning methods for printheads are known in which periodically removed within predetermined time intervals dirt particles on a nozzle plate and at the nozzle openings.
  • The in the DE 603 01 440 T2 described method discloses a solution to the above problem of nozzle plate contamination. At this time, in a first step, a solvent (ink) is provided on a nozzle plate by discharging it through nozzles. In a second step, the dirt particles collected on the nozzle plate are dissolved by brushing the nozzle plate in the presence of the solvent with a brush, and in a third step, a cleaning solvent is additionally applied to the nozzle plate. Subsequently, the cleaning solvent and the dirt particles are removed from the nozzle plate by vacuum cleaning. The application of the cleaning solvent and subsequent removal thereof provides for movement of the solvent across the nozzle plate. Although such a method is a good cleaning method of the nozzle plate. However, the process is relatively time consuming due to the high number of steps and the device relatively koplex in construction due to the required cleaning devices.
  • The EP 1 464 500 B1 describes a method of cleaning an ink jet print head having a nozzle plate with nozzles and cleaning the same by first applying a cleaning member to the nozzle plate and applying the pressure to the ink chambers such that the ink meniscus contacts the corresponding nozzle openings (in the form of an ink edge bead) protrudes without dripping ink. In a second step The nozzle plate is cleaned by moving the cleaning element along the nozzles while the ink is in the positive pressure state. Although such a cleaning method is particularly economical in terms of loss of ink during cleaning. However, this method is disadvantageous because no ink is provided on the nozzle plate, which is known to significantly improve the cleaning of the nozzle plate, since dirt particles are received in a liquid.
  • US2011181657 and US2007080990 also describe systems for cleaning the nozzle plate.
  • In conventional cleaning systems, it is known that ink is provided on the entire nozzle plate. In this case, this reaches up to the nozzle plate limiting edges and occurs in certain sections beyond the edges, so that ink settles on the side edges of the nozzle plate and dries from time to time.
  • FIG. 2 shows a method known in the prior art, in which in a first step ( FIG. 2A ) Ink has been provided on the entire nozzle plate and the ink has run out beyond the edges bounding the nozzle plate. FIG. 2B shows the step of sucking by vacuum suction.
  • The known methods, which use cleaning brushes and / or vacuum suction means, work basically well when it is only necessary to clean the surface of the nozzle plate, but are not suitable for completely eliminating the liquid and / or dried ink residues present on side edges of the nozzle plate. With each cleaning process, more ink passes over the edges of the nozzle plate, settles on the side edges and dries over time. The inventors have observed in the investigations that a considerable substrate contamination by the not completely removed on the side edges of the nozzle plate ink residues still occurs. It is true that the resulting contamination of the substrate is relatively small in comparison with the pollution which would result from non-cleaning. However, inkjet printers today are expected to be very reliable to meet the increased demands of the printing industry.
  • There is therefore a need for a cleaning method with the impurities on the side edges of a nozzle plate can be minimized at least partially.
  • It would therefore be desirable to have a process with which on the one hand to achieve a higher degree of purification than with the methods known in the art and on the other hand to have a method with which one can at least partially simplify the cleaning method. This requirement is based on the object of the present invention.
  • According to the invention the above object is achieved by a procedure according to the method of claim 1. The subclaims describe preferred variants of the present process.
  • The inventive cleaning method has the advantage that it prevents preventive acting impurities by ink residues on the side edges of the nozzle plate and the cleaning method is not de facto itself a polluting factor.
  • The invention will be described below with reference to the figures in detail and by way of example.
    • Figures 1A-1B show the surface of a nozzle plate 101 a schematic representation of a printhead 201 in plan view
    • FIG. 2 Fig. 11 shows a prior art method of cleaning a surface of a nozzle plate 101 in plan view
    • Figures 3-5 show known embodiments of a arranged in a holding frame 207 \ 205 printhead 201 in cross-sectional view
    • FIG. 6 shows the process step a) of an inventive method for cleaning a surface of a nozzle plate 101 in plan view and side view
    • FIG. 7 shows the method step b) of a method according to the invention in a method step b) for cleaning a surface of a nozzle plate 101 in plan view and side view
  • Figure 1A shows in the outside the nozzle plate 101 of a printhead, which nozzle plate 101 nozzle openings 105, from which ink drops can be ejected onto the substrate to be printed. The nozzle plate 101 in FIG. 1B includes adjustable adjustment members (not shown), via which it is known that the angle of the nozzle row of the print head can be made by a two-dimensional movement of the print head itself with respect to the feed direction thereof. The adjusting members are in the example behind the nozzle plate 101 via openings 107 provided in the nozzle plate 101 - which are generally present at the two outer opposite ends of the nozzle plate 101 - reachable.
  • A nozzle plate 101 of a printhead is defined in the context to be embodied as a plate, which is preferably substantially flat, and the face \ surface of the plate contains nozzle orifices 105, the plate being bounded by edges 103.
  • The term "printhead" is used in context as a synonym for the term "inkjet printhead".
  • FIG. 2 FIG. 2A shows an ink wetted surface of the nozzle plate 101 in which, as a result of complete wetting, the ink film 301 has passed beyond the edges 103 delimiting the nozzle plate 101 is simplified and in the example shown two opposite side edges 203 wetted. The illustration 2B shows the cleaning of the surface of the nozzle plate 101 with Vakuumabsaugmittel 305th
  • Figures 3-5 show different embodiments of printheads 201, the shamatically simplified shown each attached to different fixtures 207 \ 205.
  • In FIG. 6 and FIG. 7 For example, steps for cleaning the nozzle plate 101 are shown. If reference is made in this example to step a) or b), then the corresponding method steps a) or b) according to claim 1 are meant.
  • FIG. 6 :
  1. a) In the first process step a), the ink film 301 wetting the surface of the nozzle plate 101 is provided by discharging a predetermined amount of ink from the nozzle orifices 105, whereby the contaminants contaminating the nozzle plate 101 are at least partially taken up by the ink film 301 provided.
  • According to the invention, the amount of ink discharged is controlled by control means such that the ink film 301 formed thereby wets the surface of the nozzle plate 101 to at least 40%, preferably at least 60%, more preferably at least 80% and less than 100%, with an edge 303 of the Ink film 301 is present at a distance to each of the nozzle plate 101 bounding edge 103, wherein the distance (s) are greater than zero.
  • For example, an in FIG. 6 shown distance X 1mm amount.
  • Contaminants may be generally soluble and / or insoluble constituents of an ink (printing ink) and / or dust particles from the environment in addition to liquid and / or dried ink residues.
  • FIG. 7 :
    In a second process step b), the ink film 301 and the impurities on the nozzle plate 101 are removed by means of vacuum suction means 305.
  • A method has been described for cleaning a surface of a nozzle plate 101 of a printhead contaminated with contaminants, especially liquid and / or dried ink residues and / or dust particles 201, which nozzle plate 101 contains nozzle openings 105, the method comprising the following steps:
    1. a) Providing an ink film 301 wetting the surface of the nozzle plate 101 by discharging a predetermined amount of ink from the nozzle orifices 105, whereby the contaminants contaminating the orifice plate 101 are at least partially received by the ink film 301 provided
    2. b) Removal of the ink film 301 and the impurities on the nozzle plate 101 by means of vacuum suction means 305
  • In the method according to the invention, the amount of ink discharged is controlled by control means such that the ink film 301 formed thereby wets the surface of the nozzle plate 101 to at least 40%, preferably at least 60%, more preferably at least 80% and less than 100%, with an edge 303 the ink film 301 is spaced apart from each edge 103 delimiting the nozzle plate 101, the distance (s) being greater than zero.
  • For the removal of the ink film 301 and the impurities in step b), a relative movement is performed between the nozzle plate 101 and the vacuum suction means 305. In this case, the vacuum suction means 305 can be moved, for example, in a direction of movement 307 relative to a fixedly arranged nozzle plate 101.
  • For cleaning the nozzle plate 101, the amount of the discharged ink over a pressure applied to the ink chamber depending on the kind of the ink, i. the viscosity and / or density of the ink and the discharge time are determined.
  • The provision of the ink in step a) is preferably carried out such that no ink drops detach from the nozzle plate 101. If, during the cleaning of the nozzle plate 101, the substrate to be printed is located under the print head 201, contamination thereof is avoided. A further advantage is that a subsequent cleaning of the guide means provided for the medium to be printed or of the inkjet printing apparatus can be avoided.
  • In the method, steps a) and b) may be performed such that the provision of an ink film 301 wetting the surface of the nozzle plate 101 is accompanied by the removal of the ink film 301 and the impurities on the nozzle plate 101 by means of vacuum suction means 305 separated in time or at least partially overlapping in time ,
  • In the method, the discharge time can be chosen such that it lies in a range between 50 msec and 3000 msec and preferably between 100 msec and 500 msec. In principle, lower or higher discharge times can also be selected.
  • In the process, the viscosity of the ink may be in a range between v = 3-100 mPas · sec, and preferably between v = 8-17 mPas · s. Inks with a low or higher viscosity than the stated viscosity η of η = 3-100 mPasec can in principle also be used, as long as optimal pressure stability can be ensured with inkjet printheads.
  • In the process, the density of the ink may range between δ = 0.8-2.0 g / cm 3. Inks having a lower or higher density than said density δ of δ = 0.8-2.0 g / cm 3 may also be used in principle as long as optimum printing stability with ink jet printheads can be ensured.
  • Finally, for the sake of order, it should be pointed out that, for better understanding, the print head 201 and its components have in some cases not been shown to scale and / or enlarged and / or reduced in size.
  • It should be noted that the method according to the invention has been described for the sake of simplicity only for the cleaning of a single nozzle plate 101. However, it is clear to the person skilled in the art that the method can likewise be used for a plurality of spinning heads 201, which are arranged, for example, on a printing carriage.
  • Claims (5)

    1. Method for cleaning a surface of a nozzle plate (101) of a printing head (201), which surface is contaminated with impurities, in particular liquid and/or dried ink residues and/or dust particles, which nozzle plate (101) comprises nozzle orifices (105), wherein the method comprises the following steps:
      a) providing an ink film (301) wetting the surface of the nozzle plate (101) by discharging a predetermined amount of ink from the nozzle orifices (105), and at least partially receiving the impurities contaminating the nozzle plate (101) by the provided ink film (301)
      b) removing the ink film (301) and the impurities on the nozzle plate (101) by vacuum suction means (305), wherein
      the amount of the discharged ink is controlled by controlling means in such a way that the ink film (301) thus formed wets at least 40%, preferably at least 60%, particularly preferred at least 80% and less than 100% of the surface of the nozzle plate (101), wherein there is a rim (303) of the ink film (301) spaced from each edge (103) delimiting the nozzle plate (101), wherein the distance or distances is/are greater than zero, characterized in that in step b) a relative movement is carried out between the nozzle plate (101) and the vacuum suction means (305).
    2. Method according to claim 1 characterized in that the amount of the discharged ink is determined via a pressure applied to an ink chamber of the printing head (201), depending on the type of the ink, that is the viscosity and/or density of the ink and the discharging time.
    3. Method according to at least one of the preceding claims characterized in that the method is carried out in such a way that in step a) no ink drops release from the nozzle plate (101).
    4. Method according to at least one of the preceding claims characterized in that steps a) and b) are carried out in such a way that the provision of an ink film (301) wetting the surface of the nozzle plate (101) and the removal of the ink film (301) and of the impurities on the nozzle plate (101) by vacuum suction means (305) are carried out separately in time or overlap at least partially in time.
    5. Method according to at least one of the preceding claims characterized in that the discharging time is in a range between 50 msec and 3000 msec and preferably between 100 msec and 500 msec.
    EP15000693.0A 2014-03-19 2015-03-10 Method for cleaning a printer head Active EP2939834B1 (en)

    Priority Applications (1)

    Application Number Priority Date Filing Date Title
    ITBZ20140011 2014-03-19

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    EP2939834A1 EP2939834A1 (en) 2015-11-04
    EP2939834B1 true EP2939834B1 (en) 2019-10-23

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    Family Cites Families (5)

    * Cited by examiner, † Cited by third party
    Publication number Priority date Publication date Assignee Title
    DE60301440T2 (en) 2002-06-28 2006-05-24 Agfa-Gevaert Method for cleaning the nozzle plate
    US7083253B2 (en) 2003-03-25 2006-08-01 Toshiba Tec Kabushiki Kaisha Ink jet recording apparatus having cleaning means for the cleaning of the nozzle surface of an ink jet head
    JP3804862B2 (en) * 2003-09-12 2006-08-02 富士写真フイルム株式会社 Inkjet recording head and image forming apparatus
    US7506952B2 (en) * 2005-10-11 2009-03-24 Silverbrook Research Pty Ltd Method of removing particulates from a printhead using film transfer
    JP5504916B2 (en) * 2010-01-26 2014-05-28 株式会社リコー Droplet discharge apparatus and image forming apparatus

    Non-Patent Citations (1)

    * Cited by examiner, † Cited by third party
    Title
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