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WO1991000807A1 - Procede et agencement pour la surveillance de l'ejection de gouttelettes des buses d'une tete d'impression a jet d'encre - Google Patents

Procede et agencement pour la surveillance de l'ejection de gouttelettes des buses d'une tete d'impression a jet d'encre Download PDF

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Publication number
WO1991000807A1
WO1991000807A1 PCT/EP1990/000659 EP9000659W WO9100807A1 WO 1991000807 A1 WO1991000807 A1 WO 1991000807A1 EP 9000659 W EP9000659 W EP 9000659W WO 9100807 A1 WO9100807 A1 WO 9100807A1
Authority
WO
WIPO (PCT)
Prior art keywords
ink
sensor
ink droplets
droplets
arrangement according
Prior art date
Application number
PCT/EP1990/000659
Other languages
German (de)
English (en)
Inventor
Ernst Goepel
Andreas Kappel
Original Assignee
Siemens Aktiengesellschaft
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 Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO1991000807A1 publication Critical patent/WO1991000807A1/fr

Links

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
    • B41J2/125—Sensors, e.g. deflection sensors

Definitions

  • the invention relates to a method and an arrangement for monitoring the droplet ejection from outlet nozzles of an ink print head according to the features of claims 1 and 7.
  • Known methods for displaying characters or graphic patterns with ink printing devices are based on the fact that individual droplets are ejected in a controlled manner from outlet nozzles of an ink printing head. Such arrangements are referred to as so-called drop-on-demand (DOD) arrangements.
  • DOD drop-on-demand
  • characters or graphic patterns in the form of a large number of individual points are thus built up in a grid pattern on the record carrier.
  • the quality of the recordings made in this way, the so-called writing quality essentially depends on the number of droplets by which a sign is formed.
  • each outlet nozzle has its own drive element, for example in the form of an electrically controllable piezo element or a heating element (bubble jet principle) assigned.
  • these drive elements together with the ink channel and an ink supply system, must exhibit a behavior that is co-ordinated.
  • ink printing devices that are subject to the functional monitoring of the user is print image acceptance.
  • the user of ink printing devices must recognize in good time whether the typeface generated is faulty or not. This is particularly difficult in the case of multi-nozzle ink heads of high print resolution, since the failure of one or more nozzles of the ink print head initially only results in a slight deterioration in the print image.
  • an ink droplet detector which comprises a plurality of electrodes, at least the first electrode of which can be brought into a position in which it can Exit nozzles of the ink print head is opposite at a predetermined distance.
  • the ⁇ 'change of resistance between the first electrode and another electrode is detected, when ejected from the ink jet head, the conductive ink first electrode reached.
  • Another measure known from DE-37 32 395 A1 is to provide an ink droplet sensor for monitoring the droplet ejection from individual outlet nozzles of an ink-writing head, the surface of which faces the outlet nozzles is designed as an electrode comb with comb-like structured conductor tracks, which is formed on at least one of a non-conductive porous layer existing suction block are applied.
  • the resistance between adjacent conductor tracks changes when one or more droplets strike.
  • An evaluation circuit connected to the conductor tracks monitors the change in resistance and emits a sensor signal corresponding to this change in resistance.
  • the amount of liquid applied with the impact of one or more droplets is discharged capillary via the porous layer of the suction block.
  • the object of the invention is to provide measures for monitoring the droplet discharge, with which the function of a high-resolution ink print head with a plurality of outlet nozzles can be checked automatically and in a simple manner and which enable a safe and reliable evaluation of the measurement results thus obtained.
  • the reliability of ink printing devices can be Grip of the printer user can be increased by the function of the ink print head being checked by the sensor before and cyclically during the printing operation and, if necessary, if a failure of one or more nozzles with the sensor is detected, measures to restore the so-called service station Functionality of the ink print head can be initiated.
  • the thermal energy carried by the ejected ink droplets is used to prove the functionality of the individual outlet nozzles.
  • the ink droplets and the detector are at different temperature levels.
  • ink printing devices this is already given to a certain extent by the fact that ink printing units are heated to temperatures which are generally above room temperature by heating devices which are already present, so that the requirements for the use of the sensor arrangement according to the invention are met in a simple manner without additional means.
  • This sensor principle can be used particularly advantageously in the case of ink printing devices which work with thermal converters, so-called bubble jet ink printing heads, since a considerable part of the electrical energy supplied is carried as heat by the ejected ink droplets. This eliminates the need for any measure to produce the required temperature difference between the detector and the ink droplets.
  • Optimal operational reliability and print quality are guaranteed by the automatic checking of the ink printing device before the start of the printing operation and by the automatic control procedure during the printing operation.
  • the entire arrangement is inexpensive and inexpensive to manufacture and relieves the user of the printing device from its own, possibly imprecise controls, since the ink printing device controls itself at defined times.
  • the necessary components for the sensor arrangement are simple and easy to manufacture. If the thermal energy of the ejected ink droplets is detected by heat conduction, conventional and therefore inexpensive components such as PTC thermistor, thermistor or semiconductor components such as silicon sensors can be used as sensor elements. Infrared detectors, such as pyroelectric lithium tantalum (LiTa03), lithium niobate (LiNb0 3 ) or polyvinylidene fluoride (PVDF) detectors, are particularly suitable as receiving elements for the thermal radiation emitted by the ink droplets, which are sufficient for the evaluation ⁇ give high output signal.
  • a heat transmission film made of simple plastic can advantageously be connected between the nozzle plate of the ink print head and the sensor sensitive to heat radiation, since this enables a structure with relatively small dimensions to be realized.
  • the thermal radiation of the ink droplets is used directly, for example when the fly by the active sensor surface is detected, it is advantageous to arrange a collecting device for the ink droplets after the sensor, from which the collected ink liquid e.g. is aspirated capillary. This makes it easy to dispose of this waste ink.
  • a simple evaluation device for the sensor signals generated by the ink droplet sensor that can be produced with little effort contains only two active components in the form of operational amplifiers convert and digitize the sensor signal so that a signal is available at the output of the evaluation device which can be used in a simple manner as a criterion for deactivating the ink printing device.
  • the thermal energy carried by the ink droplets includes also depends on the size of the ink droplets, it is also possible, in addition to the general statement as to whether a nozzle ejects ink droplets, also to obtain information as to whether a nozzle ejects ink droplets of small or large mass. It is only necessary for this, not only the presence of a sensor signal, but also to evaluate the magnitude of the sensor signal.
  • FIG. 1 shows a first exemplary embodiment for the indirect use of the thermal energy carried by the ink droplets
  • FIG. 2 shows a second exemplary embodiment for the direct use of the thermal radiation emitted by the ink droplets
  • FIG. 3 shows a possible circuit arrangement of the evaluation electronics for the signals and generated by the ink droplet sensor
  • FIG. 4 waveforms when heat radiation caused by one or more ink droplets strikes the sensor.
  • a spray module 1 of an ink writing device shown only schematically in a side view in FIG. 1, contains an ink print head 2 with a nozzle plate 16, at which a plurality of outlet nozzles 13 end.
  • the energy for ejecting the ink droplets 3 is determined by thermal Generates energy (bubble jet technology).
  • the spray module 1 is adjusted and locked on guide elements, not shown here, of a so-called printer block of the ink printing device with the aid of the locking elements 14, 15, which are only indicated in the drawing.
  • several such spray modules 1 can be arranged in a row perpendicular to the drawing plane, the ink print heads of which are then connected to different ink reservoirs containing the desired printing inks.
  • a heat-sensitive ink droplet sensor 6 is arranged such that it is used indirectly to detect the thermal energy carried by the ink droplets 3.
  • a relatively thin carrier film 5 is provided in the trajectory of the ink droplets 3 ejected from the outlet nozzles 13 between the nozzle plate 16 and the ink droplet sensor 6, and the ink droplets 3 impinge on the side facing the nozzle plate 16.
  • the carrier film 5 acting as a heat transmission element can be realized as a thin film made of conventional plastic and emits the thermal energy of the sprayed-on ink droplets 3 from its rear side facing the ink droplet sensor 6 as heat radiation 11 onto an active sensor surface 7 of the sensor 6 .
  • the senor 6 contains an infrared detector 8 which emits a sensor signal i corresponding to the heat radiation 11 received.
  • An evaluation device 10 is connected downstream of the sensor 6 and, depending on the presence of the sensor signal i, either releases the ink printing device for printing operation or sets it in a fault state.
  • the ink liquid 4 which has accumulated on the carrier film 5 during the function test becomes capillary, removed by mechanical transport of the carrier film by a winding / unwinding device or by a wiping mechanism, not shown here. The waste ink thus discharged can then be disposed of in a manner known per se.
  • the thermal radiation 11 emitted by the ejected ink droplets is used directly for function monitoring of the ink print head.
  • the upper half of FIG. 2 shows this sensor arrangement in a side view, the lower half in a top view.
  • the ink droplet sensor 6, the construction of which corresponds to the construction of the sensor explained with reference to FIG. 1, is arranged outside the trajectory of the ink droplets 3 in such a way that its active sensor surface 7 lies at a short distance parallel to the trajectory of the ink droplets 3 .
  • the heat radiation 11 is detected when the ink droplets 3 fly past the active sensor surface 7.
  • the ink droplet sensor 6 has a collar-like protruding edge 17 of the active sensor surface 7, which considerably reduces possible interference from the sensor environment and generates a sensor signal i with an evaluable amplitude.
  • an evaluation device 10 is connected downstream, analogous to the arrangement in FIG.
  • FIG. 3 shows a possible circuit arrangement for utilizing the sensox signals i generated by the ink droplet sensor 6.
  • the evaluation device 10 contains two active electrical components, namely the operational amplifiers 0P1 and 0P2.
  • the two outputs of the sensor 6 are led to the inputs of the first operational amplifier 0P1, the inverting input of the operational amplifier 1 being connected to its output via an ohmic resistor Rp.
  • the connections for the supply voltage of the operational amplifier 0P1 are omitted for reasons of clarity.
  • the output of the operational amplifier 0P1 is connected via a resistor R once to the non-inverting input and once to the inverting input of the second operational amplifier 0P2.
  • a capacitor C is connected to the inverting input, the other connection of which is at reference potential, for example 0 V.
  • a resistor R v is connected between the non-inverting input of the operational amplifier 0P2 and the positive operating voltage + U B of the operational amplifier 0P2. -U ß the negative writing tive operating voltage of the operational amplifier 0P2 is be ⁇ distinguished.
  • An output signal U fi can be tapped at the output A of the operational amplifier 0P2, which can be used to activate a fault display or to switch off the ink pressure device.
  • the signal U output by the operational amplifier 0P1 is digitized in the operational amplifier 0P2, which operates as a comparator, with the aid of the integrating element, consisting of the resistor R and the capacitor C, which forms an average.
  • the resistor R "serves to generate the necessary level shift when digitizing U on the comparator.
  • FIG. 4 shows basic signal profiles as they can occur within the evaluation device 10 when the thermal radiation caused by one or more ink droplets 3 strikes the sensor 6.
  • the measures described can also be used for all other ink printing devices in which the droplet is ejected, for example, by electrical control of individual piezo elements. Due to the requirement of a uniform and reproducible droplet ejection, it is necessary to keep the temperature of the ink liquid at a constant value. It is therefore a customary measure to heat ink printing units and thus the ink liquid by means of various types of heating devices to temperatures which are generally above the room temperature. As a result, the requirements for the functional transmission according to the invention are also given.

Landscapes

  • Ink Jet (AREA)

Abstract

Pour la surveillance de l'éjection de gouttelettes des différentes buses (13) d'une tête d'impression à jet d'encre à haute résolution (2), il est prévu un détecteur de gouttelettes d'encre thermosensible (6) qui prend comme critère pour le bon fontionnement des différentes buses (3) l'énergie thermique apportée par les gouttelettes d'encre éjectées (3). A cette occasion, l'énergie thermique est détectée soit par conduction thermique, soit par le rayonnement thermique (11) émis par les gouttelettes d'encre.
PCT/EP1990/000659 1989-07-07 1990-04-24 Procede et agencement pour la surveillance de l'ejection de gouttelettes des buses d'une tete d'impression a jet d'encre WO1991000807A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE89112496.8 1989-07-07
EP89112496 1989-07-07

Publications (1)

Publication Number Publication Date
WO1991000807A1 true WO1991000807A1 (fr) 1991-01-24

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP1990/000659 WO1991000807A1 (fr) 1989-07-07 1990-04-24 Procede et agencement pour la surveillance de l'ejection de gouttelettes des buses d'une tete d'impression a jet d'encre

Country Status (1)

Country Link
WO (1) WO1991000807A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0623469A2 (fr) * 1993-05-03 1994-11-09 Hewlett-Packard Company Méthode de commande pour imprimante à jet d'encre thermique
EP1043162A1 (fr) * 1999-04-07 2000-10-11 Canon Kabushiki Kaisha Méthode de détection de liquide et appareil pour cela, appareil d'impression à jet d'encre, et méthode de détection d'encre pour appareil à jet d'encre
WO2003022591A1 (fr) * 2001-09-10 2003-03-20 Seiko Epson Corporation Depot de matieres solubles
WO2012083980A1 (fr) 2010-12-21 2012-06-28 Baumer Innotec Ag Tête d'impression à jet d'encre à contrôle optique intégré de la fonction de buse

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914772A (en) * 1972-10-27 1975-10-21 Casio Computer Co Ltd Ink jet type printing device
US4550327A (en) * 1982-01-08 1985-10-29 Canon Kabushiki Kaisha Device for discharging liquid droplets

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3914772A (en) * 1972-10-27 1975-10-21 Casio Computer Co Ltd Ink jet type printing device
US4550327A (en) * 1982-01-08 1985-10-29 Canon Kabushiki Kaisha Device for discharging liquid droplets

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0623469A2 (fr) * 1993-05-03 1994-11-09 Hewlett-Packard Company Méthode de commande pour imprimante à jet d'encre thermique
EP0623469A3 (fr) * 1993-05-03 1995-08-30 Hewlett Packard Co Méthode de commande pour imprimante à jet d'encre thermique.
EP1043162A1 (fr) * 1999-04-07 2000-10-11 Canon Kabushiki Kaisha Méthode de détection de liquide et appareil pour cela, appareil d'impression à jet d'encre, et méthode de détection d'encre pour appareil à jet d'encre
US6540318B1 (en) 1999-04-07 2003-04-01 Canon Kabushiki Kaisha Liquid detection method and apparatus therefor, ink-jet printing apparatus, and ink detection method for the ink-jet printing apparatus
WO2003022591A1 (fr) * 2001-09-10 2003-03-20 Seiko Epson Corporation Depot de matieres solubles
US7293852B2 (en) 2001-09-10 2007-11-13 Seiko Epson Corporation Deposition of soluble materials using an inkjet print head and CCD microscope
WO2012083980A1 (fr) 2010-12-21 2012-06-28 Baumer Innotec Ag Tête d'impression à jet d'encre à contrôle optique intégré de la fonction de buse
US9056465B2 (en) 2010-12-21 2015-06-16 Baumer Innotec Ag Ink-jet print head with integrated optical monitoring of the nozzle function

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