EP0326804A2 - Piezo-electrically actuated print head in an ink jet mosaic printer - Google Patents

Piezo-electrically actuated print head in an ink jet mosaic printer Download PDF

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Publication number
EP0326804A2
EP0326804A2 EP89100187A EP89100187A EP0326804A2 EP 0326804 A2 EP0326804 A2 EP 0326804A2 EP 89100187 A EP89100187 A EP 89100187A EP 89100187 A EP89100187 A EP 89100187A EP 0326804 A2 EP0326804 A2 EP 0326804A2
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EP
European Patent Office
Prior art keywords
ink
channels
pressure
outlet openings
opening
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Withdrawn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
EP89100187A
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German (de)
French (fr)
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EP0326804A3 (en
Inventor
Fred Dipl.-Ing. Johannsen
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.)
AEG Olympia Office GmbH
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AEG Olympia AG
AEG Olympia Office GmbH
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Application filed by AEG Olympia AG, AEG Olympia Office GmbH filed Critical AEG Olympia AG
Publication of EP0326804A2 publication Critical patent/EP0326804A2/en
Publication of EP0326804A3 publication Critical patent/EP0326804A3/en
Withdrawn legal-status Critical Current

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    • 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
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2/14201—Structure of print heads with piezoelectric elements
    • B41J2/14233—Structure of print heads with piezoelectric elements of film type, deformed by bending and disposed on a diaphragm
    • 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
    • B41J2/135—Nozzles
    • B41J2/14—Structure thereof only for on-demand ink jet heads
    • B41J2002/14387—Front shooter

Definitions

  • the invention relates to a piezoelectrically operated write head for ink mosaic writing devices of the type specified in the preamble of claim 1.
  • the nozzle head of a droplet recorder generally has a pressure chamber connected to a liquid container, a nozzle which emits individual droplets and is connected to the pressure chamber, as well as an electromechanical transducer, for example a piezoelectric plate.
  • Part of the pressure chamber has a flexible area or a so-called membrane.
  • a device for a spray head of an ink droplet printer in which a wall of the fluid chamber is formed by a cover plate with which a plate made of piezoceramic is connected.
  • the piezoceramic is excited by means of electrical signals via electrodes and caused to vibrate, which are transmitted to the cover plate of the fluid chamber, which ultimately leads to the ejection of liquid droplets.
  • a large number of pressure chambers and electromechanical transducers must be provided in order to produce fine-screened characters in fine writing quality with the ink droplet writing heads.
  • Such a writing head is known from DE-0S 34 12 531, in which several plates with ink channels are provided. These plates are connected airtight and have staggered outlet nozzles.
  • DE-OS 31 08 885 also discloses a plurality of ink channels arranged in a radial manner.
  • a disadvantage of these known arrangements is that the ink channels are of different lengths and therefore no in-phase leakage of ink droplets out of the way ensure access openings. This also means that it is not possible to create exactly vertical lines or clean typefaces.
  • an ink writing head is known from DE-A1 36 08 205, in which the pressure channels are all of the same length.
  • the suction channels have an unequal length, so that an in-phase exit is not always guaranteed.
  • the object of the invention is to provide a piezoelectrically operated write head for ink mosaic devices which has a multiplicity of ink channels in a compact arrangement and thereby ensures that uniformly uniform droplets of ink emerge from the outlet openings.
  • This object is achieved by the invention characterized in claim 1.
  • the write head for ink mosaic writing devices has a simple structure with the same length of the ink channels from the beginning of the pressure channels to the outlet openings and the suction channels between the pressure chambers and the damping members. This ensures that the pressure pulses generated in the pressure chambers simultaneously reach the nozzle outlet openings. This measure enables a graphics-capable fine grid to be achieved with a compact construction of the writing system.
  • FIG. 1 shows a section through a writing head 1 for ink mosaic writing devices with a plurality of ink channels 3 running in a straight line from outlet openings 2, in which the writing fluid contained in compression chambers 4 is ejected drop-shaped from the outlet openings 2 by piezoelectric deformation of a drive element.
  • the write head 1 consists of a base plate 5, a membrane plate 11 and an integrated piezo crystal plate 13.
  • the base plate 5 and the membrane plate 11 are made of glass, the ink channels 3, the pressure chambers 4 and the damping members 7 are etched deep into the base plate 5.
  • the membrane plate 11 serves as a cover for the channels 3, the pressure chambers 4, etc., and at the same time as a pump membrane, which is moved by piezo crystals 10.
  • the ink channels 3 are in fluid communication with an ink storage chamber 9 via attenuators 7 designed as diodes on the suction side of the compression chambers 4, the ink channels 3 from the ink storage chamber 9 all the way up to the outlet nozzles 2.
  • the attenuators 7 simultaneously prevent air from entering the ink channels.
  • FIG. 2 shows a piezoelectrically operated drive element which has the square-shaped piezo crystal 10.
  • This piezo crystal 10 is fixed on the elastic membrane plate 11 by means of an adhesive 12.
  • the piezo crystal 10 is also fastened to a flexible printed circuit board 13 by means of an adhesive 14, the printed circuit board 13 in turn being connected to a contact plate 15.
  • the drive elements 4, 10, 11 are alternately staggered on two circles aligned concentrically with the outlet openings 2 in the longitudinal direction of the ink channels 3, thereby ensuring a compact arrangement of the pressure chambers 4 in the write head 1.
  • the sections 17 of the ink channels 3 which open into the compression chambers 4 on the inner circle are designed in such a way that the ink channels 3 all have the same channel length from the outlet openings to the drive elements 4, 10, 11.
  • the sections 18 of the ink channels 3, which open into the compression chambers 4 of the pressure chambers arranged on the outer circle, are designed in a straight line.
  • the ink channels 3 serving as suction channels between the drive elements 4, 10 and the damping members 7 are all of the same length.
  • the ink channels 3 also have alternating straight sections 21 or curved sections 22 on the suction side.
  • the straight sections 21 are in fluid communication with the pressure chambers 4 arranged on the inner circle, while the curved sections 22 open into the outer chambers 4.
  • flow deflection elements 23, 24 are arranged at the transition points of the ink channels 3 into the pressure chambers 4, through which the ink flow into the ink channels 3, in particular in the tortuous sections 17, 22, can be conducted in such a way that no air bubbles form and get caught in these sections can.
  • the flow deflecting elements 23, 24 have a diamond-shaped cross section, the free ends of which are firmly connected to the membrane plate 11.
  • the pressure channels 17, 18 opening into the pressure chambers 4 also have a diameter several times larger than the diameters of the suction channels 21, 22 opening into the pressure chambers 4. This ensures that the flow of ink to the outlet nozzles 2 is facilitated and to the attenuators 7 more difficult.
  • the ink supply chamber 9 has at its ends ascending channels 25, 26 which end immediately above and below the outlet nozzles 2 of the ink channels 3 arranged in a row in an end face 27 of the print head 1 with outlet openings 28, 29. As a result, air contained in the ink supply chamber 9 can safely escape to the outside.
  • the base plate 5 and the membrane plate 11 are connected to one another by an adhesive connection. Since any air entrapment between these plates 5, 11, in particular in the adhesive surfaces, must be avoided, the base plate 5 has in its support surfaces 30, 31, 32, 33 for the membrane plate 11 arranged outside the ink channels 3, the pressure chambers 5 and the ink supply chamber 9 channel-shaped depressions 34, 35, 36, 37, which are connected to ventilation channels 38, 39, 40, 41. In this way, a secure adhesive connection between the plates 5, 11 is achieved.
  • the membrane plate 5 has an opening 42 to the ink supply chamber 9, which is surrounded by a cylindrical sealing element 43.
  • This sealing element is firmly connected to the membrane plate 11 and has a damping membrane 44 above the opening 42. This reliably dampens any pressure surges that may occur in the ink supply channels.
  • Below the damping membrane 44 there is an ink inlet opening 44 for a connecting hose 46 to an ink tank (not shown).
  • the ink introduced through the ink inlet opening 45 is then filtered via a filter membrane 47 in such a way that any air bubbles or dirt particles that are carried along cannot get into the ink storage chamber 9 in the write head 1.
  • the damping membrane 44 is formed in two layers, by the way, while the filter membrane 47 consists of a nylon filter fabric.

Abstract

Both for the print image and also for reliability when printing with ink jet mosaic printers, it is important that the expulsion of ink droplets out of the individual outlet nozzles occurs at the same constant speed. Since, in addition to the driving criteria, material properties and production influences also play a not inconsiderable role in this, in the known devices for expulsion of droplets an adjustment is performed. This adjustment is achieved for example by setting the pulse voltage with which the individual drive elements of an ink jet mosaic head are operated. In this case, no simple setting is provided by means of which it is ensured that the ink droplets emerge from the outlet openings 2 in phase. This is achieved according to the invention in that the sections (17, 18), serving as pressure channels, of the ink channels (3) from the pressure chambers (4) as far as the outlet openings (2) and the suction channels (21, 22) leading into the pressure chambers (4) are all constructed with identical length. Due to the fact that the ink droplets emerge from the outlet openings (2) in phase, graphic representations are possible with a fine matrix and a compact design of the print head. <IMAGE>

Description

Die Erfindung betrifft einen piezoelektrisch betriebenen Schreib­kopf für Tintenmosaikschreibeinrichtungen der im Oberbegriff des Patentanspruchs 1 angegebenen Art.The invention relates to a piezoelectrically operated write head for ink mosaic writing devices of the type specified in the preamble of claim 1.

Der Düsenkopf eines Tröpfchenschreibers weist in der Regel eine mit einem Flüssigkeitsbehälter verbundene Druckkammer, eine mit der Druckkammer verbundene, einzelne Tröpfchen abgebende Düse sowie einen elektromechanischen Wandler, beispielsweise eine piezoelektrische Platte auf. Ein Teil der Druckkammer besitzt dabei einen biegsamen Bereich bzw. eine sogenannte Membrane.The nozzle head of a droplet recorder generally has a pressure chamber connected to a liquid container, a nozzle which emits individual droplets and is connected to the pressure chamber, as well as an electromechanical transducer, for example a piezoelectric plate. Part of the pressure chamber has a flexible area or a so-called membrane.

Aus der DE-AS 22 56 667 ist eine Vorrichtung für einen Spritzkopf eines Tintentröpfchen-Druckers bekannt, bei dem eine Wand der Fluidkammer von einer Abdeckplatte gebildet wird, mit welcher eine Platte aus Piezokeramik verbunden ist. Die Piezokeramik wird mit Hilfe von elektrischen Signalen über Elektroden erregt und zu Schwingungen veranlaßt, die auf die Abdeckplatte der Fluidkammer übertragen werden, was schließlich zum Ausstoß von Flüssigkeits­tröpfchen führt.From DE-AS 22 56 667 a device for a spray head of an ink droplet printer is known, in which a wall of the fluid chamber is formed by a cover plate with which a plate made of piezoceramic is connected. The piezoceramic is excited by means of electrical signals via electrodes and caused to vibrate, which are transmitted to the cover plate of the fluid chamber, which ultimately leads to the ejection of liquid droplets.

Um mit den Tintentröpfchen-Schreibköpfen feingerasterte Schrift­zeichen in Schönschriftqualität zu erzeugen, muß eine Vielzahl von Druckkammern und elektromechanischen Wandlern vorgesehen sein. So ist durch die DE-0S 34 12 531 ein derartiger Schreibkopf bekannt, bei dem mehrere Platten mit Tintenkanälen vorgesehen sind. Diese Platten sind luftdicht miteinander verbunden und weisen versetzt angeordnete Austrittsdüsen auf. Aus der DE-OS 31 08 885 sind auch mehrere strahlenförmig angeordnete Tinten­kanäle bekannt. Ein Nachteil dieser bekannten Anordnungen besteht darin, daß die Tintenkanäle unterschiedlich lang sind und daher kein phasengleiches Austreten von Tintentröpfchen aus den Aus­ trittsöffnungen gewährleisten. Hierdurch ist es auch nicht mög­lich, genau senkrechte Linien bzw. saubere Schriftbilder zu er­zeugen.A large number of pressure chambers and electromechanical transducers must be provided in order to produce fine-screened characters in fine writing quality with the ink droplet writing heads. Such a writing head is known from DE-0S 34 12 531, in which several plates with ink channels are provided. These plates are connected airtight and have staggered outlet nozzles. DE-OS 31 08 885 also discloses a plurality of ink channels arranged in a radial manner. A disadvantage of these known arrangements is that the ink channels are of different lengths and therefore no in-phase leakage of ink droplets out of the way ensure access openings. This also means that it is not possible to create exactly vertical lines or clean typefaces.

Sowohl für das Schriftbild als auch für die Zuverlässigkeit im Schreibbetrieb bei Tintenmosaikschreibeinrichtungen ist es wei­terhin von Bedeutung, daß der Ausstoß von Tintentröpfchen aus den einzelnen Düsen mit gleicher und konstanter Geschwindigkeit erfolgt. Da hierfür neben den Ansteuerkriterien aber auch Ma­terialeigenschaften und Fertigungseinflüsse eine nicht unerheb­liche Rolle spielen, und diese nur zum Teil beeinflußbar sind, ist es bekannt geworden, für den Tröpfchenausstoß einen Abgleich vorzusehen. Das wurde bisher durch die Einstellung der Impuls­spannung mit der die einzelnen Antriebselemente eines Tinten­mosaikschreibkopfes betrieben werden, gelöst (DE-OS 28 50 016). Mit einem solchen Abgleich sind jedoch einige Nachteile verbun­den. Zum einen ist dazu ein nicht unerheblicher Schaltungsaufwand und damit ein beträchtlicher Platzbedarf erforderlich und zum anderen kann der Abgleich nicht unmittelbar im Schreibkopf durch­geführt werden. Weiterhin ist hierbei auch nicht die Zeit ein­stellbar, so daß ein phasengleiches Austreten der Tintentröpfchen aus den Austrittsöffnungen nicht erzielbar ist.For the typeface as well as for the reliability in writing operation with ink mosaic writing devices, it is also important that the droplets of ink are ejected from the individual nozzles at the same and constant speed. Since, in addition to the control criteria, material properties and manufacturing influences also play a not insignificant role, and these can only be influenced in part, it has become known to provide a comparison for the droplet ejection. This was previously achieved by setting the pulse voltage with which the individual drive elements of an ink mosaic writing head are operated (DE-OS 28 50 016). However, there are some disadvantages associated with such a comparison. On the one hand, a not inconsiderable amount of circuitry and thus a considerable amount of space are required, and on the other hand, the adjustment cannot be carried out directly in the write head. Furthermore, the time cannot be set here either, so that an in-phase exit of the ink droplets from the outlet openings cannot be achieved.

Weiterhin ist durch die DE-A1 36 08 205 ein Tintenschreibkopf bekannt, bei dem die Druckkanäle alle gleich lang ausgebildet sind. Hierbei weisen aber die Saugkanäle eine ungleiche Länge auf, so daß ein phasengleiches Austreten nicht immer gewähr­leistet ist.Furthermore, an ink writing head is known from DE-A1 36 08 205, in which the pressure channels are all of the same length. Here, however, the suction channels have an unequal length, so that an in-phase exit is not always guaranteed.

Die Aufgabe der Erfindung besteht darin, einen piezoelektrisch betriebenen Schreibkopf für Tintenmosaikeinrichtungen der in kompakter Anordnung eine Vielzahl von Tintenkanälen aufweist und dabei ein phasengleiches Austreten von insich gleichmäßigen Tintentröpfchen aus den Austrittsöffnungen gewährleistet. Diese Aufgabe wird durch die im Patentanspruch 1 gekennzeichnete Erfin­dung gelöst.The object of the invention is to provide a piezoelectrically operated write head for ink mosaic devices which has a multiplicity of ink channels in a compact arrangement and thereby ensures that uniformly uniform droplets of ink emerge from the outlet openings. This object is achieved by the invention characterized in claim 1.

Der erfindungsgemäße Schreibkopf für Tintenmosaikschreibeinrich­tungen weist einen einfachen Aufbau bei gleicher Länge der Tin­tenkanäle vom Beginn der Druckkanäle bis zu den Austrittsöffnun­gen und der Saugkanäle zwischen den Druckkammern und den Däm­pfungsgliedern auf. Hierdurch wird gewährleistet, daß die in den Druckkammern erzeugten Druckimpulse gleichzeitig die Düsenaus­trittsöffnungen erreichen. Durch diese Maßnahme kann ein grafik­fähiges Feinraster bei kompakter Bauweise des Schreibsystems er­reicht werden.The write head for ink mosaic writing devices according to the invention has a simple structure with the same length of the ink channels from the beginning of the pressure channels to the outlet openings and the suction channels between the pressure chambers and the damping members. This ensures that the pressure pulses generated in the pressure chambers simultaneously reach the nozzle outlet openings. This measure enables a graphics-capable fine grid to be achieved with a compact construction of the writing system.

Weitere vorteilhafte Ausgestaltungen des Erfindungsgegenstandes sind den weiteren Unteransprüchen zu entnehmen.Further advantageous refinements of the subject matter of the invention can be found in the further subclaims.

Die Erfindung wird anhand eines Ausführungsbeispiels im folgenden näher beschrieben. Es zeigen

  • Figur 1 einen Schreibkopf mit Draufsicht auf alle Tinte enthaltenen Kanäle und Kammern,
  • Figur 2 einen Querschnitt durch ein piezoelektrisch betriebenes Antriebselement,
  • Figur 3 eine Einzelheit aus Figur 2 und
  • Figur 4 einen Schreibkopf in Seitenansicht mit einem Tintenanschluß im Schnitt.
The invention is described in more detail below using an exemplary embodiment. Show it
  • FIG. 1 shows a write head with a top view of all channels and chambers containing ink,
  • FIG. 2 shows a cross section through a piezoelectrically operated drive element,
  • Figure 3 shows a detail of Figure 2 and
  • Figure 4 shows a write head in side view with an ink port in section.

Die Figur 1 zeigt einen Schnitt durch einen Schreibkopf 1 für Tintenmosaikschreibeinrichtungen mit mehreren von Austrittsöff­nungen 2 her strahlenförmig geradlinig verlaufenden Tintenkanälen 3, bei denen die in Kompressionskammern 4 enthaltene Schreib­flüssigkeit durch piezoelektrische Verformung eines Antriebs­elementes tropfenförmig aus den Austrittsöffnungen 2 ausgestoßen wird. Der Schreibkopf 1 besteht hierbei aus einer Grundplatte 5, einer Membranplatte 11 und einer integrierten Piezokristallplatte 13. Die Grundplatte 5 und die Membranplatte 1 1 bestehen aus Glas, wobei die Tintenkanäle 3, die Druckkammern 4 und die Dämpfungs­glieder 7 tief in die Grundplatte 5 eingeätzt sind. Die Membran­platte 11 dient als Abdeckung für die Kanäle 3, die Druckkammern 4 usw., und gleichzeitig als Pumpenmembran, die von Piezokristal­len 10 bewegt wird.FIG. 1 shows a section through a writing head 1 for ink mosaic writing devices with a plurality of ink channels 3 running in a straight line from outlet openings 2, in which the writing fluid contained in compression chambers 4 is ejected drop-shaped from the outlet openings 2 by piezoelectric deformation of a drive element. The write head 1 consists of a base plate 5, a membrane plate 11 and an integrated piezo crystal plate 13. The base plate 5 and the membrane plate 11 are made of glass, the ink channels 3, the pressure chambers 4 and the damping members 7 are etched deep into the base plate 5. The membrane plate 11 serves as a cover for the channels 3, the pressure chambers 4, etc., and at the same time as a pump membrane, which is moved by piezo crystals 10.

Die Tintenkanäle 3 stehen über auf der Saugseite der Kompres­sionskammern 4 als Dioden ausgebildete Dämpfungsglieder 7 mit einer Tintenvorratskammer 9 in Fließverbindung, wobei die Tinten­kanäle 3 von der Tintenvorratskammer 9 bis zu den Austrittsdüsen 2 alle steigend ausgebildet sind. Die Dämpfungsglieder 7 ver­hindern gleichzeitig ein Eindringen von Luft in die Tintenkanäle.The ink channels 3 are in fluid communication with an ink storage chamber 9 via attenuators 7 designed as diodes on the suction side of the compression chambers 4, the ink channels 3 from the ink storage chamber 9 all the way up to the outlet nozzles 2. The attenuators 7 simultaneously prevent air from entering the ink channels.

In der Figur 2 ist ein piezoelektrisch betriebenes Antriebsele­ment dargestellt, das den quadratförmigen Piezokristall 10 auf­weist. Dieser Piezokristall 10 ist auf der elastisch ausgebil­deten Membranplatte 11 mittels eines Klebers 12 fest angeordnet. Außerdem ist der Piezokristall 10 noch mit einer flexiblen Lei­terplatte 13 mittels eines Klebers 14 befestigt, wobei die Lei­terplatte 13 wiederum mit einer Kontaktplatte 15 in Verbindung steht.FIG. 2 shows a piezoelectrically operated drive element which has the square-shaped piezo crystal 10. This piezo crystal 10 is fixed on the elastic membrane plate 11 by means of an adhesive 12. In addition, the piezo crystal 10 is also fastened to a flexible printed circuit board 13 by means of an adhesive 14, the printed circuit board 13 in turn being connected to a contact plate 15.

Die Antriebselemente 4, 10, 11 sind auf zwei konzentrisch zu den Austrittsöffnungen 2 ausgerichteten Kreisen in Längsrichtung der Tintenkanäle 3 abwechselnd versetzt angeordnet, wodurch eine kompakte Anordnung der Druckkammern 4 in dem Schreibkopf 1 ge­währleistet wird. Die auf dem inneren Kreis in die Kompressions­kammern 4 mündenden Abschnitte 17 der Tintenkanäle 3 sind gewun­den ausgebildet, derart, daß die Tintenkanäle 3 von den Aus­trittsöffnungen bis zu den Antriebselementen 4, 10, 11 alle die gleiche Kanallänge haben. Die Abschnitte 18 der Tintenkanäle 3, die in die Kompressionskammern 4 der auf dem äußeren Kreis ange­ordneten Druckkammern münden, sind geradlinig ausgebildet. Bei der Gestaltung der gleichlangen Tintenkanallängen werden auch die die Tintenkanäle 3 mit dem senkrechten Aufzeichnungsträger 20 angeordneten Austrittsöffnungen 2 verbindenden Krümmungen 19 be­rücksichtigt. Der Einfluß der Umlenkradien der Krümmungen 19 ist mit den Kanallängen verrechnet worden, so daß die gestreckten Längen vom Beginn der Druckkanäle bis zu den Austrittsöffnungen gleich lang sind, damit die Druckimpulse die Austrittsöffnungen 2 gleichzeitig erreichen.The drive elements 4, 10, 11 are alternately staggered on two circles aligned concentrically with the outlet openings 2 in the longitudinal direction of the ink channels 3, thereby ensuring a compact arrangement of the pressure chambers 4 in the write head 1. The sections 17 of the ink channels 3 which open into the compression chambers 4 on the inner circle are designed in such a way that the ink channels 3 all have the same channel length from the outlet openings to the drive elements 4, 10, 11. The sections 18 of the ink channels 3, which open into the compression chambers 4 of the pressure chambers arranged on the outer circle, are designed in a straight line. When designing the ink channel lengths of the same length, the ink channels 3 with the vertical recording medium 20 arranged outlet openings 2 connecting curvatures 19 taken into account. The influence of the deflection radii of the curvatures 19 has been offset against the channel lengths, so that the stretched lengths from the beginning of the pressure channels to the outlet openings are of the same length, so that the pressure pulses reach the outlet openings 2 simultaneously.

Ebenfalls sind auch die als Saugkanäle dienenden Tintenkanäle 3 zwischen den Antriebselementen 4, 10 und den Dämpfungsgliedern 7 alle gleich lang ausgebildet. Zu diesem Zweck haben die Tinten­kanäle 3 auch auf der Saugseite abwechselnd gerade Abschnitte 21 oder gewundene Abschnitte 22. Hierbei stehen die geraden Ab­schnitte 21 mit den auf dem inneren Kreis angeordneten Druck­kammern 4 in Fließverbindung, während die gewundenden Abschnitte 22 in die äußeren Kammern 4 münden.Also, the ink channels 3 serving as suction channels between the drive elements 4, 10 and the damping members 7 are all of the same length. For this purpose, the ink channels 3 also have alternating straight sections 21 or curved sections 22 on the suction side. Here, the straight sections 21 are in fluid communication with the pressure chambers 4 arranged on the inner circle, while the curved sections 22 open into the outer chambers 4.

Weiterhin sind an den übergangsstellen der Tintenkanäle 3 in die Druckkammern 4 Strömungsumlenkelemente 23, 24 angeordnet, durch die die Tintenströmung in die Tintenkanäle 3, insbesondere in den gewundenen Abschnitten 17, 22 derart leitbar ist, daß in diesen Abschnitten sich keine Luftbläschen bilden und hängen bleiben können. Die Strömungsumlenkelemente 23, 24 haben einen rauten­förmigen Querschnitt, deren freie Enden mit der Membranplatte 11 fest verbunden sind.Furthermore, flow deflection elements 23, 24 are arranged at the transition points of the ink channels 3 into the pressure chambers 4, through which the ink flow into the ink channels 3, in particular in the tortuous sections 17, 22, can be conducted in such a way that no air bubbles form and get caught in these sections can. The flow deflecting elements 23, 24 have a diamond-shaped cross section, the free ends of which are firmly connected to the membrane plate 11.

Auch weisen die in die Druckkammern 4 mündenden Druckkanäle 17, 18 einen Durchmesser in mehrfacher Größe zu den Durchmessern der in die Druckkammern 4 mündenden Saugkanäle 21, 22 auf. Hierdurch wird gewährleistet, daß der Tintenfluß zu den Austrittsdüsen 2 erleichtert und zu den Dämpfungsgliedern 7 erschwert wird.The pressure channels 17, 18 opening into the pressure chambers 4 also have a diameter several times larger than the diameters of the suction channels 21, 22 opening into the pressure chambers 4. This ensures that the flow of ink to the outlet nozzles 2 is facilitated and to the attenuators 7 more difficult.

Durch die obigen Ausbildungen wird ein phasengleiches Austreten der Tintentröpfchen aus den Austrittsöffnungen ermöglicht, wo­durch ein grafikfähiges Feinraster bei kompakter Bauweise des Schreibkopfes 1 erzielbar ist.The above configurations enable the ink droplets to emerge in phase from the outlet openings, as a result of which a graphic-capable fine screen can be achieved with a compact design of the write head 1.

Die Tintenvorratskammer 9 hat an ihren Enden aufsteigende Kanäle 25, 26, die unmittelbar ober- und unterhalb der in einer Reihe angeordneten Austrittsdüsen 2 der Tintenkanäle 3 in einer Stirn­fläche 27 des Schreibkopfes 1 mit Austrittsöffnungen 28, 29 enden. Hierdurch kann in der Tintenvorratskammer 9 enthaltene Luft sicher ins Freie entweichen.The ink supply chamber 9 has at its ends ascending channels 25, 26 which end immediately above and below the outlet nozzles 2 of the ink channels 3 arranged in a row in an end face 27 of the print head 1 with outlet openings 28, 29. As a result, air contained in the ink supply chamber 9 can safely escape to the outside.

Die Grundplatte 5 und die Membranplatte 11 werden durch eine Klebeverbindung miteinander verbunden. Da hierbei jeglicher Luft­einschluß zwischen diesen Platten 5, 11, insbesondere in den Klebeflächen vermieden werden muß, weist die Grundplatte 5 in ihren außerhalb der Tintenkanäle 3, der Druckkammern 5 und der Tintenvorratskammer 9 angeordneten Auflageflächen 30, 31, 32, 33 für die Membranplatte 11 kanalförmige Vertiefungen 34, 35, 36, 37 auf, die mit Entlüftungskanälen 38, 39, 40, 41 verbunden sind. Hierdurch wird eine sichere Klebeverbindung zwischen den Platten 5, 11 erzielt.The base plate 5 and the membrane plate 11 are connected to one another by an adhesive connection. Since any air entrapment between these plates 5, 11, in particular in the adhesive surfaces, must be avoided, the base plate 5 has in its support surfaces 30, 31, 32, 33 for the membrane plate 11 arranged outside the ink channels 3, the pressure chambers 5 and the ink supply chamber 9 channel-shaped depressions 34, 35, 36, 37, which are connected to ventilation channels 38, 39, 40, 41. In this way, a secure adhesive connection between the plates 5, 11 is achieved.

Gemäß Figur 4 weist die Membranplatte 5 einen Durchbruch 42 zu der Tintenvorratskammer 9 auf, der von einem zylinderförmigen Dichtungselement 43 umgeben ist. Dieses Dichtungselement ist mit der Membranplatte 11 fest verbunden und weist über dem Durchbruch 42 eine Dämpfungsmembran 44 auf. Hierdurch werden in den Tinten­zuführkanälen eventuell entstehende Druckstöße sicher gedämpft. Unterhalb der Dämpfungsmembran 44 ist eine Tinteneintrittsöffnung 44 für einen Anschlußschlauch 46 zu einem nicht dargestellten Tintenbehälter angeordnet. Die durch die Tinteneintrittsöffnung 45 hineingeführte Tinte wird dann über eine Filtermembran 47 derart gefiltert, daß eventuell mitgeführte Luftbläschen oder Schmutzteilchen nicht in die Tintenvorratskammer 9 in dem Schreibkopf 1 gelangen können. Die Dämpfungsmembran 44 ist übri­gens zweischichtig ausgebildet, während die Filtermembran 47 aus einem Nylon-Filtergewebe besteht.According to FIG. 4, the membrane plate 5 has an opening 42 to the ink supply chamber 9, which is surrounded by a cylindrical sealing element 43. This sealing element is firmly connected to the membrane plate 11 and has a damping membrane 44 above the opening 42. This reliably dampens any pressure surges that may occur in the ink supply channels. Below the damping membrane 44 there is an ink inlet opening 44 for a connecting hose 46 to an ink tank (not shown). The ink introduced through the ink inlet opening 45 is then filtered via a filter membrane 47 in such a way that any air bubbles or dirt particles that are carried along cannot get into the ink storage chamber 9 in the write head 1. The damping membrane 44 is formed in two layers, by the way, while the filter membrane 47 consists of a nylon filter fabric.

Claims (10)

1. Piezoelektrisch betriebener Schreibkopf für Tintenmosaik­schreibeinrichtungen mit mehreren von Austrittsöffnungen her strahlenförmig verlaufenden Tintenkanälen, bei denen die in einer Kompressionskammer enthaltene Schreibflüssigkeit durch piezoelektrische Verformung eines Antriebselementes über Druckkanäle tropfenförmig aus den Austrittsöffnungen ausge­stoßen und in denen die Tinte über einen Verteilerkanal und gesondert zugeordneten Dämpfungsgliedern über Saugkanäle zugeführt wird, wobei die Druckkanäle von den Antriebsele­menten bis zu den Austrittsöffnungen alle gleich lang ausge­bildet sind, dadurch gekennzeichnet, daß die Saugkanäle zwischen den Antriebselementen (4, 10) und den Dämpfungsgliedern (7) alle gleich lang ausgebildet sind.1.Piezoelectrically operated writing head for ink mosaic writing devices with a plurality of ink channels running radially from outlet openings, in which the writing fluid contained in a compression chamber is ejected drop-shaped from the outlet openings by piezoelectric deformation of a drive element via pressure channels and in which the ink is fed via a distribution channel and separately assigned damping elements via suction channels is supplied, the pressure channels from the drive elements to the outlet openings all being of the same length, characterized in that the suction channels between the drive elements (4, 10) and the damping members (7) are all of the same length. 2. Schreibkopf nach Anspruch 1, dadurch gekennzeich­net, daß die in die Druckkammern (4) mündenden Druckkanä­le (17, 18) je einen Durchmesser in mehrfacher Größe zu dem Durchmesser der in den Druckkammern (4) mündenden Saugkanäle (21, 22) aufweisen.2. Writing head according to claim 1, characterized in that the pressure channels (17) opening into the pressure chambers (4) each have a diameter several times larger than the diameter of the suction channels (21, 22) opening into the pressure chambers (4). 3. Schreibkopf nach Anspruch 1 oder 2, dadurch gekenn­zeichnet, daß die Druckkammern (10) Strömungsumlenk­elemente (23) an den Übergangsstellen zu den Druck- (17, 18) und den Saugkanälen (21, 22) aufweisen.3. Print head according to claim 1 or 2, characterized in that the pressure chambers (10) have flow deflection elements (23) at the transition points to the pressure (17, 18) and the suction channels (21, 22). 4. Schreibkopf nach Anspruch 3, dadurch gekennzeich­net, daß die Strömungsumlenkelemente (23, 24) einen rau­tenförmigen Querschnitt haben, deren freie Enden mit der Membranplatte (11) fest verbunden sind.4. Writing head according to claim 3, characterized in that the flow deflecting elements (23, 24) have a diamond-shaped cross section, the free ends of which are firmly connected to the membrane plate (11). 5. Schreibkopf nach Anspruch 1, 2, 3 oder 4, wobei die elek­trisch betriebenen Antriebselemente elastische Membranen der Kompressionskammern zur Erzeugung von Druckimpulsen defor­mieren, dadurch gekennzeichnet, daß die be­nachbarten Antriebselemente (4, 10, 11) auf zwei konzen­trisch zu den Austrittsöffnungen (2) ausgerichteten Kreisen in Längsrichtung der Tintenkanäle (3) abwechselnd versetzt angeordnet sind und daß Abschnitte der in die auf den inne­ren Kreis angeordneten Kompressionskammern (4) mündenden Druckkanäle (17) und die in die außen angeordneten Kompres­sionskammern (4) mündenden Saugkanäle (21) zum Längenaus­gleich eine gewundene Form aufweisen.5. write head according to claim 1, 2, 3 or 4, wherein the electrically operated drive elements elastic membranes Deforming compression chambers for generating pressure pulses, characterized in that the adjacent drive elements (4, 10, 11) are alternately offset on two circles aligned concentrically with the outlet openings (2) in the longitudinal direction of the ink channels (3) and that sections of the in the the pressure channels (17) opening the inner compression chambers (4) and the suction channels (21) opening the outer compression chambers (4) have a sinuous shape for length compensation. 6. Schreibkopf nach Anspruch 5, wobei dieser eine aus Glas bestehende Grundplatte mit Ausnehmungen für die Tintenka­näle, die Druckkammern und für eine Tintenvorratskammer, eine aus Glas bestehende Membranplatte und eine Piezo­kristallplatte aufweist, dadurch gekennzeichnet, daß alle Tintenkanäle (3) aufsteigend angeordnet sind und die Saugkanäle (21, 22) über als Filter ausgebildete Dämpfungsglieder (7) mit der Tintenvorratskammer (9) in Fließverbindung stehen.6. printhead according to claim 5, wherein it has a glass base plate with recesses for the ink channels, the pressure chambers and for an ink supply chamber, a glass membrane plate and a piezo crystal plate, characterized in that all ink channels (3) are arranged in ascending order and the suction channels (21, 22) are in fluid communication with the ink supply chamber (9) via damping members (7). 7. Schreibkopf nach Anspruch 6, dadurch gekennzeich­net, daß die Tintenvorratskammer (9) an ihren Enden aufsteigende Kanäle (25, 26) zur Entlüftung aufweist, die ober- und unterhalb der in einer Reihe angeordnete Aus­trittsdüsen (2) der Tintenkanäle (3) in einer Stirnfläche (27) des Schreibkopfes (1) mit Austrittsöffnungen (28, 29) enden.7. Print head according to claim 6, characterized in that the ink supply chamber (9) has at its ends ascending channels (25, 26) for ventilation, which are arranged above and below the outlet nozzles (2) of the ink channels (3) arranged in a row an end face (27) of the write head (1) ends with outlet openings (28, 29). 8. Schreibkopf nach einem der vorhergehenden Ansprüche,da­durch gekennzeichnet, daß die Grundplatte (5) in ihren außerhalb der Tintenkammern (4), der Tintenkanäle (3) und der Tintenvorratskammer (9) angeordneten Auflageflächen (30, 31, 32, 33) für die Membranplatte (11) kanalförmige Vertiefungen (34, 35, 36, 37) aufweist, die mit Entlüftungs­kanälen (38, 39, 40, 41) verbunden sind.8. Print head according to one of the preceding claims, characterized in that the base plate (5) in their outside the ink chambers (4), the ink channels (3) and the ink supply chamber (9) arranged support surfaces (30, 31, 32, 33) for the membrane plate (11) has channel-shaped depressions (34, 35, 36, 37) which are connected to ventilation channels (38, 39, 40, 41). 9. Schreibkopf nach einem der vorhergehenden Ansprüche, da­durch gekennzeichnet, daß die Membranplatte (5) einen Durchbruch (42) zu der Tintenvorratskammer (9) auf­weist und daß der Durchbruch (42) von einem zylinderförmigen Dichtungselement (43) umgeben ist, das mit der Membranplatte (11) fest verbunden und gegenüber dem Durchbruch (42) durch eine Dämpfungsmembran (44) verschlossen ist und daß das Dichtungselement (43) unterhalb der Dämpfungsmembran (41) eine Tinteneintrittsöffnung (45) für einen Anschlußschlauch (46) zu einem Tintenbehälter und eine Filtermembran (47) aufweist.9. Writing head according to one of the preceding claims, characterized in that the membrane plate (5) has an opening (42) to the ink supply chamber (9) and that the opening (42) is surrounded by a cylindrical sealing element (43) which with the Membrane plate (11) is firmly connected and is closed to the opening (42) by a damping membrane (44) and that the sealing element (43) below the damping membrane (41) has an ink inlet opening (45) for a connecting hose (46) to an ink tank and one Has filter membrane (47). 10. Schreibkopf nach Anspruch 9, dadurch gekennzeich­net, daß das Dichtungselement (43) eine umlaufende Öff­nung (48) für einen O-förmigen Dichtungsring (49) aufweist.10. Writing head according to claim 9, characterized in that the sealing element (43) has a circumferential opening (48) for an O-shaped sealing ring (49).
EP89100187A 1988-02-05 1989-01-07 Piezo-electrically actuated print head in an ink jet mosaic printer Withdrawn EP0326804A3 (en)

Applications Claiming Priority (2)

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DE3803432 1988-02-05
DE19883803432 DE3803432A1 (en) 1988-02-05 1988-02-05 PIEZOELECTRICALLY OPERATED WRITING HEAD IN INK MOSAIC WRITING DEVICES

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EP0326804A2 true EP0326804A2 (en) 1989-08-09
EP0326804A3 EP0326804A3 (en) 1990-01-31

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Cited By (3)

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US5592203A (en) * 1992-07-31 1997-01-07 Francotyp-Postalia Gmbh Ink jet print head
US5714078A (en) * 1992-07-31 1998-02-03 Francotyp Postalia Gmbh Edge-shooter ink jet print head and method for its manufacture
WO2008029650A1 (en) * 2006-09-08 2008-03-13 Canon Kabushiki Kaisha Liquid discharge head and method of manufacturing the same

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DE4403042A1 (en) * 1992-07-31 1995-08-03 Francotyp Postalia Gmbh Edge shooter ink jet printer head
DE4336416A1 (en) * 1993-10-19 1995-08-24 Francotyp Postalia Gmbh Face shooter ink jet printhead and process for its manufacture
TW403833B (en) * 1998-06-15 2000-09-01 Ind Tech Res Inst Ink pathway design

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EP0103841A2 (en) * 1982-09-16 1984-03-28 Siemens Aktiengesellschaft Write head with piezoelectric driving elements for ink recording devices
DE3608205A1 (en) * 1986-03-12 1987-09-17 Olympia Ag Piezoelectrically operated printhead for ink mosaic printers
DE3609154A1 (en) * 1986-03-19 1987-09-24 Olympia Ag Piezoelectrically operated print head for ink jet matrix printers

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EP0103841A2 (en) * 1982-09-16 1984-03-28 Siemens Aktiengesellschaft Write head with piezoelectric driving elements for ink recording devices
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US5592203A (en) * 1992-07-31 1997-01-07 Francotyp-Postalia Gmbh Ink jet print head
US5714078A (en) * 1992-07-31 1998-02-03 Francotyp Postalia Gmbh Edge-shooter ink jet print head and method for its manufacture
US5802687A (en) * 1992-07-31 1998-09-08 Francotyp-Postalia Ag & Co. Method of manufacturing an ink jet print head
US5825382A (en) * 1992-07-31 1998-10-20 Francotyp-Postalia Ag & Co. Edge-shooter ink jet print head and method for its manufacture
WO2008029650A1 (en) * 2006-09-08 2008-03-13 Canon Kabushiki Kaisha Liquid discharge head and method of manufacturing the same
US8376525B2 (en) 2006-09-08 2013-02-19 Canon Kabushiki Kaisha Liquid discharge head and method of manufacturing the same
US8622523B2 (en) 2006-09-08 2014-01-07 Canon Kabushiki Kaisha Liquid discharge head and method of manufacturing the same

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EP0326804A3 (en) 1990-01-31

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