EP0568163B1 - Thermoelectric ink jet printhead - Google Patents

Thermoelectric ink jet printhead Download PDF

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Publication number
EP0568163B1
EP0568163B1 EP93250036A EP93250036A EP0568163B1 EP 0568163 B1 EP0568163 B1 EP 0568163B1 EP 93250036 A EP93250036 A EP 93250036A EP 93250036 A EP93250036 A EP 93250036A EP 0568163 B1 EP0568163 B1 EP 0568163B1
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EP
European Patent Office
Prior art keywords
ink
chip
printing head
supply
electrothermal
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.)
Expired - Lifetime
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EP93250036A
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German (de)
French (fr)
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EP0568163A3 (en
EP0568163A2 (en
Inventor
Wolfgang Wehl
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Eastman Kodak Co
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Eastman Kodak Co
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Publication of EP0568163A2 publication Critical patent/EP0568163A2/en
Publication of EP0568163A3 publication Critical patent/EP0568163A3/en
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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
    • B41J2/14016—Structure of bubble jet print heads
    • B41J2/14024—Assembling head parts
    • 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
    • B41J2/1433—Structure of nozzle plates
    • 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 layered electrothermal ink print head in which the direction of propagation of the electrothermally generated vapor bubble is opposite to the direction of ink ejection.
  • Known electrothermal ink print heads have a large number of individual nozzles, from which individual droplets of a defined size are generated under the action of an electronic control and ejected in a defined pattern in the direction of a recording medium.
  • the characters to be printed are produced by several ink droplets, which are lined up in a matrix.
  • One column of such a character-related matrix is expediently printed at the same time in order to meet the requirements for high printing speed and uniform typeface.
  • An ink printhead that is suitable for the printing process described Suitable, must therefore combine several (same) elements that are able to eject ink droplets at the time of need ("drop-on-demand" principle).
  • a characteristic feature of this technology is that there is an electrical resistor in the form of a heating element in a capillary filled with recording liquid, for example ink, in the vicinity of its opening. If a certain thermal energy is supplied to this heating element by means of a short current pulse, extremely rapid heat transfer to the ink liquid first results in a rapidly expanding ink vapor bubble, which then collapses relatively quickly after the energy supply has ceased and the ink liquid has cooled. The pressure wave generated by the vapor bubble inside the capillaries causes a drop of ink of limited mass to emerge from the nozzle opening onto the surface of a nearby recording medium.
  • An advantage of this bubble jet principle is that by using the phase change liquid-gaseous-liquid of the ink liquid, the relatively large and rapid volume change necessary for ink ejection is obtained from a very small active transducer area.
  • the small transducer areas in turn allow the use of modern manufacturing processes, such as high-precision photolithographic processes in layer technology, a relatively simple and inexpensive construction of ink printheads, which are characterized by high trace density and small dimensions.
  • an ink print head which essentially consists of a chip and an ink reservoir, the chip being mechanically locked on the ink reservoir by means of mounting clips.
  • This chip has three-sided and open to the fourth side Ink channels that are separated by thin substantially trapezoidal channel walls.
  • the end of the respective ink channel consists of a thin membrane, which in turn has the ejection nozzle of the associated ink channel.
  • a surface of the ink reservoir forms the outer closure of the ink channels towards the fourth side, which is open on the chip side. Since the chip is held non-positively on the ink reservoir only by the mounting bracket, the channel intermediate walls are movable on the surface of the ink reservoir. This disadvantage is exacerbated by the large length-thickness ratio of the order of 50: 1 and height-thickness ratio of 10: 1 of the channel partition walls.
  • a heating element If actuated to generate a droplet, its heating, in addition to the formation of bubbles, leads to a local overpressure in the respective ink channel. In addition to the intended droplet ejection, this overpressure leads to the fact that the intermediate channel walls delimiting the respective ink channel are bent in the direction of the adjacent ink channels. This means that in addition to the amount of energy required to eject droplets, an amount of lost energy must also be applied, which leads to duct wall diffraction. This loss of energy degrades the overall efficiency of the ink printhead.
  • channel partition diffraction affects adjacent ink channels. If the adjacent ink channels of an uncontrolled ink channel are actuated, the resulting pressure overlay in the non-actuated channel can nevertheless lead to undesired droplet ejection.
  • the invention is therefore based on the object of specifying an ink printhead which retains the design advantages of the described ink printhead and at the same time has a better efficiency and is suitable for enabling a consistently high print quality regardless of the operating mode.
  • this object is achieved in that the chip is provided on its side facing the ink reservoir with an end plate.
  • This end plate is attached to the entire available surface of the chip side. These are the edge areas of the chip and in particular the free end faces of the channel walls. This means that the duct walls are firmly clamped on all sides.
  • the pressure wave caused by the activation of the heating elements in the ink channel remains essentially limited to the respective ink channel and is converted to a higher degree into drop ejection energy. On the one hand, this significantly increases the efficiency of the respective ink channel and, on the other hand, the influence of adjacent ink channels is advantageously reduced. This minimizes the dependence of the drop mass on the control of adjacent ink channels.
  • Another advantage of the invention is that the ink tightness is ensured by the defined termination of the chip to the ink reservoir caused by the end plate.
  • the end plate has openings at the intersection of the supply channels in the ink reservoir with the ink channels in the chip.
  • Figure 1 shows a perspective view of the structure of an ink print head. This consists essentially of only two parts to be connected to one another, namely a chip 11, which contains both the heating elements, the electrical supply lines and the contact points for the electrical connection and the outlet openings (nozzles) and fastened to an ink reservoir 12 as a conclusion and is contacted.
  • the heating elements (not shown in this basic diagram), the electrical feed lines, the contact points 9 and outlet openings 10 can be produced in a single chip 11, preferably made of silicon, by planar processing steps.
  • the ink reservoir 12 has a cuboid shape into which a medium soaked in ink liquid, e.g. a sponge 13 is introduced.
  • a medium soaked in ink liquid e.g. a sponge 13
  • outlet openings provided with filters 14 are provided in the form of two supply channels 15. These supply channels 15 run parallel to one another in the longitudinal direction of the ink reservoir 12 such that they are in fluid communication with the outlet openings 10 via an ink channel 16 when a chip 11 is mounted.
  • the chip 11 is mounted on the ink reservoir 12 in a simple manner by means of mounting clips 17 arranged on the long sides of the ink reservoir 12, which take over both the mechanical connection and the electrical contacts via the contact points 9.
  • FIG. 2 shows a section through the chip according to section line II in FIG. 1.
  • the geometrical configuration of an ink channel 16 can be seen here, which has parallel walls with oblique outlet zones.
  • this ink channel 16 is sealed on the nozzle side only by a thin layer of the chip substrate material in the manner of a membrane.
  • the outlet opening 10 is provided.
  • the heating elements 4 are arranged on the side of the membrane 3 facing away from the ink channel 16.
  • the chip 11 is provided with an end plate 1 on its side facing the ink reservoir 12.
  • the end plate 1 has openings 2 which are arranged at the intersections of the ink channels 16 with the supply channels 15.
  • the cross-sectional area of the openings 2 is the same size as the sectional area that results from the intersection of the respective ink channel with the respective supply channel 15.
  • the ink channels 16 are trapezoidal in longitudinal section and the supply channels 15 are connected at the acute angles of the trapezoidal shape.
  • the pressure wave which is triggered by the ink vapor bubble as a result of the activation of the heating elements 4, will first capture the surroundings of the outlet opening 10 in its dynamic course and then spread in the direction of the supply channels 15 located at a distance. If the pressure wave reaches the surroundings of the supply channels 15, a recoil effect is triggered in that the ink is pushed back from the ink channel 16 into the supply channels 15. Only after the pressure wave has subsided does the ink be drawn back into the ink channel due to the capillary action.
  • the cross-sectional areas of the openings 2 in the end plate 1 are reduced compared to the sectional area of the respective ink channel 16 with the respective supply channel 15.
  • the recoil effect described is reduced in its effect to the extent that the amount of ink flowing back in the direction of the supply channels 15 is limited.
  • less mutual influence of the ink channels with each other, improved efficiency and reduced dependence of the drop mass on the control of adjacent ink channels is an additional advantageous effect the restoration time of the driven ink channel 16 is shortened. This enables a higher ink ejection frequency and consequently a higher writing speed.
  • FIG. 5 shows a perspective view of the end plate 1 according to the invention before it is mounted on the chip 11.
  • the end plate 1 has parallel elongated openings 2 which cover the edge regions of the ink channels 16 in the chip 11.
  • the ink channels 16 are closed in the ink ejection direction by the membrane 3, which has the outlet opening 10.
  • the end plate 1 consists of glass, silicon or ceramic and is anodically bonded to the chip 11.
  • the end plate 1 consists of a plastic film which is laminated onto the chip 11.
  • the end plate 1 also consists of a plastic film, but which is adhesive on both sides. In particular, this variant supports the ink tightness of the joint between the chip 11 and the reservoir 12 without any further technical means.
  • the end plate 1 consists of a metal foil which is anodically bonded to the chip 11.
  • the processing order depends on the material and connection method.
  • the openings 2 are then etched in the exact position relative to the ink channels 16 or structured by laser, sandblasted or finely stamped.

Description

Die Erfindung betrifft einen elektrothermischen Tintendruckkopf in Schichtbauweise, bei dem die Ausbreitungsrichtung der elektrothermisch erzeugten Dampfblase der Tintenausstoßrichtung entgegengesetzt ist.The invention relates to a layered electrothermal ink print head in which the direction of propagation of the electrothermally generated vapor bubble is opposite to the direction of ink ejection.

Bekannte elektrothermische Tintendruckköpfe (Bubble-Jet-Prinzip) weisen eine Vielzahl von Einzeldüsen auf, aus denen unter Einwirkung einer elektronischen Steuerung Einzeltröpfchen definierter Größe erzeugt und in einem definierten Muster in Richtung eines Aufzeichnungsträgers ausgestoßen werden.Known electrothermal ink print heads (bubble jet principle) have a large number of individual nozzles, from which individual droplets of a defined size are generated under the action of an electronic control and ejected in a defined pattern in the direction of a recording medium.

Die zu druckenden Zeichen werden durch jeweils mehrere Tintentröpfchen erzeugt, die matrixförmig aneinander gereiht sind.The characters to be printed are produced by several ink droplets, which are lined up in a matrix.

Zweckmäßigerweise wird jeweils eine Spalte einer derartigen zeichenbezogenen Matrix gleichzeitig gedruckt, um die Forderungen nach hoher Druckgeschwindigkeit und gleichmäßigem Schriftbild zu erfüllen.One column of such a character-related matrix is expediently printed at the same time in order to meet the requirements for high printing speed and uniform typeface.

Ein Tintendruckkopf, der sich für das geschilderte Druckverfahren eignet, muß also mehrere (gleiche) Elemente vereinigen, die in der Lage sind, Tintentröpfchen im Bedarfszeitpunkt auszustoßen ("Drop-on-demand"-Prinzip). Charakteristisches Merkmal dieser Technologie ist, daß sich in einer mit Aufzeichnungsflüssigkeit, beispielsweise Tinte, gefüllten Kapillaren und zwar in der Nähe ihrer Öffnung ein als Heizelement ausgebildeter elektrischer Widerstand befindet. Wird diesem Heizelement bei Bedarf mittels eines kurzen Stromimpulses eine bestimmte Wärmeenergie zugeführt, entsteht durch äußerst schnelle Wärmeübertragung auf die Tintenflüssigkeit zuerst eine sich rasch expandierende Tintendampfblase, die dann nach Wegfall der Energiezuführung und Abkühlung der Tintenflüssigkeit relativ schnell in sich zusammenfällt. Die durch die Dampfblase im Inneren der Kapillaren entstehende Druckwelle läßt einen Tintentropfen begrenzter Masse aus der Düsenöffnung auf die Oberfläche eines nahen Aufzeichnungsträgers austreten.An ink printhead that is suitable for the printing process described Suitable, must therefore combine several (same) elements that are able to eject ink droplets at the time of need ("drop-on-demand" principle). A characteristic feature of this technology is that there is an electrical resistor in the form of a heating element in a capillary filled with recording liquid, for example ink, in the vicinity of its opening. If a certain thermal energy is supplied to this heating element by means of a short current pulse, extremely rapid heat transfer to the ink liquid first results in a rapidly expanding ink vapor bubble, which then collapses relatively quickly after the energy supply has ceased and the ink liquid has cooled. The pressure wave generated by the vapor bubble inside the capillaries causes a drop of ink of limited mass to emerge from the nozzle opening onto the surface of a nearby recording medium.

Ein Vorteil dieses Bubble-Jet-Prinzips ist der, daß durch Ausnutzung des Phasenwechsels flüssig-gasförmig-flüssig der Tintenflüssigkeit die zum Tintenausstoß notwendige, relativ große und schnelle Volumenänderung aus einer sehr kleinen aktiven Wandlerfläche gewonnen wird. Die kleinen Wandlerflächen wiederum erlauben bei Anwendung moderner Herstellungsverfahren, wie hochpräzise fotolithographische Prozesse in Schichttechnik, einen relativ einfachen und kostengünstigen Aufbau von Tintendruckköpfen, die sich durch hohe Schreibspurendichte und geringe Abmessungen auszeichnen.An advantage of this bubble jet principle is that by using the phase change liquid-gaseous-liquid of the ink liquid, the relatively large and rapid volume change necessary for ink ejection is obtained from a very small active transducer area. The small transducer areas in turn allow the use of modern manufacturing processes, such as high-precision photolithographic processes in layer technology, a relatively simple and inexpensive construction of ink printheads, which are characterized by high trace density and small dimensions.

Aus der internationalen Anmeldung PCT/DE 91/00364 ist ein Tintendruckkopf bekannt, der im wesentlichen aus einem Chip und einem Tintenvorratsbehälter besteht, wobei der Chip mittels Montageklammern auf dem Tintenvorratsbehälter mechanisch arretiert ist. Dieser Chip weist dreiseitig abgeschlossene und zur vierten Seite hin offene Tintenkanäle auf, die durch dünne im wesentlichen trapezförmige Kanalzwischenwände voneinander getrennt sind. In Tintenausstoßrichtung besteht der Abschluß des jeweiligen Tintenkanals aus einer dünnen Membran, die ihrerseits die Ausstoßdüse des zugehörigen Tintenkanals aufweist.From the international application PCT / DE 91/00364 an ink print head is known which essentially consists of a chip and an ink reservoir, the chip being mechanically locked on the ink reservoir by means of mounting clips. This chip has three-sided and open to the fourth side Ink channels that are separated by thin substantially trapezoidal channel walls. In the ink ejection direction, the end of the respective ink channel consists of a thin membrane, which in turn has the ejection nozzle of the associated ink channel.

Eine Oberfläche des Tintenvorratsbehälters bildet den äußeren Abschluß der Tintenkanäle zur chipseitig offenen vierten Seite hin. Da der Chip lediglich durch die Montageklammer kraftschlüssig auf den Tintenvorratsbehälter gehalten wird, sind die Kanalzwischenwände auf der Oberfläche des Tintenvorratsbehälters beweglich. Verstärkt wird dieser Nachteil durch das große Längen-Dicken-Verhältnis von größenordnungsmäßig 50:1 und Höhen-Dicken-Verhältnis von 10:1 der Kanalzwischenwände.A surface of the ink reservoir forms the outer closure of the ink channels towards the fourth side, which is open on the chip side. Since the chip is held non-positively on the ink reservoir only by the mounting bracket, the channel intermediate walls are movable on the surface of the ink reservoir. This disadvantage is exacerbated by the large length-thickness ratio of the order of 50: 1 and height-thickness ratio of 10: 1 of the channel partition walls.

Wird ein Heizelement zur Erzeugung eines Tröpfchens angesteuert, führt dessen Erhitzung neben der Blasenbildung zu einem lokalen Überdruck in dem jeweiligen Tintenkanal. Dieser überdruck führt neben dem beabsichtigen Tröpfchenausstoß dazu, daß die den jeweiligen Tintenkanal begrenzenden Kanalzwischenwände in Richtung der benachbarten Tintenkanäle gebeugt werden. Das bedeutet, daß neben der zum Tröpfchenausstoß benötigten Energiemenge noch eine Verlustenergiemenge aufgebracht werden muß, die zur Kanalzwischenwandbeugung führt. Diese Verlustenergiemenge verschlechtert den Gesamtwirkungsgrad des Tintendruckkopfes.If a heating element is actuated to generate a droplet, its heating, in addition to the formation of bubbles, leads to a local overpressure in the respective ink channel. In addition to the intended droplet ejection, this overpressure leads to the fact that the intermediate channel walls delimiting the respective ink channel are bent in the direction of the adjacent ink channels. This means that in addition to the amount of energy required to eject droplets, an amount of lost energy must also be applied, which leads to duct wall diffraction. This loss of energy degrades the overall efficiency of the ink printhead.

Darüber hinaus führt die Kanalzwischenwandbeugung zur Beeinflußung benachbarter Tintenkanäle. Werden die benachbarten Tintenkanäle eines nicht angesteuerten Tintenkanals angesteuert, kann es durch die entstehende Drucküberlagerung im nicht angesteuerten Kanal trotzdem zu einem unerwünschten Tröpfchenausstoß kommen.In addition, channel partition diffraction affects adjacent ink channels. If the adjacent ink channels of an uncontrolled ink channel are actuated, the resulting pressure overlay in the non-actuated channel can nevertheless lead to undesired droplet ejection.

Je nachdem, ob benachbarte Tintenkanäle angesteuert werden oder nicht, ändern sich die Druckverhältnisse im jeweiligen Tintenkanal und damit die resultierende Tropfenmasse und die Druckqualität.Depending on whether neighboring ink channels are controlled or not, the pressure conditions in the respective ink channel and thus the resulting drop mass and the print quality change.

Der Erfindung liegt daher die Aufgabe zugrunde, einen Tintendruckkopf anzugeben, der die bauartgemäßen Vorteile des beschriebenen Tintendruckkopfes beibehält und dabei einen besseren Wirkungsgrad aufweist und geeignet ist, betriebsartunabhängig eine gleichbleibend hohe Druckqualität zu ermöglichen.The invention is therefore based on the object of specifying an ink printhead which retains the design advantages of the described ink printhead and at the same time has a better efficiency and is suitable for enabling a consistently high print quality regardless of the operating mode.

Erfindungsgemäß wird diese Aufgabe dadurch gelöst, daß der Chip an seiner dem Tintenvorratsbehälter zugewandten Seite mit einer Abschlußplatte versehen ist.According to the invention, this object is achieved in that the chip is provided on its side facing the ink reservoir with an end plate.

Diese Abschlußplatte ist an der gesamten verfügbaren Oberfläche der Chipseite befestigt. Das sind die Randbereiche des Chips und insbesondere die freien Stirnseiten der Kanalzwischenwände. Damit sind die Kanalzwischenwände allseitig fest eingespannt. Die durch die Aktivierung der Heizelemente im Tintenkanal hervorgerufene Druckwelle bleibt im wesentlichen auf den jeweiligen Tintenkanal begrenzt und wird zu einem höheren Maße in Tropfenausstoßenergie umgesetzt. Damit erhöht sich einerseits der Wirkungsgrad des jeweiligen Tintenkanals wesentlich und andererseits wird vorteilhafterweise die Beeinflußung benachbarter Tintenkanäle reduziert. Dadurch wird die Abhängigkeit der Tropfenmasse von der Ansteuerung benachbarter Tintenkanäle minimiert.This end plate is attached to the entire available surface of the chip side. These are the edge areas of the chip and in particular the free end faces of the channel walls. This means that the duct walls are firmly clamped on all sides. The pressure wave caused by the activation of the heating elements in the ink channel remains essentially limited to the respective ink channel and is converted to a higher degree into drop ejection energy. On the one hand, this significantly increases the efficiency of the respective ink channel and, on the other hand, the influence of adjacent ink channels is advantageously reduced. This minimizes the dependence of the drop mass on the control of adjacent ink channels.

Ein weiterer Vorteil der Erfindung besteht darin, daß durch den mit der Abschlußplatte bewirkten definierten Abschluß des Chips zum Tintenvorratsbehälter hin die Tintendichtheit sichergestellt wird.Another advantage of the invention is that the ink tightness is ensured by the defined termination of the chip to the ink reservoir caused by the end plate.

Die Abschlußplatte weist an den Schnittflächen der Versorungskanäle im Tintenvorratsbehälter mit den Tintenkanälen im Chip Öffnungen auf.The end plate has openings at the intersection of the supply channels in the ink reservoir with the ink channels in the chip.

Entsprechend der Dimensionierung dieser Öffnungen wird der durch die Druckwelle im Tintenkanal hervorgerufenen Rückstoß der Tinte in Richtung des Tintenvorratsbehälters minimiert.According to the dimensioning of these openings, the recoil of the ink in the direction of the ink reservoir caused by the pressure wave in the ink channel is minimized.

Durch diese Maßnahme wird der Wirkungsgrad abermals erhöht und die Beeinflußung der Tintenkanäle untereinander gesenkt.This measure increases the efficiency again and reduces the influence of the ink channels on one another.

Die Erfindung wird nachstehend anhand von Ausführungsbeispielen näher erläutert. Die dazu erforderlichen Darstellungen zeigen:

Fig. 1
eine Prinzipdarstellung eines für die Anwendung der Erfindung besonders geeigneten Tintendruckkopfes
Fig. 2
eine Schnittdarstellung durch den Chip eines solchen Tintendruckkopfes
Fig. 3
eine Schnittdarstellung durch den erfindungsgemäßen Tintendruckkopf
Fig. 4
eine Schnittdarstellung durch einen Tintendruckkopf mit querschnittsreduzierten Durchlaßöffnungen
Fig. 5
eine räumliche Prinzipdarstellung von Chip und Abschlußplatte
The invention is explained in more detail below on the basis of exemplary embodiments. The representations required for this show:
Fig. 1
a schematic diagram of an ink print head particularly suitable for the application of the invention
Fig. 2
a sectional view through the chip of such an ink print head
Fig. 3
a sectional view through the ink print head according to the invention
Fig. 4
a sectional view through an ink printhead with reduced cross-sectional openings
Fig. 5
a basic spatial representation of the chip and end plate

Die Figur 1 zeigt in perspektivischer Darstellung den Aufbau eines Tintendruckkopfes. Dieser besteht im wesentlichen aus nur zwei miteinander zu verbindenden Teilen, nämlich einem Chip 11, der sowohl die Heizelemente, die elektrischen Zuleitungen und die Kontaktstellen für den elektrischen Anschluß als auch die Auslaßöffnungen (Düsen) beinhaltet und als Abschluß auf einen Tintenvorratsbehälter 12 befestigt und kontaktiert wird. Die in diesem Prinzipbild nicht dargestellten Heizelemente, die elektrischen Zuleitungen, die Kontaktstellen 9 und Auslaßöffnungen 10 können dabei in einem einzigen, vorzugsweise aus Silizium bestehenden Chip 11 im Nutzen durch planare Bearbeitungsschritte erzeugt werden.Figure 1 shows a perspective view of the structure of an ink print head. This consists essentially of only two parts to be connected to one another, namely a chip 11, which contains both the heating elements, the electrical supply lines and the contact points for the electrical connection and the outlet openings (nozzles) and fastened to an ink reservoir 12 as a conclusion and is contacted. The heating elements (not shown in this basic diagram), the electrical feed lines, the contact points 9 and outlet openings 10 can be produced in a single chip 11, preferably made of silicon, by planar processing steps.

Der Tintenvorratsbehälter 12 weist eine quaderförmige Gestalt auf, in das ein mit Tintenflüssigkeit getränktes Medium, z.B. ein Schwamm 13 eingebracht ist. An der dem Chip 11 zugewandten Oberseite des Tintenvorratsbehälters 12 sind mit Filtern 14 versehene Auslaßöffnungen in Form von zwei Versorgungskanälen 15 vorgesehen. Diese Versorgungskanäle 15 verlaufen parallel zueinander in Längsrichtung des Tintenvorratsbehälters 12 derart, daß sie bei einem montierten Chip 11 über Tintenkanäle 16 in Fließverbindung mit den Auslaßöffnungen 10 stehen. Die Montage des Chips 11 auf den Tintenvorratsbehälter 12 geschieht auf einfache Weise durch an den Längsseiten des Tintenvorratsbehälters 12 angeordneten Montageklammern 17, die sowohl die mechanische Verbindung als auch über die Kontaktstellen 9 die elektrische Kontaktierung übernehmen.The ink reservoir 12 has a cuboid shape into which a medium soaked in ink liquid, e.g. a sponge 13 is introduced. On the top of the ink reservoir 12 facing the chip 11, outlet openings provided with filters 14 are provided in the form of two supply channels 15. These supply channels 15 run parallel to one another in the longitudinal direction of the ink reservoir 12 such that they are in fluid communication with the outlet openings 10 via an ink channel 16 when a chip 11 is mounted. The chip 11 is mounted on the ink reservoir 12 in a simple manner by means of mounting clips 17 arranged on the long sides of the ink reservoir 12, which take over both the mechanical connection and the electrical contacts via the contact points 9.

Die Figur 2 stellt einen Schnitt durch den Chip gemäß der Schnittlinie I-I in Figur 1 dar. Insbesondere ist hier die geometrische Ausgestaltung eines Tintenkanals 16 zu erkennen, der parallele Wände mit schrägen Auslaufzonen aufweist.
Wie auch aus Figur 2 hervorgeht, ist dieser Tintenkanal 16 düsenseitig lediglich durch eine dünne Schicht des Chipsubstratmaterials membranartig abgeschlossen. In dieser Membran 3 ist die Auslaßöffnung 10 vorgesehen.FIG. 2 shows a section through the chip according to section line II in FIG. 1. In particular, the geometrical configuration of an ink channel 16 can be seen here, which has parallel walls with oblique outlet zones.
As can also be seen from FIG. 2, this ink channel 16 is sealed on the nozzle side only by a thin layer of the chip substrate material in the manner of a membrane. In this membrane 3, the outlet opening 10 is provided.

Auf der dem Tintenkanal 16 abgewandten Seite der Membran 3 sind die Heizelemente 4 angeordnet.The heating elements 4 are arranged on the side of the membrane 3 facing away from the ink channel 16.

Gemäß Figur 3 ist der Chip 11 an seiner dem Tintenvorratsbehälter 12 zugewandten Seite mit einer Abschlußplatte 1 versehen. Die Abschlußplatte 1 weist Öffnungen 2 auf, die an den Überschneidungen der Tintenkanäle 16 mit den Versorgungskanälen 15 angeordnet sind. In dieser Ausführungsform ist die Querschnittsfläche der Öffnungen 2 genauso groß wie die Schnittfläche, die sich aus der Überschneidung des jeweiligen Tintenkanals mit dem jeweiligen Versorgungskanal 15 ergibt.According to FIG. 3, the chip 11 is provided with an end plate 1 on its side facing the ink reservoir 12. The end plate 1 has openings 2 which are arranged at the intersections of the ink channels 16 with the supply channels 15. In this embodiment, the cross-sectional area of the openings 2 is the same size as the sectional area that results from the intersection of the respective ink channel with the respective supply channel 15.

Wie bereits aus Figur 1 entnehmbar, sind die Tintenkanäle 16 im Längsschnitt trapezförmig gestaltet und in den spitzen Winkeln der Trapezform die Versorgngskanäle 15 angeschlossen. Demzufolge wird die Druckwelle, die durch die Tintendampfblase infolge der Aktivierung der Heizelemente 4 ausgelöst wird, in ihrem dynamischen Verlauf zunächst die Umgebung der Auslaßöffnung 10 erfassen und sich anschließend in Richtung der entfernt gelegenen Versorgungskanäle 15 ausbreiten. Erreicht die Druckwelle die Umgebung der Versorgungskanäle 15, wird ein Rückstoßeffekt ausgelöst, indem die Tinte aus dem Tintenkanal 16 in die Versorgungskanäle 15 zurückgedrückt wird. Erst nach Abklingen der Druckwelle wird die Tinte infolge der Kapillarwirkung des Tintenkanals wieder in diesen hineingezogen.As can already be seen from FIG. 1, the ink channels 16 are trapezoidal in longitudinal section and the supply channels 15 are connected at the acute angles of the trapezoidal shape. As a result, the pressure wave, which is triggered by the ink vapor bubble as a result of the activation of the heating elements 4, will first capture the surroundings of the outlet opening 10 in its dynamic course and then spread in the direction of the supply channels 15 located at a distance. If the pressure wave reaches the surroundings of the supply channels 15, a recoil effect is triggered in that the ink is pushed back from the ink channel 16 into the supply channels 15. Only after the pressure wave has subsided does the ink be drawn back into the ink channel due to the capillary action.

In weiterer Ausgestaltung der Erfindung sind gemäß Figur 4 die Querschnittsflächen der Öffnungen 2 in der Abschlußplatte 1 gegenüber der Schnittfläche des jeweiligen Tintenkanals 16 mit dem jeweiligen Versorgungskanal 15 reduziert. Mit dieser Maßnahme wird der beschriebene Rückstoßeffekt in seiner Wirkung dahingehend reduziert, daß die in Richtung der Versorgungskanäle 15 rückfließenden Tintenmenge begrenzt wird. Neben den bereits beschriebenen Vorteilen, geringere gegenseitige Beeinflußung der Tintenkanäle untereinander, verbesserter Wirkungsgrad und verringerte Abhängigkeit der Tropfenmasse von der Ansteuerung benachbarter Tintenkanäle, wird als zusätzlicher vorteilhafter Effekt die Restaurierungszeit des angesteuerten Tintenkanals 16 verkürzt. Damit ist eine höhere Tintenausstoßfrequenz und folglich eine höhere Schreibgeschwindigkeit ermöglicht.In a further embodiment of the invention, according to FIG. 4, the cross-sectional areas of the openings 2 in the end plate 1 are reduced compared to the sectional area of the respective ink channel 16 with the respective supply channel 15. With this measure, the recoil effect described is reduced in its effect to the extent that the amount of ink flowing back in the direction of the supply channels 15 is limited. In addition to the advantages already described, less mutual influence of the ink channels with each other, improved efficiency and reduced dependence of the drop mass on the control of adjacent ink channels, is an additional advantageous effect the restoration time of the driven ink channel 16 is shortened. This enables a higher ink ejection frequency and consequently a higher writing speed.

In Figur 5 ist eine perspektivische Darstellung der erfindungsgemäßen Abschlußplatte 1 vor ihrer Montage auf den Chip 11 gezeigt. Die Abschlußplatte 1 weist parallele längliche Öffnungen 2 auf, die die Randbereiche der Tintenkanäle 16 im Chip 11 überdecken. Die Tintenkanäle 16 sind in Tintenausstoßrichtung durch die Membran 3 abgeschlossen, die die Auslaßöffnung 10 aufweist.FIG. 5 shows a perspective view of the end plate 1 according to the invention before it is mounted on the chip 11. The end plate 1 has parallel elongated openings 2 which cover the edge regions of the ink channels 16 in the chip 11. The ink channels 16 are closed in the ink ejection direction by the membrane 3, which has the outlet opening 10.

In einer ersten Variante besteht die Abschlußplatte 1 aus Glas, Silizium oder Keramik und ist anodisch an den Chip 11 gebondet. In einer zweiten Variante besteht die Abschlußplatte 1 aus einer Kunststoffolie, die auf den Chip 11 auflaminiert ist. In einer dritten Variante besteht die Abschlußplatte 1 ebenfalls aus einer Kunststoffolie, die jedoch beidseitig klebend ist. Insbesondere diese Variante unterstützt unter Verzicht auf weitere technische Mittel die Tintendichtheit der Fügestelle zwischen dem Chip 11 und dem Vorratsbehälter 12.In a first variant, the end plate 1 consists of glass, silicon or ceramic and is anodically bonded to the chip 11. In a second variant, the end plate 1 consists of a plastic film which is laminated onto the chip 11. In a third variant, the end plate 1 also consists of a plastic film, but which is adhesive on both sides. In particular, this variant supports the ink tightness of the joint between the chip 11 and the reservoir 12 without any further technical means.

In einer vierten Variante besteht die Abschlußplatte 1 aus einer Metallfolie, die anodisch an den Chip 11 gebondet ist.In a fourth variant, the end plate 1 consists of a metal foil which is anodically bonded to the chip 11.

Die Bearbeitungsreihenfolge hängt vom Material und Verbindungsverfahren ab. Anschließend sind die Öffnungen 2 positionsgenau zu den Tintenkanälen 16 geätzt oder durch Laser strukturiert, sandgestrahlt oder feingestanzt.The processing order depends on the material and connection method. The openings 2 are then etched in the exact position relative to the ink channels 16 or structured by laser, sandblasted or finely stamped.

Die beschriebenen Varianten sind auf jede der vorstehend beschriebenen Ausführungsformen anwendbar.The described variants are applicable to each of the above-described embodiments.

BezugszeichenlisteReference list

11
AbschlußplatteEnd plate
22nd
Öffnungenopenings
33rd
Membranmembrane
44th
HeizelementHeating element
55
Drosselthrottle
88th
KanalzwischenwändeCanal partitions
99
KontaktstellenContact points
1010th
AuslaßöffnungenExhaust ports
1111
Chipchip
1212th
TintenvorratsbehälterInk reservoir
1313
Schwammsponge
1414
Filterfilter
1515
VersorgungskanäleSupply channels
1616
TintenkanäleInk channels
1717th
MontageklammernMounting brackets

Claims (5)

  1. An electrothermal ink printing head in layered de sign having a plurality of ink ducts with ink ejection openings, in which the heating elements, the electrical supply lines, the contact points and said ink ejection openings are combined on a single chip, in which the propagation direction of each electrothermally generated vapor bubble is opposite to the ink ejection direction, and that is detachably connected to an ink supply reservoir, where said ink ducts (16) of said chip are in a flowing connection with supply ducts (15) of said ink supply reservoir (12),
    characterized in that said chip (11) is provided on its side facing said ink supply reservoir (12) with a closure plate (1) that has openings (2) at the overlap surfaces of said ink ducts (16) with said supply ducts (15).
  2. Electrothermal ink printing head according to Claim 1, characterized in that said openings (2) in said closure plate (1) have a cross-section that is smaller than the overlap surface of the respective supply duct (15) with the respective ink duct (16).
  3. Electrothermal ink printing head according to Claim 1, characterized in that said closure plate (1) comprises one of the materials glass, ceramics, silicon or metal, and is anodically bonded to said chip (11) of said ink printing head.
  4. Electrothermal ink printing head according to Claim 1, characterized i n that said closure plate (1) comprises a plastic film laminated onto said chip (11) of said ink printing head.
  5. Electrothermal ink printing head according to Claim 4, characterized in that said film is adhesive on both sides.
EP93250036A 1992-04-28 1993-01-28 Thermoelectric ink jet printhead Expired - Lifetime EP0568163B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE4214556 1992-04-28
DE4214556A DE4214556A1 (en) 1992-04-28 1992-04-28 ELECTROTHERMIC INK PRINT HEAD

Publications (3)

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EP0568163A2 EP0568163A2 (en) 1993-11-03
EP0568163A3 EP0568163A3 (en) 1993-12-15
EP0568163B1 true EP0568163B1 (en) 1996-07-31

Family

ID=6458026

Family Applications (1)

Application Number Title Priority Date Filing Date
EP93250036A Expired - Lifetime EP0568163B1 (en) 1992-04-28 1993-01-28 Thermoelectric ink jet printhead

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US (1) US5463411A (en)
EP (1) EP0568163B1 (en)
JP (1) JPH068435A (en)
DE (2) DE4214556A1 (en)

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Also Published As

Publication number Publication date
JPH068435A (en) 1994-01-18
EP0568163A3 (en) 1993-12-15
EP0568163A2 (en) 1993-11-03
US5463411A (en) 1995-10-31
DE59303349D1 (en) 1996-09-05
DE4214556A1 (en) 1993-11-04

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