EP0026688A1 - Vibratory device with piezoelectric element for a liquid gun used in a fragmented-liquid ejection head - Google Patents

Vibratory device with piezoelectric element for a liquid gun used in a fragmented-liquid ejection head Download PDF

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Publication number
EP0026688A1
EP0026688A1 EP80401273A EP80401273A EP0026688A1 EP 0026688 A1 EP0026688 A1 EP 0026688A1 EP 80401273 A EP80401273 A EP 80401273A EP 80401273 A EP80401273 A EP 80401273A EP 0026688 A1 EP0026688 A1 EP 0026688A1
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EP
European Patent Office
Prior art keywords
liquid
resonator
vibratory device
fragmented
head
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Granted
Application number
EP80401273A
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German (de)
French (fr)
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EP0026688B1 (en
Inventor
Jean Pierre Le Pesant
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I M A J E SA
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Imaje SA
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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
    • B41J2/015—Ink jet characterised by the jet generation process
    • B41J2/02—Ink jet characterised by the jet generation process generating a continuous ink jet
    • B41J2/025—Ink jet characterised by the jet generation process generating a continuous ink jet by vibration

Definitions

  • the invention relates to a vibrating device with a piezoelectric element for a liquid cannon intended for a head for ejecting a fragmented liquid such as in particular an ink jet printing head. More precisely, it relates to means of excitation in forced mode of an ejection nozzle for the creation of drops as well as the arrangement of these means leading to obtaining a liquid cannon such as in particular a printing head with inkjet.
  • An inkjet printer must above all produce a jet of drops with well-defined characteristics: the drops must be regularly spaced, of the same size and propelled in the same direction, at the same speed.
  • drops of calibrated size are created by the breaking of a fluid jet emitted by the nozzle. This break is generally obtained thanks to the action of piezoelectric ceramics.
  • Various solutions for excitation of these ceramics exist, either in longitudinal mode called “thickness mode” by piezoelectric discs, or in transverse mode called “necking mode” by piezoelectric tubes or finally in bending mode allowing compression of a cavity.
  • the present invention aims to overcome these drawbacks and relates to a new architecture of the main means constituting a vibratory device in particular for inkjet printer: device of reduced dimensions allowing the production of printheads with several adjacent nozzles arranged in rows at a frequency which can be a few millimeters only.
  • This result is obtained thanks to the combination of transducer and resonators whose essential characteristic is to be drilled in their center to let pass the liquid supply tube which thus passes right through the vibratory device and can be made integral of the nozzle in the front part of the resonator.
  • One of the main applications of the invention is the inkjet printer, but it can be applied to any other system requiring the formation of calibrated drop trains.
  • the invention relates more particularly to a vibrating device with a piezoelectric element capable of generating a propagation of acoustic waves in a liquid to ensure the fragmentation of the liquid into droplets, characterized in that it comprises a first combination of a piezo transducer -electric coupled to a front resonator and a second combination of the piezoelectric transducer with a rear resonator, this double combination comprising a central orifice through which the liquid supply tube passes which thus passes right through the vibratory device without the liquid is in direct contact with the piezoelectric transducer.
  • a vibrating device As shown in Figure 1, a vibrating device according to the invention and the barrel which is equipped with it comprises a piezoelectric transducer 7 cooperating with a first and a second front and rear mechanical resonator respectively referenced 3 and 5 thus forming a first and a second combination transducer-resonator sounds.
  • the two resonators 3 and 5 are interconnected by clamping screws 6 which at the same time ensure the assembly of the piezoelectric transducer 7.
  • This consists of one or more piezoelectric ceramics, for example of prismatic shape any base (circular, square or rectangular) but which in all cases and in accordance with the invention are drilled right through in a direction perpendicular to their planar faces which constitute their clamping faces on the mechanical resonators 3 and 5 for allow the passage of the liquid supply tube 1 which under these conditions passes through the vibrating device without there being contact between it and the liquid.
  • the feed tube ends at one of its ends by a nozzle or ejection nozzle 4 which can be, for example made of watch sapphire pierced along its axis of revolution.
  • the ceramics are joined by their face of the same polarity to an electrical contact 8.
  • a variable and in particular periodic potential is applied to the terminals of the transducer 7 via the connections 8 and 9.
  • the connection 9 in the example described by means of Figure 1 is connected to the liquid supply tube 1 which is metallic therefore conductive. In the case where this tube is not conductive, this connection would be taken on the metal resonator 5.
  • the tranducer operates in longitudinal vibratory mode (periodic thickness variation), which causes the propagation of acoustic waves throughout the vibratory device constituted by the transducer and the mechanical resonators, the result of which is to ensure fragmentation of the jet into droplets of equal dimensions.
  • the resonant frequency depends on the nature and the shape of the resonators.
  • the vibratory device has maximum efficiency when each of its two halves is given a length corresponding to a phase shift ⁇ 1 and ⁇ 2 equal to ⁇ / 2 between the middle part (corresponding substantially to the electrical contact 8) and each of the two ends, for the acoustic excitation wave which propagates there as a result of the vibration of the piezo transducer electric.
  • the lengths AB, CD and EF being respectively equal to 12, 15 and 3 mm and the resonator being made of clockmaking brass
  • the resonance frequency is of the order of 70 Khz.
  • the resonator 3 disposed at the front is smaller in size than that of the resonator 5 disposed at the rear.
  • This configuration has the advantage of allowing on this side an emission in the air which is lower than the acoustic emission obtained on the side of the nozzle 4.
  • FIG. 2 A second alternative embodiment of a vibrating device according to the invention is shown in Figure 2.
  • the two resonators 3 and 5 front and rear having a configuration different from that of the previous figure which may prove preferable for the subsequent arrangement of this device in a given print head.
  • These two resonators are connected to each other and enclose a piezoelectric transducer 7 by means of two clamping screws 6.
  • a variable potential is applied to the terminals of the transducer 7 via the electrical connections 8 and 9.
  • the nozzle or nozzle 4 is integral with the liquid supply tube 1 at the front thereof and at the level of the front resonator 3.
  • This exemplary embodiment operates, for example, at a frequency of 120 Khz resonance.
  • this vibrating device has maximum efficiency when each of its two halves is given a length corresponding to a phase shift b ⁇ 1 and ⁇ 2 equal to ⁇ / 2 .
  • the various parts of the device being composed of different materials, the wavelength of the acoustic excitation wave which propagates there varies according to the nature of the material. This is taken into account in the calculation of the phase shifts ⁇ 1 and ⁇ 2 that are obtained at each end.
  • Another characteristic of the arrangement in accordance with the invention of the means constituting this vibratory device applied to a liquid cannon lies in the fact that it is possible to secure this cannon to the rest of the machine without requiring clamping. at the transducer.
  • a fixing device of the so-called clamping nut type 20 can be used. It is then the very liquid supply tube 1 which serves as a wedge pin between the outer part 200 and the other sliding inner part 22 of this fixing device 20.
  • Such a mounting device by clamping nut can also be chosen for fixing the supply tube and the ejection nozzle to the vibrating device on the side of the active end.
  • An example configuration of a vibratory device according to the invention of this type is shown in Figure 3.
  • the feed tube and the nozzle are made integral with the vibrating device by means of a clamping nut 20.
  • the tube feed is connected according to the invention by means of clamping nuts, on the one hand to the vibrating device at the active end (front) and on the other hand to the carriage at the non-active end (rear), which allows the piezoelectric elements to oscillate freely longitudinally along an axis parallel to that of the supply tube.
  • FIG. 4 supplemented by FIGS. 5 and 6 illustrate an example of arrangement of an assembly according to the invention of a vibratory device described above, leading to obtaining a head, for example a head printer for inkjet printer.
  • Figure 4 is a perspective view of the mounting, on a multiple support, of a mount carrying a barrel consisting essentially of a nozzle connected to the liquid supply tube and an excitation device.
  • Figure 5 shows in two sections (a) and (b), a lookout as shown in Figure 4 (Figure 5b is a section along AA 'of Figure 5a).
  • Figure 6 shows in two sections (a) and (b) a device for adjusting the orientation of this mount by pivoting about an axis.
  • the vibrating device comprising the piezoelectric ceramics 7 clamped between the resonators 3 and 5 are mounted on a mount 200.
  • the supply tube 1 is connected to the vibrating device by a clamping nut 20. This tube carries the ejection nozzle at its end.
  • At least one mount 200 as described above is enclosed in a support 60 which can be single or multiple capable in the latter case, of receiving a plurality of mountings.
  • the carriage or the plurality of carriage (of which only one is shown in FIG. 4) is held in place by means of an axis 80 around which each carriage can pivot as shown in arrow B.
  • Adjusting screws 70 allow jet orientation in the plane of Figure 6a.
  • the resonators do not have a symmetry of revolution, but rather a flattened shape (more visible in Figure 4) which allows multiple mounting with a periodicity (a 0 b) which can be for example 4 mm while also allowing mounting and tightening using screws.
  • the resonators are put in place using clamping nuts when the feed tube is in the proper position.
  • a notable advantage of the clamping nuts lies in the fact that they make it possible to very easily remove and replace the feed tube and the nozzle in the event of a malfunction or irreparable blockage.
  • an advantage of the invention is to make the vibratory devices associated with each nozzle independent, in particular with regard to acoustic vibration, which minimizes the interaction between the cannons .
  • Another advantage of the invention is that the dimensions of the barrel are reduced the higher the excitation frequency. This is particularly advantageous in the case of inkjet printing where an increase in the printing speed generally requires, on the one hand, a high excitation frequency in order to obtain a large number of droplets per second and on the other hand, a nozzle periodicity of only a few millimeters in order to minimize the time of flight of the drops to take account of the speed of movement of the paper.
  • the invention applies more particularly to ink jet printing techniques, in particular at high speed, but it also applies to techniques involving the creation of liquid droplets of calibrated size. in large numbers such as for example mist, aerosol, sprays for the elimination of smoke and dust.

Abstract

1. A vibratory device having a piezo-electric element capable of producing a propagation of acoustic waves within a liquid in order to ensure the fragmentation of the liquid into droplets, comprising a liquid supply pipe and a piezo-electric transducer, characterised in that it comprises a first combination of a piezo-electric transducer (7) coupled with a front resonator (3) and a second combination of this piezo-electric transducer (7) coupled with a rear resonator (5), this double combination comprising a central orifice traversed by the liquid supply pipe (1) which thus passes through the vibratory device, the means for securing the supply pipe being such that they permit the piezo-electric transducer (7) to oscillate freely in the longitudinal direction along an axis parallel to that of the supply pipe.

Description

L'invention concerne un dispositif vibratoire à élément piezo-électrique pour canon à liquide destiné à une tête d'éjection d'un liquide fragmenté telle que notamment une tête d'impression à jet d'encre. Elle concerne plus précisément des moyens d'excitation en mode forcé d'une buse d'éjection pour la création de gouttes ainsi que l'agencement de ces moyens conduisant à l'obtention de canon à liquide tel que notamment une tête d'impression à jet d'encre.The invention relates to a vibrating device with a piezoelectric element for a liquid cannon intended for a head for ejecting a fragmented liquid such as in particular an ink jet printing head. More precisely, it relates to means of excitation in forced mode of an ejection nozzle for the creation of drops as well as the arrangement of these means leading to obtaining a liquid cannon such as in particular a printing head with inkjet.

Une imprimante à jet d'encre doit avant tout produire un jet de gouttes ayant des caractéristiques bien définies : les gouttes doivent être régulièrement espacées, de même grosseur et propulsées dans la même direction, à la même vitesse. Pour cela on crée des gouttes de taille calibrée par la brisure d'un jet fluide émis par la buse. Cette brisure est généralement obtenue grâce à l'action de céramiques piezo-électriques. Diverses solutions d'excitation de ces céramiques existent, soit en mode longitudinal dit "mode d'épaisseur" par des disques piezo-électriques, soit en mode transversal dit "mode de striction" par des tubes piezo-électriques soit enfin en mode de flexion permettant la compression d'une cavité. Parmi les principaux inconvénients que présentent ces systèmes on peut citer notamment le problème de l'encombrement, dû aux difficultés de fixation entre eux des céramiques et du tube d'alimentation, celui du réglage de différents paramètres tels que l'orientation du jet de liquide qui donne naissance au train de gouttes, enfin le problème de la fixation de la buse elle-même qui présente toujours de grandes difficultés.An inkjet printer must above all produce a jet of drops with well-defined characteristics: the drops must be regularly spaced, of the same size and propelled in the same direction, at the same speed. For this, drops of calibrated size are created by the breaking of a fluid jet emitted by the nozzle. This break is generally obtained thanks to the action of piezoelectric ceramics. Various solutions for excitation of these ceramics exist, either in longitudinal mode called "thickness mode" by piezoelectric discs, or in transverse mode called "necking mode" by piezoelectric tubes or finally in bending mode allowing compression of a cavity. Among the main drawbacks that these systems present, we can cite in particular the problem of space, due to the difficulties of fixing ceramics and the feed tube to each other, that of the adjustment of various parameters such as the orientation of the liquid jet. which gives rise to the train of drops, finally the problem of fixing the nozzle itself which always presents great difficulties.

La présente invention a pour but de pallier ces inconvénients et concerne une nouvelle architecture des principaux moyens constituant un dispositif vibratoire notamment pour imprimante à jet d'encre : dispositif de dimensions réduites permettant la réalisation de têtes d'impression à plusieurs buses adjacentes disposées en rangées selon une périodicité qui peut être de quelques millimètres seulement. Ce résultat est obtenu grâce à la combinaison de transducteur et de résonateurs dont la caractéristique essentielle est d'être percés en leur centre pour laisser passer le tube d'alimentation en liquide qui traverse ainsi de part en part le dispositif vibratoire et peut être rendu solidaire de la buse dans la partie avant du résonateur.The present invention aims to overcome these drawbacks and relates to a new architecture of the main means constituting a vibratory device in particular for inkjet printer: device of reduced dimensions allowing the production of printheads with several adjacent nozzles arranged in rows at a frequency which can be a few millimeters only. This result is obtained thanks to the combination of transducer and resonators whose essential characteristic is to be drilled in their center to let pass the liquid supply tube which thus passes right through the vibratory device and can be made integral of the nozzle in the front part of the resonator.

Une des principales applications de l'invention est l'imprimante à jet d'encre mais elle peut s'appliquer à tout autre système nécessitant la formation de trains de gouttes calibrées.One of the main applications of the invention is the inkjet printer, but it can be applied to any other system requiring the formation of calibrated drop trains.

L'invention concerne plus particulièrement un dispositif vibratoire à élément piezo-électrique capable de générer une propagation d'ondes acoustiques dans un liquide pour assurer la fragmentation du liquide en gouttelettes, caractérisé en ce qu'il comprend une première combinaison d'un transducteur piezo-électrique couplé à un résonateur avant et une seconde combinaison du transducteur piezo-électrique avec un résonateur arrière, cette double combinaison comportant un orifice central à travers lequel passe le tube d'alimentation en liquide qui traverse ainsi de part en part le dispositif vibratoire sans que le liquide soit en contact direct avec le transducteur piezo-électrique.The invention relates more particularly to a vibrating device with a piezoelectric element capable of generating a propagation of acoustic waves in a liquid to ensure the fragmentation of the liquid into droplets, characterized in that it comprises a first combination of a piezo transducer -electric coupled to a front resonator and a second combination of the piezoelectric transducer with a rear resonator, this double combination comprising a central orifice through which the liquid supply tube passes which thus passes right through the vibratory device without the liquid is in direct contact with the piezoelectric transducer.

L'invention sera mieux comprise à l'aide des explications qui vont suivre et des figures jointes parmi lesquelles

  • - les figures 1 à 3 représentent schématiquement deux variantes de réalisations d'un dispositif vibratoire conforme à l'invention ;
  • - les figures 4 à 6 illustrent schématiquement un agencement des dispositifs selon l'invention constituant une tête d'éjection dont la buse est orientable dans différents plans.
The invention will be better understood with the aid of the explanations which follow and of the appended figures among which
  • - Figures 1 to 3 schematically represent two alternative embodiments of a vibrating device according to the invention;
  • - Figures 4 to 6 schematically illustrate an arrangement of the devices according to the invention constituting an ejection head whose nozzle is orientable in different planes.

Pour plus de clarté, les mêmes éléments portent les mêmes références dans toutes les figures.For the sake of clarity, the same elements are given the same references in all the figures.

Comme le montre la figure 1, un dispositif vibratoire conforme à l'invention et le canon qui en est équipé comprend un transducteur piezo-électrique 7 coopérant avec un premier et un second résonateur mécanique avant et arrière respectivement référencés 3 et 5 formant ainsi une première et une seconde combinaisons transducteur-résonateur. Les deux résonateurs 3 et 5 sont reliés entre eux par des vis de serrage 6 qui assurent en même temps l'assemblage du transducteur piezo-électrique 7. Celui-ci est constitué d'une ou plusieurs céramiques piezo-électriques par exemple de forme prismatique à base quelconque (circulaire, carrée ou rectangulaire) mais qui dans tous les cas et conformément à l'invention sont percées de part en part selon une direction perpendiculaire à leurs faces planes qui constituent leurs faces de serrage sur les résonateurs mécaniques 3 et 5 pour permettre le passage du tube d'alimentation en liquide 1 qui dans ces conditions traverse le dispositif vibratoire sans qu'il y ait de contact entre lui et le liquide. Le tube d'alimentation se termine à l'une de ses extrémités par un ajutage ou buse d'éjection 4 qui peut être, par exemple réalisée en saphir d'horlogerie percé selon son axe de révolution.As shown in Figure 1, a vibrating device according to the invention and the barrel which is equipped with it comprises a piezoelectric transducer 7 cooperating with a first and a second front and rear mechanical resonator respectively referenced 3 and 5 thus forming a first and a second combination transducer-resonator sounds. The two resonators 3 and 5 are interconnected by clamping screws 6 which at the same time ensure the assembly of the piezoelectric transducer 7. This consists of one or more piezoelectric ceramics, for example of prismatic shape any base (circular, square or rectangular) but which in all cases and in accordance with the invention are drilled right through in a direction perpendicular to their planar faces which constitute their clamping faces on the mechanical resonators 3 and 5 for allow the passage of the liquid supply tube 1 which under these conditions passes through the vibrating device without there being contact between it and the liquid. The feed tube ends at one of its ends by a nozzle or ejection nozzle 4 which can be, for example made of watch sapphire pierced along its axis of revolution.

Les céramiques sont accolées par leur face de même polarité à un contact électrique 8. Un potentiel variable et en particulier périodique est appliqué aux bornes du transducteur 7 par l'intermédiaire des connexions 8 et 9. La connexion 9 dans l'exemple décrit au moyen de la figure 1 est reliée au tube d'alimentation en liquide 1 qui est métallique donc conducteur. Dans le cas ou ce tube ne serait pas conducteur, cette connexion serait prise sur le résonateur métallique 5. Le tranducteur fonctionne en mode vibratoire longitudinal (variation périodique d'épaisseur), ce qui entraîne la propagation d'ondes acoustiques dans l'ensemble du dispositif vibratoire constitué par le transducteur et les résonateurs mécaniques dont le résultat est d'assurer une fragmentation du jet en gouttelettes d'égales dimensions.The ceramics are joined by their face of the same polarity to an electrical contact 8. A variable and in particular periodic potential is applied to the terminals of the transducer 7 via the connections 8 and 9. The connection 9 in the example described by means of Figure 1 is connected to the liquid supply tube 1 which is metallic therefore conductive. In the case where this tube is not conductive, this connection would be taken on the metal resonator 5. The tranducer operates in longitudinal vibratory mode (periodic thickness variation), which causes the propagation of acoustic waves throughout the vibratory device constituted by the transducer and the mechanical resonators, the result of which is to ensure fragmentation of the jet into droplets of equal dimensions.

La fréquence de résonance dépend de la nature et de la forme des résonateurs. Le dispositif vibratoire a une efficacité maximum lorsque l'on donne à chacune de ses deux moitiés une longueur correspondant à un déphasage Δϕ1 et Δϕ2 égal à π/2 entre la partie médiane (correspondant sensiblement au contact électrique 8) et chacune des deux extrémités, pour l'onde d'excitation acoustique qui s'y propage par suite de la vibration du transducteur piezo-électrique. Dans l'exemple illustré sur la figure 1 les longueurs AB, CD et EF étant respectivement égales à 12, 15 et 3 mm et le résonateur étant réalisé en laiton d'horlogerie, la fréquence de résonance est de l'ordre de 70 Khz. il faut noter que le résonateur 3 disposé à l'avant (du côté de la buse 4) est de taille inférieure à celui du résonateur 5 disposé à l'arrière. Cette configuration présente l'avantage de permettre de ce côté une émission dans l'air qui soit inférieure à l'émission acoustique obtenue du côté de la buse 4.The resonant frequency depends on the nature and the shape of the resonators. The vibratory device has maximum efficiency when each of its two halves is given a length corresponding to a phase shift Δϕ 1 and Δϕ 2 equal to π / 2 between the middle part (corresponding substantially to the electrical contact 8) and each of the two ends, for the acoustic excitation wave which propagates there as a result of the vibration of the piezo transducer electric. In the example illustrated in FIG. 1, the lengths AB, CD and EF being respectively equal to 12, 15 and 3 mm and the resonator being made of clockmaking brass, the resonance frequency is of the order of 70 Khz. it should be noted that the resonator 3 disposed at the front (on the side of the nozzle 4) is smaller in size than that of the resonator 5 disposed at the rear. This configuration has the advantage of allowing on this side an emission in the air which is lower than the acoustic emission obtained on the side of the nozzle 4.

Une seconde variante de réalisation d'un dispositif vibratoire conforme à l'invention est représentée sur la figure 2. On retrouve les deux résonateurs 3 et 5 avant et arrière présentant une configuration différente de celle de la figure précédente qui peut s'avérer préférable pour l'agencement ultérieur de ce dispositif dans une tête d'impression donnée. Ces deux résonateurs sont reliés l'un à l'autre et enserrent un transducteur piezo-électrique 7 au moyen de deux vis de serrage 6. Comme dans l'exemple précédent un potentiel variable est appliqué aux bornes du transducteur 7 par l'intermédiaire des connexions électriques 8 et 9. L'ajutage ou buse 4 est solidaire du tube d'alimentation en liquide 1 à l'avant de celui-ci et au niveau du résonateur avant 3. Cet exemple de réalisation fonctionne par exemple, à une fréquence de résonnance de 120 Khz.A second alternative embodiment of a vibrating device according to the invention is shown in Figure 2. We find the two resonators 3 and 5 front and rear having a configuration different from that of the previous figure which may prove preferable for the subsequent arrangement of this device in a given print head. These two resonators are connected to each other and enclose a piezoelectric transducer 7 by means of two clamping screws 6. As in the previous example, a variable potential is applied to the terminals of the transducer 7 via the electrical connections 8 and 9. The nozzle or nozzle 4 is integral with the liquid supply tube 1 at the front thereof and at the level of the front resonator 3. This exemplary embodiment operates, for example, at a frequency of 120 Khz resonance.

Comme dans le cas de la variante précédente, ce dispositif vibratoire a une efficacité maximum lorsqu'on donne à chacune de ses deux moitiés une longueur correspondant à un déphasage b ϕ1 et Δϕ2 égal à π/2 . Les diverses parties du dispositif étant composées de matériaux différents, la longueur d'onde de l'onde acoustique d'excitation qui s'y propage varie selon la nature du matériau. On en tient compte dans le calcul des déphasages Δϕ1 et Δϕ2 qu'on obtient à chaque extrémité.As in the case of the previous variant, this vibrating device has maximum efficiency when each of its two halves is given a length corresponding to a phase shift b ϕ 1 and Δϕ 2 equal to π / 2 . The various parts of the device being composed of different materials, the wavelength of the acoustic excitation wave which propagates there varies according to the nature of the material. This is taken into account in the calculation of the phase shifts Δϕ 1 and Δϕ 2 that are obtained at each end.

En résumé donc, selon une première caractéristique, un dispositif conforme à l'invention comprend notamment la combinaison des moyens suivants :

  • - un tube d'alimentation de fluide, en matériau résistant à la corrosion due à la circulation du fluide ;
  • - une buse d'éjection formant l'orifice de ce tube ;
  • - au moins une céramique ou cristal piezo-électrique de forme annulaire comportant un orifice central permettant le passage du tube d'alimentation en fluide, étant entendu que l'utilisation de deux éléments piezo-électriques permet de rendre le fonctionnement plus symétrique, facilite les connexions et permet d'obtenir un noeud de vibration dans la partie centrale ;
  • - des masses métalliques situées de part et d'autre du ou des éléments piezo-électriques et constituant des résonateurs acoustiques permettant d'augmenter l'efficacité du système, les masses situées de part et d'autre pouvant être constituées de métaux de nature différente afin de différencier les impédances acoustiques et de diminuer la puissance émise par l'extrémité dite non active du dispositif opposé à l'extrémité dite active qui est située du côté de la buse d'éjection.
In summary therefore, according to a first characteristic, a device according to the invention comprises in particular the combination of the following means:
  • - a fluid supply tube, made of a material resistant to corrosion due to the circulation of the fluid;
  • - an ejection nozzle forming the orifice of this tube;
  • at least one ceramic or piezoelectric crystal of annular shape comprising a central orifice allowing the passage of the fluid supply tube, it being understood that the use of two piezoelectric elements makes it possible to make the operation more symmetrical, facilitates the connections and allows to obtain a vibration node in the central part;
  • - metallic masses located on either side of the piezoelectric element (s) and constituting acoustic resonators making it possible to increase the efficiency of the system, the masses situated on either side being able to be made of metals of different nature in order to differentiate the acoustic impedances and to reduce the power emitted by the so-called non-active end of the device opposite the so-called active end which is located on the side of the ejection nozzle.

Une autre caractéristique de l'agencement conforme à_ l'invention des moyens constituant ce dispositif vibratoire appliqué à un canon à liquide réside dans le fait que l'on peut assurer la fixation de ce canon au reste de la machine sans faire appel à un serrage au niveau du transducteur. En effet, on peut utiliser un dispositif de fixation du type dit à noix de serrage 20. C'est alors le tube même d'alimentation en liquide 1 qui sert de cheville de coincement entre la partie extérieure 200 et l'autre intérieure coulissante 22 de ce dispositif de fixation 20.Another characteristic of the arrangement in accordance with the invention of the means constituting this vibratory device applied to a liquid cannon lies in the fact that it is possible to secure this cannon to the rest of the machine without requiring clamping. at the transducer. In fact, a fixing device of the so-called clamping nut type 20 can be used. It is then the very liquid supply tube 1 which serves as a wedge pin between the outer part 200 and the other sliding inner part 22 of this fixing device 20.

Un tel dispositif de montage par noix de serrage peut également être choisi pour la fixation du tube d'alimentation et de la buse d'éjection au dispositif vibratoire du côté de l'extrémité active. Un exemple de configuration d'un dispositif vibratoire conforme à l'invention de ce type est représenté sur la figure 3. On y retrouve le tube d'alimentation en liquide l, la buse d'éjection 4, les céramiques piezo-électriques 7 liées aux résonateurs 3 et 5 au moyen des vis de serrage 6. Le tube d'alimentation et la buse sont rendus solidaires du dispositif vibratoire au moyen d'une noix de serrage 20.Such a mounting device by clamping nut can also be chosen for fixing the supply tube and the ejection nozzle to the vibrating device on the side of the active end. An example configuration of a vibratory device according to the invention of this type is shown in Figure 3. There are the liquid supply tube l, the ejection nozzle 4, the piezoelectric ceramics 7 linked to the resonators 3 and 5 by means of the clamping screws 6. The feed tube and the nozzle are made integral with the vibrating device by means of a clamping nut 20.

En résumé donc, selon une seconde caractéristique, le tube d'alimentation est relié selon l'invention au moyen de noix de serrage, d'une part au dispositif vibratoire à l'extrémité active (avant) et d'autre part à l'affût à l'extrémité non active (arrière), ce qui permet aux éléments piezo-électriques d'osciller librement longitudinalement selon un axe parallèle à celui du tube d'alimentation.In summary therefore, according to a second characteristic, the tube feed is connected according to the invention by means of clamping nuts, on the one hand to the vibrating device at the active end (front) and on the other hand to the carriage at the non-active end (rear), which allows the piezoelectric elements to oscillate freely longitudinally along an axis parallel to that of the supply tube.

La figure 4 complétée par les figures 5 et 6 illustrent un exemple d'agencement d'un montage selon l'invention d'un dispositif vibratoire décrit ci-dessus, conduisant à l'obtention d'une tête, par exemple d'une tête d'impression pour imprimante à jet d'encre.FIG. 4 supplemented by FIGS. 5 and 6 illustrate an example of arrangement of an assembly according to the invention of a vibratory device described above, leading to obtaining a head, for example a head printer for inkjet printer.

La figure 4 est une vue en perspective du montage, sur un support multiple, d'un affût portant un canon constitué essentiellement d'une buse reliée au tube d'alimentation en liquide et d'un dispositif d'excitation.Figure 4 is a perspective view of the mounting, on a multiple support, of a mount carrying a barrel consisting essentially of a nozzle connected to the liquid supply tube and an excitation device.

La figure 5 représente selon deux coupes (a) et (b), un affût tel que représenté sur la figure 4 (La figure 5b est une coupe selon AA' de la figure 5a). La figure 6 représente selon deux coupes (a) et (b) un dispositif de réglage de l'orientation de cet affût par pivotement autour d'un axe. Ces figures ainsi que la figure 6 vue selon deux coupes (a) et (b) sont maintenant décrites simultanément. Le dispositif vibratoire comportant les céramiques piezo-électriques 7 serrées entre les résonateurs 3 et 5 sont montés sur un affût 200. Le tube d'alimentation 1 est relié au dispositif vibratoire par une noix de serrage 20. Ce tube porte la buse d'éjection à son extrémité. Il peut tourner autour de lui-même (comme le montre la flèche A) ce qui permet de pallier les défauts de centrage éventuels existant au niveau de la buse et d'amener le jet dans le plan des vis de réglage 70 (c'est-à-dire dans le plan de la figure 6à). Une vis de blocage 30 maintient le tube dans la position optimale. Au moins un affût 200 tel que décrit ci-dessus est enserré dans un support 60 qui peut être simple ou multiple capable dans ce dernier cas, de recevoir une pluralité d'affûts. L'affût ou la pluralité d'affûts (dont un seul est représenté sur la figure 4) est maintenu en place au moyen d'un axe 80 autour duquel chaque affût peut pivoter comme le montre la flèche B. Des vis de réglage 70 permettent l'orientation du jet dans le plan de la figure 6a. Compte tenu des dimensions réduites des résonateurs mécaniques et de la nécessité de faire tourner le tube d'alimentation pour obtenir le réglage défini ci-dessus, deux conditions sont notamment réalisées. D'une part, les résonateurs n'ont pas une symétrie de révolution, mais plutôt une forme applatie (plus visible sur la figure 4) ce qui permet un montage multiple avec une périodicité (a 0 b) qui peut être par exemple de 4 mm tout en permettant par ailleurs, le montage et le serrage à l'aide de vis. D'autre part, les résonateurs sont mis en place à l'aide de noix de serrage quand le tube d'alimentation se trouve dans la position convenable. Un avantage notoire des noix de serrage réside dans le fait qu'elles permettent de retirer et de remplacer très aisément le tube d'alimentation et la buse en cas de mauvais fonctionnement ou de bouchage irrémédiable.Figure 5 shows in two sections (a) and (b), a lookout as shown in Figure 4 (Figure 5b is a section along AA 'of Figure 5a). Figure 6 shows in two sections (a) and (b) a device for adjusting the orientation of this mount by pivoting about an axis. These figures as well as FIG. 6 seen according to two sections (a) and (b) are now described simultaneously. The vibrating device comprising the piezoelectric ceramics 7 clamped between the resonators 3 and 5 are mounted on a mount 200. The supply tube 1 is connected to the vibrating device by a clamping nut 20. This tube carries the ejection nozzle at its end. It can rotate around itself (as shown by arrow A) which makes it possible to compensate for any centering defects existing at the level of the nozzle and to bring the jet into the plane of the adjustment screws 70 (this is i.e. in the plane of Figure 6a). A locking screw 30 keeps the tube in the optimal position. At least one mount 200 as described above is enclosed in a support 60 which can be single or multiple capable in the latter case, of receiving a plurality of mountings. The carriage or the plurality of carriage (of which only one is shown in FIG. 4) is held in place by means of an axis 80 around which each carriage can pivot as shown in arrow B. Adjusting screws 70 allow jet orientation in the plane of Figure 6a. Given the reduced dimensions of the mechanical resonators and the need to rotate the supply tube to obtain the adjustment defined above, two conditions are notably fulfilled. On the one hand, the resonators do not have a symmetry of revolution, but rather a flattened shape (more visible in Figure 4) which allows multiple mounting with a periodicity (a 0 b) which can be for example 4 mm while also allowing mounting and tightening using screws. On the other hand, the resonators are put in place using clamping nuts when the feed tube is in the proper position. A notable advantage of the clamping nuts lies in the fact that they make it possible to very easily remove and replace the feed tube and the nozzle in the event of a malfunction or irreparable blockage.

Dans le cas d'une tête comportant plusieurs canons à encre, un avantage de l'invention est de rendre indépendants les dispositifs vibratoires associés à chaque buse en particulier en ce qui concerne la vibration acoustique, ce qui rend minimum l'interaction entre les canons. Un autre avantage de l'invention est de conduire à des dimensions du canon d'autant plus réduites que la fréquence d'excitation est plus élevée. Ceci est particulièrement avantageux dans le cas de l'impression par jet d'encre où une augmentation de la vitesse d'impression requiert généralement, d'une part une fréquence d'excitation élevée afin d'obtenir un grand nombre de gouttelettes par seconde et d'autre part une périodicité de buses de seulement quelques millimètres afin de minimiser le temps de vol des gouttes pour tenir compte de la vitesse de défilement du papier.In the case of a head comprising several ink cannons, an advantage of the invention is to make the vibratory devices associated with each nozzle independent, in particular with regard to acoustic vibration, which minimizes the interaction between the cannons . Another advantage of the invention is that the dimensions of the barrel are reduced the higher the excitation frequency. This is particularly advantageous in the case of inkjet printing where an increase in the printing speed generally requires, on the one hand, a high excitation frequency in order to obtain a large number of droplets per second and on the other hand, a nozzle periodicity of only a few millimeters in order to minimize the time of flight of the drops to take account of the speed of movement of the paper.

Comme cela a déjà été dit précédemment, l'invention s'applique plus particulièrement aux techniques d'impression à jet d'encre notamment à vitesse élevée mais elle s'applique également aux techniques faisant appel à la création de gouttelettes de liquide de taille calibrée en grand nombre telles que par exemple brouillard, aérosol, pulvérisations pour élimination des fumées et poussières.As has already been said previously, the invention applies more particularly to ink jet printing techniques, in particular at high speed, but it also applies to techniques involving the creation of liquid droplets of calibrated size. in large numbers such as for example mist, aerosol, sprays for the elimination of smoke and dust.

Claims (11)

1. Dispositif vibratoire à élément piezo-électrique capable de générer une propagation d'ondes acoustiques dans un liquide pour assurer la fragmentation du liquide en gouttelettes, caractérisé en ce qu'il comprend une première combinaison d'un transducteur piezo-électrique couplé à un résonateur avant et une seconde combinaison du transducteur piezo-électrique couplé à un résonateur arrière, cette double combinaison comportant un orifice central à travers lequel passe le tube d'alimentation en liquide qui traverse ainsi de part en part le dispositif vibratoire sans que le liquide soit en contact direct avec le transducteur piezo-électrique.1. Vibratory device with piezoelectric element capable of generating a propagation of acoustic waves in a liquid to ensure the fragmentation of the liquid into droplets, characterized in that it comprises a first combination of a piezoelectric transducer coupled to a front resonator and a second combination of the piezoelectric transducer coupled to a rear resonator, this double combination comprising a central orifice through which the liquid supply tube passes which thus passes right through the vibratory device without the liquid being in direct contact with the piezoelectric transducer. 2. Dispositif vibratoire selon la revendication 1, caractérisé en ce que la première et la seconde combinaison du transducteur avec le résonateur avant et avec le résonateur arrière sont dissymétriques.2. Vibratory device according to claim 1, characterized in that the first and the second combination of the transducer with the front resonator and with the rear resonator are asymmetrical. 3. Dispositif vibratoire selon la revendication 2, caractérisé en ce que le dimensionnement et la nature des matériaux sont choisis pour les résonateurs de telle sorte qu'il existe respectivement entre la face avant du résonateur avant, la face arrière du résonateur arrière et la partie médiane du transducteur un déphasage Δ lPt et3. Vibratory device according to claim 2, characterized in that the dimensioning and the nature of the materials are chosen for the resonators so that there exist respectively between the front face of the front resonator, the rear face of the rear resonator and the part median of the transducer a phase shift Δ lP t and
Figure imgb0001
Figure imgb0001
 4. Dispositif vibratoire selon la revendication 3, caractérisé en ce que le résonateur avant, placé du côté de la buse est de taille inférieure à celle du résonateur arrière.4. Vibratory device according to claim 3, characterized in that the front resonator, placed on the side of the nozzle is of size smaller than that of the rear resonator. 5. Canon à liquide, caractérisé en ce qu'il est équipé d'un dispositif vibratoire selon l'une des revendications précédentes.5. Liquid cannon, characterized in that it is equipped with a vibrating device according to one of the preceding claims. 6. Tête d'éjection d'un liquide fragmenté caractérisée en ce qu'elle comprend un canon à liquide selon la revendication 5, dans laquelle le tube d'alimentation en liquide est serré sur le résonateur avant au moyen d'une noix de serrage.6. Head for ejecting a fragmented liquid characterized in that it comprises a liquid cannon according to claim 5, in which the liquid supply tube is clamped on the front resonator by means of a clamping nut . 7. Tête d'éjection d'un liquide fragmenté, caractérisée en ce qu'elle comprend un canon à liquide selon la revendication 5, caractérisé en ce que ce canon est monté sur un affût, de telle sorte que le tube d'alimentation se trouve fixé sur cet affût au moyen d'une noix de serrage de manière à pouvoir être tourné autour de lui-même.7. Head for ejecting a fragmented liquid, characterized in that it comprises a liquid cannon according to claim 5, characterized in that this cannon is mounted on a mount, so that the feed tube is attached to this mount by means of a clamping nut so that it can be rotated around itself. 8. Tête d'éjection d'un liquide fragmenté selon la revendication 7, caractérisée en ce qu'au moins un affût est positionné dans un support, cet affût pouvant être pivoté, autour d'un axe et serré dans une position déterminée au moyen de vis de serrage.8. Head for ejecting a fragmented liquid according to claim 7, characterized in that at least one mount is positioned in a support, this mount being able to be pivoted about an axis and clamped in a position determined by means of clamping screws. 9. Tête d'éjection d'un liquide fragmenté selon la revendication 8, caractérisée en ce que ce support est un support multiple capable de recevoir une pluralité d'affûts pivotables chacun autour d'un axe commun.9. Ejection head of a fragmented liquid according to claim 8, characterized in that this support is a multiple support capable of receiving a plurality of mountings each pivotable about a common axis. 10. Tête d'éjection d'un liquide fragmenté selon l'une des revendications 6 à 9, caractérisée en ce que le liquide est de l'encre se fragmentant sous la forme d'un jet d'encre pour imprimante.10. Head for ejecting a fragmented liquid according to one of claims 6 to 9, characterized in that the liquid is ink fragmenting in the form of an ink jet for printer.
EP19800401273 1979-09-26 1980-09-05 Vibratory device with piezoelectric element for a liquid gun used in a fragmented-liquid ejection head Expired EP0026688B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR7923934 1979-09-26
FR7923934A FR2465528A1 (en) 1979-09-26 1979-09-26 VIBRATION DEVICE WITH PIEZOELECTRIC ELEMENT FOR LIQUID GUNS FOR EYEING HEAD OF A FRAGMENTED LIQUID

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EP0026688A1 true EP0026688A1 (en) 1981-04-08
EP0026688B1 EP0026688B1 (en) 1984-05-30

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WO1999046126A1 (en) * 1998-03-09 1999-09-16 Hegedus Gyoergy Liquid dispensing apparatus

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FR2542257B1 (en) * 1983-03-07 1985-08-02 Imaje Sa INK JET PRINTING HEAD AND PRINTER HAVING THE SAME
JPS61138558A (en) * 1984-12-11 1986-06-26 Toa Nenryo Kogyo Kk Oscillator for ultrasonic wave injection nozzle
ATE71201T1 (en) * 1986-05-09 1992-01-15 Sono Tek Corp CENTRALLY BOLTED ULTRASONIC ATOMIZER.

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FR2101843A5 (en) * 1970-08-05 1972-03-31 Dick Co Ab
GB1293980A (en) * 1970-11-13 1972-10-25 Standard Telephones Cables Ltd Ink jet printer pen unit
FR2136531A5 (en) * 1971-04-19 1972-12-22 Dick Co Ab
US4005435A (en) * 1975-05-15 1977-01-25 Burroughs Corporation Liquid jet droplet generator

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FR2101843A5 (en) * 1970-08-05 1972-03-31 Dick Co Ab
GB1293980A (en) * 1970-11-13 1972-10-25 Standard Telephones Cables Ltd Ink jet printer pen unit
FR2136531A5 (en) * 1971-04-19 1972-12-22 Dick Co Ab
US4005435A (en) * 1975-05-15 1977-01-25 Burroughs Corporation Liquid jet droplet generator

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1999046126A1 (en) * 1998-03-09 1999-09-16 Hegedus Gyoergy Liquid dispensing apparatus
US6460980B1 (en) 1998-03-09 2002-10-08 Hegedus Gyoergy Liquid dispensing apparatus

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DE3068038D1 (en) 1984-07-05
FR2465528B1 (en) 1983-09-16
FR2465528A1 (en) 1981-03-27
EP0026688B1 (en) 1984-05-30

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