EP0331591A1 - Electroacoustic capsule with a piezo-electric diaphragm - Google Patents

Electroacoustic capsule with a piezo-electric diaphragm Download PDF

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Publication number
EP0331591A1
EP0331591A1 EP89420071A EP89420071A EP0331591A1 EP 0331591 A1 EP0331591 A1 EP 0331591A1 EP 89420071 A EP89420071 A EP 89420071A EP 89420071 A EP89420071 A EP 89420071A EP 0331591 A1 EP0331591 A1 EP 0331591A1
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EP
European Patent Office
Prior art keywords
cover
capsule
seal
periphery
capsule according
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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.)
Ceased
Application number
EP89420071A
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German (de)
French (fr)
Inventor
Christian Cognasse
Peter Graham
Bernard Maury
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Horlogerie Photographique Francaise SA
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Horlogerie Photographique Francaise SA
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Publication of EP0331591A1 publication Critical patent/EP0331591A1/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/16—Mounting or tensioning of diaphragms or cones
    • H04R7/18—Mounting or tensioning of diaphragms or cones at the periphery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers

Definitions

  • the present invention relates to electroacoustic transducers, the vibrating element of which consists of a membrane with a layer of piezoelectric material provided with electrodes and held around its periphery in a capsule case.
  • the housing comprises a base body provided with a central cavity, the periphery of which forms a bearing surface for the periphery of the piezoelectric membrane; the housing further comprises a cover connecting at its periphery to the base body, and comprising an internal recess communicating with the outside via at least one orifice.
  • the periphery of the cover has a rigid internal annular relief bearing on the periphery of the membrane to keep it pressed against a joint. annular interposed between said membrane and the periphery of the cavity of the base body.
  • the periphery of the cavity of the base body has a rigid annular relief forming a bearing surface, the membrane periphery being held against said annular relief by a annular seal interposed between the cover and the membrane.
  • the central base body cavity defines, with the piezoelectric membrane, a basic interior cavity.
  • the interior cover recess defines, with the piezoelectric membrane, an interior cover cavity.
  • the shape and dimensions of the interior base and cover cavities contribute significantly to determining the acoustic characteristics of the capsule.
  • the capsule is intended to be generally inserted in an external housing, and, in this case, the external face of the cover defines, with the wall of the housing, an external cavity whose dimensions and shape also contribute to the definition of the acoustic characteristics of the whole.
  • the capsule and the case in which it is inserted constitute a stack of elements which define several cavities whose shape and size very significantly influence the result.
  • transducer acoustics This stacking is generally carried out by automatic means, the joining being able to be ensured by welding, by crimping or any other means.
  • the piezoelectric membrane is maintained by the interposition of at least one annular seal which is a separate part.
  • the assembly requires a stacking of a relatively large number of elements, which results in a non-negligible production cost.
  • the object of the present invention is in particular to avoid the drawbacks of known methods and devices, by proposing a new capsule structure with a piezoelectric membrane making it possible to produce, with automatic assembly means, capsules having shapes and dimensions of interior cavities. accurately determinable; it follows that, according to the invention, the shape and the dimension of the internal cavities, as well as the bearing force of the retaining members of the periphery of the membrane, can be obtained with great regularity and great precision, and the this minimizes the problems associated with dispersion in the case of mass production.
  • the invention defines a capsule structure comprising means ensuring regular, precise and known adaptation with good certainty on the internal face of the outer casing in which the capsule is to be attached.
  • the number of elements to be assembled is significantly reduced during assembly of the capsule.
  • the problems usually associated with the use of seals are also avoided sealing, known and usable seals generally being of irregular dimensions, which induces flatness defects of the holding surfaces of the piezoelectric membrane.
  • Another object of the invention is to provide means making it possible to automate the manufacture of such a capsule as much as possible, by simultaneously producing, in a single operation, all of the seals intended on the one hand to maintain the piezoelectric membrane, and secondly to receive the wall of the outer casing into which the capsule is inserted.
  • the inner annular relief of the cover consists of an inner seal molded in injectable elastomer.
  • the seal is welded to the cover; it follows that no leakage is possible between the seal and the cover, and the sealing of the inner cavity of the cover around its periphery is substantially improved, and the sealing between the inner cavity of the cover and the inner cavity of basic body.
  • the cover further comprises an outer annular relief in injectable elastomer molded, for example of the same material as the inner seal, and forming an outer seal against which the wall of an outer housing can be pressed in which we insert the capsule.
  • the inner seal and the outer seal are connected to each other by bridges made of the same material as that constituting the seals, and passing through holes in the cover, distributed over the periphery of the cover.
  • overmolding operation is understood to mean either a traditional overmolding technique consisting in injecting the material constituting the seals into a mold containing the preformed cover, or a bi-injection technique in which the two operations of molding the cover and overmolding the seal can be provided by the same device in two successive phases close together.
  • the cover further comprises a rigid peripheral external annular relief, continuous or not, bordering the external seal and forming a reference surface to limit the crushing of the external seal during the insertion of the capsule in a box.
  • the size of the outer capsule cavity is thus determined precisely and constantly.
  • the cover further comprises a rigid peripheral internal annular relief, continuous or not, bordering the internal seal and forming a reference surface to limit the crushing of the internal seal during the production of the capsule by assembling its constituent parts.
  • the capsule according to the present invention comprises a piezoelectric membrane 1.
  • a piezoelectric membrane of known type composed of a thin metallic or insulating film, forming the base substrate of the membrane, and on which is secured at least one piezoelectric ceramic layer, the two faces of which are metallized and constitute the electrodes.
  • Electrical connection means for example of a known type, ensure the connection of the electrodes to output terminals such as terminal 2 intended to be connected to external electronic circuits.
  • the membrane 1, for example of substantially circular shape, is held around its periphery in a capsule case.
  • the housing comprises a base body 4 provided with a central cavity 5, the periphery of which forms a support surface 6 for the membrane periphery 1.
  • the support surface 6 is advantageously constituted by a rigid annular relief, on which rests the lower edge of the membrane 1.
  • the housing further comprises a cover 7, connecting at its periphery 8 to the base body 4.
  • the cover 7 and the base body 4 are connected to each other according to respective peripheral contact surfaces 9 and 10 determined with precision, to achieve an easily reproducible assembly.
  • the cover 7 has an internal recess 11 communicating with the outside through a series of orifices such as the orifice 12, regularly distributed in the wall of the cover as shown in the figures.
  • the cover recess 11 defines an interior cover cavity;
  • the central base body cavity 5 defines an interior base body cavity; the interior cavities are separated from each other by the piezoelectric membrane 1.
  • the periphery of the cover 7 has an internal annular relief 13, in abutment on the membrane periphery, that is to say in abutment on the upper periphery of the membrane, the annular relief 13 consisting of an internal seal molded in injectable elastomer. It is advantageous to use an injectable elastomer marketed under the brand name ALCRYN by the company DU PONT DE NEMOURS.
  • the interior annular relief 13 forming an interior seal can be molded into an annular groove in the interior face of the cover, as shown in section in FIG. 2.
  • the cover 7 further comprises an external annular relief 14 also made of molded injectable elastomer, for example of the same material as the internal annular relief 13, and forming an external seal against which the wall of an external casing can be pressed. insert the capsule.
  • This outer casing wall is schematically represented by the dashed line 15 in FIG. 2.
  • the cover 7 also comprises an external annular relief rigid device 16, continuous or not, externally bordering the external seal 14, and forming a reference surface to limit the crushing of the external seal 14 during insertion of the capsule against the wall 15 of an external casing.
  • the external annular relief significantly facilitates centering during assembly of the capsule.
  • the inner seal 13 and the outer seal 14 are advantageously connected to each other by at least one bridge of material such as the bridge 17.
  • a hole or a series of through holes are regularly provided in the cover 7. distributed over the periphery as shown in Figure 1, the holes for the simultaneous injection of material and its distribution by forming at the same time the outer seal 14, the bridges 17 and the inner seal 13, by molding the cover.
  • the inner 13 and outer 14 seals each form a continuous ring.
  • the inner seal and / or the outer seal can be discontinuous, to define for example a radial passage for connectors or other elements. Such a discontinuity would be difficult to achieve if an added seal is used. This would indeed cause great difficulties in positioning and preparing the seals.
  • the cover 7 can be produced in two successive operations separated from one another: a first operation of molding the rigid shell forming the main structure of the cover; a second operation consisting in overmolding the prefabricated rigid shell, in a mold, by injecting the material intended to form the seals 13 and 14.
  • such a cover can be produced by a bi-injection technique, in two close phases, a first injection phase for forming the rigid cover shell, a second phase of injection of the material which should form the seals. 13 and 14.

Abstract

The capsule comprises a piezoelectric diaphragm (1) held around its periphery between a bearing surface (6) of a base body (4) and an inner O-ring (13) of a cover (7). The inner ring (13) of the cover consists of an overfilled injectable elastomer. The cover further comprises an outer O-ring (14) also made of an overfilled injectable elastomer. <IMAGE>

Description

La présente invention se rapporte aux transducteurs électroa­coustiques dont l'élément vibrant est constitué d'une membrane à couche de matière piézoélectrique munie d'électrodes et maintenue sur son pourtour dans un boitier de capsule.The present invention relates to electroacoustic transducers, the vibrating element of which consists of a membrane with a layer of piezoelectric material provided with electrodes and held around its periphery in a capsule case.

Dans les capsules connues, le boitier comprend un corps de base muni d'une cavité centrale dont la périphérie forme surface d'appui pour la périphérie de la membrane piézoélectrique ; le boitier comprend en outre un couvercle se raccordant par sa périphérie au corps de base, et comportant un évidement intérieur communiquant avec l'extérieur par au moins un orifice. Par exemple, dans le brevet FR-A-2 511 570, ou dans le brevet FR-A-2 337 480, la périphérie du couvercle comporte un relief annulaire intérieur rigide en appui sur la périphérie de membrane pour la maintenir plaquée contre un joint annulaire interposé entre ladite membrane et la périphérie de cavité du corps de base.In known capsules, the housing comprises a base body provided with a central cavity, the periphery of which forms a bearing surface for the periphery of the piezoelectric membrane; the housing further comprises a cover connecting at its periphery to the base body, and comprising an internal recess communicating with the outside via at least one orifice. For example, in patent FR-A-2,511,570, or in patent FR-A-2,337,480, the periphery of the cover has a rigid internal annular relief bearing on the periphery of the membrane to keep it pressed against a joint. annular interposed between said membrane and the periphery of the cavity of the base body.

Dans les brevets FR-A-1 334 235 et FR-A-2 275 182, la périphérie de cavité du corps de base comporte un relief annulaire rigide formant surface d'appui, la périphérie de membrane étant maintenue contre ladit relief annulaire par un joint annulaire interposé entre le couvercle et la membrane.In patents FR-A-1 334 235 and FR-A-2 275 182, the periphery of the cavity of the base body has a rigid annular relief forming a bearing surface, the membrane periphery being held against said annular relief by a annular seal interposed between the cover and the membrane.

Dans la demande de brevet DE-A-2 123 649, la membrane est pincée dans une fente d'un joint périphérique lui-même interposé entre le couvercle et le corps de base.In patent application DE-A-2 123 649, the membrane is pinched in a slot of a peripheral seal itself interposed between the cover and the base body.

La cavité centrale de corps de base définit, avec la membrane piézoélectrique, une cavité intérieure de base. L'évidement intérieur de couvercle définit, avec la membrane piézoélectrique, une cavité inté­rieure de couvercle. La forme et les dimensions des cavités intérieures de base et de couvercle contribuent sensiblement à la détermination des caractéristiques acoustiques de la capsule.The central base body cavity defines, with the piezoelectric membrane, a basic interior cavity. The interior cover recess defines, with the piezoelectric membrane, an interior cover cavity. The shape and dimensions of the interior base and cover cavities contribute significantly to determining the acoustic characteristics of the capsule.

En outre, la capsule est destinée à être généralement insérée dans un boitier externe, et, dans ce cas, la face extérieure du couvercle définit, avec la paroi du boitier, une cavité extérieure dont les dimensions et la forme contribuent également à la définition des caractéristiques acoustiques de l'ensemble.In addition, the capsule is intended to be generally inserted in an external housing, and, in this case, the external face of the cover defines, with the wall of the housing, an external cavity whose dimensions and shape also contribute to the definition of the acoustic characteristics of the whole.

Ainsi, la capsule et le boitier dans lequel elle est insérée constituent un empilage d'éléments qui définissent plusieurs cavités dont la forme et la dimension influencent très sensiblement le résultat acoustique du transducteur. Cet empilage est généralement réalisé par des moyens automatiques, la solidarisation pouvant être assurée par soudage, par sertissage ou tout autre moyen.Thus, the capsule and the case in which it is inserted constitute a stack of elements which define several cavities whose shape and size very significantly influence the result. transducer acoustics. This stacking is generally carried out by automatic means, the joining being able to be ensured by welding, by crimping or any other means.

Dans les capsules connues, on constate qu'il apparaît, en cours de fabrication, des écarts relativement importants dans l'empilage obtenu, ces écarts entraînant une dispersion sensible dans les dimen­sions des différentes cavités intérieures ou extérieures ainsi réali­sées, et dans la force d'appui des organes de maintien du pourtour de membrane. Il en résulte des dispersions sensibles dans les qualités électroacoustiques du transducteur.In known capsules, it can be seen that there appear, during manufacture, relatively large deviations in the stack obtained, these deviations resulting in a significant dispersion in the dimensions of the various interior or exterior cavities thus produced, and in the force d support of the retaining members around the membrane. This results in significant dispersions in the electroacoustic qualities of the transducer.

Par ailleurs, dans les capsules connues, on maintient la membrane piézoélectrique par l'interposition d'au moins un joint annulaire qui est une pièce distincte. Il en résulte que l'assemblage nécessite un empilage d'un nombre d'éléments relativement important, qui entraîne un coût de production non négligeable.Furthermore, in known capsules, the piezoelectric membrane is maintained by the interposition of at least one annular seal which is a separate part. As a result, the assembly requires a stacking of a relatively large number of elements, which results in a non-negligible production cost.

La présente invention a notamment pour object d'éviter les inconvénients des procédés et dispositifs connus, en proposant une nouvelle structure de capsule à membrane piézoélectrique permettant de réaliser, avec des moyens automatiques d'assemblage, des capsules présentant des formes et dimensions de cavités intérieures déterminables avec précision ; il en résulte que, selon l'invention, la forme et la dimension des cavités intérieures, ainsi que la force d'appui des organes de maintien du pourtour de membrane, peuvent être obtenues avec une grande régularité et une grande précision, et l'on minimise ainsi les problèmes liés à la dispersion dans le cas d'une fabrication en grande série.The object of the present invention is in particular to avoid the drawbacks of known methods and devices, by proposing a new capsule structure with a piezoelectric membrane making it possible to produce, with automatic assembly means, capsules having shapes and dimensions of interior cavities. accurately determinable; it follows that, according to the invention, the shape and the dimension of the internal cavities, as well as the bearing force of the retaining members of the periphery of the membrane, can be obtained with great regularity and great precision, and the this minimizes the problems associated with dispersion in the case of mass production.

Selon un autre objet de l'invention, on cherche à réduire au maximum les dispersions apparaissant dans la réalisation des cavités extérieures de la capsule, ces cavités extérieures étant réalisées ultérieurement lors de l'assemblage de la capsule dans un boitier extérieur. Pour cela, l'invention définit une structure de capsule comportant des moyens assurant une adaptation régulière, précise et connue avec une bonne certitude sur la face interne du boitier extérieur dans lequel doit être rapportée la capsule.According to another object of the invention, it is sought to reduce as much as possible the dispersions appearing in the production of the outer cavities of the capsule, these outer cavities being produced subsequently during the assembly of the capsule in an outer casing. For this, the invention defines a capsule structure comprising means ensuring regular, precise and known adaptation with good certainty on the internal face of the outer casing in which the capsule is to be attached.

Selon un autre objet de l'invention, on réduit sensiblement le nombre des éléments à assembler lors du montage de la capsule. On évite également les problèmes habituellement liés à l'utilisation de joints d'étanchéité, les joints d'étanchéité connus et utilisables étant généralement de dimensions peu régulières, ce qui induit des défauts de planéité des surfaces de maintien de la membrane piézoélectrique.According to another object of the invention, the number of elements to be assembled is significantly reduced during assembly of the capsule. The problems usually associated with the use of seals are also avoided sealing, known and usable seals generally being of irregular dimensions, which induces flatness defects of the holding surfaces of the piezoelectric membrane.

Un autre objet de l'invention est de prévoir des moyens permettant d'automatiser au maximum la fabrication d'une telle capsule, en réalisant de manière simultanée, en une seule opération, l'ensemble des joints d'étanchéité destinés d'une part à maintenir la membrane piézoélectrique, et d'autre part à recevoir la paroi du boitier extérieur dans lequel s'insère la capsule.Another object of the invention is to provide means making it possible to automate the manufacture of such a capsule as much as possible, by simultaneously producing, in a single operation, all of the seals intended on the one hand to maintain the piezoelectric membrane, and secondly to receive the wall of the outer casing into which the capsule is inserted.

Pour atteindre ces objets ainsi que d'autres, selon la présente invention, le relief annulaire intérieur du couvercle est constitué d'un joint intérieur surmoulé en élastomère injectable. Selon cette structu­re, le joint se trouve soudé au couvercle ; il en résulte qu'aucune fuite n'est possible entre le joint et le couvercle, et on améliore sensiblement l'étanchéité de la cavité intérieure du couvercle dans son pourtour, et l'étanchéité entre la cavité intérieure du couvercle et la cavité intérieure de corps de base. Par la technique de surmoulage, on produit un joint dont la surface portante destinée à porter sur la membrane piézoélectrique présente une grande régularité et une grande précision de positionnement ; il en résulte un maintien très précis de la membrane piézoélectrique par rapport au couvercle, et une bonne définition du volume et de la forme de la cavité intérieure du couvercle; le surmoulage permet en particulier de rattraper d'éventuels défauts de planéité pouvant apparaître lors du moulage du couvercle.To achieve these and other objects, according to the present invention, the inner annular relief of the cover consists of an inner seal molded in injectable elastomer. According to this structure, the seal is welded to the cover; it follows that no leakage is possible between the seal and the cover, and the sealing of the inner cavity of the cover around its periphery is substantially improved, and the sealing between the inner cavity of the cover and the inner cavity of basic body. By the overmolding technique, a joint is produced whose bearing surface intended to bear on the piezoelectric membrane has great regularity and great positioning precision; this results in very precise maintenance of the piezoelectric membrane relative to the cover, and a good definition of the volume and of the shape of the interior cavity of the cover; overmolding in particular makes it possible to make up for any flatness defects which may appear during the molding of the cover.

Selon un mode de réalisation avantageux, le couvercle comprend en outre un relief annulaire extérieur en élastomère injectable surmoulé, par exemple en même matière que le joint intérieur, et formant un joint extérieur contre lequel peut se plaquer la paroi d'un boitier extérieur dans lequel on insère la capsule. On s'assure ainsi que la capsule sera correctement utilisée, c'est à dire que l'utilisateur ultérieur l'adaptera dans le boitier avec le joint extérieur permettant l'étanchéité périphérique de la cavité extérieure de capsule.According to an advantageous embodiment, the cover further comprises an outer annular relief in injectable elastomer molded, for example of the same material as the inner seal, and forming an outer seal against which the wall of an outer housing can be pressed in which we insert the capsule. This ensures that the capsule will be used correctly, that is to say that the subsequent user will adapt it in the case with the external seal allowing the peripheral sealing of the external capsule cavity.

Selon un mode de réalisation, le joint intérieur et le joint extérieur sont reliés l'un à l'autre par des ponts en même matière que celle constituant les joints, et traversant des trous du couvercle, répartis sur la périphérie du couvercle. De cette façon, les joints intérieur et extérieur peuvent être réalisés en une seule opération de surmoulage. On entend par opération de surmoulage soit une technique de surmoulage traditionnelle consistant à injecter la matière constituant les joints dans un moule contenant le couvercle préformé, soit une technique de bi-injection dans laquelle les deux opérations de moulage de couvercle et de surmoulage du joint peuvent être assurées par un même dispositif selon deux phases successives rapprochées. Ces deux façons de procéder sont bien connues dans la technique, et ne demandent aucune adaptation particulière pour réaliser le couvercle selon la présente invention.According to one embodiment, the inner seal and the outer seal are connected to each other by bridges made of the same material as that constituting the seals, and passing through holes in the cover, distributed over the periphery of the cover. In this way, the interior and exterior joints can be made in a single operation of overmolding. The term overmolding operation is understood to mean either a traditional overmolding technique consisting in injecting the material constituting the seals into a mold containing the preformed cover, or a bi-injection technique in which the two operations of molding the cover and overmolding the seal can be provided by the same device in two successive phases close together. These two ways of proceeding are well known in the art, and do not require any particular adaptation for producing the cover according to the present invention.

Selon un mode de réalisation avantageux de l'invention, le couvercle comprend en outre un relief annulaire extérieur périphérique rigide, continu on non, bordant le joint extérieur et formant surface de référence pour limiter l'écrasement du joint extérieur lors de l'inser­tion de la capsule dans un boitier. On détermine ainsi de manière précise et constante la dimension de la cavité extérieure de capsule.According to an advantageous embodiment of the invention, the cover further comprises a rigid peripheral external annular relief, continuous or not, bordering the external seal and forming a reference surface to limit the crushing of the external seal during the insertion of the capsule in a box. The size of the outer capsule cavity is thus determined precisely and constantly.

Selon un mode de réalisation, le couvercle comprend en outre un relief annulaire intérieur périphérique rigide, continu ou non, bordant le joint intérieur et formant surface de référence pour limiter l'écrasement du joint intérieur lors de la réalisation de la capsule par assemblage de ses parties constitutives.According to one embodiment, the cover further comprises a rigid peripheral internal annular relief, continuous or not, bordering the internal seal and forming a reference surface to limit the crushing of the internal seal during the production of the capsule by assembling its constituent parts.

D'autres objets, caractéristiques et avantages de la présente invention ressortiront de la description suivante de modes de réalisa­tion particuliers, faite en relation avec les figures jointes, parmi lesquelles :

  • - la figure 1 représente une vue de dessus d'une capsule piézoélectrique selon la présente invention ; et
  • - la figure 2 représente une vue de côté en deux demi-coupes radiales selon les demi-plans A-B de la figure 1.
Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, given in relation to the attached figures, among which:
  • - Figure 1 shows a top view of a piezoelectric capsule according to the present invention; and
  • FIG. 2 represents a side view in two radial half-sections according to the half-planes AB of FIG. 1.

Dans le mode de réalisation représenté sur les figures, la capsule selon la présente invention comprend une membrane piézoélectri­que 1. On peut par exemple utiliser une membrane piézoélectrique de type connu, composée d'un film mince métallique ou isolant, formant le substrat de base de la membrane, et sur lequel est solidarisée au moins une couche de céramique piézoélectrique dont les deux faces sont métallisées et constituent les électrodes. Des moyens de connection électrique, par exemple de type connu, assurent la connection des électrodes jusqu'à des bornes de sortie telles que la borne 2 destinées à être reliées à des circuits électroniques extérieurs. La membrane 1, par exemple de forme sensiblement circulaire, est maintenue sur son pourtour dans un boitier de capsule.In the embodiment shown in the figures, the capsule according to the present invention comprises a piezoelectric membrane 1. It is possible, for example, to use a piezoelectric membrane of known type, composed of a thin metallic or insulating film, forming the base substrate of the membrane, and on which is secured at least one piezoelectric ceramic layer, the two faces of which are metallized and constitute the electrodes. Electrical connection means, for example of a known type, ensure the connection of the electrodes to output terminals such as terminal 2 intended to be connected to external electronic circuits. The membrane 1, for example of substantially circular shape, is held around its periphery in a capsule case.

Le boitier comprend un corps de base 4 muni d'une cavité centrale 5 dont la périphérie forme surface d'appui 6 pour la périphérie de membrane 1. La surface d'appui 6 est avantageusement constituée par un relief annulaire rigide, sur lequel vient reposer le bord inférieur de la membrane 1.The housing comprises a base body 4 provided with a central cavity 5, the periphery of which forms a support surface 6 for the membrane periphery 1. The support surface 6 is advantageously constituted by a rigid annular relief, on which rests the lower edge of the membrane 1.

Le boitier comprend en outre un couvercle 7, se raccordant par sa périphérie 8 au corps de base 4. De préférence, le couvercle 7 et le corps de base 4 se raccordent l'un à l'autre selon des surfaces de contact périphériques respectives 9 et 10 déterminées avec précision, pour réaliser un assemblage aisément reproductible. Le couvercle 7 comporte un évidement intérieur 11 communiquant avec l'extérieur par une série d'orifices tels que l'orifice 12, régulièrement répartis dans la paroi du couvercle comme le représentent les figures. L'évidement 11 de couvercle définit une cavité intérieure de couvercle ; la cavité centrale 5 de corps de base définit une cavité intérieure de corps de base ; les cavités intérieures sont séparées l'une de l'autre par la membrane piézoélectrique 1.The housing further comprises a cover 7, connecting at its periphery 8 to the base body 4. Preferably, the cover 7 and the base body 4 are connected to each other according to respective peripheral contact surfaces 9 and 10 determined with precision, to achieve an easily reproducible assembly. The cover 7 has an internal recess 11 communicating with the outside through a series of orifices such as the orifice 12, regularly distributed in the wall of the cover as shown in the figures. The cover recess 11 defines an interior cover cavity; the central base body cavity 5 defines an interior base body cavity; the interior cavities are separated from each other by the piezoelectric membrane 1.

La périphérie du couvercle 7 comporte un relief annulaire intérieur 13, en appui sur la périphérie de membrane, c'est à dire en appui sur le pourtour supérieur de membrane, le relief annulaire 13 étant constitué d'un joint intérieur surmoulé en élastomère injectable. On peut avantageusement utiliser un élastomère injectable commercialisé sous la marque ALCRYN par la société DU PONT DE NEMOURS.The periphery of the cover 7 has an internal annular relief 13, in abutment on the membrane periphery, that is to say in abutment on the upper periphery of the membrane, the annular relief 13 consisting of an internal seal molded in injectable elastomer. It is advantageous to use an injectable elastomer marketed under the brand name ALCRYN by the company DU PONT DE NEMOURS.

A titre d'exemple, le relief annulaire intérieur 13 formant joint intérieur peut être surmoulé dans une gorge annulaire de la face intérieure de couvercle, comme le représente en coupe la figure 2.By way of example, the interior annular relief 13 forming an interior seal can be molded into an annular groove in the interior face of the cover, as shown in section in FIG. 2.

Le couvercle 7 comprend en outre un relief annulaire extérieur 14 également en élastomère injectable surmoulé, par exemple en même matière que le relief annulaire intérieur 13, et formant un joint extérieur contre lequel peut venir se plaquer la paroi d'un boitier extérieur dans lequel on insère la capsule. Cette paroi de boitier extérieur est schématiquement représentée par le trait mixte 15 sur la figure 2.The cover 7 further comprises an external annular relief 14 also made of molded injectable elastomer, for example of the same material as the internal annular relief 13, and forming an external seal against which the wall of an external casing can be pressed. insert the capsule. This outer casing wall is schematically represented by the dashed line 15 in FIG. 2.

Le couvercle 7 comprend en outre un relief annulaire extérieur périphérique rigide 16, continu ou non, bordant extérieurement le joint extérieur 14, et formant une surface de référence pour limiter l'écrasement du joint extérieur 14 lors de l'insertion de la capsule contre la paroi 15 d'un boitier extérieur. Le relief annulaire extérieur facilite sensiblement le centrage lors du montage de la capsule.The cover 7 also comprises an external annular relief rigid device 16, continuous or not, externally bordering the external seal 14, and forming a reference surface to limit the crushing of the external seal 14 during insertion of the capsule against the wall 15 of an external casing. The external annular relief significantly facilitates centering during assembly of the capsule.

Le joint intérieur 13 et le joint extérieur 14 sont avantageu­sement reliés l'un à l'autre par au moins un pont de matière tels que le pont 17. On ménage pour cela dans le couvercle 7 un trou ou une série de trous traversants, régulièrement répartis sur la périphérie comme le représente la figure 1, les trous permettant l'injection simultanée de matière et sa répartition par former en même temps le joint extérieur 14, les ponts 17 et le joint intérieur 13, par surmoulage du couvercle.The inner seal 13 and the outer seal 14 are advantageously connected to each other by at least one bridge of material such as the bridge 17. For this, a hole or a series of through holes are regularly provided in the cover 7. distributed over the periphery as shown in Figure 1, the holes for the simultaneous injection of material and its distribution by forming at the same time the outer seal 14, the bridges 17 and the inner seal 13, by molding the cover.

Dans le mode de réalisation représenté sur les figures, les joints intérieur 13 et extérieur 14 forment chacun un anneau continu.In the embodiment shown in the figures, the inner 13 and outer 14 seals each form a continuous ring.

En alternative, et grâce au fait que l'on utilise un surmoulage pour réaliser les joints, le joint intérieur et/ou le joint extérieur peuvent être discontinus, pour définir par exemple un passage radial pour des connecteurs ou autres éléments. Une telle discontinuité serait difficilement réalisable en cas d'utilisation d'un joint rapporté. Cela entraînerait en effet de grandes difficultés de positionnement et de préparation des joints.Alternatively, and thanks to the fact that an overmolding is used to make the seals, the inner seal and / or the outer seal can be discontinuous, to define for example a radial passage for connectors or other elements. Such a discontinuity would be difficult to achieve if an added seal is used. This would indeed cause great difficulties in positioning and preparing the seals.

Lors de la fabrication de la capsule selon l'invention, on peut réaliser le couvercle 7 en deux opérations successives séparées l'une de l'autre : une première opération de moulage de la coque rigide formant la structure principale du couvercle ; une seconde opération consistant à surmouler la coque rigide préfabriquée, dans un moule, en injectant la matière destinée à former les joints 13 et 14.During the manufacture of the capsule according to the invention, the cover 7 can be produced in two successive operations separated from one another: a first operation of molding the rigid shell forming the main structure of the cover; a second operation consisting in overmolding the prefabricated rigid shell, in a mold, by injecting the material intended to form the seals 13 and 14.

En alternative, on peut réaliser un tel couvercle par une technique de bi-injection, en deux phases rapprochées, une première phase d'injection pour formation de la coque rigide de couvercle, une seconde phase d'injection de la matière devant former les joints 13 et 14.As an alternative, such a cover can be produced by a bi-injection technique, in two close phases, a first injection phase for forming the rigid cover shell, a second phase of injection of the material which should form the seals. 13 and 14.

La présente invention n'est pas limitée aux modes de réalisa­tion qui ont été explicitement décrits, mais elle en inclut les diverses variantes et généralisations contenues dans le domaine des revendica­tions ci-après.The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variants and generalizations thereof contained in the field of claims below.

Claims (9)

1 - Capsule électroacoustique à membrane piézoélectrique, dont l'élément vibrant est constitué d'une membrane (1) à couche de matière piézoélectrique munie d'électrodes et maintenue sur son pourtour dans un boitier de capsule, le boitier comprenant un corps de base (4) muni d'une cavité centrale (5) dont la périphérie (6) forme surface d'appui pour la périphérie de membrane, le boitier comprenant en outre un couvercle (7) se raccordant par sa périphérie (8) au corps de base et comportant un évidement intérieur (11) communiquant avec l'extérieur par au moins un orifice (12), la périphérie du couvercle comportant un relief annulaire intérieur (13) en appui sur la périphérie de membrane et la maintenant plaquée contre la périphérie (6) de cavité du corps de base,
caractérisée en ce que le relief annulaire intérieur (13) du couvercle (7) est constitué d'un joint intérieur surmoulé en élastomère injecta­ble.1 - Electroacoustic capsule with piezoelectric membrane, the vibrating element of which consists of a membrane (1) with a layer of piezoelectric material provided with electrodes and held on its periphery in a capsule housing, the housing comprising a basic body ( 4) provided with a central cavity (5) whose periphery (6) forms a bearing surface for the periphery of the membrane, the housing further comprising a cover (7) which is connected by its periphery (8) to the base body and comprising an internal recess (11) communicating with the outside via at least one orifice (12), the periphery of the cover comprising an internal annular relief (13) bearing on the periphery of the membrane and keeping it pressed against the periphery (6 ) base body cavity,
characterized in that the interior annular relief (13) of the cover (7) consists of an interior seal molded in injectable elastomer. 2 - Capsule selon la revendication 1, caractérisée en ce que le couvercle (7) comprend en outre un relief annulaire extérieur (14) en élastomère injectable surmoulé, formant un joint extérieur contre lequel peut se plaquer la paroi antérieure (15) d'un boitier extérieur dans lequel on insère la capsule.2 - Capsule according to claim 1, characterized in that the cover (7) further comprises an external annular relief (14) in injected elastomer molded, forming an external seal against which can be pressed against the front wall (15) of a outer case in which the capsule is inserted. 3 - Capsule selon la revendication 2, caractérisée en ce que le joint intérieur (13) et le joint extérieur (14) sont reliés l'un à l'autre par un ou plusieurs ponts (17) de matière répartis sur la périphérie du couvercle.3 - capsule according to claim 2, characterized in that the inner seal (13) and the outer seal (14) are connected to one another by one or more bridges (17) of material distributed over the periphery of the cover . 4 - Capsule selon la revendication 3, caractérisée en ce que les joints intérieur (13) et extérieur (14) forment chacun un anneau continu.4 - Capsule according to claim 3, characterized in that the inner (13) and outer (14) seals each form a continuous ring. 5 - Capsule selon la revendication 3, caractérisée en ce que le joint intérieur (13) et/ou le joint extérieur (14) sont discontinus.5 - Capsule according to claim 3, characterized in that the inner seal (13) and / or the outer seal (14) are discontinuous. 6 - Capsule selon l'une quelconque des revendications 1 à 5, caractérisée en ce que le couvercle (7) comprend en outre un relief annulaire extérieur périphérique rigide (16), continu ou non, bordant le joint extérieur (14) et formant moyen de centrage et/ou surface de référence pour limiter l'écrasement du joint extérieur (14) lors de l'insertion de la capsule contre une paroi (15) de boitier.6 - Capsule according to any one of claims 1 to 5, characterized in that the cover (7) further comprises a rigid peripheral external annular relief (16), continuous or not, bordering the external seal (14) and forming means centering and / or reference surface to limit the crushing of the outer seal (14) during insertion of the capsule against a wall (15) of the housing. 7 - Capsule selon l'une quelconque des revendications 1 à 6, caractérisée en ce que le couvercle (7) comprend en outre un relief annulaire intérieur périphérique rigide, continu ou non, bordant le joint intérieur (13) et formant surface de référence pour limiter l'écrasement du joint intérieur (13) lors du montage de la capsule.7 - Capsule according to any one of claims 1 to 6, characterized in that the cover (7) further comprises a rigid peripheral internal annular relief, continuous or not, bordering the internal seal (13) and forming a reference surface to limit the crushing of the internal seal (13) when mounting the capsule. 8 - Procédé pour réaliser une capsule selon l'une quelconque des revendications 1 à 7, caractérisé en ce que les joints (13, 14) sont réalisés par surmoulage d'une coque rigide préferabriquée de couvercle.8 - Method for producing a capsule according to any one of claims 1 to 7, characterized in that the seals (13, 14) are produced by overmolding of a prefabricated rigid shell cover. 9 - Procédé pour réaliser une capsule selon l'une quelconque des revendications 1 à 7, caractérisé en ce que le couvercle est réalisé par bi-injection, une première injection pour la matière constituant la coque rigide de couvercle, une seconde injection pour réaliser les joints.9 - Method for producing a capsule according to any one of claims 1 to 7, characterized in that the cover is produced by bi-injection, a first injection for the material constituting the rigid shell of the cover, a second injection to produce the joints.
EP89420071A 1988-03-01 1989-02-27 Electroacoustic capsule with a piezo-electric diaphragm Ceased EP0331591A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8802969 1988-03-01
FR8802969A FR2628282B1 (en) 1988-03-01 1988-03-01 ELECTROACOUSTIC CAPSULE WITH PIEZOELECTRIC MEMBRANE

Publications (1)

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EP0331591A1 true EP0331591A1 (en) 1989-09-06

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EP89420071A Ceased EP0331591A1 (en) 1988-03-01 1989-02-27 Electroacoustic capsule with a piezo-electric diaphragm

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EP (1) EP0331591A1 (en)
JP (1) JPH0214700A (en)
FR (1) FR2628282B1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0475208A2 (en) * 1990-08-30 1992-03-18 Leson S.A. Electroacoustic piezoelectric transducer
EP0595514A2 (en) * 1992-10-27 1994-05-04 TDK Corporation Piezoelectric transducer
CN112291690A (en) * 2019-07-22 2021-01-29 英飞凌科技股份有限公司 Pressure sensor

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1334235A (en) * 1961-09-29 1963-08-02 Siemens Ag Electro-acoustic transformer
DE2123649A1 (en) * 1971-05-12 1972-11-16 Siemens AG, 1000 Berlin u. 8000 München Acoustic coupler
FR2275182A1 (en) * 1974-06-18 1976-01-16 Speidel Blasius CONTACT MICROPHONE FOR MEASURING BLOOD PRESSURE
FR2337480A1 (en) * 1975-12-30 1977-07-29 Sits Soc It Telecom Siemens ELECTRO-ACOUSTIC TRANSDUCER, IN PARTICULAR OF THE PIEZOCERAMIC PLATE TYPE

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1334235A (en) * 1961-09-29 1963-08-02 Siemens Ag Electro-acoustic transformer
DE2123649A1 (en) * 1971-05-12 1972-11-16 Siemens AG, 1000 Berlin u. 8000 München Acoustic coupler
FR2275182A1 (en) * 1974-06-18 1976-01-16 Speidel Blasius CONTACT MICROPHONE FOR MEASURING BLOOD PRESSURE
FR2337480A1 (en) * 1975-12-30 1977-07-29 Sits Soc It Telecom Siemens ELECTRO-ACOUSTIC TRANSDUCER, IN PARTICULAR OF THE PIEZOCERAMIC PLATE TYPE

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0475208A2 (en) * 1990-08-30 1992-03-18 Leson S.A. Electroacoustic piezoelectric transducer
EP0475208A3 (en) * 1990-08-30 1992-10-14 S. Eletro-Acustica S.A. Electroacoustic piezoelectric transducer
US5245669A (en) * 1990-08-30 1993-09-14 Leson Laboratorio De Engenharia Sonica S.A. Electroacoustic transducer
EP0595514A2 (en) * 1992-10-27 1994-05-04 TDK Corporation Piezoelectric transducer
EP0595514A3 (en) * 1992-10-27 1996-10-09 Tdk Corp Piezoelectric transducer
CN112291690A (en) * 2019-07-22 2021-01-29 英飞凌科技股份有限公司 Pressure sensor
CN112291690B (en) * 2019-07-22 2024-04-05 英飞凌科技股份有限公司 Pressure sensor

Also Published As

Publication number Publication date
FR2628282A1 (en) 1989-09-08
JPH0214700A (en) 1990-01-18
FR2628282B1 (en) 1990-08-24

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