EP0555139A1 - Shielding method and shielded keyboard obtained by that method - Google Patents

Shielding method and shielded keyboard obtained by that method Download PDF

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Publication number
EP0555139A1
EP0555139A1 EP19930400255 EP93400255A EP0555139A1 EP 0555139 A1 EP0555139 A1 EP 0555139A1 EP 19930400255 EP19930400255 EP 19930400255 EP 93400255 A EP93400255 A EP 93400255A EP 0555139 A1 EP0555139 A1 EP 0555139A1
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EP
European Patent Office
Prior art keywords
keyboard
metal
screen
contact
metallic
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19930400255
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German (de)
French (fr)
Inventor
Alain Fattaz
Jean Julien
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thales SA
Original Assignee
Thomson CSF SA
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Filing date
Publication date
Application filed by Thomson CSF SA filed Critical Thomson CSF SA
Publication of EP0555139A1 publication Critical patent/EP0555139A1/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H13/00—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch
    • H01H13/70—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard
    • H01H13/702—Switches having rectilinearly-movable operating part or parts adapted for pushing or pulling in one direction only, e.g. push-button switch having a plurality of operating members associated with different sets of contacts, e.g. keyboard with contacts carried by or formed from layers in a multilayer structure, e.g. membrane switches
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2207/00—Connections
    • H01H2207/01—Connections from bottom to top layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2209/00—Layers
    • H01H2209/068—Properties of the membrane
    • H01H2209/07—Properties of the membrane metallic
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H2239/00—Miscellaneous
    • H01H2239/008—Static electricity considerations

Definitions

  • the present invention relates to a shielding method and a shielded keyboard obtained by this method for the electromagnetic protection of electronic equipment.
  • the keyboard is a device allowing an interactive or unidirectional exchange of information between a user and electronic equipment which processes this information.
  • the information entered first on keyboards is translated into electrical pulses which pass through the keyboard to the electronic equipment.
  • they can, on the one hand, be disturbed by an aggressive external magnetic environment, such as high power motors, electronic power tubes, strong explosions etc ..., generating powerful electromagnetic radiation which can be reflected at the level of the electronic equipment by errors of transmission of information, see by the destruction of electronic components.
  • any current flow in an electrical conductor is accompanied by an induced magnetic field and an electric field both proportional to the intensity of this current, the magnetic and electric fields, although weak by electromagnetic radiation to the outside of the keyboard which can be detected and interpreted remotely from electronic equipment, and can also be the disturbing element of the environment.
  • a known solution, described in patent 2,621,209 consists, to shield a flat membrane keyboard, to use a flexible metal envelope to cover the printed circuits overflowing the thickness of the keyboard and to fold the edges towards the rear of the keyboard in order to come into contact around its periphery with the mass of the electronic equipment on which the keyboard is fixed.
  • This flexible metal casing consists of a fine mesh metal mesh allowing the possible display of equipment displays. In the case where there is no display, the fine mesh mesh can be replaced by a flexible metallic sheet of small thickness fixed according to the same principle as for the wire mesh, on which the indications of a front face of a keyboard can be directly related.
  • the mesh due to the overflow of the outer edges of the keyboard is subject to wear by friction and degrades progressively, no longer ensuring, in the more or less long term, effective shielding of the keyboard. It is the same for the metal sheet, which because of its thinness of the order of 50 to 100 meters, tears on its folding edges.
  • the mesh of the mesh that is too fine lets light through poorly and makes it difficult to read the displays.
  • Bonding the mesh on the active inner layers of the keyboard is difficult due to the poor surface condition of the mesh which is made up of interlaced conductive wires.
  • the object of the invention is to overcome the aforementioned drawbacks.
  • the subject of the invention is a method of shielding a keyboard comprising, in order, a metal screen, at least two printed circuits isolated by at least one insulating layer, the two printed circuits and the insulating layer constituting inner active layers, and resting on a metallic support, characterized in that it consists in covering the inner active layers of the keyboard with the metallic screen without overflowing them, and in establishing a ground contact between the metallic screen and the metal support through openings in the active interior layers of the keyboard.
  • the invention also relates to an armored forceps produced by the method according to the invention.
  • the main advantage of the invention establishing a ground contact through the keyboard between the metal screen and the metal support of the keyboard is that it provides effective mechanical protection of the screen which cannot be thereby damaged by rubbing against objects outside the keyboard.
  • no metallic element is in contact with the ambient atmosphere, thus avoiding corrosion of the keyboard.
  • Figure 1 illustrates a particular embodiment of the shielding method according to the invention according to an overlay in exploded view of several constituent layers 1 to 5 of a flat rectangular membrane keyboard designed to rest on a flat metal support 6.
  • This figure highlights a particular distribution of the ground contact around the entire periphery of the metallic support 6.
  • Openings 8 arranged in the active inner layers 3, 4 and 5 of the keyboard allow the passage of metallic contacts 9. The number, the shape and the dimensions of the openings 8 depend on the type of contact used.
  • the keyboard comprises respectively from the outside towards the inside of the keyboard, that is to say in the figure from right to left, an upper layer 1 (or plastron) of polycarbonate, which can carry keyboard indications on its external face, a screen metallic 2 made of partially open nickel-beryllium copper-beryllium alloy on areas 10i covering, for example, displays not shown in the electronic equipment 7 shown in FIG. 2, or keys on the keyboard also not shown.
  • the openwork areas are formed by grids produced according to the method described for example in patent 2,638,596 filed by the Applicant, ensuring good visibility of the indications of the displays and sufficient flexibility of the keys of the keyboard while not increasing the effort. on the keys compared to an unshielded keyboard.
  • the keyboard has three active inner layers 3, 4 and 5 formed in the order of a first flexible printed circuit 3, an insulating interlayer 4 and a second flexible printed circuit 5, the printed faces of the two printed circuits 3 and 5 being opposite.
  • the different layers 1 to 5 are glued using a non-conductive glue, juxtaposed one on the other, and are themselves glued by the same glue on a metal support 6 representing the front panel of electronic equipment. 7 as shown in FIG. 2.
  • the 3 interior active layers 3, 4 and 5 of the keyboard constitute the three conventional layers of an unshielded flat keyboard. These are perforated on their inner periphery by the openings 8 to allow the passage of the metallic contacts 9 between the metallic screen 2 and the metallic support 6.
  • the contacts 9 are also distributed on the inner periphery of the metallic screen 2 and ensure the shielding of the keyboard by pressing successive layers 1 to 5 bonded, therefore metal contacts 9 between the metal screen 2 and the metal support 6.
  • the four layers 2 to 5 are covered with the top layer 1 also bonded which can carry keyboard indications on its external face.
  • the identical dimensions of the five layers 1 to 5 bonded to the metal support 6 are advantageously provided slightly smaller than the dimensions of the metal support 6 to avoid any overflow of glue from the keyboard.
  • the ground contact between the metallic screen 2 and the metallic support 6 is ensured by the multiple metallic contacts 9 distributed over the inner periphery of the keyboard.
  • Each metal contact 9 is cut and preformed projecting from its cutting plane formed by either the metal screen 2 or by a metal strip 12 attached to the metal support 6. One of their ends is fixed and the other , free, is protruding.
  • the contact 9 thus formed passes through the inner active layers 3, 4, 5 through the openings 8 respectively opposite one another from one layer to the other and opposite the contact 9.
  • the upper layer 1 is bonded to the face upper of the metal screen 2.
  • the ground contact is ensured by deformation of the contact 9 tending to flatten it under the effect of a pressure exerted by the stacking and the bonding of the successive layers 1 to 5 of the keyboard .
  • the quality of the contact depends mainly on the mechanical and electrical properties of the material used for its production, respectively the elasticity and the conductivity of the material, and by way of example it can be made of nickel-plated copper-beryllium alloy.
  • the metal contact 9 comprises, as shown in FIGS. 3a and 3b, a rectangular blade cut in the thickness of the metal screen 2, parallel to one of its edges and preformed to give the blade a concave shape protruding from the underside of the metal screen 2.
  • the metal contact 9 comprises a flat rectangular blade whose free end is folded back on itself.
  • the same contact 9 is used but it is folded over the edge of the openings 8 arranged in the inner active layers 3, 4 and 5. In this case, the length of the opening 8 is reduced compared to the other embodiments.
  • the additional thickness introduced by the folding of the contact blade 9, is contained in a recess 11 hollowed out in the metal support 6 corresponding to this thickness and the tolerances of which are adapted to ensure the mechanical and electrical mass of the shielding.
  • the metallic contact 9 comprises a narrow metal strip 12 attached to the inner edge of the upper face of the metal support 6, one side along the large dimension of the strip 12 is free and oriented towards the outside of the metal support 6 and serrated projecting from the plane formed by the flat strip 12, and the opposite side facing inward of the metal support 6 is glued thereon.
  • the additional thickness introduced by the thickness of the contact strip 12 is contained in a groove 13 arranged in the metal support 6 opposite the contact strip 12.
  • a number of teeth 14 corresponding to the dimension given to the opening 8 arranged in the inner active layers 3, 4 and 5 provides the mechanical and electrical mass of the shielding.
  • the performance of the shielding produced according to the method according to the invention could be quantified by a measurement of the attenuation of electromagnetic radiation emitted towards the outside of the keyboard.
  • the efficiency of the shielding could be measured with respect to a reference which is the case where the attenuation of the electric and magnetic fields is zero, therefore without any shielding, the limit of the measurement system being given by the maximum attenuation obtained in the case of a solid metal plate representing the keyboard.
  • the invention is not limited to the embodiments of the shielding of a rectangular flat keyboard described in the present invention; the number of contacts, their shape, their size and their positioning can always be adapted as a function of the type of contact used and the useful dimensions of the keyboard to guarantee a ground contact, therefore a shielding whose performance is close to that of the invention Likewise, any keyboard of the membrane keyboard type of any shape as well as the combination of several different types of contacts are within the scope of the present invention.
  • the top layer 1 can also be deleted. All possible indications that can be transferred directly to the upper face of the metal screen 2.

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  • Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)

Abstract

The method of shielding a keyboard comprising, in order, a metal screen (2), at least two printed circuits (3 and 5) insulated by at least one insulating layer (4), the two printed circuits (3 and 5) and the insulating layer (4) constituting active layers (3, 4, 5) inside the keyboard, and resting on a metal support (6), consists in covering the inside active layers (3, 4, 5) of the keyboard with the metal screen (2) without overhanging them, and in establishing an earth contact (9) between the metal screen (6) and the metal support (6) through openings (8) made in the inside active layers (4, 5, 6) of the keyboard. Application: protection against electromagnetic attack of EMD and Tempest type on electronic equipment which includes keyboards. <IMAGE>

Description

La présente invention concerne un procédé de blindage et un clavier blindé obtenu par ce procédé pour la protection électromagnétique des matériels électroniques.The present invention relates to a shielding method and a shielded keyboard obtained by this method for the electromagnetic protection of electronic equipment.

Un des points sensibles dans le blindage d'un équipement électronique se situe au niveau du clavier. Le clavier est un organe permettant un échange interactif ou unidirectionnel d'informations entre un utilisateur et un équipement électronique qui traite ces informations. Les informations saisies tout d'abord aux claviers sont traduites sous forme d'impulsions électriques qui transitent via le clavier vers l'équipement électronique. Pendant ce transit, elles peuvent, d'une part être perturbées par un environnement magnétique extérieur agressif, tels que des moteurs de forte puissance, des tubes électroniques de puissance, de fortes explosions etc..., générant des rayonnements électromagnétiques puissants pouvant se traduire au niveau de l'équipement électronique par des erreurs de transmission des informations, voir par la destruction de composants électroniques. D'autre part, comme tout passage de courant dans un conducteur électrique s'accompagne d'un champ magnétique induit et d'un champ électrique tous deux proportionnels à l'intensité de ce courant, les champs magnétique et électrique, quoique faibles se traduisent par un rayonnement électromagnétique vers l'extérieur du clavier qui peut être détecté et interprété à distance de l'équipement électronique, et peut être aussi l'élément perturbateur de l'environnement.One of the sensitive points in the shielding of electronic equipment is located at the keyboard. The keyboard is a device allowing an interactive or unidirectional exchange of information between a user and electronic equipment which processes this information. The information entered first on keyboards is translated into electrical pulses which pass through the keyboard to the electronic equipment. During this transit, they can, on the one hand, be disturbed by an aggressive external magnetic environment, such as high power motors, electronic power tubes, strong explosions etc ..., generating powerful electromagnetic radiation which can be reflected at the level of the electronic equipment by errors of transmission of information, see by the destruction of electronic components. On the other hand, as any current flow in an electrical conductor is accompanied by an induced magnetic field and an electric field both proportional to the intensity of this current, the magnetic and electric fields, although weak by electromagnetic radiation to the outside of the keyboard which can be detected and interpreted remotely from electronic equipment, and can also be the disturbing element of the environment.

Pour se protéger du rayonnement électromagnétique venant de l'extérieur et pour protéger le matériel contre des fuites électromagnétiques dirigées vers l'extérieur, ces protections respectivement de type appelé EMP, abréviation anglaise de Electro Magne- tic Pulse, et Tempest, doivent répondre aux exigences de plus en plus strictes vis-à-vis du blindage des matériels électroniques. Une solution connue, décrite dans le brevet 2 621 209 consiste, pour blinder un clavier plat à membrane, à employer une enveloppe métallique souple pour recouvrir les circuits imprimés en débordant sur l'épaisseur du clavier et d'en rabattre les bords vers l'arrière du clavier afin de venir en contact sur son pourtour avec la masse de l'équipement électronique sur lequel vient se fixer le clavier. Cette enveloppe métallique souple est constituée d'un grillage métallique à mailles fines permettant la visualisation éventuelle d'afficheurs de l'équipement, Dans le cas où il n'y a pas d'afficheur, le grillage à mailles fines peut être remplacé par une feuille métallique souple de faible épaisseur fixée selon le même principe que pour le grillage, sur laquelle peuvent être rapportées directement les indications d'une face avant d'un clavier.To protect themselves from electromagnetic radiation coming from outside and to protect the material against electromagnetic leaks directed towards outside, these protections respectively of type called EMP, English abbreviation of Electro Magnetic Pulse, and Tempest, must meet the requirements increasingly strict vis-à-vis the shielding of electronic equipment. A known solution, described in patent 2,621,209 consists, to shield a flat membrane keyboard, to use a flexible metal envelope to cover the printed circuits overflowing the thickness of the keyboard and to fold the edges towards the rear of the keyboard in order to come into contact around its periphery with the mass of the electronic equipment on which the keyboard is fixed. This flexible metal casing consists of a fine mesh metal mesh allowing the possible display of equipment displays. In the case where there is no display, the fine mesh mesh can be replaced by a flexible metallic sheet of small thickness fixed according to the same principle as for the wire mesh, on which the indications of a front face of a keyboard can be directly related.

Cette solution présente cependant plusieurs inconvénients.This solution however has several drawbacks.

Le grillage, du fait du débordement des bords extérieurs du clavier est soumis à une usure par frottement et se dégrade progressivement n'assurant plus, à plus ou moins long terme, un blindage efficace du clavier. Il en est de même, pour la feuille métallique, qui du fait de sa faible épaisseur de l'ordre de 50 à 100 mètres, se déchire sur ses arêtes de pliage.The mesh, due to the overflow of the outer edges of the keyboard is subject to wear by friction and degrades progressively, no longer ensuring, in the more or less long term, effective shielding of the keyboard. It is the same for the metal sheet, which because of its thinness of the order of 50 to 100 meters, tears on its folding edges.

Pour un clavier comportant des zones d'affichage d'informations, par exemple des afficheurs à cristaux liquides, le maillage du grillage trop fin laisse mal passer la lumière et rend difficile la lecture des afficheurs.For a keyboard comprising areas for displaying information, for example liquid crystal displays, the mesh of the mesh that is too fine lets light through poorly and makes it difficult to read the displays.

Le collage du grillage sur les couches actives intérieures du clavier est délicat du fait du mauvais état de surface du grillage qui est constitué de fils conducteurs entrelacés.Bonding the mesh on the active inner layers of the keyboard is difficult due to the poor surface condition of the mesh which is made up of interlaced conductive wires.

Le but de l'invention est de pallier les inconvénients précités.The object of the invention is to overcome the aforementioned drawbacks.

A cet effet, l'invention a pour objet, un procédé de blindage d'un clavier comprenant dans l'ordre un écran métallique, au moins deux circuits imprimés isolés par au moins une couche isolante, les deux circuits imprimés et la couche isolante constituant des couches actives intérieures, et reposant sur un support métallique, caractérisé en ce qu'il consiste à recouvrir les couches actives intérieures du clavier par l'écran métallique sans les déborder, et à établir un contact de masse entre l'écran métallique et le support métallique à travers des ouvertures aménagées dans les couches actives intérieures du clavier.To this end, the subject of the invention is a method of shielding a keyboard comprising, in order, a metal screen, at least two printed circuits isolated by at least one insulating layer, the two printed circuits and the insulating layer constituting inner active layers, and resting on a metallic support, characterized in that it consists in covering the inner active layers of the keyboard with the metallic screen without overflowing them, and in establishing a ground contact between the metallic screen and the metal support through openings in the active interior layers of the keyboard.

L'invention a également pour objet un davier blindé réalisé par le procédé selon l'invention.The invention also relates to an armored forceps produced by the method according to the invention.

L'invention établissant un contact de masse au travers du clavier entre l'écran métallique et le support métallique du clavier a pour principal avantage qu'elle permet d'assurer une protection mécanique efficace de l'écran qui ne peut pas être ainsi détérioré par frottement contre des objets extérieurs au clavier. De plus, aucun élément métallique n'est en contact avec l'atmosphère ambiante, évitant ainsi la corrosion du clavier.The main advantage of the invention establishing a ground contact through the keyboard between the metal screen and the metal support of the keyboard is that it provides effective mechanical protection of the screen which cannot be thereby damaged by rubbing against objects outside the keyboard. In addition, no metallic element is in contact with the ambient atmosphere, thus avoiding corrosion of the keyboard.

D'autres caractéristiques et avantages de l'invention apparaîtront ci-après à l'aide de la description qui suit faite en regard des dessins annexés qui représentent :

  • - La figure 1, une vue éclatée en perspective pour illustrer un premier mode d'assemblage d'un clavier mettant en oeuvre le procédé de blindage selon l'invention.
  • - La figure 2 une vue en coupe du mode d'assemblage représenté à la figure 1 ;
  • - Les figures 3a, 4a, 5a et 6a des vues en coupes des modes de réalisation de contacts métalliques mis en oeuvre pour la réalisation d'un clavier blindé selon l'invention ;
  • - Les figures 3b, 4b et 5b, des vues en perspective illustrant les modes de réalisation respectifs aux figures 3a, 4a et 5a ;
  • - La figure 6b, une vue éclatée en perspective illustrant le mode de réalisation suivant la figure 6a.
Other characteristics and advantages of the invention will appear below with the aid of the description which follows given with reference to the appended drawings which represent:
  • - Figure 1, an exploded perspective view to illustrate a first method of assembling a keyboard implementing the shielding method according to the invention.
  • - Figure 2 a sectional view of the assembly mode shown in Figure 1;
  • - Figures 3a, 4a, 5a and 6a sectional views of embodiments of metal contacts used for the production of a shielded keyboard according to the invention;
  • - Figures 3b, 4b and 5b, perspective views illustrating the respective embodiments in Figures 3a, 4a and 5a;
  • - Figure 6b, an exploded perspective view there polishing the embodiment according to FIG. 6a.

Par souci de clarté les épaisseurs relatives des différents éléments des figures précitées n'ont pas été respectées de même, les éléments communs à chacune des figures sont identifiés par leur même repère.For the sake of clarity, the relative thicknesses of the various elements of the aforementioned figures have not been respected in the same way, the elements common to each of the figures are identified by their same reference.

La figure 1 illustre un mode particulier de réalisation du procédé de blindage selon l'invention suivant une superposition en vue éclatée de plusieurs couches constitutives 1 à 5 d'un clavier plat rectangulaire à membrane conçu pour reposer sur un support plat métallique 6. Cette figure, met en évidence une répartition particulière du contact de masse sur tout le pourtour du support métallique 6. Des ouvertures 8 aménagées dans les couches actives intérieures 3, 4 et 5 du clavier permettent le passage de contacts métalliques 9. Le nombre, la forme et les dimensions des ouvertures 8 dépendent du type de contact utilisé.Figure 1 illustrates a particular embodiment of the shielding method according to the invention according to an overlay in exploded view of several constituent layers 1 to 5 of a flat rectangular membrane keyboard designed to rest on a flat metal support 6. This figure , highlights a particular distribution of the ground contact around the entire periphery of the metallic support 6. Openings 8 arranged in the active inner layers 3, 4 and 5 of the keyboard allow the passage of metallic contacts 9. The number, the shape and the dimensions of the openings 8 depend on the type of contact used.

Le clavier comporte respectivement de l'extérieur vers l'intérieur du clavier, soit sur la figure de droite à gauche, une couche supérieure 1 (ou plastron) en po- lycarbonate, pouvant porter des indications de clavier sur sa face externe, un écran métallique 2 en alliage cuivre-béryllium nickelé partiellement ajouré sur des zones 10i recouvrant parexemple, des afficheurs non représentés de l'équipement électronique 7 représenté figure 2, ou des touches du clavier également non représentées. Les zones ajourées sont formées par des grillages réalisés suivant le procédé décrit par exemple dans le brevet 2 638 596 déposé par la Demanderesse, assurant une bonne visibilité des indications des afficheurs et une souplesse suffisante des touches du clavier en n'augmentant pas l'effort sur les touches par rapport à un clavier non blindé. Le clavier comporte trois couches actives intérieures 3, 4 et 5 constituées dans l'ordre d'un premier circuit imprimé souple 3, d'une couche intercalaire isolante 4 et d'un second circuit imprimé souple 5, les faces imprimées des deux circuits imprimés 3 et 5 étant en regard. Les différentes couches 1 à 5 sont collées à l'aide d'une colle non conductrice, juxtaposées les unes sur les autres, et sont elles-mêmes collées par la même colle sur un support métallique 6 représentant le panneau avant d'un équipement électronique 7 de la manière représentée sur la figure 2.The keyboard comprises respectively from the outside towards the inside of the keyboard, that is to say in the figure from right to left, an upper layer 1 (or plastron) of polycarbonate, which can carry keyboard indications on its external face, a screen metallic 2 made of partially open nickel-beryllium copper-beryllium alloy on areas 10i covering, for example, displays not shown in the electronic equipment 7 shown in FIG. 2, or keys on the keyboard also not shown. The openwork areas are formed by grids produced according to the method described for example in patent 2,638,596 filed by the Applicant, ensuring good visibility of the indications of the displays and sufficient flexibility of the keys of the keyboard while not increasing the effort. on the keys compared to an unshielded keyboard. The keyboard has three active inner layers 3, 4 and 5 formed in the order of a first flexible printed circuit 3, an insulating interlayer 4 and a second flexible printed circuit 5, the printed faces of the two printed circuits 3 and 5 being opposite. The different layers 1 to 5 are glued using a non-conductive glue, juxtaposed one on the other, and are themselves glued by the same glue on a metal support 6 representing the front panel of electronic equipment. 7 as shown in FIG. 2.

Sur cette figure les 3 couches actives intérieures 3, 4 et 5 du clavier constituent les trois couches classiques d'un clavier plat non blindé. Celles-ci sont ajourées sur leur pourtour intérieur par les ouvertures 8 pour laisser le passage des contacts métalliques 9 entre l'écran métallique 2 et le support métallique 6. Les contacts 9 sont également répartis sur le pourtour intérieur de l'écran métallique 2 et assurent le blindage du clavier par pression des couches successives 1 à 5 collées, donc des contacts métalliques 9 entre l'écran métallique 2 et le support métallique 6. Les quatre couches 2 à 5 sont recouvertes de la couche supérieure 1 également collée pouvant porter des indications de clavier sur sa face externe. Les dimensions identiques des cinq couches 1 à 5 collées sur le support métallique 6 sont avantageusement prévues légèrement inférieures aux dimensions du support métallique 6 pour éviter tout débordement de colle du clavier.In this figure the 3 interior active layers 3, 4 and 5 of the keyboard constitute the three conventional layers of an unshielded flat keyboard. These are perforated on their inner periphery by the openings 8 to allow the passage of the metallic contacts 9 between the metallic screen 2 and the metallic support 6. The contacts 9 are also distributed on the inner periphery of the metallic screen 2 and ensure the shielding of the keyboard by pressing successive layers 1 to 5 bonded, therefore metal contacts 9 between the metal screen 2 and the metal support 6. The four layers 2 to 5 are covered with the top layer 1 also bonded which can carry keyboard indications on its external face. The identical dimensions of the five layers 1 to 5 bonded to the metal support 6 are advantageously provided slightly smaller than the dimensions of the metal support 6 to avoid any overflow of glue from the keyboard.

Tous les modes de réalisation du procédé selon l'invention décrits ci-après comportent les mêmes caractéristiques communes décrites ci-dessous.All the embodiments of the method according to the invention described below have the same common characteristics described below.

Ainsi, le contact de masse entre l'écran métallique 2 et le support métallique 6 est assuré par les contacts métalliques 9 multiples répartis sur le pourtour intérieur du clavier. Chaque contact métallique 9 est découpé et préformé en saillie de son plan de découpe constitué par, soit l'écran métallique 2, soit par une bande métallique 12 rapportée sur le support métallique 6. L'une de leurs extrémités est fixe et l'autre, libre, est en saillie. Le contact 9 ainsi formé traverse les couches actives intérieures 3, 4, 5 par les ouvertures 8 respectivement les unes en face des autres d'une couche à l'autre et en regard du contact 9. La couche supérieure 1 est collée sur la face supérieure de l'écran métallique 2. Le contact de masse est assuré grâce à une déformation du contact 9 tendant à l'aplatir sous l'effet d'une pression exercée par l'empilage et le collage des couches successives 1 à 5 du clavier. La qualité du contact dépend principalement des propriétés mécanique et électrique du matériau utilisé pour sa réalisation soient respectivement l'élasticité et la conductibilité du matériau, et à titre d'exemple il pourra être réalisé en alliage de cuivre-béryllium nickelé.Thus, the ground contact between the metallic screen 2 and the metallic support 6 is ensured by the multiple metallic contacts 9 distributed over the inner periphery of the keyboard. Each metal contact 9 is cut and preformed projecting from its cutting plane formed by either the metal screen 2 or by a metal strip 12 attached to the metal support 6. One of their ends is fixed and the other , free, is protruding. The contact 9 thus formed passes through the inner active layers 3, 4, 5 through the openings 8 respectively opposite one another from one layer to the other and opposite the contact 9. The upper layer 1 is bonded to the face upper of the metal screen 2. The ground contact is ensured by deformation of the contact 9 tending to flatten it under the effect of a pressure exerted by the stacking and the bonding of the successive layers 1 to 5 of the keyboard . The quality of the contact depends mainly on the mechanical and electrical properties of the material used for its production, respectively the elasticity and the conductivity of the material, and by way of example it can be made of nickel-plated copper-beryllium alloy.

Dans le premier mode de réalisation, le contact métallique 9 comporte de la façon représentée aux figures 3a et 3b une lame de forme rectangulaire découpée dans l'épaisseur de l'écran métallique 2, parallèlement à un de ses bords et préformée pour donner à la lame une forme concave faisant saillie de la face inférieure de l'écran métallique 2.In the first embodiment, the metal contact 9 comprises, as shown in FIGS. 3a and 3b, a rectangular blade cut in the thickness of the metal screen 2, parallel to one of its edges and preformed to give the blade a concave shape protruding from the underside of the metal screen 2.

Dans le second mode de réalisation, montré aux figures 4a et 4b le contact métallique 9 comporte une lame plate rectangulaire dont l'extrémité libre est repliée sur elle-même.In the second embodiment, shown in FIGS. 4a and 4b, the metal contact 9 comprises a flat rectangular blade whose free end is folded back on itself.

Dans le troisième mode de réalisation décrit dans les figures 5a et 5b, le même contact 9 est utilisé mais celui-ci est replié sur le chant des ouvertures 8 aménagées dans les couches actives intérieures 3,4 et 5. Dans ce cas, la longueur de l'ouverture 8 est réduite par rapport aux autres modes de réalisation. La surépaisseur introduite par le repliement de la lame du contact 9, est contenue dans un évidement 11 creusé dans le support métallique 6 correspondant à cette épaisseur et dont les tolérances sont adaptées pour assurer la masse mécanique et électrique du blindage.In the third embodiment described in Figures 5a and 5b, the same contact 9 is used but it is folded over the edge of the openings 8 arranged in the inner active layers 3, 4 and 5. In this case, the length of the opening 8 is reduced compared to the other embodiments. The additional thickness introduced by the folding of the contact blade 9, is contained in a recess 11 hollowed out in the metal support 6 corresponding to this thickness and the tolerances of which are adapted to ensure the mechanical and electrical mass of the shielding.

Enfin suivant le quatrième mode de réalisation représenté par les figures 6a et 6b, le contact métallique 9 comporte une bande métallique étroite 12 rapportée sur le bord intérieur de la face supérieure du support métallique 6 dont un côté suivant la grande dimension de la bande 12 est libre et orienté vers l'extérieur du support métallique 6 et dentelé en saillie du plan formé par la bande plate 12, et dont le côté opposé orienté vers l'intérieur du support métallique 6 est collé sur celui-ci. La surépaisseur introduite par l'épaisseur de la bande de contact 12 est contenue dans une rainure 13 aménagée dans le support métallique 6 en regard de la bande de contact 12. Un nombre de dents 14 correspondant à la dimension donnée à l'ouverture 8 aménagée dans les couches actives intérieures 3, 4 et 5 assure la masse mécanique et électrique du blindage.Finally according to the fourth embodiment represented by FIGS. 6a and 6b, the metallic contact 9 comprises a narrow metal strip 12 attached to the inner edge of the upper face of the metal support 6, one side along the large dimension of the strip 12 is free and oriented towards the outside of the metal support 6 and serrated projecting from the plane formed by the flat strip 12, and the opposite side facing inward of the metal support 6 is glued thereon. The additional thickness introduced by the thickness of the contact strip 12 is contained in a groove 13 arranged in the metal support 6 opposite the contact strip 12. A number of teeth 14 corresponding to the dimension given to the opening 8 arranged in the inner active layers 3, 4 and 5 provides the mechanical and electrical mass of the shielding.

La performance du blindage réalisé suivant le procédé selon l'invention a pu être chiffrée par une mesure de l'atténuation des rayonnements électromagnétiques émis vers l'extérieur du clavier.L'efficacité du blindage a pu être mesurée par rapport à une référence qui est le cas où l'atténuation des champs électrique et magnétique est nulle, donc sans aucun blindage, la limite du système de mesure étant donnée par l'atténuation maximale obtenue dans le cas d'une plaque métallique pleine figurant le clavier.The performance of the shielding produced according to the method according to the invention could be quantified by a measurement of the attenuation of electromagnetic radiation emitted towards the outside of the keyboard. The efficiency of the shielding could be measured with respect to a reference which is the case where the attenuation of the electric and magnetic fields is zero, therefore without any shielding, the limit of the measurement system being given by the maximum attenuation obtained in the case of a solid metal plate representing the keyboard.

Au delà de f = 10 MHz, c'est le champ électrique qui prédomine. Pour cette fréquence l'atténuation du champ électrique émis vers l'extérieur du clavier atteint environ 110 dB.Beyond f = 10 MHz, the electric field prevails. For this frequency the attenuation of the electric field emitted to the outside of the keyboard reaches approximately 110 dB.

L'invention n'est pas limitée aux modes de réalisation du blindage d'un clavier plat rectangulaire décrits dans la présente invention ; le nombre des contacts, leur forme, leur dimension et leur positionnement peuvent toujours être adaptés en fonction du type de contact utilisé et des dimensions utiles du clavier pour garantir un contact de masse donc un blindage dont les performances sont proches de celles de l'invention De même, tout clavier de type clavier à membrane de forme quelconque ainsi que la combinaison de plusieurs types différents de contacts rentrent dans le cadre de la présente invention.The invention is not limited to the embodiments of the shielding of a rectangular flat keyboard described in the present invention; the number of contacts, their shape, their size and their positioning can always be adapted as a function of the type of contact used and the useful dimensions of the keyboard to guarantee a ground contact, therefore a shielding whose performance is close to that of the invention Likewise, any keyboard of the membrane keyboard type of any shape as well as the combination of several different types of contacts are within the scope of the present invention.

La couche supérieure 1 peut aussi être supprimée. Toutes les indications éventuelles pouvant être reportées directement sur la face supérieure de l'écran métallique 2.The top layer 1 can also be deleted. All possible indications that can be transferred directly to the upper face of the metal screen 2.

Claims (10)

1. Procédé de blindage d'un clavier comprenant dans l'ordre un écran métallique (2), au moins deux circuits imprimés (3 et 5) isolés par au moins une couche isolante (4), les deux circuits imprimés (3 et 5) et la couche isolante (4) constituant des couches actives intérieures (3, 4, 5), et reposant sur un support métallique (6), caractérisé en ce qu'il consiste à recouvrir les couches actives intérieures (3, 4, 5) du clavier par l'écran métallique (2) sans les déborder, et à établir un contact de masse entre l'écran métallique (2) et le support métallique (6) à travers des ouvertures (8) aménagées dans les couches actives intérieures (4, 5, 6) du clavier.1. Method for shielding a keyboard comprising, in order, a metal screen (2), at least two printed circuits (3 and 5) isolated by at least one insulating layer (4), the two printed circuits (3 and 5 ) and the insulating layer (4) constituting interior active layers (3, 4, 5), and resting on a metal support (6), characterized in that it consists in covering the interior active layers (3, 4, 5 ) of the keyboard by the metallic screen (2) without overflowing them, and in establishing a ground contact between the metallic screen (2) and the metallic support (6) through openings (8) arranged in the inner active layers (4, 5, 6) on the keyboard. 2. Procédé selon la revendication 1, caractérisé en ce qu'il consiste à répartir le contact de masse (9) sur le pourtour intérieur du clavier.2. Method according to claim 1, characterized in that it consists in distributing the ground contact (9) on the inner periphery of the keyboard. 3. Clavier, caractérisé en ce qu'il est réalisé selon le procédé décrit dans l'une quelconque des revendications 1 et 2 et en ce que le contact de masse entre l'écran métallique (2) et le support métallique (6) comporte des contacts métalliques (9) multiples.3. Keyboard, characterized in that it is produced according to the method described in any one of claims 1 and 2 and in that the ground contact between the metallic screen (2) and the metallic support (6) comprises multiple metal contacts (9). 4. Clavier selon la revendication 3, caractérisé en ce que le contact de masse comporte des contacts métalliques (9) découpés et préformés en saillie de leur plan de découpe dont l'une des extrémités est solidaire de son plan de découpe et l'autre est libre.4. Keyboard according to claim 3, characterized in that the ground contact comprises metal contacts (9) cut and preformed projecting from their cutting plane, one end of which is integral with its cutting plane and the other is free. 5. Clavier selon l'une quelconque des revendications 3 et 4, caractérisé en ce que chaque contact métallique (9) est découpé et préformé dans l'épaisseur de l'écran métallique (2) en faisant saillie de la face inférieure de l'écran métallique (2) pour donner une élasticité au contact.5. Keyboard according to any one of claims 3 and 4, characterized in that each metal contact (9) is cut and preformed in the thickness of the metal screen (2) projecting from the underside of the metallic screen (2) to give elasticity to the contact. 6. Clavier selon l'une quelconque des revendications 3 à 5, caractérisé en ce que chaque contact (9) comporte une lame découpée et préformée dans l'écran métallique (2) donnant à la lame une forme rectangulaire concave faisant saillie de la face inférieure de l'écran métallique (2) pour appuyer sur le support métallique (6).6. Keyboard according to any one of claims 3 to 5, characterized in that each contact (9) comprises a blade cut out and preformed in the metal screen (2) giving the blade a concave rectangular shape projecting from the face bottom of the metal screen (2) to press on the metal support (6). 7. Clavier selon l'une quelconque des revendications 3 à 5, caractérisée en ce que chaque contact (9) comporte une lame découpée et préformée donnant à la lame une forme rectangulaire plate faisant saillie de la face inférieure de l'écran métallique (2).7. Keyboard according to any one of claims 3 to 5, characterized in that each contact (9) comprises a cut and preformed blade giving the blade a flat rectangular shape projecting from the underside of the metal screen (2 ). 8. Clavier selon la revendication 7, caractérisé en ce que la lame comporte une extrémité libre pliée sur elle-même pour appuyer sur le support métallique (6).8. Keyboard according to claim 7, characterized in that the blade has a free end folded on itself to press on the metal support (6). 9. Clavier selon la revendication 8, caractérisé en ce que la lame comporte une extrémité libre, repliée sur le chant des ouvertures (8) aménagées dans les couches actives intérieures (3,4, 5) du clavier en regard de la lame.9. Keyboard according to claim 8, characterized in that the blade has a free end, folded over the edge of the openings (8) arranged in the inner active layers (3,4, 5) of the keyboard opposite the blade. 10. Clavier selon la revendication 3, caractérisé en ce que le contact de masse entre l'écran métallique (2) et le support métallique (6) comporte des bandes de contact (12) rapportées sur les bords intérieurs de la face supérieure du support métallique (6) comportant chacune au moins un côté libre orienté vers l'extérieur du support métallique (6) et dentelé tout le long de la grande dimension du côté libre de la bande de contact (12) avec un nombre de dents (14) préformées en saillie de leur plan de découpe, le nombre de dents (14) étant fonction de la longueur de l'ouverture (8), en regard des dents (14), aménagée dans les couches actives intérieures (3, 4, 5) du clavier, et le côté opposé au côté libre étant fixé sur le support métallique (6).10. Keyboard according to claim 3, characterized in that that the ground contact between the metallic screen (2) and the metallic support (6) comprises contact strips (12) attached to the inner edges of the upper face of the metallic support (6) each comprising at least one free side oriented towards the outside of the metal support (6) and serrated all along the large dimension of the free side of the contact strip (12) with a number of preformed teeth (14) projecting from their cutting plane, the number of teeth (14) being a function of the length of the opening (8), facing the teeth (14), arranged in the inner active layers (3, 4, 5) of the keyboard, and the side opposite to the free side being fixed on the metal support (6).
EP19930400255 1992-02-07 1993-02-02 Shielding method and shielded keyboard obtained by that method Withdrawn EP0555139A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR9201405 1992-02-07
FR9201405A FR2687273A1 (en) 1992-02-07 1992-02-07 SHIELDING METHOD AND ARMORED KEYBOARD OBTAINED BY THIS METHOD.

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EP0555139A1 true EP0555139A1 (en) 1993-08-11

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2307105A (en) * 1995-11-13 1997-05-14 Motorola Inc Membrane shield

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0127164A2 (en) * 1983-05-27 1984-12-05 Siemens Aktiengesellschaft Interlocking device for a two-part keyboard housing
FR2621209A1 (en) * 1987-09-25 1989-03-31 Thomson Csf Screened flat keyboard and electronic equipment equipped with at least one such keyboard
EP0366537A1 (en) * 1988-10-28 1990-05-02 Thomson-Csf Process for making a screening, screening obtained by this process and an electronic equipment comprising this screening
US5015802A (en) * 1990-08-27 1991-05-14 Enlight Corporation Computer casing connector

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0127164A2 (en) * 1983-05-27 1984-12-05 Siemens Aktiengesellschaft Interlocking device for a two-part keyboard housing
FR2621209A1 (en) * 1987-09-25 1989-03-31 Thomson Csf Screened flat keyboard and electronic equipment equipped with at least one such keyboard
EP0366537A1 (en) * 1988-10-28 1990-05-02 Thomson-Csf Process for making a screening, screening obtained by this process and an electronic equipment comprising this screening
US5015802A (en) * 1990-08-27 1991-05-14 Enlight Corporation Computer casing connector

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2307105A (en) * 1995-11-13 1997-05-14 Motorola Inc Membrane shield

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