FR2690300A1 - Loudspeaker, microphone dust protection mask - is off gauze with injection moulded decorative grid on one side and reinforcing ribs on other side both formed with same material, etc. - Google Patents

Abstract

Mask comprises a mould synthetic internal grid (2) on one face (4) of a gauze (1). On the opposite face (7) of the gauze (1) are ribs (5,6) of the same material as the grid, but moulded in a different shape to give strength and allow fixing of the mask. The grid (2) provides external decorative finish to the mask. Also claimed is prodn. by placing the gauze in a mould and ingjecting the plastic in liq. state into one side only which flows through the gauze to form both grid and ribs. The material can be chosen from a large range. USE/ADVANTAGE - Protecion mask for cavity housing delicate instruments partic. microphones, loudspeakers, measuring instruments. Allows economic prodn., sepn. of reinforcing members and decorative members and high precision moulding.

Description

 The present invention relates to a cover intended to protect from dust and any other foreign body a cavity inside which is a fragile object such as microphone, loudspeaker, measuring instrument, or else an empty cavity which must remain clean. while allowing air or sound circulation. The invention furthermore covers a method of manufacturing the cover mentioned above.

 In some current caches a fabric is embedded between the frames defining their contours. However, this large area fabric is very susceptible to damage if it is not protected by a grid. We therefore thought of making grids involving the installation, by gluing or any other means, of a material allowing the passage of air, on synthetic structures arranged in the form of a mesh.

This material may, however, detach from the mesh and be made sensitive to vibrations, which consequently prevents it from protecting the cavity or its contents from dust or foreign bodies which may enter it.

 To this end, covers have been made comprising two grids produced separately, between which one or more layers of fabric have been placed. In this case, the grids are held in place using mechanical means such as screws or other assembly means, but this technology is expensive since it comprises several parts which must be assembled.

 Furthermore, as another technical drawback, in particular in the case of speaker protection, the assembly means can loosen or slacken as a result of vibrations and in this way they produce annoying noise; the parts thus loosened or released may fall into the cavity or onto the object to be protected.

 Given the drawbacks stated above, a type of cover has been produced, the two sides of a double grid of plastic or synthetic material being injected on the two respective faces of the fabric allowing the passage of air and stopping the dust. . However, this method has the drawback of not being able to guarantee a perfect surface condition on the visible face of the cover, due to the presence of injection points. In addition, the injected material risks closing off the grid openings, due to its pressure on each side of the tissue during injection.

 It has also been proposed to produce a double grid enclosing the fabric by its two sides and the two identical meshes of which meet through the fabric by means of an injection associated with a pressure difference between the two faces, in order to obtain a cover in one piece. This allows the passage of air while ensuring cleanliness in the cavity to be protected, but it is then mandatory to make the same mesh pattern in its inner part as in the visible outer part, which involves the same drawbacks as in the previous case. In addition, the necessary precision of the tools as well as that of the mold and its equipment results in a high cost price, which explains the high cost of a cache of the latter type, to which is added the cost. a very fluid material, essential to cross the structure of the fabric.

 The present invention therefore aims to remedy the various drawbacks mentioned above, by providing a cover that does not obstruct the passage of air while protecting the cavity from dust or other foreign bodies, resulting from a reliable manufacturing not requiring not very high precision in order to be easy to implement, and being able to be carried out with the widest possible range of synthetic material, therefore economical. In addition, the cover according to the invention makes it possible to dissociate the interior reinforcement patterns from the visible exterior patterns, which increases its practical possibilities.

 According to the invention, the protective cover is of the type comprising at least one mesh of synthetic material molded on one face of a cheesecloth, said mesh being intended to constitute the visible external surface of the cover and being able to take any decorative form, and it presents, on the opposite face of the cheesecloth, ribs of the same synthetic material molded according to a structure of a shape which can be different from that of said mesh in order to be essentially adapted to the reinforcement and to the fixing of the cover.

 For the manufacture of a cover as defined above, the method according to the invention consists in placing aftetamine between the two parts of an injection mold provided with circulation channels, and in injecting a heat-fusible synthetic material in the liquid state of a single side of the cheesecloth parallel to the latter, whereby the mesh and the reinforcing structure are formed in one operation on the cheesecloth, thus forming the cover in one piece.

Other characteristics and advantages of the invention will emerge more clearly from the description which follows, given with reference to the appended drawings in which
FIG. 1 represents a plan view of a fragment of the external surface of a cover according to the invention; and
FIG. 2 represents a sectional view along AA of the cover of FIG. 1.

 In these drawings, the same references designate the same elements.

 Referring to the drawings, a cover according to the invention comprises a cheesecloth 1 made of any suitable material such as fabric, knitted fabric or felt, capable of stopping dust while allowing air and sound to circulate. A mesh, of general reference 2, for example in the form of a honeycomb in relief 3 and constituted by a heat-fusible synthetic material is fixed to the upper face 4 of the cheesecloth by direct molding on the latter in order to constitute the visible external surface of the cover. Ribs 5, 6 are arranged in a structure essentially adapted to the reinforcement or to the fixing of the cover, on the opposite face 7 of the cheesecloth. Therefore, this structure can be different from the decorative shape of the mesh 2 and form reinforcements as well as all fixing members on the cavity for which the cover is intended.

 As mentioned above, the ribs are made of the same material as that of the mesh 2 and they are also fixed to the face 7 of the cheesecloth by direct molding.

According to the arrangement as described above, the cover thus consists of cheesecloth, mesh and ribs in one piece.

 The cover thus produced, disposed on a cavity to be protected from dust or the fall of foreign bodies, therefore provides mechanical protection of said cavity by means of the mesh and the ribs, the latter also allowing suitable fixing to the cavity. . The dust protection barrier), however, allowing free circulation of air, is ensured by means of the cheesecloth itself reinforced by the grid.

 The heat-fusible synthetic material is fixed to the cheesecloth by molding by means of a mold (not shown) in two parts corresponding respectively to the mesh 2 and to the ribs 5, 6 and provided with the necessary circulation channels.

The cheesecloth is placed between the two parts of the mold and the synthetic material is injected in the liquid state on a single side (F1, fig. 2) of the cheesecloth, parallel to said cheesecloth. The liquid material then forms the mesh 2 as well as the ribs 5, 6 thanks to the mold circulation channels on either side of the cheesecloth, to form the entire structure of the cover in one piece. It should be noted that the connection between the synthetic material and the cheesecloth takes place in a simple manner by thermofusion, without it being in particular necessary to apply a vacuum during molding. Therefore, the synthetic material does not have to present particular properties of fluidity in addition to its fusibility and can be chosen from a wide range of economical products.

 It is understood that the present invention has been described and shown for explanatory purposes but in no way limitative and that any useful modification may be made to it, in particular in the field of technical equivalences, without going beyond its ambit.

Claims (2)

RETCATIONS  1. Protective cover against dust and foreign bodies, intended to be fixed on a cavity to be protected, of the type comprising at least one mesh (2) of synthetic material molded on one face (4) of a cheesecloth (1) , said mesh being intended to constitute the visible external surface of the cover and being able to take on any decorative form, characterized in that it has, on the opposite face (7) of i1 cheesecloth, ribs (5, 6) of the same synthetic material molded according to a structure of a shape which may be different from that of said mesh so as to be essentially adapted to the reinforcement and to the fixing of the cover.  2. A method of manufacturing a cover according to claim 1, by molding a heat-fusible material on a cheesecloth, characterized in that the cheesecloth (1) is placed between the two parts of a mold injection device provided with circulation channels, and that a heat-fusible synthetic material is injected in the liquid state on a single side (F1) of the cheesecloth parallel to the latter, whereby the formation is formed in one operation mesh (2) and the reinforcing structure (5, 6) on the cheesecloth, thus forming the cover in one piece.