EP1031256B1 - Linear loudspeaker - Google Patents

Abstract

The invention concerns a loudspeaker having an elongate parallelepiped hollow body, whereof one longitudinal surface is made up of a stretched elongate rectangular planar diaphragm. The diaphragm is suspended by its edges to the body adjacent side surfaces, and is integral with an elongate rigid inner part extending in the body longitudinal direction, and bearing a mobile electromagnetic coil, parallel to the diaphragm. The coil is arranged between two fixed magnets located along the body two longitudinal side surfaces which form, with the base of said body, polar parts. Said loudspeaker is useful as component of an active anti-noise system, associated with a double glazing.

Description

The present invention relates to a loudspeaker, which is characterized by a geometric shape and a particular overall design.

Currently, there are in practice only conical diaphragm speakers, the diameter of which is at least equal to 3 cm, and whose depth exceeds always 2 cm. In general, conventional speakers, especially those with a certain power, are of larger dimensions, and given their shape and their size, they cannot be housed in a small volume and, in particular, in a narrow space. These drawbacks make in particular current speakers unfit for use in certain specific applications, particularly in active soundproofing systems by creating an "anti-noise".

We know, however, from US Patent No. 4,792,978, a loudspeaker which can be designated as "linear", in meaning that it has an elongated rectangular shape, and has a correspondingly shaped membrane, vibration by an electromagnetic system with coil oblong shape. The coil, linked to the membrane, extends here in a plane perpendicular to said membrane. This coil moves between elongated permanent magnets, of opposite polarities. As a result, the coil does not not move in a homogeneous and closed magnetic field, this which affects the sound quality of the coil.

US Patent No. 4,550,428 describes a loudspeaker generally classic in shape, i.e. circular, comprising a cylindrical coil parallel to the membrane, a permanent annular magnet and a pole piece Central. Despite the arrangement of the coil, this document remains distant from the object of the present invention.

European patent application No. 0 710 946 discloses a double wall acoustic attenuation device active, using speakers arranged at the edge a double wall, such as double glazing, in the blade of air between the two walls. However, this device uses circular speakers, diameter important, and can therefore only be applied to duplicates walls with thick air space.

The present invention aims to remedy all the aforementioned drawbacks, by providing a speaker for "linear" type, which can be accommodated in a reduced volume and especially in a narrow space, while having a performance comparable to that of a conventional speaker that couldn't go into the same volume, this speaker having in addition an excellent quality of sound reproduction.

To this end, the invention essentially has for object an elongated overall speaker says linear speaker, consisting of a hollow body elongated parallelepiped, one side of which longitudinal at least partially consists of a flat membrane of elongated rectangular shape, suspended by its edges from the adjacent side faces of said body or under the bottom of said body, and integral an elongated rigid internal wing which extends in the longitudinal direction of said body, substantially in the longitudinal median plane thereof, and which bears a mobile electromagnetic coil of elongated profile, disposed between two fixed elongated magnets, associated with fixed pole parts, characterized in that the coil electromagnetic mobile is parallel to the membrane, and in that the two fixed elongated magnets between which it is arranged are placed respectively along two longitudinal side faces of said body, these faces lateral and the bottom of the body forming said parts fixed polar, which also includes a polar part central fixed, located in the longitudinal median plane of the body and received in a longitudinal recess of the wing internal rigid of the membrane, said membrane being tensioned so as to allow its symmetrical deformation of on either side of its rest position during vibratory movement of this membrane when the speaker is excited.

According to a preferred embodiment of the invention, the elongated planar membrane consists of a rigid part, covered with an elastic film, and / or includes such a film, the edges of which are fixed to the side faces adjacent to or below the bottom of the body loudspeaker, this fixing being able to be carried out by a bonding or mechanical pinching. The elastic film is itself linked to the rigid part of the membrane by bonding, or by overmolding, or by a bond mechanical.

Thus, the invention provides a speaker whose membrane is not tapered like on a speaker classic, but has a specific geometry, in the occurrence of a flat, rectangular and elongated shape, so narrow in one sense and very wide in another meaning, in relation to the overall form elongated parallelepiped of the speaker, which justifies its designation as a linear speaker. The speaker membrane object of the invention has only an external or peripheral suspension, unlike conical speaker membranes classics which have an external suspension and a internal suspension (the latter being designated usually as a "spider"). Furthermore, conversely of a conventional speaker, not only some polar parts but also the magnets are placed at the outside of the coil, the rigid internal wing of the membrane being, however, hollowed out to receive the portion central fixed polar, located in the median plane longitudinal of the speaker body.

Geometric shape and layout particular of the components of the loudspeaker thus realize an optimization, allowing for example to obtain a speaker with a width of 2 cm, a 2 cm deep and more or less long large, for example of the order of 50 cm, having a very satisfactory performance. In particular, given of the significant length of the membrane, it displaces a large mass of air during its vibration, which allows to have a good performance in the low frequencies. Thanks to its elongated coil, practically extending over the entire length of the membrane, below this last, the forces are distributed evenly over the length of the membrane, thus avoiding distortions. The central polar part, also extending practically over the entire length of the membrane, ensures good guidance of the movement thereof, over its entire length. The unique suspension of the membrane contributes to constructive simplicity and compactness of the speaker subject of the invention.

In addition, with the suspension proposed by the invention, the membrane is suspended so as to find it tense permanently and in a "balanced" way, that is to say by generating the same restoring force elastic for movement in one direction or the other of the rigid internal part linked to this membrane, so that it has, during its movement vibratory, symmetrical deformation on both sides from its rest position. In other words, the deformation of the vibrating membrane is the same (in value absolute), for a positive or negative alternation of the electrical signal applied to the speaker input. The symmetrical deformation of the vibrating membrane allows ensure good electromechanical conversion linearity, especially at low frequencies, avoiding distortion, disruptive to the sound reproduction in general but also for particular applications of active noise canceling system. The suspension produced according to the invention is also very flexible, which leads to a high yield of transducer.

It will also be noted that, by means of the voltage of the membrane, the restoring force can be adjusted, according to the needs of the bandwidth necessary to use, as well as the distortion necessary to the application of either public address or noise canceling active, applying the law F = kx.

The orientation of the coil parallel to the membrane (while it is perpendicular to it in the US patent No. 4792978 cited above), also leads to locating and moving the coil in a homogeneous and closed magnetic field, to which the central pole part contributes, which is as important for achieving optimal behavior of the membrane.

According to an embodiment of the invention, the membrane spans the entire length of the speaker body. Alternatively, the membrane extends over part of the total length of the speaker body, said body thus delimiting towards its ends, on either side of the membrane, two internal spaces voids constituting a chord volume.

Because of its configuration, especially its small cross section, the speaker object of the invention can be used in particular as a component of a active noise canceling system, including one or more speakers linear as defined above, arranged in border of a double wall, such as double glazing, in the air gap between the two walls and / or inside of a framing profile of this double wall. In this application, the speaker object of the invention allows for an electro-acoustic system practically invisible, and does not harm comfort neither to the light transmission of the glazing, the proposed system to improve insulation phonic double glazing especially in the bass frequencies.

Figure 1 est une vue d'ensemble, en perspective, d'un haut-parleur conforme à la présente invention ;

Figure 2 est une vue en coupe transversale de ce haut-parleur, suivant II-II de figure 1 ;

Figure 3 est une vue en coupe longitudinale du même haut-parleur, suivant III-III de figure 2 ;

Figures 4, 5 et 6 sont des vues partielles, en coupe transversale, montrant des variantes de la suspension de la membrane du haut-parleur ;

Figure 7 est une vue très schématique d'une autre forme d'exécution de ce haut-parleur linéaire, avec volume d'accord ;

Figure 8 est une vue de face d'un double vitrage avec système anti-bruit actif représentant une application du haut-parleur objet de l'invention ;

Figure 9 est une vue en coupe montrant un détail de montage du haut-parleur, dans l'application illustrée par la figure 8.

The invention will be better understood with the aid of the description which follows, with reference to the appended diagrammatic drawing representing, by way of examples, some embodiments of this linear loudspeaker, and by illustrating a particular application:

Figure 1 is an overall perspective view of a loudspeaker according to the present invention;

Figure 2 is a cross-sectional view of this speaker, according to II-II of Figure 1;

Figure 3 is a longitudinal sectional view of the same speaker, along III-III of Figure 2;

Figures 4, 5 and 6 are partial views, in cross section, showing variants of the suspension of the speaker membrane;

Figure 7 is a very schematic view of another embodiment of this linear speaker, with tuning volume;

Figure 8 is a front view of a double glazing with active anti-noise system representing an application of the speaker object of the invention;

Figure 9 is a sectional view showing a detail of mounting the loudspeaker, in the application illustrated by Figure 8.

Figures 1 to 3 give a representation schematic of a linear speaker, which presents itself externally as a body 1 in the form of elongated rectangle parallelepiped, having for example a length of 50 cm, a width of 2 cm and a depth of 2 cm.

The two longitudinal side faces 2 and the bottom 3 of the speaker body 1 form parts fixed outdoor fleeces, supplemented by a part central fixed polar 4, located in the median plane longitudinal P of body 1 of the loudspeaker. All of these polar parts are advantageously united under the shape of an "E" profile. Inside body 1 of speaker are arranged two fixed permanent magnets 5 elongated, placed respectively along the two longitudinal side faces 2, above the bottom 3. The speaker body 1 can be closed, both ends, by flanges 6 of square shape or rectangular.

On the upper longitudinal face of the body 1 of the speaker, opposite the bottom 3, is stretched a elongated flat membrane generally designated by the item 7. The membrane 7 consists of a part in light and rigid material 8, plate-like elongated rectangular, and a film with properties elastic 9, such as a polyethylene film covering the rigid part 8. The two protruding longitudinal edges 10 of the elastic film 9 are folded against the faces longitudinal side 2 of body 1, and are fixed externally on these faces 2 or under the bottom 3 by a bonding or mechanical pinching using a suitable mounting. The elastic film 9 is also linked to the rigid part 8 of the membrane 7 by bonding to the upper surface of the rigid part 8, or by overmolding, or by mechanical pinching by means of an appropriate assembly.

The rigid part 8 of the membrane 7, in the form of plate, is extended towards the inside of the body 1 by a longitudinal wing 11, extending in the median plane longitudinal P of body 1 of the loudspeaker, between the two magnets 5 and towards the bottom 3, the whole of the rigid part thus presenting a "T" profile. The wing longitudinal 11 has a longitudinal recess 12, open towards the bottom 3, in which is engaged so sliding central fixed pole part 4. A coil electromagnetic mobile 13, parallel to the membrane 7 and very elongated profile, is carried by the wing longitudinal 11 which extends the rigid part 8 of the membrane 7. The two fixed magnets 5 are thus placed at the outside of the voice coil 13 on either side of the two long sides of this coil 13. Power coil 13 causes the vibration of the membrane 7, suspended elastically by its elastic film 9 at the fixed part of the loudspeaker, the deformation of the membrane 7 during vibration being symmetrical on the one hand and other of its average rest position.

Figures 4, 5 and 6 illustrate variants of the suspension of the diaphragm 7 of the loudspeaker, the The structure is, for the rest, not modified. In all these variants, the membrane 7 proper is limited to its rigid part 8.

In the case of FIG. 4, the junction between the membrane 7 and the side faces 2 of the body 1 of the loudspeaker is ensured by an elastic seal 14 in the form of sausage, for example rubber, glued on the one hand under the edges of the rigid part 8 of the membrane 7, and on the other hand on the upper edges of the faces side 2 of the body 1. The seal 14 is alternately compressed and stretched (in its section) during movement vibrating membrane 7.

In the case of FIG. 5, the junction between the membrane 7 and the side faces 2 of the body 1 of the loudspeaker is ensured by an elastic seal 15 in the form of bellows, that is to say having a zigzag section, which is also glued on the one hand under the edges of the rigid part 8 of the membrane 7, and on the other hand on the upper edges of the lateral faces 2 of the body 1.

In the case of FIG. 6, the junction between the membrane 7 and the side faces 2 of the body 1 of the loudspeaker is ensured by an elastic seal 15 in the form of sausage, glued on the one hand against the edges of the part rigid 8 of the membrane 7, and on the other hand against the inside of the lateral faces of the body 1, practically at the level of the upper edges of these lateral faces 2.

In the embodiment described so far, in particular with reference to FIGS. 1 to 3, the membrane 7 extends over the entire length of the speaker body 1. Figure 7 shows another embodiment of this speaker linear, in which the membrane 7 extends over a fraction of the total length of the speaker body 1, and more particularly in the region alone median of this body. Magnetic components of the speaker are also limited in length to this middle region. So are formed towards the two ends of the loudspeaker, on both sides of the occupied region by the membrane 7, two empty internal spaces 17, which constitute a volume of agreement.

Figures 8 and 9 illustrate an application particular of the linear speaker previously described. The loudspeaker is here a component of an anti-noise system active, which equips 18 double glazing and aims to reduce the noise in the air gap of the double glazing.

Usually, double glazing 18 has a frame 19, produced by profiles, and two parallel panes defining the air space. The active noise canceling system is generally made up of by speakers, microphones and electronics control. In the example illustrated in the drawing, this system includes four linear speakers 20, arranged respectively on the four sides of the frame 19 of the double glazing 18, and eight control microphones 21 also carried by the frame 18. The loudspeakers linear 20 produce a sufficient sound field for the destruction, by superposition, of propagating noises in the air space, and this active anti-noise system allows increase the soundproofing of the double glazing 18 in low frequencies.

In this app, each speaker linear 20 can be presented as a monobloc component independent, installed inside a profile of the frame 19 of the double glazing 18, so as to achieve an invisible anti-noise system, and does not reduce not the transmission of light through the windows.

Alternatively, as shown in Figure 9, each linear speaker 20 can be inserted into a interruption of a profile 22 of the frame 19, a connecting piece 23 ensuring the connection between each end of the body 1 of the speaker 20 and the profile 22. This assembly allows to benefit from a volume of agreement for the loudspeakers 20, in the framing profiles such that the profile 22 which extends between these speakers, this achieving the equivalent of the configuration according to the figure 7.

We would not stray from the scope of the invention by modifying the external dimensions of the loudspeaker, in particular its length, or its constituent materials especially with regard to the elastic film of its membrane, or the elastic suspension mode of said membrane. This is how, in particular, the film elastic of the membrane could be fixed not on the side faces of the speaker body but under the speaker bottom, wrapping elastic film possibly completely said body.

In the same vein, the narrow and elongated speaker object of the invention allows sound use, for active noise processing in a air space, not only in double glazing but also in any type of double wall. More generally the particular shape of this speaker allows you to insert it into a very small volume, making it virtually invisible, which also allows its integration into the proper structure of a room or furniture, or in the structure of a vehicle, or in ducts even in small sections, practically without introducing pressure drops. other linear speaker layouts and applications object of the invention can thus be: insertion into the door frame, for the sound of a room, or mounting in or on exhaust or ventilation, for active noise treatment in these ducts.

Claims (8)

1. Loudspeaker of elongate overall shape, termed a linear loudspeaker, consisting of a parallelepipedal hollow body (1) of elongate shape, a longitudinal face of which consists at least partially of a plane diaphragm (7) of elongate rectangular shape, suspended by its edges (10) from the adjacent lateral faces (2) of the said body (1) or under the base (3) of the said body (1), and integral with an elongate internal rigid wing (11) which runs in the longitudinal direction of the said body (1), substantially in the longitudinal midplane (P) of the latter, and which bears a moving electromagnetic coil (13) of elongate profile, located between two fixed elongate magnets (5), associated with fixed pole parts, characterised in that the moving electromagnetic coil (13) is parallel to the diaphragm (7), and that the two fixed elongate magnets (5), between which said coil is arranged, are located respectively along two longitudinal lateral faces (2) of the said body (1) , these lateral faces (2) and the base (3) of the body (1) forming said fixed pole parts, which also comprise a central fixed pole part (4), situated in the longitudinal midplane (P) of the body (1) and received in a longitudinal recess (12) of the internal rigid wing (11) of the diaphragm (7), the said diaphragm (7) being stretched in such a way as to allow its symmetric deformation on either side of its position of rest, in the course of the vibrational motion of this diaphragm (7) when the loudspeaker is excited.
2. Linear loudspeaker according to claim 1, characterised in that the elongate plane diaphragm (7) is composed of a rigid part (8), covered with an elastic film (9), and/or comprises such a film, of which the edges (10) are fixed onto the adjacent lateral faces (2) or under the base (3) of the body (1) of the loudspeaker.
3. Linear loudspeaker according to claim 2, characterised in that the edges (10) of the elastic film (9) of the diaphragm (7) are fixed by gluing or by mechanical crimping onto the adjacent lateral faces (2) of the body (1) of the loudspeaker.
4. Linear loudspeaker according to claim 2 or 3, characterised in that the elastic film (9) is attached to the rigid part (8) of the diaphragm (7) by gluing or by overmolding or by a mechanical link.
5. Linear loudspeaker according to claim 1, characterised in that the edges of the diaphragm (7) are attached to the adjacent lateral faces (2) of the body (1) of the loudspeaker by way of an elastic peripheral seal (14, 15, 16), especially in the shape of a roll bead or bellows.
6. Linear loudspeaker according to any one of claims 1 to 5, characterised in that the diaphragm (7) runs along the entire length of the body (1) of the loudspeaker.
7. Linear loudspeaker according to any one of claims 1 to 5, characterised in that the diaphragm (7) runs along a part of the total length of the body (1) of the loudspeaker, the said body (1) thus delimiting near its ends, on either side of the diaphragm (7), two empty internal spaces (7) constituting a tuning volume.
8. Use of a linear loudspeaker according to any one of claims 1 to 7, as a component of an active anti-noise system, comprising one or several linear loudspeakers (20) arranged as a border of a double wall, such as double glazing (18), in the air gap between the two walls and/or inside a frame member (19, 22) of this double wall (18).

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