EP0649269B1 - Speaker enclosure with extended range of diffusion - Google Patents

Abstract

The invention relates to a speaker enclosure (1) with extended spatial diffusion, which enclosure comprises at least two acoustic transducers which, each having a favoured acoustic emission axis (2A), are oriented in such a way that their favoured emission axes are themselves oriented in different directions (D1 to D4), particularly divergent directions when they are viewed in projection in an angular orientation sector defined in space. It is characterised in that the various transducers with the favoured emission axes (2A) oriented in different directions (D1 to D4) are arranged with their points (7) called "point source base" situated on a line, called base line, which extends in a substantially midplane and is perpendicular to that of the angular sector in question. <IMAGE>

Description

The invention relates to an acoustic enclosure with extended spatial diffusion.

The invention also relates to an assembly comprising at least two enclosures produced in accordance with the invention.

For example, this set is one of two elements of a stereophonic reproduction group.

By acoustic speaker with wide spatial diffusion, we include an enclosure which, relative to the enclosures classics which are called directional for a domain of determined frequencies, present at least in one sector angular determined in space, a certain omnidirectionality for the frequency domain considered.

By frequency domain determined, it will be understood in particular the domain of frequencies generated by acoustic transducers whether they are "medium", "tweeters", bass or broadband.

Specifically, the invention relates to an acoustic enclosure comprising at least two acoustic transducers, the emission axes are oriented in divergent directions in the angular sector considered of space.

By acoustic transducers, we will understand everything device for translating a signal into sounds any, for example, electrical which is otherwise applied.

The so-called omnidirectional speakers known for a long time date are constituted by a chest comprising a wall which defines several external faces, including a front face, that is to say a face which, facing the listeners, is inscribed in an approximately semi-cylindrical envelope form and in which are arranged at least two cutouts at the periphery of each of which a acoustic transducer also internal to the boot.

This enclosure architecture is generally reserved to so-called power speakers, such as speakers intended for the sound system of places in which the listeners are distributed in front of a stage on which each enclosure is placed, i.e. in cases where listeners are located in an angular sector of about a hundred eighty degrees, in front of any frontal point of the scene.

If the power speakers that have this type of architecture actually allow better spatial distribution of acoustic radiation pressure total in the sound volume, however they the disadvantage of inducing differences in acoustic phase notable in said sound volume.

By differences in acoustic phase, we will understand phase differences which appear at at least one point of sector S, between wave fronts of acoustic signals which were emitted by the transducers.

To remedy this drawback, it is known DE-A-3,723,409, to implement a device which allows a auditor (A1) determined to artificially tune in phase the acoustic signals at the listening point where it is located and this, by shifting the electrical signals that generate the so-called acoustic signals.

For an auditor (A2) located at another listening point (or when the auditor (A1) moves), a new agreement acoustic phases must be operated.

As illustrated in FIG. 6 of the attached drawings, failing to electrically make a new agreement, acoustic phase differences appear.

One of the results that the invention aims to obtain is precisely an enclosure that ensures the implementation acoustic phase of the different acoustic transducers that it entails by guaranteeing an increased distribution of sound pressure in relation to the speakers of the state of technical.

This result is obtained by the invention by adjusting in space the position of the different transducers of any acoustic enclosure whose transducers are arranged in a column.

The state of the art certainly includes a device (US-A-4,953,223) describing an acoustic enclosure whose transducers are, on the one hand, arranged in a column and, on the other hand, each orientable around the longitudinal axis of this column, but the orientation of these transducers does not sufficient to obtain the result targeted by the invention.

On the one hand, the column of transducers of the document US-A-4.953.223 is a three-way speaker only consists of three spectral transducers different emission levels (treble, mid, bass), which is first vice for obtaining the result and, on the other hand, even on the assumption that the emission spectra of different transducers would overlap locally, nothing in the aforementioned area only indicates the situation of the points "point source base" that they contain is adjusted to the way of the invention.

The defect of this enclosure in column of the state of the technique is illustrated in Figure 7 of the accompanying drawings.

The subject of the invention is precisely an enclosure acoustic with wide spatial diffusion, which enclosure is characterized in that the different transducers on the axes privileged issues oriented in different directions, are arranged with their points called "source base point "located on a line, called base, which extends in a plane substantially median and perpendicular to that of the angular sector considered.

The subject of the invention is also an assembly comprising at least two enclosures produced in accordance with the invention.

• figure 1 : une vue de face d'une enceinte acoustique selon l'invention,
• figure 2 : une vue selon F de l'enceinte acoustique de la figure 1,
• figure 3 : une superposition de deux plans de coupes partielles A-A et B-B répertoriés en figure 1,
• figure 4 : une vue en coupe partielle selon IV IV et à plus grande échelle de l'enceinte acoustique de la figure 1.
• figure 5 : une vue en coupe partielle de la figure 1 selon un plan médian vertical,
• figures 6 et 7 : vus de dessus, deux dispositifs de l'état de la technique avec différents fronts d'ondes acoustiques émis par les transducteurs qu'ils comprennent, vers au moins un auditeur (A1, A2),
• figure 8 : vu de dessus, le dispositif de l'invention avec les fronts d'ondes acoustiques qu'il émet vers deux auditeurs (A1, A2).

The invention will be clearly understood on reading the description below given by way of nonlimiting example with regard to the appended drawing which schematically represents:

• FIG. 1: a front view of an acoustic enclosure according to the invention,
• FIG. 2: a view along F of the acoustic enclosure of FIG. 1,
• FIG. 3: a superposition of two partial section planes AA and BB listed in FIG. 1,
• Figure 4: a partial sectional view along IV IV and on a larger scale of the acoustic enclosure of Figure 1.
• FIG. 5: a partial sectional view of FIG. 1 along a vertical median plane,
• FIGS. 6 and 7: seen from above, two devices of the state of the art with different acoustic wave fronts emitted by the transducers which they comprise, towards at least one listener (A1, A2),
• FIG. 8: seen from above, the device of the invention with the acoustic wave fronts that it emits towards two listeners (A1, A2).

Referring to the drawing, we see an acoustic enclosure 1 with wide spatial diffusion, i.e. an enclosure 1 which is qualified as omnidirectional at least in sector angular S of orientation defined in space, because it includes at least two acoustic transducers 2, for example, electro-acoustic, which, each having a 2A axis privileged acoustic emission, have emission spectra which overlap at least locally and are oriented in such a way that their preferred emission axes are as for them oriented in directions D1 to D4 different, especially divergent when observed projected in the angular sector S considered (figure 2).

By acoustic enclosure, we will therefore understand a device capable of producing sounds in a frequency domain determined.

In Figure 2 the preferred emission axes and the directions D1 to D4 have been shown combined and only the marks D1 to D4 have been worn.

The enclosure 1 consists of a trunk 3 comprising a wall 4 which defines several external faces, including one face front 5 (fully visible in Figure 1), i.e. a face intended to be turned towards listeners A1, A2 (symbolized in Figure 8) and in which are arranged at at least two cutouts 6 on the periphery of each of which connects an acoustic transducer 2 in addition essentially internal to the trunk 3.

Each acoustic transducer 2 has a fictitious point remarkable 7 says "equivalent point source base", which point 7 is located, in particular axially at transducer, usually at a distance D beyond of the central front face 9A of a membrane 9 which the said transducer 2 (Figure 3).

In general, the position of point 7 says "source base point "is determined by the manufacturer of the transducer acoustic 2.

This point "point source base" is actually an area fictitious from which the acoustic waves generated seem to be emitted by the transducer.

In the figures, point 7 has been represented in the center of a circle divided into quadrants.

As shown in the drawing, the transducers the enclosure are arranged substantially in a column 10 of axis 10A longitudinal approximately orthogonal to the said sector angular.

Without being limiting for the invention, we will consider that sector S, in which listening is carried out, is substantially horizontal because the listeners preferentially sit or stand and so they hold their heads substantially vertically, which determines the position of their ears.

Axis 10A of column 10 is therefore considered approximately vertical.

Instead of being arranged with their emission axes oriented in different directions D1 to D4 located in a plane approximately parallel to the angular sector S in which enclosure 1 must have a certain omnidirectionality, the various transducers with privileged emission axes 2A oriented in different directions D1 to D4, are arranged with their points 7 called "point source base" are located on a line L, called the base, which extends in a plane P substantially median and perpendicular to that of angular sector S considered.

Although it does not appear in the drawing, the transducers are each controlled by an external signal.

• d'une part, de manière à produire des sons de fréquences situées dans un domaine défini et,
• d'autre part, à être en phase acoustique.

Remarkably, for the enclosure, the various transducers are controlled by the same signal:

• on the one hand, so as to produce sounds of frequencies located in a defined domain and,
• on the other hand, to be in the acoustic phase.

The respect of these particularities makes it possible to obtain the essential result of the invention, namely, an enclosure which ensures the acoustic phase of the different acoustic transducers it includes, despite their different orientations, and this by guaranteeing increased distribution of sound pressure compared to prior art speakers that are said omnidirectional.

Figure 8 of the accompanying drawings shows that the enclosure acoustics of the invention provides acoustic tuning in all points of a sector S located in front of the enclosure.

In FIG. 8, the fronts F of the acoustic waves emitted in phase by the various transducers of the enclosure the invention are perceived in the acoustic phase by an auditor located at any point in sector S located in front the enclosure.

In Figures 6 and 7 where two speakers are shown state of the art, wave fronts emitted in phase by the different transducers cannot that exceptionally (figure 6) be perceived in phase in a determined point of sector S.

The acoustic wave fronts F were each symbolized by an arc of a circle whose center is the point "base of point source "from the transducer that generated it.

In FIGS. 7 and 8, the radii R of the different arcs of circle symbolizing the wave fronts are identical for the different transducers because the acoustic signals have was issued simultaneously.

In the case of Figure 6, the radii of the different arcs are different because the signals that generate the corresponding wave fronts have been shifted in time for their agreement in phase for an auditor A1.

In the case of the devices of FIGS. 6 and 7, there are differences in acoustic phase a, b between the different wave fronts for at least one auditor A2 from sector S.

In the case of the invention, the plane P which contains the baseline also contains the longitudinal axis 10A of the column 10.

All these particularities therefore make it possible to approach the characteristics of a point source.

In Figures 2 to 4, the trace of the baseline L in the plane of the figure and the so-called source base point point have been shown combined and the L mark worn in parentheses.

Advantageously, the so-called base line L is rectilinear.

• en vue de l'appui sur un autre caisson, au moins une surface externe 12, dite d'appui, qui est approximativement orthogonale à la ligne L sur laquelle les points 7 dits "base de source ponctuelle" sont disposés et,
• en vue du port au moins indirect d'un transducteur 2, une surface 13, dite frontale, équipée d'une découpe 6 à laquelle se trouve raccordé ce transducteur 2, par ailleurs interne audit caisson, laquelle surface frontale 13 est approximativement parallèle à la ligne L de base dans sa fraction traversant ce caisson 11,
• en vue d'une orientation relative de chaque caisson par rapport à un autre, et ce, autour de la ligne de base L, au moins un élément d'un moyen 14 d'orientation et de positionnement à cet effet, comprenant deux éléments complémentaires.

The trunk 3 of the enclosure 1 consists of at least two boxes 11 which, each housing at least one acoustic transducer 2, each have:

• in view of the support on another box, at least one external surface 12, called the support surface, which is approximately orthogonal to the line L on which the points 7 called "point source base" are arranged and,
• with a view to carrying, at least indirectly, a transducer 2, a so-called frontal surface 13 equipped with a cutout 6 to which this transducer 2 is connected, which is also internal to said box, which frontal surface 13 is approximately parallel to the base line L in its fraction crossing this box 11,
• for a relative orientation of each box relative to another, and this, around the base line L, at least one element of a means 14 for orientation and positioning for this purpose, comprising two complementary elements .

These technical features allow the different transducers that the enclosure includes can be precisely oriented, in particular by adjustment.

Also, it is noted that such an enclosure can be modularly constructed.

• la surface frontale 13 de chaque caisson 11 est sensiblement plane et elle présente des bords 13A qui déterminent un quadrilatère rectangle,
• à cette surface frontale 13, en deux opposés de ses bords, se raccorde sensiblement une surface latérale 15 de forme d'enveloppe approximativement cylindrique de révolution,
• les différents caissons 11 d'un coffre d'enceinte ont, dans un plan parallèle à la surface d'appui 12 du caisson, sensiblement une même section et ce, de manière telle que, lorsqu'ils sont superposés, ils présentent leurs surfaces latérales 15 approximativement en continuité, cependant qu'ils sont orientés différemment pour présenter chacun leur surface frontale 13 dans une direction déterminée par rapport à au moins un autre caisson de l'enceinte,
• la découpe 6 réalisée dans chaque face frontale 13 pour constituer l'ouverture dans laquelle débouche un transducteur 2, à une position déterminée essentiellement par rapport à ceux de ses bords auxquels se raccorde la surface latérale 15, et ce, en fonction de l'orientation relative de chaque caisson par rapport à au moins un autre caisson 11 de l'enceinte.

Notably:

• the front surface 13 of each box 11 is substantially flat and it has edges 13A which determine a rectangular quadrilateral,
• to this front surface 13, at two opposite of its edges, is substantially connected a side surface 15 of envelope form approximately cylindrical of revolution,
• the various boxes 11 of an enclosure chest have, in a plane parallel to the bearing surface 12 of the box, substantially the same section, so that, when they are superimposed, they have their lateral surfaces 15 approximately in continuity, however they are oriented differently to each present their front surface 13 in a determined direction relative to at least one other box of the enclosure,
• the cutout 6 produced in each front face 13 to constitute the opening into which a transducer 2 opens, at a position determined essentially with respect to those of its edges to which the lateral surface 15 is connected, and this, depending on the orientation relative of each box relative to at least one other box 11 of the enclosure.

Compliance with these technical details makes it possible to build a particularly neutral enclosure during its use, that is to say, an enclosure whose walls and structure generate parasitic vibrations which are inaudible.

The different boxes 11 which produce the same enclosure have, in their wall having the surfaces 12 support, at least one cutout 12A which constitutes a wide passage putting the internal volumes of the boxes 11 in communication.

This last feature makes it possible to build a large volume speaker for bass reproduction frequencies with minimum attenuation and fidelity maximum.

The enclosure constructed according to the invention applies particularly to quality sound systems in large rooms, but also to the creation of high installation fidelity or so-called "monitor" enclosure, ie enclosure benchmark for studios specializing in reproduction sounds.

The wall 4 of the enclosure has been represented locally cylindrical of revolution, but this is only one simplification of representation and has no character limiting for the invention.

Likewise, the sound absorbent adapted to the optimization of each box with its transducer has not been shown.

Although not shown, several speakers constructed according to the invention and producing sounds in different frequency domains, can be superimposed to constitute an assembly in accordance with the invention; it's at say a set whose transducers present their point 7 says "point source base" on a baseline L which extends in a substantially median and perpendicular plane P to that of the angular sector S in which the enclosures are presumed omnidirectional.

Claims (9)

1. A speaker enclosure (1) with extended spatial diffusion, said enclosure comprising at least two sound transducers (2) which, each having a preferred sound-transmission axis (2A), have transmission spectra that overlap at least locally and are oriented in such a way that their preferred-transmission axes are oriented in different directions (D1 to D4), notably diverging when they are observed in projection in an angular sector (S) of defined spatial orientation,

   the transducers being arranged in a column (10) with a longitudinal axis (10A) approximately orthogonal to the said angular sector S,

   each of these transducers (2) exhibiting a notable imaginary point (7) which, being called a "equivalent point source base", is situated, particularly axially to the transducer, generally at a certain distance D beyond the front face (9A) of a membrane (9) which the said transducer (2) comprises,

   this enclosure being CHARACTERISED in that the various transducers with preferred transmission axes (2A) oriented in different directions (D1 to D4) are arranged with their points (7) called "point source base" situated on a line (L) called a base line, which extends in a plane (P) substantially median and perpendicular to that of the angular sector under consideration (S).
2. A speaker enclosure according to Claim 1, the transducers of which are each driven by an external signal, characterised in that the various transducers are driven by the same signal:

   on the one hand, to produce sounds of frequencies situated within a defined range and,

   on the other hand, so as to be in acoustic phase.
3. A speaker enclosure according to Claim 1 or 2 and composed of a cabinet (3) comprising a wall (4) which defines several external faces, including a front face (5), that is, a face intended to be turned towards listeners, and in which there are arranged at least two slots (6) at the periphery of each of which a sound transducer (2) is connected, furthermore essentially internal to the cabinet (3), characterised in that the cabinet (3) of the enclosure (1) is composed of at least two boxes (11) which, each screening a sound transducer (2), each exhibit:

   in order to be supported on another box, at least one external surface (12) called a support surface, which is approximately orthogonal to the line (L) on which the points (7) called "point source base" must be arranged and

   in order to carry a transducer (2), at least indirectly, a surface (13) called a front surface, provided with a slot (6) to which this transducer (2) is connected, moreover internal to the said box, the said front surface (13) being approximately parallel to the base line (L) in its portion which crosses this box (11).
4. A speaker enclosure according to any one of Claims 1 to 3, characterised by, for the purpose of relative orientation of each box in relation to another around the base line (L), at least one element of a means (14) of orientation and of positioning to this effect, comprising two complementary elements.
5. A speaker enclosure according to any one of Claims 1 to 4, characterised in that:

   the front surface (13) of each box (11) is substantially plane and it exhibits edges (13A) which determine a rectangular quadrilateral,

   to this front surface (13), on two opposite edges thereof, there is substantially connected a lateral surface (15) in the form of an approximately cylindrical revolution envelope.
6. A speaker enclosure according to any one of Claims 1 to 5, characterised in that the different boxes (11) of an enclosure cabinet have, in a plane parallel to the support surface (12) of the box, substantially an identical section, in such a way that, when they are superimposed, they present their lateral surfaces (15) approximately in continuity, while they are oriented differently so that each presents their front surface (13) in a direction determined in relation to at least one other box of the enclosure.
7. A speaker enclosure according to any one of Claims 1 to 6, characterised in that the slot (6) made in each front face (13) to constitute the opening in which a transducer (2) emerges, at a position determined essentially in relation to those of its edges at which the lateral surface (15) is connected, as a function of the relative orientation of each box in relation to at least one other box (11) of the enclosure.
8. A speaker enclosure according to any one of Claims 1 to 7, characterised in that the different boxes (11) making up the same enclosure comprise, in their wall presenting the support surfaces (12), at least one slot (12A) which constitutes a broad passage placing the internal volumes of the boxes (11) in communication.
9. An assembly comprising at least two enclosures according to any one of Claims 1 to 8 and of a type producing sounds in different frequency ranges, characterised in that, to make up the assembly, the enclosures are superimposed in such a way that the base points (7) of the transducers which the transducers comprise are situated on a base line (L) which extends in a plane substantially median and perpendicular to that of the angular sector (S) in which the enclosures are presumed to be omnidirectional.

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