Directional electro-acoustic conversion system and array of electro-acoustic conversion systems comprising such a system

Abstract

The invention relates to a directional electro-acoustic conversion system (100) comprising: a casing (10) comprising walls delimiting an internal volume (104) of the casing, a front wall (101) and a first side wall (102a); and at least a first loudspeaker (11a), which has a main emission axis (112a) and is configured to emit in a frequency range between 30 Hz and 400 Hz, and a second loudspeaker (12a), which has a main emission axis (122a) and is configured to emit in a frequency range between 30 Hz and 400 Hz, the first loudspeaker (11a) being arranged in the front wall (101) and the second loudspeaker (12a) being arranged in the first side wall (102a), and the emission axis (112a) and the emission axis (122a) forming therebetween an angle α of between -45° and 90°. The invention also relates to an array (900) of electro-acoustic conversion systems comprising at least two directional electro-acoustic conversion systems (100).

Description

[0001] Directional electro-acoustic conversion system and network of electro-acoustic conversion systems including such a system

[0002] technical field

[0003] The present invention relates to the field of sound diffusion systems. It relates more particularly to a directional electro-acoustic conversion system, notably in at least one frequency band between approximately 30 Hz and 400 Hz.

[0004] The present invention finds in particular a direct application in the field of event management, for sound diffusion during concerts, shows and other events in front of a large audience and more particularly in open or semi-open environments.

[0005] State of the art

[0006] Broadcasting music in large outdoor spaces presents a technical challenge in order to ensure that the sound reproduction of amplified music is as faithful as possible within the audience area, and that emergence is as low as possible outside of this area.

[0007] Electro-acoustic conversion systems were then developed to optimize sound diffusion by seeking in particular to improve the directivity of said systems in two perpendicular planes of propagation of acoustic waves, a first plane, typically vertical with respect to the ground, and a second plane orthogonal to the first, i.e. typically horizontal.

[0008] For example, in the vertical plane of sound emission, it is possible to obtain a directional system—that is, one offering directivity oriented in a preferred direction, known as cardioid directivity, as opposed to omnidirectional directivity, which is identical in all directions—by means of stacking a plurality of acoustic systems, thus forming a vertical column that can reach several meters in height. Such a system is then considered a linear acoustic source, more commonly referred to in English as a "Line Source Array." Furthermore, the systems within this plurality are generally stacked at an open angle, usually small, i.e., a few degrees, vertically producing a constructive pressure field in the principal direction of emission.We know of a system which includes a vertical set of speakers which can be suspended and which allows in particular the vertical angle between each speaker of the system to be adjusted in order to homogenize the sound level over the depth of the audience area.

[0009] In the vertical plane, this system is directional. However, in a horizontal transverse plane, the directivity of this system is not satisfactory because below typically 400 Hz, the horizontal directivity of the system widens until it becomes omnidirectional around typically 100 Hz.

[0010] In the horizontal plane, other "cardioid" systems are also used to improve directivity. To achieve good diffusion efficiency in the frequency range below 400 Hz, such a system includes a subwoofer equipped with several drivers positioned at different locations within the subwoofer. Appropriate signal processing on each of the subwoofer's drivers limits the acoustic power emitted, particularly towards the rear of the subwoofer, and increases the power emitted towards the front, thus improving the system's directivity.

[0011] A loudspeaker system is also known, comprising at least one primary low-frequency sound source and at least one treble (high-frequency) and / or mid-frequency (mid-frequency) sound source. At least one loudspeaker is located on the side of the enclosure and oriented perpendicularly to the main radiation direction. This system provides controlled directivity in the horizontal plane for all useful frequencies, including the 30 Hz to 400 Hz band. To achieve controlled directivity in the 30 Hz to 400 Hz band, a low-pass filter is applied to the loudspeaker(s) located on the side of the enclosure so that they do not emit above certain frequencies. Without the application of low-pass filters, the loudspeaker(s) located on the sides of the enclosure would emit mid-frequencies towards the sides of the system, and the system's directivity would no longer be controllable.

[0012] Thus, current systems require the use of a multitude of loudspeakers, some of which are used only on a narrow frequency band.

[0013] This raises the question of optimizing the use of this type of system. It can be advantageous to maximize the ratio between the speaker's weight and its sound pressure level, generally referred to as "SPL" (SPL being the English acronym for Sound Pressure Level), to achieve greater output power with the same number of speakers. The present invention aims to remedy, at least in part, the aforementioned drawbacks, while also offering additional advantages.

[0014] To this end, the present invention relates to a directional electroacoustic conversion system comprising a box having walls delimiting an internal volume of the box, a first of the walls forming a front wall and a second of the walls forming a first side wall, the box further comprising at least one partition dividing the internal volume of the box into two chambers separated from each other by the partition, a first of the two chambers comprising the front wall of the box, and a second of the two chambers comprising the first side wall of said box, the system further comprising: a first loudspeaker having a principal emission axis, called the primary emission axis, and being configured to emit in a frequency range of at least between 30 Hz and 400 Hz;a second loudspeaker having a principal emission axis, called the secondary emission axis, and being configured to emit in a frequency range of at least between 30 Hz and 400 Hz; the first loudspeaker being disposed in the front wall and the second loudspeaker being disposed in the first side wall; and the primary emission axis and the secondary emission axis forming an angle α between them of between -45° and 90°.

[0015] The principal axis of emission of a loudspeaker refers to the axis along which the sound pressure is at its maximum. The principal axis of emission corresponds, for example, to the axis of symmetry of the loudspeaker, in other words, the axis passing through the center of a loudspeaker diaphragm.

[0016] When angle α is between 0° and 90°, the primary and secondary emission axes are in a "convergent" configuration with respect to the front wall of the system, while when angle α is between -45° and 0°, the primary and secondary emission axes are in a "divergent" configuration with respect to the wall. An angle α of 0° corresponds to a configuration in which the primary and secondary emission axes are parallel.

[0017] The directional electro-acoustic conversion system thus configured and having an angle α between -45° and 90° between the primary emission axis of the first loudspeaker and the secondary emission axis of the second loudspeaker makes it possible to obtain a cardioid type directivity in the frequency range of at least between 30 Hz and 400 Hz.

[0018] The enclosure configuration with speakers arranged on different walls allows for better management of the system's directivity, particularly in the low frequencies where directivity is naturally more difficult to control.

[0019] A gain in directivity and / or power is obtained, compared with systems that only use one speaker, or a plurality of speakers arranged in the front wall.

[0020] Separating the internal volume into two chambers with a partition offers the possibility of treating the sound waves emitted by each speaker differently, which contributes to better control of the overall acoustic response of the system.

[0021] This system configuration allows for the provision of sound reinforcement for events taking place in locations near sensitive areas where ambient noise levels are strictly controlled. In these sensitive areas, the noise level must not exceed a relatively low threshold to limit potential noise pollution. Examples of such sensitive areas include school complexes, residential areas, and healthcare facilities (hospitals, nursing homes, etc.).

[0022] According to one characteristic, the primary emission axis and the secondary emission axis form an angle α of 45°.

[0023] According to another characteristic, the primary emission axis and the secondary emission axis form an angle α of 0°.

[0024] The choice of the value of angle a depends on the desired effect on directivity and / or acoustic power, allowing for example to maximize phase coherence between loudspeakers or to improve the focusing of the sound intensity of the system.

[0025] According to one characteristic, the enclosure has a second side wall, the front wall being located between the first side wall and the second side wall, said enclosure having a third speaker arranged in the second side wall, the third speaker being identical to the second speaker.

[0026] The use of a third speaker allows for higher sound levels while maintaining a cardioid directivity pattern.

[0027] According to another characteristic, the secondary emission axis of the second speaker and the secondary emission axis of the third speaker form a converging angle between 0° and 90°. This configuration allows the acoustic intensity to be concentrated on a focal area, thus directing sound waves into specific environments. Alternatively, the secondary emission axis of the second speaker and the secondary emission axis of the third speaker form a diverging angle between 0° and 90°.

[0028] The system thus configured makes it possible to widen the sound coverage in the horizontal plane while maintaining a cardioid type directivity.

[0029] According to one feature, the system includes a fourth speaker which is located in the front wall of the cabinet, the fourth speaker being identical to the first speaker.

[0030] The use of a fourth speaker placed in the front wall increases the acoustic power emitted by the system, without changing the directivity which is still cardioid type.

[0031] According to one characteristic, the primary emission axis of the first loudspeaker and the primary emission axis of the fourth loudspeaker form a Paving angle between 0° and 90°, said angle being convergent.

[0032] According to one characteristic, the primary emission axis of the first loudspeaker and the primary emission axis of the fourth loudspeaker form a Paving angle between 0° and 90°, said angle being divergent.

[0033] As before, the system thus configured allows, depending on whether the Pavant angle is convergent or divergent, either to concentrate the acoustic intensity on a focal area, and therefore to direct the sound waves into specific environments, or to widen the sound coverage in the horizontal plane, while maintaining a cardioid type directivity in both cases.

[0034] According to one characteristic, the system further includes at least one high-frequency loudspeaker having an emission frequency band of at least between 5 kHz and 20 kHz, and the high-frequency loudspeaker being positioned in the front wall of the enclosure.

[0035] The use of at least one high-frequency speaker allows emission over a frequency band extending beyond the frequency range between 30 Hz and 400 Hz.

[0036] According to another feature, the system further comprises at least one mid-frequency loudspeaker having a frequency response of at least 500 Hz to 2 kHz, and the mid-frequency loudspeaker is positioned in the front panel of the enclosure. According to another feature, the high-frequency loudspeaker is positioned between the first and fourth loudspeakers (11b) and equidistant from said loudspeakers.

[0037] The system thus configured allows a balanced distribution of sound intensity in a frequency range from 30 Hz to 20 kHz.

[0038] Finally, the invention also relates to a network of electroacoustic conversion systems comprising at least two electroacoustic conversion systems, a first of the at least two electroacoustic conversion systems being a directional electroacoustic conversion system exhibiting at least some of the preceding characteristics.

[0039] The invention, according to an exemplary embodiment, will be well understood and its advantages will become more apparent upon reading the detailed description that follows, given by way of example and in no way limiting, with reference to the attached drawings in which: [Fig. 1] Figure 1 represents a directional electro-acoustic conversion system, according to a first exemplary embodiment of the invention, respectively in perspective view (A), front view (B), section view (C);

[0040] [Fig. 2] Figure 2 represents a directional electro-acoustic conversion system, according to a second embodiment of the invention, respectively in perspective view (A), front view (B), section view (C);

[0041] [Fig. 3] Figure 3 represents a directional electro-acoustic conversion system, according to a third embodiment of the invention, respectively in perspective view (A), front view (B), section view (C);

[0042] [Fig. 4] Figure 4 represents a directional electro-acoustic conversion system, according to a fourth embodiment of the invention, respectively in perspective view (A), front view (B), section view (C);

[0043] [Fig. 5] Figure 5 represents a directional electro-acoustic conversion system, according to a fifth embodiment of the invention, respectively in perspective view (A), front view (B), section view (C);

[0044] [Fig. 6] Figure 6 represents a directional electro-acoustic conversion system, according to a sixth embodiment of the invention, respectively in perspective view (A), front view (B), section view (C);

[0045] [Fig. 7] Figure 7 represents a perspective view of an array of electro-acoustic conversion systems, according to an example of an embodiment of the present invention; and [Fig. 8] Figure 8 represents an example of an isobaric horizontal directivity diagram of an array comprising twenty electro-acoustic conversion systems according to the third example of an embodiment of the invention.

[0046] Identical elements represented in the aforementioned figures are identified by identical numerical references.

[0047] A "directional" system here refers to an acoustic system producing acoustic radiation that is maximal along a principal axis of the acoustic system, in other words for an angle of 0°, and for which the acoustic radiation is effective for angles between approximately + / - 65° with respect to said axis.

[0048] We consider the following frequency bands here:

[0049] Low, for a frequency between 20 Hz and 500 Hz;

[0050] Medium, for a frequency between 500 Hz and 2 kHz; and High, for a frequency between 2 kHz and 20 kHz.

[0051] This definition of frequency bands is given for guidance purposes only, the limit values ​​may vary, or even overlap.

[0052] In the context of the present invention, the term "convergent" is used to describe an angle formed by the principal axes of sound emission of two loudspeakers arranged in such a configuration that their sound emission axes tend towards a common point or a focal point. Conversely, the term "divergent" is used to describe an angle formed by the principal axes of sound emission of two loudspeakers arranged in such a configuration that their sound emission axes are oriented so that they diverge from each other.

[0053] Figure 1 represents a directional electro-acoustic conversion system 100, according to a first embodiment of the invention.

[0054] Figure 1 in (A) shows a perspective view of the directional electroacoustic conversion system 100.

[0055] The directional electro-acoustic conversion system 100 comprises a box 10 having a plurality of walls delimiting an internal volume 104, visible in Figure 1 at (C). The plurality of walls includes in particular a front wall 101, a first side wall 102a, a second side wall 102b and a rear wall 103.

[0056] In this particular embodiment, the system 100 includes a first loudspeaker 11a and a fourth loudspeaker 11b arranged in the front wall 101 of the box 10. The system 100 also includes a second loudspeaker 12a arranged in the first side wall 102a of the box 10, as well as a third loudspeaker 12b arranged in the second side wall 102b of said box.

[0057] The internal volume 104 is delimited on figure 1 in (C) by dotted lines.

[0058] The box 10 further comprises at least one partition 105 dividing the internal volume 104 of said box into two chambers separated from each other by the partition 105. A first chamber 106 comprises the front wall 101 of the box 10, and a second chamber 107 comprises the first side wall 102a as well as, in the present embodiment, the second side wall 102b of said box.

[0059] In an alternative embodiment (not shown here), the second chamber 107 is itself divided into two parts. Thus, the second loudspeaker 12a and the third loudspeaker 12b each have their own rear volume, each of these volumes having at least one vent. This configuration can be applied to all the embodiments described subsequently.

[0060] Each speaker 11a, 11b, 12a and 12b is configured to emit in a frequency range of at least between 30 Hz and 400 Hz.

[0061] In one particular embodiment, speakers 11a and 11b are different from speakers 12a and 12b.

[0062] In addition, for system 100 to emit in frequency ranges above 400 Hz, said system includes at least one mid-frequency loudspeaker 13a, 13b, 13c, and 13d, as well as at least one high-frequency loudspeaker 14. In the embodiment shown in Figure 1, system 100 includes four mid-frequency loudspeakers 13a, 13b, 13c, and 13d and one high-frequency loudspeaker 14 arranged in the front wall 101 of the enclosure 10. The presence of a mid-frequency loudspeaker 13a, 13b, 13c, and 13d is optional. According to one embodiment, system 100 may be without mid-frequency loudspeakers 13a, 13b, 13c, and 13d. This is the case for the fourth example, the fifth example and the sixth example of realization, respectively represented in figure 4, figure 5 and figure 6.

[0063] The first loudspeaker 11a and the fourth loudspeaker 11b each have a principal emission axis, called the primary emission axis, 112a and 112b respectively. The second loudspeaker 12a and the third loudspeaker 12b each have a principal emission axis, called the secondary emission axes, 122a and 122b respectively. The primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a form an angle α between -45° and 90°. In the example shown here, the angle α is approximately 25°. The primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a are therefore in a "convergent" configuration with respect to the front wall 101 of the enclosure 10.

[0064] Similarly, the primary emission axis 112b of the fourth speaker 11b and the secondary emission axis 122b of the third speaker 12b form an angle α between them between -45° and 90°, which is here about 25°.

[0065] The primary emission axis 112b of the fourth speaker 11b and the secondary emission axis 122b of the third speaker 12b are therefore in a "convergent" configuration with respect to the front wall 101 of the enclosure 10.

[0066] In the example shown here, the first loudspeaker 11a, the second loudspeaker 12a, the third loudspeaker 12b, and the fourth loudspeaker 11b are mounted conventionally on the enclosure 10, that is, with their diaphragms facing outwards. In other embodiments, all or some of the loudspeakers constituting the system 100 are mounted in a so-called "inverted" configuration, that is, with their diaphragms facing inwards into the enclosure 10, while their magnets and voice coils are located outside the enclosure. This type of mounting optimizes the internal volume 104 of the enclosure 10 and also results in better heat dissipation from the loudspeaker's magnet and voice coil, compared to a conventional mounting where the heat is not dissipated outside the enclosure 10 but remains confined inside, or is partially dissipated through one or more vents.Furthermore, this type of mounting improves the coupling of the speakers in the 100 system.

[0067] In another embodiment, at least one loudspeaker is mounted recessed from a wall of the enclosure 10, i.e., not flush with said wall. Thus, at least one loudspeaker is placed recessed from the mounting wall, for example in a cavity or enclosure.

[0068] In another embodiment example, at least one loudspeaker is equipped with an accessory such as a hyperbolic, exponential or tractrix type acoustic horn (according to the mathematical definition of the tractrix curve).

[0069] When the loudspeaker is recessed from the mounting wall and / or when the loudspeaker is equipped with an accessory, the principal emission axis of the loudspeaker in this example is defined as being equivalent to that of a loudspeaker mounted flush with the wall. An example of this type of system is shown in Figure 7 where the loudspeakers are recessed from the front wall and equipped with an accessory at the diaphragm level. The forward orientation of the second and third loudspeakers 12a and 12b improves the acoustic performance of the system. In particular, a wider low-frequency range than with prior art is achieved by increasing the power radiated forward.

[0070] Furthermore, the size of the 100 system is limited due to the orientation of the second and third speakers 12a and 12b, which are oriented "in front" of the subwoofer and at the same time convergently.

[0071] This particular orientation generates a Piaterai angle between the secondary emission axis 122a of the second loudspeaker 12a and the secondary emission axis 122b of the third loudspeaker 12b. The Piaterai angle is between 0° and 90°. In this embodiment, the Piaterai angle is equal to 45° and is convergent.

[0072] Furthermore, the primary emission axis 112a of the first loudspeaker 11a and the primary emission axis 112b of the fourth loudspeaker 11b form a Pavant angle between 0° and 90°. In this embodiment, the Pavant angle is equal to 0°, i.e. their emission axes are parallel.

[0073] Furthermore, the system 100 includes at least one vent. In this particular embodiment, the system 100 includes two vents 111a and 111b arranged in the front wall 101 of the box 10, and a vent 121 arranged in the rear wall 103, without this configuration presenting a limitation to the present invention.

[0074] Figure 1 in (C) shows a cross-sectional view of system 100 along axis AA illustrated in figure 1 in (B).

[0075] Figure 2 represents the directional electro-acoustic conversion system 100, according to a second embodiment of the invention.

[0076] This embodiment differs from the previous one by the orientation of the second speaker 12a and the third speaker 12b.

[0077] The angle between the secondary emission axis 122a of the second speaker 12a and the secondary emission axis 122b of the third speaker 12b is equal to 0°.

[0078] The Pavant angle between the primary emission axis 112a of the first loudspeaker 11a and the primary emission axis 112b of the fourth loudspeaker 11b is equal to 0°, as in the previous embodiment.

[0079] In the example illustrated here, the primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a are parallel, so the angle α is equal to 0°. Similarly, the primary emission axis 112b of the fourth loudspeaker 11b and the secondary emission axis 122b of the third loudspeaker 12b are parallel, so the angle α is equal to 0°.

[0080] Figure 3 represents the directional electro-acoustic conversion system 100, according to a third embodiment of the invention.

[0081] This embodiment differs from the first embodiment by the orientation of the second speaker 12a and the third speaker 12b.

[0082] In this particular embodiment, the Pavant angle is equal to 0°, and the uerai angle is equal to 45° and is divergent. Compared to the embodiment shown in Figure 1, the second loudspeaker 12a and the third loudspeaker 12b are oriented "in front" of the enclosure 10 and simultaneously divergently, and not oriented "in front" and simultaneously convergently.

[0083] In this example, the angle α between the primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a is approximately -20°. The primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a are therefore in a "divergent" configuration with respect to the front wall 101 of the enclosure 10.

[0084] Similarly, the angle α between the primary emission axis 112b of the fourth speaker 11b and the secondary emission axis 122b of the third speaker 12b is approximately -20°. Thus, the primary emission axis 112b of the fourth speaker 11b and the secondary emission axis 122b of the third speaker 12b are therefore in a "divergent" configuration with respect to the front wall 101 of the enclosure 10.

[0085] Figure 4 represents the directional electro-acoustic conversion system 100, according to a fourth embodiment of the invention.

[0086] This embodiment differs from the first embodiment by the orientation of the second speaker 12a and the third speaker 12b, as well as by the orientation of the first speaker 11a and the fourth speaker 11b.

[0087] In this particular embodiment, the Pavant angle is equal to 90°, and the Piaterai angle is equal to 0° and is convergent. Thus, the first loudspeaker 11a and the fourth loudspeaker 11b are oriented "in front" of the enclosure 10 and simultaneously convergently.

[0088] In this example, the angle α between the primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a is approximately 45°. The primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a are therefore in a "convergent" configuration with respect to the front wall 101 of the enclosure 10.

[0089] Similarly, the angle α between the primary emission axis 112b of the fourth speaker 11b and the secondary emission axis 122b of the third speaker 12b is approximately 45°. Thus, the primary emission axis 112b of the fourth speaker 11b and the secondary emission axis 122b of the third speaker 12b are in a "convergent" configuration with respect to the front wall 101 of the enclosure 10.

[0090] This configuration has the advantage of having a reduced footprint, for example compared to the 100 system shown in Figure 2, while having a cardioid type directivity in the frequency band from 30 Hz to 400 Hz, in particular.

[0091] In another embodiment not shown here, the high-frequency loudspeakers 14 are replaced by at least one mid-frequency loudspeaker 13a, 13b, 13c, and 13d, while maintaining the same system architecture 100, all other things being equal. The same applies to the embodiment shown in Figure 5.

[0092] Figure 5 shows a directional electro-acoustic conversion system 100, according to a fifth embodiment of the invention. This fifth embodiment is a combination of the electro-acoustic conversion systems shown in Figure 1 and Figure 4.

[0093] This fifth embodiment differs from the first embodiment by the orientation of the first speaker 11a and the fourth speaker 11b, and differs from the fourth embodiment by the orientation of the second speaker 12a and the third speaker 12b.

[0094] In this particular embodiment, the Pavant angle is equal to 90°, which is convergent, and the Piaterai angle is also equal to 90°, which is also convergent. Thus, the first loudspeaker 11a and the fourth loudspeaker 11b are oriented "in front" of the enclosure and simultaneously convergently. The same is true for the second loudspeaker 12a and the third loudspeaker 12b, which are oriented "in front" of the enclosure 10 and simultaneously convergently.

[0095] In the example illustrated here, the primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a are parallel, so the angle α is equal to 0°. Similarly, the primary emission axis 112b of the fourth loudspeaker 11b and the secondary emission axis 122b of the third loudspeaker 12b are parallel, so the angle α is equal to 0°.

[0096] Compared to the electroacoustic conversion system configurations presented previously, this configuration is even more compact while having a cardioid directivity in the frequency band from 30 Hz to 400 Hz, in particular.

[0097] Figure 6 represents the directional electro-acoustic conversion system 100, according to a sixth embodiment of the invention.

[0098] This embodiment differs from the first embodiment in that said system does not include a fourth speaker 11b, nor mid-frequency speakers 13a, 13b, 13c and 13d, nor high-frequency speakers 14.

[0099] In this particular embodiment, the peterai angle is approximately 55° and is convergent. Thus, the second speaker 12a and the third speaker 12b are oriented "in front" of the enclosure 10 and simultaneously convergently.

[0100] In this example, the angle α between the primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a is approximately 27°. The primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122a of the second loudspeaker 12a are therefore in a "convergent" configuration with respect to the front wall 101 of the enclosure 10.

[0101] Similarly, the angle α between the primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122b of the third loudspeaker 12b is approximately 45°. Thus, the primary emission axis 112a of the first loudspeaker 11a and the secondary emission axis 122b of the third loudspeaker 12b are in a "convergent" configuration with respect to the front wall 101 of the enclosure 10. Compared to the electroacoustic conversion system configurations presented previously, this configuration is even more compact while maintaining cardioid directivity in the frequency range from 30 Hz to 400 Hz, in particular. Therefore, for similar loudspeakers, using three low-frequency drivers instead of four reduces the system mass 100.

[0102] In yet another embodiment, not shown here, the system comprises two low-frequency loudspeakers. Based on the embodiment in Figure 6, the first loudspeaker 11a is then arranged in the front wall 101 of the enclosure 10, and the second loudspeaker 12a is arranged in the first side wall 102a of the enclosure 10. Compared to the embodiment in Figure 6, this two-loudspeaker low-frequency loudspeaker embodiment further reduces the size of the electro-acoustic conversion system, while maintaining cardioid directivity in the frequency band from 30 Hz to 400 Hz, in particular. The electro-acoustic conversion systems described above allow control of the directivity over the entire useful frequency range of said systems, i.e., from 30 Hz to 20 kHz.

[0103] Figure 7 represents a perspective view of a 900 network of electro-acoustic conversion systems comprising at least two electro-acoustic conversion systems.

[0104] According to the present embodiment, at least one of the at least two electro-acoustic conversion systems is a directional electro-acoustic conversion system according to any one of the embodiments described with reference to Figures 1 to 6.

[0105] In particular, here, all the systems on the 900 network are identical.

[0106] In the particular embodiment shown in Figure 7, the 900 network comprises nine systems 100a, 100b, 100c, 10Od, 100e, 10Of, 100g, 100h and 10Oi without this being a limitation to the present invention.

[0107] The systems 100a, 100b, 100c, 10Od, 100e, 100f, 100g, 100h and 10Oi are assembled together, one after the other, vertically and by means of a fastening device not shown here. Two consecutive systems 100a, 100b, 100c, 10Od, 100e, 10Of, 100g, 100h and 10Oi respectively form a pair 19a, 19b, 19c, 19d, 19e, 19f, 19g and 19h. Within each pair 19a, 19b, 19c, 19d, 19e, 19f, 19g and 19h, the systems 100a, 100b, 100c, 10Od, 100e, 10Of, 100g, 100h and 10Oi are arranged according to an angle of inclination specific to said pairs.

[0108] The 900 network allows for cardioid directivity over the frequency band from 30 Hz to 20000 Hz, both in the horizontal and vertical planes.

[0109] Figure 8 represents an example of an isobaric diagram of the horizontal directivity of a network similar to the 900 network of Figure 7, comprising twenty 100 electro-acoustic conversion systems according to the third embodiment of the invention shown in Figure 3.

[0110] The diagram represents a sound pressure level 81 expressed on a scale in decibels and in shades of gray, as a function of a frequency axis 82 on the x-axis and an angle axis 83 on the y-axis. To obtain the desired cardioid directivity over the frequency band from 30 Hz to 400 Hz, the loudspeakers 11a, 11b, 12a, and 12b are controlled in amplitude and phase by means of passive and / or active filters that process the signal before it is emitted.

[0111] On the diagram, three zones 89a, 89b and 89c extending respectively from 30 Hz to 80 Hz, from 80 Hz to 270 Hz, and from 270 Hz to 2000 Hz are represented by being delimited by frames in dotted lines.

[0112] A first zone 89a of the three zones corresponds to a frequency band where the 900 network has an effective directivity between + / - 75° relative to a main emission axis of the 900 network of electro-acoustic conversion systems taken as an example.

[0113] A second zone 89b of the three zones corresponds to a frequency band where the 900 network has an effective directivity that decreases between + / - 75°, at about 100 Hz, down to + / - 35°, at about 270 Hz.

[0114] Finally, a third zone, 89c, of the three zones corresponds to a frequency band where the 900 network has an effective directivity of approximately + / - 35°. The directivity can be considered constant from 270 Hz and over the rest of the audible frequency band (the diagram only goes up to 2000 Hz for readability).

[0115] It is also noted that in the frequency band from 30 Hz to 400 Hz, the sound pressure level is low, even negligible towards the rear of the 900 network, said level being less than or equal to -12 dB beyond an angle of + / - 90°.

Claims

DEMANDS 1. A directional electro-acoustic conversion system (100) comprising an enclosure (10) having walls delimiting an internal volume (104) of the enclosure, a first wall forming a front wall (101) and a second wall forming a first side wall (102a), the enclosure further comprising at least one partition (105) dividing the internal volume (104) of the enclosure into two chambers separated from each other by the partition (105), a first of the two chambers (106) comprising the front wall (101) of the enclosure (10), and a second of the two chambers (107) comprising the first side wall (102a) of said enclosure, the system (100) further comprising at least one first loudspeaker (11a) having a principal emission axis, called the primary emission axis (112a), and being configured to emit in a frequency range of at least between 30 Hz and 400 Hz, and a second loudspeaker (12a) having a principal emission axis, called a secondary emission axis (122a),and being configured to emit in a frequency range of at least between 30 Hz and 400 Hz, the first loudspeaker (11a) being disposed in the front wall (101) and the second loudspeaker (12a) being disposed in the first side wall (102a), and the primary emission axis (112a) and the secondary emission axis (122a) forming an angle α between them of between -45° and 90°.

2. System (100) according to claim 1, characterized in that the primary emission axis (112a) and the secondary emission axis (122a) form an angle a of 45°.

3. System (100) according to claim 1, characterized in that the primary emission axis (112a) and the secondary emission axis (122a) form an angle a of 0°.

4. System (100) according to any one of claims 1 to 3, characterized in that the enclosure (10) comprises a second side wall (102b), the front wall (101) being located between the first side wall (102a) and the second side wall (102b), and in that it comprises a third loudspeaker (12b), the third loudspeaker (12b) being arranged in the second side wall (102b), the third loudspeaker (12b) being identical to the second loudspeaker (12a).

5. System (100) according to claim 4, characterized in that the secondary emission axis (122a) of the second loudspeaker (12a) and the secondary emission axis (122b) of the third loudspeaker (12b) form a Piaterai angle between 0° and 90°, said angle being either convergent or divergent.

6. System (100) according to any one of claims 1 to 5, characterized in that it comprises a fourth loudspeaker (11b), the fourth loudspeaker (11b) being disposed in the front wall (101) of the enclosure (10), and the fourth loudspeaker (11b) being identical to the first loudspeaker (11a).

7. System (100) according to claim 6, characterized in that the primary emission axis (112a) of the first loudspeaker (11a) and the primary emission axis (112b) of the fourth loudspeaker (11b) form a Pavant angle between 0° and 90°, said angle being either convergent or divergent.

8. System (100) according to any one of the preceding claims, characterized in that it further comprises at least one high-frequency loudspeaker (14) having an emission frequency band of at least between 5 kHz and 20 kHz, and the high-frequency loudspeaker (14) being positioned in the front wall (101) of the enclosure.

9. System (100) according to claims 6 and 8, characterized in that the high-frequency loudspeaker (14) is positioned between the first loudspeaker (11a) and the fourth loudspeaker (11b) and equidistant from each of said loudspeakers.

10. Network (900) of electro-acoustic conversion systems comprising at least two electro-acoustic conversion systems, characterized in that at least a first of the at least two electro-acoustic conversion systems is a directional electro-acoustic conversion system (100) according to any one of claims 1 to 9.

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