Loudspeaker grating with directional-sound function

Abstract

The present invention relates to a grating (4) for a loudspeaker (6), comprising a wall (4.1) with a rear face (4.3) and front face (4.2), and provided with slots forming passages between the rear face and the front face, notable in that the wall comprises resonators opening onto a lateral face of at least one of the slots, so as to slow the propagation of soundwaves through said at least one slot. The invention also relates to a motor vehicle (2) comprising at least one loudspeaker and at least one loudspeaker grating positioned in front of the at least one loudspeaker, notable in that the at least one loudspeaker grating is in accordance with the invention.

Description

[0001] DESCRIPTION

[0002] TITLE: SPEAKER GRILLE WITH SOUND DIRECTIVITY FUNCTION

[0003] Technical field

[0004] The present invention claims priority from French application 2203318 filed on April 11, 2022, the content of which (text, drawings and claims) is incorporated herein by reference.

[0005] The present invention relates to the field of motor vehicles, more particularly to the field of motor vehicle loudspeakers.

[0006] Prior art

[0007] Current motor vehicles are equipped with loudspeakers generally integrated into compartments of the passenger compartment, such as door panels, the dashboard and the headrests and / or seat backs. In this regard, it is known to use protective grilles usually comprising several holes sized to allow diffusion of an acoustic field.

[0008] The arrangement of loudspeakers in the passenger compartment of a motor vehicle presents several constraints, for example a problem of space requirement, respect for aesthetics, the complexity of electrical connections, etc., making it difficult to direct the said loudspeakers towards the passengers. As a result, the sound broadcast towards the passengers is less immersive.

[0009] The protective grilles known from current loudspeakers have no acoustic function. Indeed, such grilles do not allow for directional control of the radiated sound field.

[0010] To ensure the directivity of the acoustic field radiated by the loudspeakers, one solution is to achieve directivity control by arranging different independently controlled sources in the passenger compartment of the motor vehicle. However, such a solution can be very expensive and difficult to implement.

[0011] Published patent document JP 07225588 A discloses a sound system comprising a plurality of loudspeakers attached to the doors of a motor vehicle, each of said loudspeakers comprising a protective grille having slots arranged in a particular manner in order to direct the sound towards the passengers of the motor vehicle.

[0012] However, the solution proposed by the document has room for improvement in order to ensure better directivity of the radiated acoustic field and effectively overcome the aforementioned problem.

[0013] Statement of the invention

[0014] The present invention aims to overcome at least one of the drawbacks of the aforementioned state of the art. More particularly, the invention aims to propose a metamaterial grille for a loudspeaker providing functions of directivity and modification of the acoustic field emitted by said loudspeaker, in a simple and economical manner.

[0015] To this end, the invention relates to a loudspeaker grille, comprising a wall with a rear face and a front face, and provided with slots forming passages between the rear face and the front face, remarkable in that the wall comprises resonators opening onto a lateral face of at least one of the slots, so as to slow down the propagation of acoustic waves through said at least one slot.

[0016] The resonators correspond to a volume of recess in the wall, each of said resonators being capable of producing a resonance phenomenon to an acoustic field emitted by the loudspeaker. Advantageously, each resonator acts as an acoustic impedance.

[0017] Preferably, the resonators correspond to Helmholtz resonators and / or cylindrical cavities and / or wave tubes and / or interconnected cavities of variable sizes.

[0018] Advantageously, the grid is a metamaterial having a geometric structure enabling it to perform functions of focusing and / or widening and / or deflection of the acoustic waves passing through said metamaterial.

[0019] According to one embodiment, the resonators are distributed along the at least one slot along a main extent of the wall. According to one embodiment, the resonators are distributed along the at least one slot along a thickness of the wall.

[0020] According to one embodiment, the resonators are distributed along the at least one slot along a thickness of the wall and are side by side and at least two in number, preferably at least three.

[0021] According to one embodiment, the resonators are distributed in an extent of the wall and / or in a thickness of the wall in an inhomogeneous manner so as to modify the distribution of the propagation speeds of the acoustic waves passing through the wall.

[0022] According to one embodiment, the distribution of the slots and the resonators forms in at least one direction along the extent of the wall, a monotonous or bell-shaped gradient.

[0023] Advantageously, characteristics of the resonators such as their shapes and volumes make it possible at least in part to obtain a propagation of the acoustic waves through the slots which is either following the monotonic gradient or in the shape of a bell.

[0024] According to one embodiment, each of the resonators is a Helmholtz resonator comprising a cavity formed in the wall and a conduit of section smaller than the cavity fluidly connecting the cavity to the lateral face of the at least one slot.

[0025] According to one embodiment, the cavity has a volume of between 1 mm 3 and 400 mm 3 .

[0026] The invention also relates to a motor vehicle comprising at least one loudspeaker and at least one loudspeaker grille arranged in front of the at least one loudspeaker, remarkable in that the at least one loudspeaker grille is according to the invention.

[0027] According to one embodiment, the at least one loudspeaker grille is configured to modify the distribution of the propagation speeds of the acoustic waves passing through the wall so as to direct said acoustic waves towards the ears of at least one of the occupants of the motor vehicle. Advantageously, the modification of the direction of the acoustic waves by the grille of the invention may also be accompanied by a modification of the shape of the acoustic waves in order to ensure focusing and / or broadening functions.

[0028] Advantageously, the arrangement of the grille of the present invention in front of the loudspeakers in the passenger compartment of the motor vehicle makes it possible to relax certain installation constraints due to the fact that it is possible to deflect the sound beam emitted by said loudspeakers, and this, in a completely passive manner without any external energy input, making the solution economical.

[0029] In addition, the speaker grille of the invention makes it possible to better control the field radiated by the speaker and thus control the sound field in the passenger compartment of the motor vehicle.

[0030] Brief description of the drawings

[0031] [Fig 1] illustrates a top view of a motor vehicle comprising a speaker grille according to the invention;

[0032] [Fig 2] shows an enlarged sectional view of a portion of the speaker grille of Fig. 1;

[0033] [Fig 3] illustrates three examples of embodiments of the grid of the invention as well as effects on an acoustic field passing through the grid of each of said three examples;

[0034] [Fig 4] schematically represents a comparison between an acoustic field diffused through a state-of-the-art grille and an acoustic field diffused through the grille according to the invention, said grille being arranged in a door trim of the motor vehicle;

[0035] [Fig 5] schematically represents a comparison between an acoustic field diffused through a state-of-the-art grid and an acoustic field diffused through the grid according to the invention, said grid being arranged in a dashboard of the motor vehicle;

[0036] [Fig 6] schematically represents a comparison between an acoustic field diffused through a state-of-the-art grid and an acoustic field diffused through the grid according to the invention, said grid being arranged in a seat of the motor vehicle. Detailed description

[0037] Figure 1 illustrates a top view of a motor vehicle 2 comprising a grille 4 of a loudspeaker 6 according to the invention.

[0038] The loudspeaker 6 is arranged in FIG. 1 in a door trim 8 inside a passenger compartment of the motor vehicle, but it can be arranged in a seat 10 or in a dashboard 12 of the motor vehicle 2, the different possible layouts will be detailed in detail later in this description.

[0039] The grid 4 comprises a wall 4.1 having a front face 4.2 and a rear face 4.3.

[0040] The loudspeaker 6 diffuses acoustic waves 14 which will reach the rear face 4.3 to pass through the wall 4.1, this is possible thanks to slots forming passages between the rear face 4.3 and the front face 4.2.

[0041] Figure 2 shows an enlarged sectional view A of a side portion of the grid 4 of Figure 1.

[0042] With reference to Figure 2, the slots 4.5 extend from the rear face 4.3 towards the front face 4.2 (along the transverse axis Y) and form screens 4.6 in the wall 4.1 of the grid 4. For this purpose, the slots 4.5 extend over an entire thickness E of the wall 4.1.

[0043] Preferably, the thickness E is between 5 mm and 100 mm, and more preferably between 10 mm and 80 mm.

[0044] Preferably, the thickness E is constant (along X). However, the thickness E may vary axially so that the front face 4.1 and / or the rear face 4.3 have(s) a non-planar surface. For example, the thickness E may be less significant on the lateral sides of the grid 4 than a central part of the latter.

[0045] The slots 4.5 comprise a width f which can advantageously vary between each of the slots 4.5 of the grid 4 along an axial and transverse extent (X and Y). For this purpose, a width d of the screens 4.6 can also vary. This variation will allow the grid 4 to at least partially modify the directivity of the acoustic field emitted by the loudspeaker. The modification of the directivity will be detailed in the present description. Preferably, the slots 4.5 are parallel along an axial extent.

[0046] However, the width f of said slots 4.5 may vary according to the thickness E (along Y) thus forming slots 4.5 narrowing and / or widening between the rear face 4.3 and the front face 4.2 of the wall 4.1.

[0047] In this Figure 2, the slots 4.5 are illustrated as being parallel to the Z axis. However, the grille 4 may be arranged in front of the loudspeaker 6 of Figure 1 in another orientation about the Y axis, thus tilting the slots 4.5 relative to the Z axis.

[0048] The wall 4.1 comprises resonators 16 arranged to the right of the screen 4.6 and opening onto a lateral face 4.7 of the slot 4.5.

[0049] Preferably, the resonators 16 are distributed over the entire thickness E and along a main extent (along the X and Z axes) of the wall 4.1.

[0050] Figure 2 illustrates five resonators 16 arranged side by side in line with each screen 4.6. However, the number of resonators 16 can vary from two to a plurality of resonators 16, depending on the dimensions of the grid 4 and depending on the need to modify the distribution of the propagation speeds of the acoustic waves emitted by the loudspeaker.

[0051] It should be noted that the grid 4 may comprise screens 4.6 devoid of resonators 16 and other screens comprising said resonators 16. In this regard, at most one half of a total number of screens 4.6 of the grid 4 may be devoid of resonators 16.

[0052] Preferably, the volume of each resonator 16 is between 1 mm 3 and 600 mm 3 , and more preferably between 10 mm 3 and 300 mm 3 . Such volumes of resonators 16 are preferably adapted to acoustic wave frequencies 14 between 1000 Hz and 10 KHz. For this purpose, the higher the frequency, the smaller the volume of the resonators 16, and vice versa.

[0053] Preferably, the distribution of the resonators 16 on the wall 4.1 is carried out in a non-homogeneous manner, for example the resonators 16 are not necessarily aligned according to the thickness E of the wall 4.1. Advantageously, it is possible to determine the volume and the quantity of the resonators 16, as well as their distribution in the wall 4.1 by means of dedicated software.

[0054] Preferably, each of the resonators 16 is a Helmholtz resonator comprising a cavity 16.1 formed in the screen 4.6 and a conduit 16.2 of smaller section than the cavity 16.1 making it possible to fluidically connect the cavity 16.1 to the lateral face 4.1 of the slot 4.5.

[0055] Preferably, the cavity 16.1 has a volume of between 1 mm 3 and 400 mm 3 . More preferably, the volume of the cavity 16.1 is greater than 10 mm 3 and / or less than 300 mm 3 .

[0056] In an alternative not shown, the screens 4.6 comprise Helmholtz resonators 16 which can follow one another, creating a chain of two cavities 16.1 which follow one another and are connected by a second conduit 16.2.

[0057] However, the present invention is not limited to Helmholtz resonators only. Indeed, the wall 4.1 of the grid 4 may also comprise a combination of at least one of the following resonators: Helmholtz resonators and / or cylindrical cavities and / or wave tubes and / or interconnected cavities of variable sizes.

[0058] Advantageously, the resonators 16 act as an acoustic impedance causing a resonance phenomenon making it possible to locally slow down the propagation of the acoustic waves through the slot 4.5. This makes it possible to modify the amplitude and the phase of the acoustic field passing through each of the slots 4.5. For this purpose, each slot 4.5 will be considered as a secondary acoustic source with respect to the loudspeaker, and the outgoing acoustic field having passed through the grid 4 and diffused into the passenger compartment of the vehicle will be considered as a combination of said secondary sources.

[0059] Figure 3 illustrates three exemplary embodiments of the grille of the invention as well as effects on the acoustic field passing through the grille of each of said three examples. The reference signs of each of the examples will be incremented by 100 in order to facilitate the distinction between each exemplary embodiment of the grille of the invention. It should be noted that the overall shape of the grilles is not limited to the rectangular shapes illustrated in Figure 3. Indeed, the grilles can have a circular shape or a specific shape depending on the aesthetic and / or functional need for integration into the motor vehicle.

[0060] With reference to a left part of Figure 3, the grid 104 according to a first exemplary embodiment comprises a plurality of slots 104.5 distributed symmetrically relative to a central part of the grid 104.

[0061] In this configuration, the width f of the slots 104.5 is greater in the lateral ends of the grid 104 than in the central part, and in parallel, the width d of the screens 104.6 is greater in the central part and gradually narrows towards the two lateral ends of the grid 104.

[0062] Advantageously, this makes it possible to further slow down the propagation speed of the acoustic waves passing through the slots 104.5 located in the central part of the grid 104, compared to the waves passing through the lateral ends of the grid 104.

[0063] This allows us to plot a wave propagation speed curve 120, we can see that the latter illustrates an inverted bell-shaped gradient showing the slowing down of the wave propagation speed in the central part.

[0064] At the same time, a colorimetric representation 130, commonly designated by a directivity color chart 130, illustrates the grid 104 diffusing the acoustic waves 14 emanating from the loudspeaker 6, the grid 104 here provides a focusing function by directing the outgoing acoustic field 114, called the main lobe 114, in a centered manner parallel to the axial direction.

[0065] Advantageously, the focusing function meets a need for personalized listening in the passenger compartment of the motor vehicle.

[0066] With reference to a central portion of Figure 3, the grid 204 according to a second exemplary embodiment comprises a plurality of slots 204.5 distributed symmetrically relative to a central portion of the grid 204.

[0067] Conversely to the grid 104, the width f of the slots 204.5 is larger in the central portion of the grid 204, and the width d of the screens 104.6 is larger in the two lateral ends of the grid 204. Preferably, the lateral ends of the grid 204 allow the speed of the sound waves to be slowed further in these lateral ends, resulting in a bell curve 220. This corresponds to a broadening function of the acoustic waves 14. A broadened main lobe 214 can be observed at the level of the directivity color chart 230.

[0068] Advantageously, the widening function meets a need for general listening of the acoustic field diffused by all passengers in the motor vehicle.

[0069] With reference to a right portion of Figure 3, the grid 304 according to a third exemplary embodiment comprises a plurality of slots 304.5 distributed monotonically with a width f decreasing from an extreme left side to an extreme right side.

[0070] Preferably, the screens 304.6 located in the extreme right side of the grid 304 are wider than the screens 304.6 on the extreme left side, and in parallel, the slots 304.5 on the extreme right side are narrower. This makes it possible at least in part to obtain a monotonic gradient as illustrated by the curve 320. This corresponds to a deflection function of the acoustic waves 14. A deflected main lobe 314 can be observed at the level of the directivity color chart 330.

[0071] Advantageously, the function of deflecting the diffused acoustic field makes it possible to overcome the constraints of installing the loudspeakers in the passenger compartment of the motor vehicle; for example, the loudspeakers can be arranged in a position which is lower in the passenger compartment while improving the directivity of the diffused acoustic field towards the occupant.

[0072] Figures 4 to 6 schematically represent a comparison between an acoustic field diffused through a state-of-the-art grid, and an acoustic field diffused through the grid of the invention. It should be noted that these figures are greatly simplified in order to facilitate their understanding.

[0073] Referring to a left portion of Figure 4, the loudspeaker 6 diffuses an acoustic field 14 after passing through a state-of-the-art grille 7 which is generally molded to the door trim. It is observed that the diffused acoustic field 14 propagates substantially omnidirectionally relative to the grille 7 and fails to effectively reach the occupant's ear 1.

[0074] With reference to a right part of figure 4, the grid 7 of the state of the art is replaced by the grid 4 of the invention which makes it possible to diffuse a deflected acoustic field 14' which can effectively reach the ear 1 of the occupant.

[0075] Preferably, the loudspeaker 6 is spaced a distance p from the rear face 4.3 so as to allow the acoustic waves to flatten out before reaching said rear face 4.3. However, the grille 4 is capable of modifying non-planar acoustic waves. In this configuration, the distance p can be considerably small, i.e. distance p equal to 5 mm.

[0076] The distance p can be between 5 mm and 150 mm, and preferably between 10 mm and 50 mm.

[0077] With reference to Figure 5, the grid 4 of the state of the art which is molded or attached to the dashboard trim 12 illustrated in the left part of Figure 5 is replaced by the grid 4 of the invention as can be seen in the right part of Figure 5.

[0078] Advantageously, it will thus be possible to free itself from the constraints of installation and orientation of the loudspeaker 6. Indeed, by placing the grille 4 in front of the loudspeaker 6 located at the nose of the dashboard 12 and difficult to orient towards the ear 1 of the occupant, the grille 4 makes it possible to overcome this constraint by improving the directivity of the deflected acoustic field 14' to easily reach the ear 1 of the occupant.

[0079] Referring to Figure 6, current motor vehicles are increasingly integrating speakers into the seats, such as the speaker 6 in the left portion of Figure 6 which is integrated into a back of the seat 10, in order to create a listening bubble effect for the occupant. However, it will be noted that the acoustic field 14 is not sufficiently focused in order to maximize the listening bubble effect.

[0080] The grid 7 is then replaced by the grid 4 according to the invention, as illustrated in the right-hand part of Figure 6. It can be seen that the deflected acoustic field 14' is directly oriented towards the ear 1 of the occupant. Advantageously, the introduction of the grid 7 according to the invention makes it possible to considerably improve the perception of the sound intended for the occupant of the seat 10.

Claims

DEMANDS [Claim 1.] Grille (4; 104; 204; 304) for loudspeaker (6), comprising a wall (4.1) with a rear face (4.3) and a front face (4.1), and provided with slots (4.5; 104.5; 204.5; 304.5) forming passages between the rear face (4.3) and the front face (4.2); characterized in that the wall (4.1) comprises resonators (16) opening onto a lateral face (4.7) of at least one of the slots (4.5; 104.5; 204.5; 304.5), so as to slow down the propagation of acoustic waves (14) through said at least one slit (4.5; 104.5; 204.5; 304.5). [Claim 2.] Grille (4; 104; 204; 304) for loudspeaker (6), according to claim 1, wherein the resonators (16) are distributed along at least one slot (4.5; 104.5; 204.5; 304.5) along a principal extent of the wall (4.1). [Claim 3.] Grille (4; 104; 204; 304) for loudspeaker (6), according to any one of claims 1 and 2, in which the resonators (16) are distributed along at least one slot (4.5; 104.5; 204.5; 304.5) along a thickness (E) of the wall (4.1). [Claim 4.] Grille (4; 104; 204; 304) for loudspeaker (6), according to claim 3, wherein the resonators (16) are distributed along at least one slot (4.5; 104.5; 204.5; 304.5) along a thickness (E) of the wall (4.1) and are side by side and of at least two, preferably at least three. [Claim 5.] Grille (4; 104; 204; 304) for loudspeaker (6), according to any one of claims 1 to 4, wherein the resonators (16) are distributed in an extent of the wall (4.1) and / or in a thickness (E) of the wall (4.1) in an inhomogeneous manner so as to modify the distribution of the propagation velocities of the acoustic waves (14') passing through the wall. [Claim 6.] Grille (4; 104; 204; 304) for loudspeaker (6), according to claim 5, wherein the distribution of the slots (4.5; 104.5; 204.5; 304.5) and resonators (16) form in at least one direction along the extent of the wall (4.1), a monotonic gradient (320) or a bell-shaped gradient (120; 220). [Claim 7.] Grille (4; 104; 204; 304) for loudspeaker (6), according to any one of claims 1 to 6, wherein each of the resonators (16) is a Helmholtz resonator (16) comprising a cavity (16.1) formed in the wall (4.1) and a conduit (16.2) of cross-section less than the cavity (16.1) fluidically connecting the cavity (16.1) to the lateral face (4.7) of at least one slot (4.5; 104.5; 204.5; 304.5). [Claim 8.] Grille (4; 104; 204; 304) for loudspeaker (6), according to claim 7, wherein the cavity (16.1) has a volume between 1 mm 3 and 400 mm 3 . [Claim 9.] Motor vehicle (2) comprising at least one loudspeaker (6) and at least one loudspeaker grille (4; 104; 204; 304) (6) disposed in front of at least one loudspeaker (6), characterized in that at least one loudspeaker grille (4; 104; 204; 304) (6) is according to any one of claims 1 to 8. [Claim 10.] Motor vehicle (2) according to claim 9, wherein at least one loudspeaker grille (4; 104; 204; 304) (6) is configured to modify the distribution of the propagation velocities of the acoustic waves (14') passing through the wall (4.1) so as to direct said acoustic waves (14') towards the ears (1) of at least one of the occupants of the motor vehicle (2).

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