Acoustic system for a motor vehicle seat with a headrest

Abstract

An acoustic system for a motor vehicle seat with a headrest comprises: · a U-shaped shell (15) shaped so as to be able to surround the headrest of the seat in a substantially horizontal plane; · loudspeakers (21, 23), called tweeters, suitable for generating and controlling sound in the 900-20 000 Hz frequency band, and positioned at the top of the branches of the U such that, when the system is in position on the seat, they are directed substantially forwards, in the direction of the ears of a passenger seated in the seat; and · loudspeakers (22, 24, 25, 27, 29, 31), called medium-range loudspeakers, suitable for generating and controlling sound in the 80-2000 Hz frequency band and distributed over the outer periphery of the shell.

Description

[0001] Description

[0002] Title of the invention: Acoustic system for a seat with headrest of a motor vehicle

[0003] Technical field

[0004] [1]The present invention claims priority from French application 2401193 filed on February 7, 2024, the content of which (text, drawings and claims) is incorporated herein by reference. The present invention relates to an acoustic system for a seat with a headrest of a motor vehicle.

[0005] State of the art

[0006] [2]Many companies and researchers are interested in personalized listening zones (PSZ) to provide specific sound spaces for each listener for different applications (transportation, home audio, etc.).

[0007] [3]The minimum requirement for a PSZ system is to be able to reproduce a specific acoustic field over a so-called bright zone (BZ) while minimizing the sound level in a different zone called dark zone (DZ) without using headphones or insulating panels.

[0008] [4]According to perceptual studies, a listener experiences a "sound bubble" effect if the difference in sound level between the two areas is at least 30 dB. This level difference can be achieved for frequencies below 1 kHz using a system of a few loudspeakers equipped with suitable filters and installed in headrests.

[0009] [5]Otherwise, to reproduce high frequency signals (>1 kHz), a tweeter type loudspeaker is usually used which can be associated with a midrange type loudspeaker to be able to go down to 1 kHz (and even below).

[0010] [6]Today, to favor one listening area over another in a passenger compartment, we seek to bring the speaker(s) closer to the listeners in order to minimize the noise level emitted and take maximum advantage of the natural attenuation of sound as it propagates through the air. There are therefore many patents presenting different arrangements / integrations of speakers in a headrest.

[0011] [7]There are also active noise control systems that allow a “counter-noise” to be sent to reduce the perceived annoyance.

[0012] [8]However, conventional headrest speaker solutions do not achieve this level of "isolation": only 15 to 20 dB are achievable across the entire audible spectrum (20Hz-20kHz). This is due in particular to the presence of reflective and diffracting surfaces. In addition, these solutions are not very robust and perform poorly at high frequencies in the presence of a complex acoustic environment.

[0013] [9]And as for active noise control techniques, they are rather suited to frequencies <1 kHz, because beyond that, the wavelength being "small", sources close to the ears are required and it is very difficult at frequencies >1 kHz to control a large area; only spot checks could be considered which does not meet the need and does not allow a "bubble" to be generated.

[0014]

[0010] There is therefore a real need for an acoustic system for a seat with a headrest in a motor vehicle which resolves all or part of the aforementioned drawbacks.

[0015] Description of the invention

[0016]

[0011] To resolve one or more of the drawbacks cited above, according to a first embodiment, an acoustic system for a seat with a headrest of a motor vehicle comprises:

[0017] • a U-shaped shell shaped to be able to surround the headrest of the seat in a substantially horizontal plane;

[0018] • loudspeakers, called tweeter loudspeakers, adapted to generate and control sound in the frequency band 900 - 20000 Hz; and positioned at the top of the branches of the U such that, when the system is in position on the seat, they are directed substantially forward and towards the ears of a passenger seated in the seat; and

[0019] • loudspeakers, known as mid-range loudspeakers, adapted to generate and control sound in the 80 - 2000 Hz frequency band and distributed around the external perimeter of the hull.

[0020]

[0012] Thus, it is possible to create a sound bubble around the head of the seat occupant.

[0021]

[0013] Particular characteristics or embodiments, usable alone or in combination, are:

[0022] • the shell has an inclined plane on the bottom of the U such that, when the system is in position on the seat, the plane is oriented towards the rear and upwards, said plane comprising at least one mid-range speaker;

[0023] • at least one midrange speaker is fixed on the outside of a branch of the U of the shell;

[0024] • the midrange speaker fixed on the outside of a branch is inclined forward;

[0025] • a midrange speaker is installed in the tops of the branches of the U, next to the treble speakers;

[0026] • the tops of the branches of the U of the hull include a speaker protection grille; and / or

[0027] • the shell includes, inside the U, an area for attaching the system to the headrest.

[0028]

[0014] In a second embodiment, a plural acoustic system for a row of seats comprises as many acoustic systems as above as there are seats in the row, the shells of said systems being secured to each other by at least one connecting piece.

[0029]

[0015] In a particular embodiment, for a row of 3 seats, the plural acoustic system is such that the system associated with the middle seat is such that at least one midrange speaker is fixed on a branch of the U and is oriented towards the front.

[0030]

[0016] In a third embodiment, a motor vehicle comprises a system according to the first or second embodiment. Brief description of the figures

[0031]

[0017] The invention will be better understood on reading the following description, given solely by way of example, and with reference to the appended figures in which:

[0032] • [Fig 1] represents a front view of a row of seats comprising acoustic systems according to one embodiment;

[0033] • [Fig 2] represents a top view of the row of seats of Fig. 1;

[0034] • [Fig 3] represents a rear three-quarter perspective view of the row of seats in Fig. 1;

[0035] • [Fig 4] represents a three-quarter front perspective view of an acoustic system of Fig. 1;

[0036] • [Fig 5] represents a three-quarter rear perspective view of an acoustic system of Fig. 1;

[0037] • [Fig 6] represents a front view of an acoustic system of Fig. 1;

[0038] • [Fig 7] represents a three-quarter front perspective view of the acoustic system of Fig. 4 without the protective grilles; and

[0039] • [Fig 8] represents a top view of a row of seats comprising acoustic systems according to another embodiment.

[0040] Methods of implementation

[0041]

[0018] The embodiments presented below refer to a motor vehicle, a car. However, those skilled in the art understand that these can also be used with other types of vehicle such as vans, vans, etc. and more generally any transport vehicle.

[0042]

[0019] The terms “front”, “rear”, “top”, “bottom”, “transverse” are understood in relation to the vehicle and therefore, for equipment, in its intended position in the vehicle.

[0020] Figs. 1, 2 and 3 represent two seats 1, 3 of a rear row of a motor vehicle (not shown). Each seat comprises a headrest 5, 7.

[0043]

[0021] According to a classic configuration, a rear board 9, also called a rear shelf, is fixed to the rear of the seats 1, 3, and delimits the top of the trunk.

[0044]

[0022] Around each headrest is positioned an acoustic system 11, 13.

[0045]

[0023] Figs. 4, 5, 6 and 7 represent one of the acoustic systems 11, 13, for example system 11.

[0046]

[0024] It comprises a U-shaped shell 15 in a substantially horizontal plane to surround the headrest 5.

[0047]

[0025] The tops of the branches of the U are closed by substantially vertical grilles 17, 19 which protect loudspeakers 21, 22, 23, 24.

[0048]

[0026] The loudspeakers 21, 23, called treble loudspeakers, are adapted to generate and control a sound in the frequency band 900 - 20000 Hz. Due to their positions, when the system is in position on the seat, they are directed substantially forward and towards the ears of a passenger seated in the seat. These small loudspeakers are installed in a matrix in order to allow, via suitable signal processing, the creation of an acoustic beam oriented precisely towards the ears of the passenger.

[0049]

[0027] The loudspeakers 22, 24 as well as the loudspeakers 25, 27, 29, 31, 33 are called midrange loudspeakers, because they are adapted to generate and control a sound in the frequency band 80 - 2000 Hz. The loudspeakers 25, 27, 29, 31, 33 are distributed around the external periphery of the shell 15.

[0050]

[0028] In particular, the loudspeakers 27, 29, 31 are fixed on an inclined plane 35 formed in the bottom of the U of the shell 15, this inclined plane being oriented towards the rear and the top.

[0051]

[0029] The loudspeakers 25, 33 are fixed on the outside of each branch of the U of the shell 15 and they are slightly oriented towards the front.

[0052]

[0030] Furthermore, the shell 15 comprises, inside the U, an attachment zone 37 of the system to the headrest 5. The attachment zone has a substantially flat shape pierced with at least one hole 39 adapted to allow the passage of a sliding rod of the headrest 5 and thus to be able to modify the height of the headrest 5 without changing the position of the acoustic system. The shell 15 also comprises an area 41 adapted to fix the system on the top of the back of the seat.

[0053]

[0031] The operation of the systems 11, 13 is as follows.

[0054]

[0032] As an acoustic system, the shell is multi-compartmentalized to serve as an enclosure for the different loudspeakers. Each loudspeaker includes its own compartment to avoid acoustic interactions between loudspeakers via the shell.

[0055]

[0033] The arrangement of the midrange loudspeakers 22, 24, 25, 27, 29, 31, 33 is such that it makes it possible both to produce a direct field towards the occupant's ears, but also to process the waves re-emitted by the various reflective surfaces (from an acoustic point of view) of a motor vehicle interior. Hence their distribution all around the occupant's head. It should be noted that it is desirable to have at least 1 loudspeaker on the rear face in order to process the waves reflected by the rear window.

[0056]

[0034] For the treble loudspeakers, the wavelengths being smaller, the sound is more directional and the absorption of the passenger compartment greater, so the loudspeakers are oriented towards the occupant's ears.

[0057]

[0035] The selection of frequency ranges of the loudspeakers, in particular for the midrange loudspeakers, allows the use of small loudspeakers. This advantageously facilitates integration into the seats without modifying them and limits the size of the acoustic system around the headrest. This also allows the loudspeakers to be kept in the near field, which promotes a natural contrast due to the proximity of the sources in the light zone and a strong geometric sound attenuation in the dark zone.

[0058]

[0036] The invention has been illustrated and described in detail in the drawings and the preceding description. This should be considered as illustrative and given by way of example and not as limiting the invention to this description alone. Numerous alternative embodiments are possible.

[0059]

[0037] For a row of 3 seats, Fig. 8, it is thus possible to have a single-piece plural acoustic system by joining the acoustic systems of each seat together by one or more connecting pieces. For example, the shells can be integrated into a single mold. For the middle seat 81, the mid-range side speakers 83, 85 (corresponding to the references 25, 33 in the embodiment described above) are positioned so as to be oriented towards the front.

[0038] It is also possible to have an embodiment in which the headrest and the acoustic system are joined together.

Claims

Claims 1. Acoustic system (11, 13) for a seat (1, 3) with headrest (5, 7) of a motor vehicle comprising: • a U-shaped shell (15) shaped to be able to surround the headrest of the seat in a substantially horizontal plane; • loudspeakers (21, 23), called treble loudspeakers, adapted to generate and control a sound in the frequency band 900 - 20000 Hz; and positioned at the top of the branches of the U such that, when the system is in position on the seat, they are directed substantially forward and towards the ears of a passenger seated in the seat; and • loudspeakers (22, 24, 25, 27, 29, 31, 33), called midrange loudspeakers, adapted to generate and control a sound in the frequency band 80 - 2000 Hz and distributed around the external periphery of the shell.

2. System according to claim 1, in which the shell has an inclined plane (35) on the bottom of the U such that, when the system is in position on the seat, the plane is oriented towards the rear and upwards, said plane comprising at least one midrange speaker (27, 29, 31).

3. System according to claim 1 or 2, in which at least one midrange speaker (25, 33) is fixed on the outside of a branch of the U of the shell.

4. System according to claim 3, in which the midrange speaker fixed on the outside of a branch is inclined forward.

5. System according to claim 1, 2, 3 or 4, in which a midrange speaker (22, 24) is installed in the tops of the branches of the U, next to the treble speakers (21, 23).

6. System according to any one of the preceding claims, in which the tops of the branches of the U of the shell comprise a protective grille (17, 19) for the loudspeakers.

7. System according to any one of the preceding claims, in which the shell comprises, inside the U, an attachment zone (37) from the system to the headrest.

8. Plural acoustic system for a row of seats comprising as many acoustic systems according to any one of claims 1 to 7 as there are seats in the row, the shells of said systems being secured to each other by at least one connecting piece.

9. A plural acoustic system according to claim 8 for a row of 3 seats, and such that the system associated with the middle seat is such that at least one midrange speaker is fixed on a branch of the U and is oriented towards the front.

10. Motor vehicle comprising an acoustic system according to any one of the preceding claims.

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