US-12621602-B2 - Loudspeaker assembly for headrest

US12621602B2US 12621602 B2US12621602 B2US 12621602B2US-12621602-B2

Abstract

A loudspeaker assembly is disclosed that includes a headrest having a front face and a rear face; a bass dipole loudspeaker mounted to the headrest, wherein the loudspeaker includes a diaphragm having first and second radiating surfaces, wherein the radiating surfaces are located on opposite faces of the diaphragm, wherein the diaphragm moves at bass frequencies such that the radiating surfaces produce sound; a bass waveguide to guide bass produced by the first radiating surface via a forward-facing opening provided by the waveguide, wherein the loudspeaker is mounted such that bass produced by the second radiating surface propagates out from the rear face and such that the first radiating surface is closer to the rear face than to the front face. The forward-facing opening is larger than the first radiating surface as projected onto a plane perpendicular to a movement axis of the loudspeaker.

Inventors

David Corynen

Assignees

PSS BELGIUM NV

Dates

Publication Date: 20260505
Application Date: 20221104
Priority Date: 20211110

Claims (15)

1 . A loudspeaker assembly including: a headrest having a front face facing in a forwards direction and a rear face facing in a rearwards direction, wherein the rearwards direction is opposite to the forwards direction, wherein the headrest is for use with a user's head located in front of the front face of the headrest; a bass dipole loudspeaker mounted to the headrest, wherein the bass dipole loudspeaker includes a drive unit and a diaphragm, wherein the diaphragm has a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite faces of the diaphragm, wherein the drive unit is configured to move the diaphragm at bass frequencies such that the first and second radiating surfaces produce sound at bass frequencies; a bass waveguide configured to guide bass sound produced by the first radiating surface out from the front face of the headrest via at least one forward-facing opening provided by the bass waveguide, wherein the bass dipole loudspeaker is mounted to the headrest such that bass sound produced by the second radiating surface is able to propagate out from the rear face of the headrest; wherein the bass dipole loudspeaker is mounted to the headrest such that the first radiating surface of the diaphragm is, when the diaphragm is at rest, closer to the rear face of the headrest than to the front face of the headrest; wherein the area of the at least one forward-facing opening is at least 1.5 times larger than the area of the first radiating surface as projected onto a plane perpendicular to a movement axis of the bass dipole loudspeaker.
2 . The loudspeaker assembly according to claim 1 , wherein the area of the at least one forward-facing opening of the bass waveguide is at least 2 times larger than the area of the first radiating surface.
3 . The loudspeaker assembly according to claim 1 , wherein the area of the first radiating surface of the bass dipole loudspeaker as projected onto a plane perpendicular to a movement axis of the bass dipole loudspeaker is 80 cm 2 .
4 . The loudspeaker assembly according to claim 1 , wherein the headrest includes one or more mounting pins for mounting the headrest to a seat, and the bass dipole loudspeaker is mounted to the headrest in a position that is rearwards of the one or more mounting pins.
5 . The loudspeaker assembly according to claim 1 , wherein the headrest includes a rigid chassis, wherein the bass waveguide is formed at least in part by the rigid chassis.
6 . The loudspeaker assembly according to claim 5 , wherein the rigid chassis includes one or more solid walls configured to guide bass sound produced by the first radiating surface towards the at least one forward-facing opening of the rigid chassis.
7 . The loudspeaker assembly according to claim 5 , wherein the rigid chassis includes one or more perforated walls, covered with a portion of non-rigid material configured to guide bass sound produced by the first radiating surface towards the at least one forward-facing opening of the bass waveguide.
8 . The loudspeaker assembly according to claim 5 , wherein the at least one forward-facing opening of the rigid chassis is covered by a front grille that is configured to allow bass sound to propagate therethrough substantially uninhibited.
9 . The loudspeaker assembly according to claim 1 , the bass waveguide includes one or more portions of a non-rigid material configured to guide bass sound produced by the first radiating surface towards the at least one forward-facing opening of the bass waveguide, wherein the one or more portions of non-rigid material are formed of a material having a specific airflow resistance that is 100 Pa·s/m or higher.
10 . The loudspeaker assembly according to claim 9 , wherein the specific airflow resistance of the one or more portions of non-rigid material is 500 Pa·s/m or lower.
11 . The loudspeaker assembly according to claim 1 , wherein the headrest includes one or more mid-high frequency loudspeakers.
12 . The loudspeaker assembly according to claim 11 , wherein the/each mid-high frequency loudspeaker is located within the bass waveguide.
13 . The loudspeaker assembly according to claim 1 , wherein the loudspeaker assembly has two or more bass dipole loudspeakers, wherein each bass dipole loudspeaker shares the same bass waveguide, wherein the area of the at least one forward-facing opening is larger than the sum of the areas of each first radiating surface of a respective bass dipole loudspeaker as projected onto a respective plane perpendicular to a movement axis of that respective bass dipole loudspeaker.
14 . The loudspeaker assembly according to claim 1 , wherein, if there is one bass dipole loudspeaker included in the loudspeaker assembly, the area of the first radiating surface of the bass dipole loudspeaker as projected onto a plane perpendicular to a movement axis of the bass dipole loudspeaker is 100 cm 2 or more, and if there is more than one bass dipole loudspeaker included in the loudspeaker assembly, the sum of the areas of each first radiating surface of a respective bass dipole loudspeaker as projected onto a respective plane perpendicular to a respective movement axis of that respective bass dipole loudspeaker is 100 cm 2 or more.
15 . A seat assembly that comprises: a seat for seating a user, wherein the seat includes a headrest having a front face facing in a forwards direction and a rear face facing in a rearwards direction, wherein the rearwards direction is opposite to the forwards direction, wherein the headrest is for use with a user's head located in front of the front face of the headrest; and a loudspeaker assembly including: a bass dipole loudspeaker mounted to the headrest, wherein the bass dipole loudspeaker includes a drive unit and a diaphragm, wherein the diaphragm has a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite faces of the diaphragm, wherein the drive unit is configured to move the diaphragm at bass frequencies such that the first and second radiating surfaces produce sound at bass frequencies; a bass waveguide configured to guide bass sound produced by the first radiating surface out from the front face of the headrest via at least one forward-facing opening provided by the bass waveguide, wherein the bass dipole loudspeaker is mounted to the headrest such that bass sound produced by the second radiating surface is able to propagate out from the rear face of the headrest; wherein the bass dipole loudspeaker is mounted to the headrest such that the first radiating surface of the diaphragm is, when the diaphragm is at rest, closer to the rear face of the headrest than to the front face of the headrest; wherein the area of the at least one forward-facing opening is at least 1.5 times larger than the area of the first radiating surface as projected onto a plane perpendicular to a movement axis of the bass dipole loudspeaker; wherein the seat is configured to position a user who is sat down in the seat such that the head of the user is located in front of the front face of the headrest with the head of the user being located within 30 cm from the front face of the headrest.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a U.S. National Phase Application of International Patent Application No. PCT/EP2022/080799, filed 4 Nov. 2022, which claims priority to United Kingdom Patent Application No. GB2116175.7, filed 10 Nov. 2021. FIELD OF THE INVENTION The present invention relates to a loudspeaker assembly. BACKGROUND A dipole loudspeaker can be understood as a loudspeaker whose diaphragm has a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite faces of the diaphragm, wherein a drive unit of the dipole loudspeaker is configured to move the diaphragm such that the first and second radiating surfaces produce bass sound which projects outwardly in opposite directions from the dipole loudspeaker. It is known to incorporate a bass dipole loudspeaker in a headrest for the purpose of producing highly localised sound, see for example: WO2019/121266, which discloses a bass dipole loudspeaker suitable for incorporating into a car headrest;PCT/EP2021/064765, which discloses another bass dipole loudspeaker suitable for incorporating into a car headrest;PCT/EP2021/068397, which discloses another bass dipole loudspeaker suitable for incorporating into a car headrest;WO2021/185777, which discloses a mid-high frequency loudspeaker suitable for incorporating into a car headrest alongside a bass dipole loudspeaker;GB2112473.0, which discloses another mid-high frequency loudspeaker suitable for incorporating into a car headrest alongside a bass dipole loudspeaker. The present invention has been devised in light of the above considerations. SUMMARY OF THE INVENTION In a first aspect, the present invention provides: A loudspeaker assembly including: a headrest having a front face facing in a forwards direction and a rear face facing in a rearwards direction, wherein the rearwards direction is opposite to the forwards direction, wherein the headrest is for use with a user's head located in front of the front face of the headrest;a bass dipole loudspeaker mounted to the headrest, wherein the bass dipole loudspeaker includes a drive unit and a diaphragm, wherein the diaphragm has a first radiating surface and a second radiating surface, wherein the first radiating surface and the second radiating surface are located on opposite faces of the diaphragm, wherein the drive unit is configured to move the diaphragm at bass frequencies such that the first and second radiating surfaces produce sound at bass frequencies;a bass waveguide configured to guide bass sound produced by the first radiating surface out from the front face of the headrest via at least one forward-facing opening provided by the bass waveguide, wherein the bass dipole loudspeaker is mounted to the headrest such that bass sound produced by the second radiating surface is able to propagate out from the rear face of the headrest;wherein the bass dipole loudspeaker is mounted to the headrest such that the first radiating surface of the diaphragm is, when the diaphragm is at rest, closer to the rear face of the headrest than to the front face of the headrest;wherein the area of the at least one forward-facing opening is larger than the area of the first radiating surface as projected onto a plane perpendicular to a movement axis of the bass dipole loudspeaker. As explained in more detail below, the combination of mounting the bass dipole loudspeaker towards the rear face of the headrest (such that the first radiating surface of the diaphragm is, when the diaphragm is at rest, closer to the rear face of the headrest than to the front face of the headrest), together with the bass waveguide having a large forward-facing opening area (that is larger than the area of the first radiating surface as projected onto a plane perpendicular to a movement axis of the bass dipole loudspeaker) helps to increase the sound pressure level (SPL) that can be produced by the bass dipole loudspeaker before a user whose head is located in front of the front face of the headrest experiences what is referred to herein as “tactile fizzle”. Herein, “tactile fizzle” refers to a tactile sensation experienced by a user whose head is close to the front face of a headrest incorporating a bass dipole loudspeaker, which can be experienced as a quickly oscillating blowing sensation. As explained in more detail below, and without wishing to be bound by theory, the present inventor believes “tactile fizzle” is caused by high air particle velocity speeds which can be perceived by a user when the SPL produced by the bass dipole loudspeaker exceeds a certain threshold (see FIG. 3a). A user who perceives “tactile fizzle” may find the effect distracting or unpleasant. Because a loudspeaker assembly according to the first aspect of the present invention is able to increase the SPL that can be produced by the bass dipole loudspeaker before a user whose head is located in fr