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1. WO2020094733 - SYSTÈME DE RÉDUCTION ACTIVE DE BRUIT POUR CASQUE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

CLAIMS:

1 . An active noise cancellation (ANC) system for a helmet, for preferentially attenuating sound pressure in a first frequency range in a defined spatial region at a first side of the helmet, the ANC system comprising:

a mounting plate, a first face of the mounting plate configured to be disposed, in use, against an inner surface of the helmet to form, with the helmet, a chamber;

a loudspeaker provided on the first face of the mounting plate such that, when the mounting plate is mounted on the helmet, the loudspeaker is within the chamber, the plate comprising an aperture for allowing transmission of sound from the loudspeaker to the spatial region;

at least one reference microphone mounted on a second face of the plate for measuring the sound pressure level; and

an ANC control system for determining, based on output signals from the reference microphone(s), a drive signal for driving the loudspeaker to generate a sound signal that at least partially attenuates, in the defined spatial region and in the first frequency range, sound signals from at least one noise source.

2. An ANC system as claimed in claim 1 and comprising an acoustic enclosure extending from the first face of the plate for receiving the loudspeaker.

3. An ANC system as claimed in claim 1 or 2 wherein the ANC control system is configured to determine the drive signal based on an output signal from a second microphone, the second microphone for measuring a signal indicative of the sound pressure level at the spatial region.

4. An ANC system as claimed in claim 3 wherein the second microphone is mounted on the plate.

5. An ANC system as claimed in claim 4 wherein the second microphone is mounted on the second surface of the plate.

6. An ANC system as claimed in any preceding claim wherein the first face of the plate is contoured so as to be generally complementary to the inner surface of the helmet.

7. An ANC system as claimed in any preceding claim wherein the second face of the plate is contoured so as to be generally complementary to the face of a person.

8. An ANC system as claimed in any preceding claim and comprising an acoustic enclosure surrounding the aperture for allowing transmission of sound from the loudspeaker and extending from the second face of the plate.

9. An ANC system as claimed in any preceding claim wherein the ANC control system is mounted on the plate.

10 An ANC system as claimed in any preceding claim wherein the ANC control system is disposed in a common package with the loudspeaker

1 1 . A helmet comprising an active noise cancellation (ANC) system for preferentially attenuating sound pressure in a first frequency range in a defined spatial region at a first side of the helmet, comprising:

a loudspeaker disposed in a recess in an inner layer of the helmet;

a mounting plate, a first side of the mounting plate disposed against an inner surface of the helmet, the plate disposed over the recess such that the plate and the inner layer form a chamber containing the loudspeaker, the plate having an aperture allowing transmission of sound from the loudspeaker to the defined spatial region; at least one reference microphone mounted on a second face of the plate for measuring the sound pressure level at a respective location on the first side of the helmet spaced from the defined spatial region ; and

an ANC control system for determining, based on output signals from the reference microphone(s), a drive signal for driving the loudspeaker to generate a sound signal that at least partially attenuates, in the defined spatial region and in the first frequency range, sound signals from at least one noise source.

12. A helmet as claimed in claim 1 1 and comprising an acoustic enclosure extending from the first face of the plate for receiving the loudspeaker.

13. An ANC system as claimed in claim 1 1 or 12 wherein the ANC control system is configured to determine the drive signal based on an output signal from a second

microphone, the second microphone for measuring a signal indicative of the sound pressure level at the spatial region.

14. A helmet as claimed in claim 13 wherein the second microphone is mounted on the plate.

15. A helmet as claimed in claim 14 wherein the second microphone is mounted on the second face of the plate.

16. A helmet as claimed in any of claims 1 1 to 15 wherein the first face of the plate is contoured so as to be generally complementary to the inner surface of the helmet.

17. A helmet as claimed in any of claims 1 1 to 16 wherein the second face of the plate is contoured so as to be generally complementary to the face of a person.

18. A helmet as claimed in any of claims 1 1 to 17 and comprising an acoustic enclosure surrounding the aperture for allowing transmission of sound from the loudspeaker and extending from the second face of the plate.

19 A helmet as claimed in any of claims 1 1 to 18 wherein the ANC control system is mounted on the plate.

20 A helmet as claimed in any of claims 1 1 to 19 wherein the ANC control system is disposed in a common package with the loudspeaker.

21 . A helmet as claimed in any of claims 1 1 to 20 wherein the plate is provided between the inner layer of the helmet and a lining layer.

22. A helmet as claimed in claim 21 wherein the plate comprises at least one second aperture, and the lining layer is secured to the inner layer by a fastener passing through the second aperture.