Traitement en cours

Veuillez attendre...

Paramétrages

Paramétrages

Aller à Demande

1. WO2021040521 - OPTIMISATION D'UN RÉSEAU DE MEMBRANES ACOUSTIQUES

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

[ EN ]

CLAIMS

1. An acoustic device (100) comprising

- an array of acoustic membranes (1,2, 3, 4) formed on a foil (10); and

- a controller (50) configured to generate respective driving signals to vibrate the acoustic membranes (1,2, 3, 4) at their respective resonance frequency (Fr) for generating respective acoustic waves (W1,W2,W3,W4), wherein at least a first subset of the array is formed by in-phase pairs of adjacent acoustic membranes (1,2) connected to receive the same driving signal (Si) from the controller (50), wherein each in-phase pair comprises a respective first acoustic membrane (1) and adjacent, second acoustic membrane (2), wherein the first acoustic membrane (1) is distanced from the second acoustic membrane (2) by a first intermediate section (lOi) of the foil (10) there between,

wherein a first distance (X12) of the first intermediate section (lOi) between the first acoustic membrane (1) and the second acoustic membrane (2) is a first integer number (N12), plus-or-minus a first fraction (dl2) of less than one-tenth, times a predetermined lamb wavelength (As) of lamb waves (Ws) generated by the acoustic membranes (1,2) at the resonance frequency (Fr) traveling through the intermediate section (lOi) between the adjacent acoustic membranes (1,2).

2. The device according to claim 1, wherein at least a second subset of the array is formed by phase-delayed pairs of adjacent acoustic membranes (3,4) connected to receive phase-delayed driving signals (Sl,S2) from the controller (50), wherein each phase- delayed pair comprises a third acoustic membrane (3) and an adjacent, fourth acoustic membrane (4), wherein the third acoustic membrane (3) is distanced from the fourth acoustic membrane (4) by a second intermediate section (lOj) of the foil (10) there between,

wherein a second distance (X34) of the second intermediate section (lOj) between the third and fourth acoustic membranes (3,4) is a second integer number (N34), plus-or-minus a non-zero, second fraction (d34), times a predetermined lamb wavelength (As) of lamb waves (Ws) generated by the acoustic membranes (3,4) at the resonance frequency (Fr) traveling through the intermediate section (lOi) between the adjacent acoustic membranes (3,4), wherein the second fraction (d34) is predetermined in accordance with a phase delay (cp34) between the third and fourth acoustic membranes (3,4).

3. The device according to any of the preceding claims, wherein zero or non-zero phase delays (cpl2, cp34) between respective pairs of acoustic membranes (1,2;3,4) are determined such that respective acoustic waves (W1,W2,W3,W4) generated by the acoustic membranes (1,2, 3, 4) constructively interfere at a focal point (C) above the array.

4. The device according to any of the preceding claims, wherein acoustic membranes (3,4) forming a respective phase delayed-pair of adjacent membranes are disposed at respective distances Z3 and Z4 from a common focal point (C) above the foil (10),

wherein the distances Z3 and Z4 are determined as

Z3 = (JV3 + DF3/2p ) · la and Z4 = (JV4 + DF4/2p ) · la ,

where Aa is a wavelength of acoustic waves generated by the membranes (3,4), N3 and N4 are integers values determined by a number of full wavelengths fitting between the respective membranes and the focal point, and DF3 and DF4 are respective phases of the membranes;

wherein a distance X34 between the phase delayed-pair of membranes (3,4) is determined by

34 = 0^34 + DF34/2p ) · le ,

where As is the lamb wavelength (As), N34 is an integer values determined by a number of full wavelengths fitting between the respective transducer and the focal point, and DF34 is a phase difference between the respective phase delayed-pair of membranes (3,4);

wherein the distance X34 is selected such that

(DF34/2TG ) = |(DF3/2p ) - (DF4/2p )| ± d34 ,

where d34 is a maximum allowed fractional phase difference with a value of less than one-tenth.

5. The device according to any of the preceding claims, wherein each of the driving signals (Sl,S2,S3) comprise a respective driving frequency corresponding to the resonance frequency (Fr) of the membranes.

6. The device according to any of the preceding claims, wherein the acoustic membranes are arranged along a pattern of concentric circles (R1,R2,R3,R4),

wherein at least a subset of adjacent membranes (1,2;2,3) on the same circle (Rl) form in-phase pairs configured to vibrate with the same phase, each in-phase pair having a respective first distance (X12,X23) there between to provide constructive interference of lamb waves traveling over said first distance through an intermediate section of foil and arriving at the adjacent in-phase membrane;

7. The device according to any of the preceding claims, wherein at least a subset of adjacent membranes (2,4;3,4) on the neighboring circles (R1,R2) form phase-delayed pairs configured to vibrate with a predetermined phase difference, each phase-delayed pair having a respective second distance (X24,X34) there between to provide constructive interference of lamb waves traveling over said second distance through an intermediate section of foil and arriving at the adjacent phase-delayed

membrane.

8. The device according to any of the preceding claims, wherein at least some adjacent membranes (3,4;3,5) on the neighboring circles (R1,R2) form phase-delayed pairs with different distances (X34,X35) there between, wherein the distances differ by an integer number of wavelengths.

9. The device according to any of the preceding claims, wherein the acoustic membranes (1,2, 3, 4) are formed as an integral part of the foil (10), wherein an actuated surface of the acoustic membranes (1,2, 3, 4) comprises a layer (10b) of the foil.

10. The device according to any of the preceding claims, wherein the resonance frequency (Fr) is determined, by one or more of the membrane material properties and diameter of the acoustic membranes, wherein the lamb wavelength (As) is determined by the resonance frequency (Fr) at which the lamb waves (Ws) are generated, as well as material properties and thickness of the intermediate sections (lOi, lOj) of the foil (10), wherein the intermediate sections (lOi, lOj) of the foil (10) have a total thickness of less than one millimeter, and the acoustic membranes have a total thickness that is at least a factor two lower than the thickness of the intermediate sections (10i,10j) of the foil (10).

11. A method of manufacturing an acoustic device (100), the method comprising

- determining a layout for an array of acoustic membranes (1,2, 3, 4) formed on a foil (10), wherein each of the acoustic membranes (1,2, 3, 4) is configured to vibrate at a resonance frequency (Fr) of the acoustic membranes (1,2, 3, 4) for generating respective acoustic waves

(W1,W2,W3,W4);

- determining relative phases (DF12,DF34) at which the acoustic membranes (1,2, 4, 5) are to be actuated for generating a predetermined interference pattern (C) between the acoustic waves (W1,W2,W3,W4);

- determining a lamb wavelength (As) of lamb waves (Ws) at the resonance frequency (Fr) traveling through intermediate sections (lOi, lOj) of the foil (10) between adjacent acoustic membranes (1,2; 3,4) in the array;

wherein distances (X12,X34) of the intermediate sections (lOi, lOj) between the adjacent acoustic membranes (1,2; 3,4) in the layout are determined in accordance with the relative phases (DF12,DF34) and the lamb wavelength (As) for having the lamb waves (Ws) generated by actuating a first acoustic membrane (1,3) of the pair of adjacent acoustic membranes, and traveling through the respective intermediate section (lOi, lOj), arrive in phase with a second acoustic membrane (2,4) of the pair of adjacent acoustic membranes.

12. The method according to claim 11, wherein at least a first subset of the array is formed by in-phase pairs of adjacent acoustic membranes (1,2), wherein each in-phase pair comprises a respective first acoustic membrane (1) and adjacent, second acoustic membrane (2), wherein the first acoustic membrane (1) is distanced from the second acoustic membrane (2) by a first intermediate section (lOi) of the foil (10) there between, wherein a first distance (X12) of the first intermediate section (lOi) between the first acoustic membrane (1) and the second acoustic membrane (2) is a first integer number (N12), plus-or-minus a first fraction (dl2) of less than one-tenth, times a predetermined lamb wavelength (As) of lamb waves (Ws) generated by the acoustic membranes (1,2) at the resonance frequency (Fr) traveling through the intermediate section (lOi) between the adjacent acoustic membranes (1,2).

13. The method according to claim 11 or 12, wherein at least a second subset of the array is formed by phase-delayed pairs of adjacent acoustic membranes (3,4), wherein each phase-delayed pair comprises a third acoustic membrane (3) and an adjacent, fourth acoustic membrane (4), wherein the third acoustic membrane (3) is distanced from the fourth acoustic membrane (4) by a second intermediate section (lOj) of the foil (10) there between, wherein a second distance (X34) of the second intermediate section (lOj) between the third and fourth acoustic membranes (3,4) is a second integer number (N34), plus-or-minus a non-zero, second fraction (d34), times a predetermined lamb wavelength (As) of lamb waves (Ws) generated by the acoustic membranes (3,4) at the resonance frequency (Fr) traveling through the intermediate section (lOi) between the adjacent acoustic membranes (3,4), wherein the second fraction (d34) is predetermined in accordance with a phase delay (cp34) between the third and fourth acoustic membranes (3,4).

14. The method according to any of claims 11-13, wherein a thickness of intermediate sections of foil between respective pairs of acoustic membranes is varied to affect propagation of lamb waves (Ws) such that lamb waves, generated by one acoustic membrane of a respective pair, arrive in phase with an adjacent acoustic membrane of the respective pair.

15. The method according to any of claims 11-14, wherein the acoustic membranes in the array are arranged along a spiral pattern.