A CONVERGENT AEROSOL-GENERATOR

Abstract

An aerosol-generator for an aerosol-generating device is provided, including: a surface acoustic wave atomiser including: a substrate including an active surface defining an atomisation region, and at least one transducer positioned on the active surface to generate surface acoustic waves for defining an acoustic wavefront on the active surface; and a supply element arranged to supply a liquid aerosol-forming substrate to the atomisation region so that liquid aerosol-forming substrate in the atomisation region defines an interface between the active surface, the liquid aerosol-forming substrate, and the atmosphere, in which the at least one transducer and the supply element are configured so that a shape of the acoustic wavefront at the interface corresponds to a shape of at least part of the interface. An aerosol-generating device including the aerosol-generator is also provided.

Claims

1.-22. (canceled)

23. An aerosol-generator for an aerosol-generating device, the aerosol-generator comprising: a surface acoustic wave atomiser comprising: a substrate comprising an active surface defining an atomisation region, and at least one transducer positioned on the active surface of the substrate to generate surface acoustic waves for defining an acoustic wavefront on the active surface of the substrate; and a supply element arranged to supply a liquid aerosol-forming substrate to the atomisation region so that liquid aerosol-forming substrate in the atomisation region defines an interface between the active surface, the liquid aerosol-forming substrate, and the atmosphere, wherein the at least one transducer and the supply element are configured so that a shape of the acoustic wavefront at the interface corresponds to a shape of at least part of the interface.

24. The aerosol-generator according to claim 23, wherein the at least one transducer comprises an interdigital transducer comprising an array of interleaved electrodes, and wherein a spacing between consecutive interleaved electrodes varies with direction across the active surface.

25. The aerosol-generator according to claim 24, wherein each of the interleaved electrodes has an elliptical shape, and wherein the interleaved electrodes are arranged concentrically on the active surface.

26. The aerosol-generator according to claim 25, wherein the atomisation region is positioned at a centre of the array of concentric interleaved electrodes.

27. The aerosol-generator according to claim 25, wherein the interdigital transducer defines a first direction extending along the major axes of the concentric interleaved electrodes and a second direction extending along the minor axes of the concentric interleaved electrodes, and wherein the spacing between the consecutive interleaved electrodes is greater in the first direction than the second direction.

28. The aerosol-generator according to claim 24, wherein the array of interleaved electrodes has a symmetrical shape comprising a first line of symmetry extending in a first direction and a second line of symmetry extending in a second direction, and wherein the first direction is orthogonal to the second direction.

29. The aerosol-generator according to claim 23, wherein the at least one transducer comprises a first interdigital transducer comprising a first array of interleaved electrodes and a second interdigital transducer comprising a second array of interleaved electrodes, and wherein a spacing between consecutive electrodes of the first array of interleaved electrodes is different from a spacing between consecutive electrodes of the second array of interleaved electrodes.

30. The aerosol-generator according to claim 29, wherein the first interdigital transducer is configured to generate surface acoustic waves in a first direction along the active surface towards the atomisation region, wherein the second interdigital transducer is configured to generate surface acoustic waves in a second direction along the active surface towards the atomisation region, and wherein the first direction is different from the second direction.

31. The aerosol-generator according to claim 30, wherein each of the first interdigital transducer and the second interdigital transducer is further configured to generate plane surface acoustic waves.

32. The aerosol-generator according to claim 30, wherein the first direction is orthogonal to the second direction.

33. The aerosol-generator according to claim 23, wherein the at least one transducer comprises an interdigital transducer comprising an array of interleaved electrodes, wherein each of the interleaved electrodes has a circular shape, wherein the interleaved electrodes are arranged concentrically on the active surface, wherein the atomisation region is positioned at a centre of the array of concentric interleaved electrodes, wherein the supply element comprises an opening in the active surface of the substrate and positioned within the atomisation region, and wherein the opening has an elliptical shape.

34. The aerosol-generator according to claim 33, wherein the elliptical opening defines a first direction extending along the major axis of the opening and a second direction extending along the minor axis of the opening.

35. An aerosol-generator for an aerosol-generating device, the aerosol-generator comprising: a surface acoustic wave atomiser comprising: a substrate comprising an active surface defining an atomisation region, a first transducer positioned on the active surface of the substrate to generate surface acoustic waves in a first direction along the active surface towards the atomisation region, and a second transducer positioned on the active surface of the substrate to generate surface acoustic waves in a second direction along the active surface towards the atomisation region, wherein the first direction is different from the second direction; a supply element arranged to supply a liquid aerosol-forming substrate to the atomisation region; and a controller configured to provide a first drive signal to the first transducer and a second drive signal to the second transducer, wherein the first drive signal is different from the second drive signal.

36. The aerosol-generator according to claim 35, wherein a power of the first drive signal is different from a power of the second drive signal.

37. The aerosol-generator according to claim 36, wherein the substrate has a first electromechanical coupling coefficient in the first direction and a second electromechanical coupling coefficient in the second direction, wherein the first electromechanical coupling coefficient is larger than the second electromechanical coupling coefficient, and wherein the power of the first drive signal is smaller than the power of the second drive signal.

38. The aerosol-generator according to claim 37, wherein a ratio of the first electromechanical coupling coefficient to the second electromechanical coupling coefficient is the same as a ratio of the power of the second drive signal to the power of the first drive signal.

39. The aerosol-generator according to claim 35, wherein the first direction is orthogonal to the second direction.

40. The aerosol-generator according to claim 27, wherein the substrate comprises a crystalline material, wherein the active surface is defined by a lattice plane of the crystalline material, and wherein each of the first direction and the second direction is aligned with a lattice vector of the lattice plane.

41. An aerosol-generator for an aerosol-generating device, the aerosol-generator comprising: a surface acoustic wave atomiser comprising: a substrate comprising an active surface defining an atomisation region, and a transducer positioned on the active surface of the substrate to generate surface acoustic waves on the active surface of the substrate, wherein a portion of the active surface of the substrate underlying at least a portion of the transducer comprises a surface treatment; and a supply element arranged to supply a liquid aerosol-forming substrate to the atomisation region.

42. The aerosol-generator according to claim 41, wherein the surface treatment comprises a proton exchange treatment.

43. The aerosol-generator according to claim 42, wherein the substrate comprises lithium niobate, and wherein the proton exchange treatment comprises replacement of lithium ions with hydrogen ions in a portion of the active surface comprising the surface treatment.

44. An aerosol-generating device, comprising: an aerosol-generator according to claim 23; a controller configured to control the at least one transducer; a power supply; and a liquid storage portion configured to receive a liquid aerosol-forming substrate, wherein the supply element is arranged to supply the liquid aerosol-forming substrate from the liquid storage portion to the atomisation region.

Description

[0108] The invention will be further described, by way of example only, with reference to the accompanying drawings, in which:

[0109] FIG. 1 shows a top view of an aerosol-generator according to a first embodiment of the present disclosure;

[0110] FIG. 2 shows a cross-sectional view of the aerosol-generator of FIG. 1 taken along line 1-1;

[0111] FIG. 3 shows a cross-sectional view of an aerosol-generating device comprising the aerosol-generator of FIG. 1;

[0112] FIG. 4 shows a top view of an aerosol-generator according to a second embodiment of the present disclosure;

[0113] FIG. 5 shows a top view of an aerosol-generator according to a third embodiment of the present disclosure;

[0114] FIG. 6 shows a top view of an aerosol-generator according to a fourth embodiment of the present disclosure; and

[0115] FIG. 7 shows a top view of an aerosol-generator according to a fifth embodiment of the present disclosure.

[0116] FIGS. 1 and 2 show an aerosol-generator 100 according to a first embodiment of the present disclosure. The aerosol-generator 100 comprises a surface acoustic wave atomiser 102 and a supply element 104 for supplying a liquid aerosol-forming substrate to the surface acoustic wave atomiser 102.

[0117] The surface acoustic wave atomiser 102 comprises a substrate 106 comprising a sheet of piezoelectric material, and a transducer 108 arranged on an active surface 110 of the substrate 106. The transducer 108 is an interdigital transducer comprising an array of interleaved electrodes 112. Each of the interleaved electrodes 112 has an elliptical shape and the interleaved electrodes 112 are arranged concentrically on the active surface 110 of the substrate 106. During use, the transducer 108 generates surface acoustic waves on the active surface 110 of the substrate 106. The concentric elliptical shape of the array of interleaved electrodes 112 generates surface acoustic waves having an acoustic wavefront focussed towards an atomisation region 116 on the active surface 110 of the substrate 106.

[0118] The supply element 104 comprises a channel 118 extending through the substrate 106 between an inlet 120 at a passive surface 122 of the substrate 106 and an outlet 124 at the active surface 110 of the substrate 106. The outlet 124 is positioned within the atomisation region 116. The outlet 124 has a substantially circular shape. The supply element 104 also comprises a flow control element 130 comprising a micro pump. During use, a liquid aerosol-forming substrate is supplied by the flow control element 130 through the channel 118 to the atomisation region 116 where it is atomised by surface acoustic waves generated by the transducer 108.

[0119] The aerosol-generator 100 also comprises a controller 132 arranged to control the transducer 108 and the flow control element 130. In the embodiment shown in FIG. 1 the controller 132 is positioned on the substrate 106 of the surface acoustic wave atomiser 102; however, the skilled person will appreciate that the controller 132 may be provided separately from the surface acoustic wave atomiser 102.

[0120] The controller 132 is configured to provide a drive signal to the transducer 108 for generating surface acoustic waves on the active surface 110 of the substrate 106. The controller 132 is also configured to provide flow signals and stop signals to the flow control element 130 to start and stop a flow of a liquid aerosol-forming substrate through the channel 118 and into the atomisation region 116. The controller 132 is configured to provide the drive signal to the transducer 108 only when the flow control element 130 is supplying the liquid aerosol-forming substrate to the atomisation region 116.

[0121] The transducer 108 defines a first direction 140 extending along the major axes of the elliptically shaped interleaved electrodes 112. The transducer 108 also defines a second direction 142 extending along the minor axes of the elliptically shaped interleaved electrodes 112. The elliptical shape of the interleaved electrodes 112 is such that the spacing between consecutive interleaved electrodes 112 is greater in the first direction 140 than the second direction 142.

[0122] The piezoelectric material forming the substrate 106 comprises a crystalline material, wherein the active surface 110 of the substrate 106 is defined by a lattice plane of the crystalline material. The transducer 108 is arranged on the active surface 110 of the substrate 106 so that each of the first direction and the second direction defined by the transducer 108 is aligned with a lattice vector of the lattice plane. The combination of the elliptical shape of the interleaved electrodes 112, the greater spacing between consecutive interleaved electrodes 112 in the first direction 140, and the alignment of the first and second directions 140, 142 with lattice vectors of the lattice plane defining the active surface 110 of the substrate 106 compensates for the anisotropy in the wave speed of surface acoustic waves across the active surface 110. Therefore, during use, the transducer 108 generates surface acoustic waves having a substantially circular acoustic wavefront that converges on the atomisation region 116 and the substantially circular outlet 124 of the supply element 104.

[0123] FIG. 3 shows a cross-sectional view of an aerosol-generating device 200 comprising the aerosol-generator 100 of FIGS. 1 and 2. The aerosol-generating device 200 also comprises a liquid storage portion 202 containing a liquid aerosol-forming substrate 204. The flow control element 130 of the aerosol-generator 100 is arranged to supply the liquid aerosol-forming substrate 204 from the liquid storage portion 202 to the inlet 120 of the aerosol-generator 100.

[0124] The aerosol-generating device 200 also comprises a power supply 208 comprising a rechargeable battery for supplying electrical power to the controller 132, the transducer 108 and the flow control element 130.

[0125] The aerosol-generating device 200 also comprises a housing 212 in which the aerosol-generator 100, the liquid storage portion 202 and the power supply 208 are contained. The housing 212 defines an air inlet 214, a mouthpiece 216, and an air outlet 218. During use, a user draws on the mouthpiece 216 to draw air through the housing 212 from the air inlet 214 to the air outlet 218. Aerosol generated by the aerosol-generator 100 is entrained in the airflow through the housing 212 for delivery to the user.

[0126] FIG. 4 shows an aerosol-generator 300 according to a second embodiment of the present disclosure. The aerosol-generator 300 comprises a surface acoustic wave atomiser 302 and a supply element 304 for supplying a liquid aerosol-forming substrate to the surface acoustic wave atomiser 302.

[0127] The surface acoustic wave atomiser 302 comprises a substrate 306 comprising a sheet of piezoelectric material, a first transducer 308 arranged on an active surface 310 of the substrate 306 and a second transducer 309 arranged on the active surface 310 of the substrate 306 and a second transducer 309.

[0128] The first transducer 308 is an interdigital transducer comprising a first array of interleaved electrodes 312. Each of the interleaved electrodes 312 has a linear shape and the interleaved electrodes 312 are arranged parallel to each other on the active surface 310 of the substrate 306. During use, the first transducer 308 generates substantially planar surface acoustic waves on the active surface 310 of the substrate 306 and directed towards an atomisation region 316 on the active surface 310 of the substrate 306.

[0129] The second transducer 309 is an interdigital transducer comprising a second array of interleaved electrodes 313. Each of the interleaved electrodes 313 has a linear shape and the interleaved electrodes 313 are arranged parallel to each other on the active surface 310 of the substrate 306. During use, the second transducer 309 generates substantially planar surface acoustic waves on the active surface 310 of the substrate 306 and directed towards an atomisation region 316 on the active surface 310 of the substrate 306.

[0130] The supply element 304 is similar to the supply element 104 described with reference to FIG. 1. The supply element 304 comprises a channel 318 extending through the substrate 306 between an inlet at a passive surface of the substrate 306 and an outlet 324 at the active surface 310 of the substrate 306. The outlet 324 is positioned within the atomisation region 316. The outlet 324 has a substantially square shape. The supply element 304 also comprises a flow control element comprising a micro pump. During use, a liquid aerosol-forming substrate is supplied by the flow control element through the channel 318 to the atomisation region 316 where it is atomised by surface acoustic waves generated by the first and second transducers 308, 309.

[0131] The aerosol-generator 300 also comprises a controller 332 arranged to control the first and second transducers 308, 309 and the flow control element. In the embodiment shown in FIG. 4 the controller 332 is positioned on the substrate 306 of the surface acoustic wave atomiser 302; however, the skilled person will appreciate that the controller 332 may be provided separately from the surface acoustic wave atomiser 302.

[0132] The controller 332 is configured to provide first and second drive signals to the first and second transducers 308, 309 for generating surface acoustic waves on the active surface 310 of the substrate 306. The controller 332 is also configured to provide flow signals and stop signals to the flow control element to start and stop a flow of a liquid aerosol-forming substrate through the channel 318 and into the atomisation region 316. The controller 332 is configured to provide the first and second drive signals to the first and second transducers 308, 309 only when the flow control element is supplying the liquid aerosol-forming substrate to the atomisation region 316.

[0133] The first transducer 308 is arranged on the active surface 310 of the substrate 306 to generate surface acoustic waves in a first direction 340. The second transducer 309 is arranged on the active surface 310 of the substrate 306 to generate surface acoustic waves in a second direction 342. The spacing in the first direction 340 between consecutive interleaved electrodes 312 of the first transducer 308 is greater than the spacing in the second direction 342 between consecutive interleaved electrodes 313 of the second transducer 309.

[0134] The piezoelectric material forming the substrate 306 comprises a crystalline material, wherein the active surface 310 of the substrate 306 is defined by a lattice plane of the crystalline material. The first and second transducers 308, 309 are arranged on the active surface 310 of the substrate 306 so that each of the first direction and the second direction defined by the first and second transducers 308, 309 is aligned with a lattice vector of the lattice plane. The combination of the greater spacing between consecutive interleaved electrodes 312 in the first direction 340 and the alignment of the first and second directions 340, 342 with lattice vectors of the lattice plane defining the active surface 310 of the substrate 306 compensates for the anisotropy in the wave speed of surface acoustic waves across the active surface 310. Therefore, during use, surface acoustic waves generated by the first transducer 308 may arrive at the atomisation region 316 concurrently with surface acoustic waves generated by the second transducer 309.

[0135] FIG. 5 shows an aerosol-generator 400 according to a third embodiment of the present disclosure. The aerosol-generator 400 comprises a surface acoustic wave atomiser 402 and a supply element 404 for supplying a liquid aerosol-forming substrate to the surface acoustic wave atomiser 402.

[0136] The surface acoustic wave atomiser 402 comprises a substrate 406 comprising a sheet of piezoelectric material, and a transducer 408 arranged on an active surface 410 of the substrate 406. The transducer 408 is an interdigital transducer comprising an array of interleaved electrodes 412. Each of the interleaved electrodes 412 has a substantially circular shape and the interleaved electrodes 412 are arranged concentrically on the active surface 410 of the substrate 406. During use, the transducer 408 generates surface acoustic waves on the active surface 410 of the substrate 406. The concentric circular shape of the array of interleaved electrodes 412 generates surface acoustic waves having an acoustic wavefront focussed towards an atomisation region 416 on the active surface 410 of the substrate 406.

[0137] The supply element 404 is similar to the supply element 104 described with reference to FIG. 1. The supply element 404 comprises a channel 418 extending through the substrate 406 between an inlet at a passive surface of the substrate 406 and an outlet 424 at the active surface 410 of the substrate 406. The outlet 424 is positioned within the atomisation region 416. The outlet 424 has an elliptical shape. The supply element 404 also comprises a flow control element comprising a micro pump. During use, a liquid aerosol-forming substrate is supplied by the flow control element through the channel 418 to the atomisation region 416 where it is atomised by surface acoustic waves generated by the transducer 408.

[0138] The aerosol-generator 400 also comprises a controller 432 arranged to control the transducer 408 and the flow control element. In the embodiment shown in FIG. 4 the controller 432 is positioned on the substrate 406 of the surface acoustic wave atomiser 402; however, the skilled person will appreciate that the controller 432 may be provided separately from the surface acoustic wave atomiser 402.

[0139] The controller 432 is configured to provide a drive signal to the transducer 408 for generating surface acoustic waves on the active surface 410 of the substrate 406. The controller 432 is also configured to provide flow signals and stop signals to the flow control element to start and stop a flow of a liquid aerosol-forming substrate through the channel 418 and into the atomisation region 416. The controller 432 is configured to provide the drive signal to the transducer 408 only when the flow control element is supplying the liquid aerosol-forming substrate to the atomisation region 416.

[0140] The elliptically shaped outlet 424 defines a first direction 440 extending along the minor axis of the elliptically shaped outlet 424. The elliptically shaped outlet 424 also defines a second direction 442 extending along the major axis of the elliptically shaped outlet 424.

[0141] The piezoelectric material forming the substrate 406 comprises a crystalline material, wherein the active surface 410 of the substrate 406 is defined by a lattice plane of the crystalline material. The elliptically shaped outlet 424 is arranged on the active surface 410 of the substrate 406 so that each of the first direction and the second direction defined by the elliptically shaped outlet 424 is aligned with a lattice vector of the lattice plane. Although the interleaved electrodes 412 of the transducer 408 each have a substantially circular shape, anisotropy in the wave speed of surface acoustic waves across the active surface 410 of the substrate results in surface acoustic waves generated by the transducer 408 having an elliptical acoustic wavefront. The combination of the elliptical shape of the outlet 424 and the alignment of the first and second directions 440, 442 with lattice vectors of the lattice plane defining the active surface 410 of the substrate 406 compensates for the anisotropy in the wave speed of surface acoustic waves across the active surface 410. Therefore, during use, the transducer 408 generates surface acoustic waves having an elliptical acoustic wavefront that converges on the atomisation region 416 and the elliptically shaped outlet 424 of the supply element 404.

[0142] FIG. 6 shows an aerosol-generator 500 according to a fourth embodiment of the present disclosure. The aerosol-generator 500 comprises a surface acoustic wave atomiser 502 and a supply element 504 for supplying a liquid aerosol-forming substrate to the surface acoustic wave atomiser 502.

[0143] The surface acoustic wave atomiser 502 comprises a substrate 506 comprising a sheet of piezoelectric material, and a first transducer 508, a second transducer 509, a third transducer 511 and a fourth transducer 517 each arranged on an active surface 510 of the substrate 506.

[0144] Each of the first transducer 508, the second transducer 509, the third transducer 511 and the fourth transducer 517 is an interdigital transducer comprising an array of interleaved electrodes 512. Each of the interleaved electrodes 512 has a linear shape and the interleaved electrodes 512 are arranged parallel to each other on the active surface 510 of the substrate 506. During use, each of the first transducer 508, the second transducer 509, the third transducer 511 and the fourth transducer 517 generates substantially planar surface acoustic waves on the active surface 510 of the substrate 506 and directed towards an atomisation region 516 on the active surface 510 of the substrate 506.

[0145] The supply element 504 is similar to the supply element 104 described with reference to FIG. 1. The supply element 504 comprises a channel 518 extending through the substrate 506 between an inlet at a passive surface of the substrate 506 and an outlet 524 at the active surface 510 of the substrate 506. The outlet 524 is positioned within the atomisation region 516. The outlet 524 has a substantially square shape. The supply element 504 also comprises a flow control element comprising a micro pump. During use, a liquid aerosol-forming substrate is supplied by the flow control element through the channel 518 to the atomisation region 516 where it is atomised by surface acoustic waves generated by the first and second transducers 508, 509.

[0146] The aerosol-generator 500 also comprises a controller 532 arranged to control the first, second, third and fourth transducers 508, 509, 511, 517 and the flow control element. In the embodiment shown in FIG. 6 the controller 532 is positioned on the substrate 506 of the surface acoustic wave atomiser 502; however, the skilled person will appreciate that the controller 532 may be provided separately from the surface acoustic wave atomiser 502.

[0147] The controller 532 is configured to provide a first drive signal 550 to the first transducer 508 for generating surface acoustic waves in a first direction 540 on the active surface 510 of the substrate 506.

[0148] The controller 532 is configured to provide a second drive signal 552 to the second transducer 509 for generating surface acoustic waves in a second direction 542 on the active surface 510 of the substrate 506.

[0149] The controller 532 is configured to provide a third drive signal 554 to the third transducer 511 for generating surface acoustic waves in a third direction 544 on the active surface 510 of the substrate 506.

[0150] The controller 532 is configured to provide a fourth drive signal 556 to the fourth transducer 517 for generating surface acoustic waves in a fourth direction 546 on the active surface 510 of the substrate 506.

[0151] The controller 532 is also configured to provide flow signals and stop signals to the flow control element to start and stop a flow of a liquid aerosol-forming substrate through the channel 518 and into the atomisation region 516. The controller 532 is configured to provide the first, second, third and fourth drive signals 550, 552, 554, 556 to the first, second, third and fourth transducers 508, 509, 511, 517 only when the flow control element is supplying the liquid aerosol-forming substrate to the atomisation region 516.

[0152] The controller 532 is configured so that the powers of each of the first, second, third and fourth drive signals 550, 552, 554, 556 are different to each other.

[0153] The piezoelectric material forming the substrate 506 comprises a crystalline material, wherein the active surface 510 of the substrate 506 is defined by a lattice plane of the crystalline material. The first, second, third and fourth transducers 508, 509, 511, 517 are arranged on the active surface 510 of the substrate 506 so that each of the first, second, third and fourth directions 540, 542, 544, 546 is aligned with a lattice vector of the lattice plane. The combination of the different powers of the first, second, third and fourth drive signals 550, 552, 554, 556 and the alignment of the first and second directions 540, 542 with lattice vectors of the lattice plane defining the active surface 510 of the substrate 506 compensates for the anisotropy in the electromechanical coupling coefficient across the active surface 510. Therefore, during use, surface acoustic waves generated by each of the first, second, third and fourth transducers 508, 509, 511, 517 have the same amplitude.

[0154] FIG. 7 shows an aerosol-generator 600 according to a fifth embodiment of the present disclosure. The aerosol-generator 600 comprises a surface acoustic wave atomiser 602 and a supply element 504.

[0155] The supply element 504 of the aerosol-generator 600 is identical to the supply element 504 described with reference to FIG. 6 and like reference numerals are used to designate like parts.

[0156] The surface acoustic wave atomiser 602 is similar to the surface acoustic wave atomiser 502 described with reference to FIG. 6 and like reference numerals are used to designate like parts. The surface acoustic wave atomiser 602 differs from the surface acoustic wave atomiser 502 by the addition of a surface treatment 660 of a portion of the active surface 510 of the substrate 506 underlying the first, second, third and fourth transducers 508, 509, 511, 517. The surface treatment 660 comprises a proton exchange treatment and provides the active surface 510 of the substrate 506 with a substantially isotropic electromechanical coupling coefficient in the area to which the surface treatment 660 is applied. Therefore, the controller 632 is configured to provide a common drive signal 650 to each of the first, second, third and fourth transducers 508, 509, 511, 517.