EP4385346A1

EP4385346A1 - A heater for an aerosol generating device configured to operate with an electrically conductive consumable article

Info

Publication number: EP4385346A1
Application number: EP22213590.7A
Authority: EP
Inventors: Boris UYTTERHAEGEN; Laurent Houtsaeger; Jérôme MCDONALD; Julia Schindler; Willy Huwyler; Alec WRIGHT
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2022-12-14
Filing date: 2022-12-14
Publication date: 2024-06-19

Abstract

This invention relates to a heater for an aerosol generating device configured to operate with a consumable (1) comprising an electrically conductive heating layer of aerosol precursor material (1), the heater comprising: 2 electrically conductive layers (4, 5) facing each other and spaced apart from each other so as to sandwich said electrically conductive heating layer of aerosol precursor material (1), wherein: a first one (4) of the 2 electrically conductive layers (4, 5) comprises at least 1 electrode (41 to 44), a second one (5) of the 2 electrically conductive layers (4, 5) comprises at least 2 electrodes (51 to 54) which are separated from each other by an electrically non-conductive space (9) and which face at least partially one electrode (41 to 44) of said first electrically conductive layer (4).

Description

FIELD OF THE INVENTION

The invention relates to the technical field of aerosol generating devices configured for the generation of an inhalable aerosol by a user. Particularly, the invention relates to a heater for an aerosol generating device configured to operate with a consumable article comprising an electrically conductive heating layer of aerosol precursor material.

BACKGROUND OF THE INVENTION

Aerosol generating devices comprising electrodes for heating electrically conductive aerosol generation precursors are known in the art. The aerosol precursor material may be provided in a consumable article that is insertable in the aerosol generating device to provide fast and uniform heating of an aerosol precursor material with limited energy. The aerosol precursor material may comprise a non-tobacco flavor generating substrate, such as for example a mentholated component.
In order to achieve fast and efficient aerosol generation, from heating of the aerosol precursor material, electrically conductive material such as charcoal may be mixed in the aerosol generation to allow heating of the aerosol precursor material and generation of an aerosol therefrom by conduction of an electrical current delivered to the aerosol precursor material by the electrodes of the aerosol generation device. The electrical current flows then from a power source via the electrodes through the charcoal particles in the aerosol precursor material to vaporize volatile flavor components contained therein. The electrodes design should enable fast, energy efficient, reliable and safe working.
However, the following issues have been identified and need to be contemplated:

heating of aerosol precursor material may not always be as uniform as expected,
heating of the electrodes may be hindered by inertia of the electrodes, therefore increases the heating time, and altering energy efficiency of the heating
electrodes may require protection to avoid harming users and may require regular cleaning due to deposits and dirt on their surfaces contacting the aerosol precursor material cartridge.

US 2020/229510 discloses an aerosol generating system comprising several electrodes on each side of a consumable article (see elements 1055 a-b-c-d on figure 9) containing a liquid aerosol generation composition.
Such electrodes structure is unable of homogeneous heating of a solid aerosol generation substrate sandwiched between the electrodes.
US 11006668 and WO 2020/165450 disclose other aerosol generating systems comprising electrodes sandwiching a consumable article in between, but there is only one electrode on each side of the consumable article. which does not heat sufficiently homogeneously the consumable article sandwiched between the electrodes.

SUMMARY OF THE INVENTION

An object of the present invention is to alleviate at least partly deficiencies of the previously identified prior arts.
To that aim the invention proposes a heater for an aerosol generating device configured to operate with a consumable article comprising an electrically conductive heating layer of aerosol precursor material, the heater comprising: 2 electrically conductive layers facing each other and spaced apart from each other so as to sandwich said electrically conductive heating layer of aerosol precursor material, wherein: a first one of the 2 electrically conductive layers comprises at least 1 electrode, a second one of the 2 electrically conductive layers comprises at least 2 electrodes which are separated from each other by an electrically non-conductive space and which face at least partially one electrode of said first electrically conductive layer.
The aerosol precursor material is an aerosol generating solid substrate. This aerosol generating solid substrate is sandwiched between the 2 electrodes. This aerosol generating solid substrate is in contact with and even pressed by the 2 electrodes facing each other. This aerosol generating solid substrate is kept between by the 2 electrodes facing each other, simply by the pression exerted by the 2 electrodes facing each other. This pression does not damage or deteriorate the aerosol generating solid substrate. This pression does not remove the porous nature of the aerosol generating solid substrate, it does not remove the existing voids within the porous aerosol generating solid substrate, so that the vapor can still benefit from theses existing voids to form within and to move through this porous aerosol generating solid substrate.
The heater of the invention is suitable for an aerosol generating device in which at least 2 or more electrodes are provided to homogeneously heat a consumable article, to reduce or to avoid hot spots, and to distribute more homogeneously the heat, all along and all across, the consumable and the electrically conductive heating layer of aerosol precursor material contained therein.
There are at least 2 or more electrodes are structured and disposed to heat more uniformly the consumable sandwiched between the electrodes, than a single electrode would do.
Another object of the invention relates to an aerosol generating assembly comprising: a consumable article; an aerosol generating device configured to operate with the consumable article and comprising a heater as previously described.
In embodiments of the invention, each electrode presents a surface configured to extend along an external surface of the consumable and be in contact with this external surface.
In embodiments of the invention, the electrodes are flat electrodes extending along an external surface of the aerosol precursor material in the consumable article in use.
Hence, these large and extended electrodes allow for much more uniform heating than would sharp electrodes.
In embodiments of the invention, the electrodes, taken altogether, extend along at least half the length of an elongate aerosol precursor material layer in the consumable article in use.
Hence, these large and extended electrodes allow for much more uniform heating than would electrodes only located at respective ends of the elongate consumable.
In embodiments of the invention, said first electrically conductive layer comprises at least 2 electrodes which are separated from each other by an electrically non-conductive space and which face at least partially one electrode of said second electrically conductive layer.
Hence, this relative disposition of electrodes belonging to opposite conductive layers allows for a more uniform heating of the consumable article sandwiched between the electrodes in use.
In embodiments of the invention, each electrode of said second electrically conductive layer faces at least partially at least 2 electrodes of said first electrically conductive layer, and/or at least one electrode of said first electrically conductive layer faces at least partially at least 2 electrodes of said second electrically conductive layer.
Hence, this relative disposition of electrodes belonging to opposite conductive layers allows for a more uniform heating of the consumable article sandwiched between the electrodes in use.
In embodiments of the invention, all electrodes of said first electrically conductive layer are powered at a negative tension, all electrodes of said second electrically conductive layer are powered at a positive tension.
Hence, this relative disposition of electrodes belonging to opposite conductive layers allows for a uniform heating of the consumable article sandwiched between the electrodes in use, while keeping a very simple electrical powering of the electrodes.
In embodiments of the invention, no electrode of said second electrically conductive layer is powered at any tension, one or more electrodes of said first electrically conductive layer is or are powered at a negative tension, one or more electrodes of said first electrically conductive layer is or are powered at a positive tension.
Hence, this relative disposition of electrodes belonging to opposite conductive layers allows for a more uniform heating of the consumable article sandwiched between the electrodes in use, while keeping a rather simple electrical powering of the electrodes.
In embodiments of the invention, only one electrode of said first electrically conductive layer is powered at a negative tension, only one electrode of said first electrically conductive layer is powered at a positive tension, said negative tension powered electrode and said positive tension powered electrode of said second electrically conductive layer are configured to face opposite ends of said consumable electrically conductive heating layer.
Hence, this relative disposition of electrodes belonging to opposite conductive layers allows for a more uniform heating of the consumable article sandwiched between the electrodes in use, while keeping a rather simple electrical powering of the electrodes.
In embodiments of the invention, all electrodes of said first electrically conductive layer are : powered at: either a negative predetermined tension, or a positive predetermined tension, and disposed relatively so that 2 electrodes powered at a positive tension are separated by an electrode powered at a negative tension and/or so that 2 electrodes powered at a negative tension are separated by an electrode powered at a positive tension.
Hence, this relative disposition of electrodes belonging to opposite conductive layers allows for a more uniform heating of the consumable article sandwiched between the electrodes in use, while keeping a rather simple electrical powering of the electrodes.
In embodiments of the invention, only one electrode of said first electrically conductive layer is powered at a negative tension, only one electrode of said first electrically conductive layer is powered at a positive tension, only one electrode of said second electrically conductive layer is powered at a negative tension, only one electrode of said second electrically conductive layer is powered at a positive tension, said negative tension powered electrode and said positive tension powered electrode of said second electrically conductive layer are located at opposite ends of said consumable electrically conductive heating layer, said negative tension powered electrode and said positive tension powered electrode of said first electrically conductive layer are located at opposite ends of said consumable article electrically conductive heating layer, said negative tension powered electrode of said second electrically conductive layer faces said negative tension powered electrode of said first electrically conductive layer, said positive tension powered electrode of said second electrically conductive layer faces said positive tension powered electrode of said first electrically conductive layer.
Hence, this relative disposition of electrodes belonging to opposite conductive layers allows for a more uniform heating of the consumable sandwiched between the electrodes, while keeping a rather simple electrical powering of the electrodes.
In embodiments of the invention, according to a first electrode structure embodiment, each electrode is a single and flat surface.
In embodiments of the invention, according to a second electrode structure embodiment, each electrode comprises two conductive strips shaped as two combs which are intricated within each other.
In embodiments of the invention, according to a third electrode structure embodiment, each electrode comprises several conductive strips parallel to one another and equidistant from one another, these conductive strips being raised with respect to their common non-conductive flat support, these conductive strips being narrower than the spaces between these conductive strips.
In embodiments of the invention according to a fourth electrode structure embodiment, each electrode comprises several conductive strips parallel to one another and equidistant from one another, these conductive strips and their common non-conductive flat support making altogether a flat surface, these conductive strips being wider than the spaces between these conductive strips.
Further features and advantages of the invention will appear from the following description of embodiments of the invention, given as non-limiting examples, with reference to the accompanying drawings listed hereunder.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows a sectional view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a first embodiment of the invention.
Fig. 2A shows an exploded view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a second embodiment of the invention.
Fig. 2B shows a perspective view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a second embodiment of the invention.
Fig. 2C shows a sectional view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a second embodiment of the invention.
Fig. 3 shows a sectional view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a third embodiment of the invention.
Fig. 4 shows a sectional view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a fourth embodiment of the invention.
Fig. 5A shows an exploded view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a fifth embodiment of the invention.
Fig. 5B shows a perspective view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a fifth embodiment of the invention.
Fig. 5C shows a sectional view of an example of disposition and structure of 2 electrically conductive layers of a heater for an aerosol generating device according to a fifth embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "aerosol precursor material" is a label used to mean a medium that generates an aerosol or vapour when heated. It may be synonymous with vapour precursor material, aerosol generation or generating medium, substrate, material or composition. Aerosol precursor material includes liquid or solid materials that provide volatilized components upon heating, typically in the form of vapour or an aerosol. Aerosol precursor material may be a non-tobacco-containing material or a tobacco-containing material. Aerosol precursor material may, for example, include one or more of tobacco per se, tobacco derivatives, expanded tobacco, reconstituted tobacco, tobacco extract, homogenized tobacco or tobacco substitutes. Aerosol precursor material also may include other, non-tobacco, products, which, depending on the product, may or may not contain nicotine. Aerosol precursor material may comprise one or more humectants, such as glycerol or propylene glycol.
Also, as used herein, a vapour is a substance in the gas phase at a temperature lower than its critical temperature, which means that the vapour can be condensed to a liquid by increasing its pressure without reducing the temperature, whereas an aerosol is a suspension of fine solid particles or liquid droplets, in air, another gas or a vapour. It should, however, be noted that the terms 'aerosol' and 'vapour' may be used interchangeably in this specification, particularly with regard to the form of the inhalable medium that is generated for inhalation by a user.
Fig. 1 shows a sectional view of an example of a heater H for an aerosol generating device according to a first embodiment of the invention in cooperation with a consumable article 1. The heater H comprises a first heater part 2 and a second heater part 3 comprising each an electrically conductive layer 4, 5 forming a contacting surface of the first and second heater parts 2, 3.
The first and second heater parts 2, 3 are in addition arranged such that their respective electrically conductive layers 4, 5 are facing each other and are spaced apart from each other by a distance G, thereby defining a gap in between the electrically conductive layers 4, 5. In practice, the electrically conductive layers 4, 5 form respectively a first set of electrodes 41, 42, 43, 44 and a second set of electrodes 51, 52, 53, 54. The first set of electrodes are space apart from the second set of electrodes by the distance G.
A consumable article 1 comprising a layer of an aerosol precursor material 1a is provided in the gap between the two heater parts 2, 3 in contact with the two electrically conductive layers 4, 5 facing thereof. The aerosol precursor material 1a has a thickness T substantially equal to the distance G between the electrically conductive layers 4, 5 of the heater. It comprises one or more electrical conductors (not shown in the drawing) capable of conducting electric current delivered to the aerosol precursor material 1a from the electrically conductive layers 4, 5 contacting said aerosol precursor material 1a to heat it and to generate an aerosol. The size and arrangement of the one or more electrical conductors is set such that as an electrical electric power is passed through them, the temperature of the electrical conductors increases to heat the aerosol precursor material 1a. The one or more electrical conductors may be present in a particulate form throughout the aerosol precursor material 1a.
The aerosol precursor material 1a may comprise one or more dedicated heating layers, which are regions in which there is a high level of electrical conductors, or a relatively higher level of conduction due to the nature or number of electrical conductors. In other examples, electrical conductors are distributed throughout the aerosol precursor material 1a. In one example, the aerosol precursor material 1a may be coated in one or more electrical conductors. The electrical conductors may take the form of graphite or charcoal particles. The electrical conductors may take the form of powder, loose or agglomerated particles mixed with the aerosol precursor material 1a or layered with it. It is also conceivable to use other conductive materials which are approved in particular at least in the tobacco industry or food industry. The aerosol precursor material 1 is configured to electrically connect the two electrically conductive layers 4, 5 of the heater that it is located between. In this case, providing electric power to the at least two electrically conductive layers 4, 5 is used interchangeably with providing electrical power to the aerosol precursor material 1a.
A first one 4 of the two electrically conductive layers 4 and 5 comprises four electrodes 41, 42, 43, 44, which are separated from each other by an electrically non-conductive space 8. These electrodes 41, 42, 43, 44 face respectively corresponding four electrodes 51, 52, 53, 54 of the second electrically conductive layer 5, which are separated from each other by an electrically non-conductive space 9. As represented in Fig. 1, the electrically non-conductive spaces 8 of the first electrically conductive layer 4 and the electrically non-conductive spaces 9 of the second electrically conductive layer 5 are symmetrical to each other about a median longitudinal axis A of consumable article 1 and of substantially identical dimensions in all directions of space X, Y, Z.
All electrodes 41, 42, 43, 44 of the first electrically conductive layer 4 and all electrodes 51, 52, 53, 54 of the second electrically conductive layer 5 are identical to each other.
Each electrode 41 to 54 presents an electrically conductive body 10 and an electrically conductive coating 11 which in use is in contact with an electrically conductive external surface 12 of the aerosol precursor material 1a of the consumable article.
Each electrode 41 to 54 presents a surface, preferably a substantially flat surface, configured to extend along an external surface 12 of the consumable article 1 and to be in contact with this external surface 12.
The electrodes 41, 42, 43, 44 taken altogether, extend along at least half (L/2) the length L of the consumable article 1, preferably along at least three quarters of the length L of the consumable article 1, more preferably at 90% of the length L of the consumable article 1, even more preferably along the whole length L of the elongate aerosol precursor material 1. Likewise, the electrodes 51, 52, 53, 54 taken altogether, extend along at least half (L/2) the length L of the consumable article 1 on another, symmetrical side thereof, preferably along at least three quarters of the length L of the consumable article 1, more preferably at 90% of the length L of the consumable article 1, even more preferably along the whole length L of the consumable article 1.
All electrodes 41 to 44 of the first electrically conductive layer 4 of the heater are powered at a negative tension by a power source, not represented in fig. 1, to which they are connected. All electrodes 51 to 54 of the second electrically conductive layer 5 are powered at a positive tension by a power source, not represented in fig. 1, to which they are connected. The respective power sources of electrodes 41 to 44 and 51 to 54 may be individual power sources such as lithium-ion batteries or a same power source, likewise a lithium-ion battery for example, connected to both sets of electrodes 41 to 44 and 51 to 54 respectively.
Upon delivery of current to the heater parts 2, 3 electrical current flows, from each of the electrodes 51 to 54 of the second electrically conductive layer 5 toward the electrodes 41 to 44 of the first electrically conductive layer 4 respectively, through the aerosol precursor material 1.
Except when and how mentioned to the contrary, the electrodes 41 to 54 have a similar structure and disposition in all next figures as they had in figure 1.
Fig. 2A to 2C show an exploded view, a perspective view and a sectional view of a heater H for an aerosol generating device according to a second embodiment of the invention, in cooperation with a consumable article 1. As in the first embodiment of Fig. 1, the inventive heater in that second embodiment comprises a first heater part 2 and a second heater part 3 comprising each an electrically conductive layer 4, 5 forming a contacting surface of the first and second heater parts 2, 3. The first and second heater parts 2, 3 are arranged such that their respective electrically conductive layers 4, 5 are facing each other and are spaced apart from each other by a distance G, thereby defining a gap in between the electrically conductive layers 4, 5. The electrically conductive layers 4, 5 form respectively a first set of electrodes 41, 42, 43, 44 and a second set of electrodes 51, 52, 53, 54. The first set of electrodes are spaced apart from the second set of electrodes by the distance G.
The consumable article 1 is identical to that described in relation to Fig. 1 and will not be described further in relation to that second embodiment of the heater H. The consumable article 1 comprises at least one layer of aerosol precursor material 1a that has a thickness T substantially equal to the distance G between the electrically conductive layers 4, 5 of the heater H. The consumable article is sandwiched in use between a first upper heater part 2 and second lower heater part 3. The first electrically conductive layer 4 which is located under the first upper heater part 2 goes toward the upper external surface 12 located on the aerosol precursor material 1a. The second electrically conductive layer 5 which is located on the second lower heater part 3 goes toward the lower external surface 12 located under the aerosol precursor material 1a. The thickness T of the aerosol precursor material 1a is along vertical direction y.
The electrodes 41, 42, 43, 44 of the first conductive layer 4 are separated from each other by electrically non-conductive spaces 8a, 8b. They face respectively the electrodes 51, 52, 53, 54, of the second electrically conductive layer 5, which are also separated from each other by electrically non-conductive spaces 9a, 9b. Like the two sets of electrodes 41, 42, 43, 44 and 51, 52, 53, 54 the electrically non-conductive spaces 8a, 8b of the first electrically conductive layer 4 and the electrically non-conductive spaces 9a, 9b of the second electrically conductive layer 5 are facing each other with respect to the median longitudinal axis A of the consumable article 1. However, contrary to the first embodiment of the heater H in Fig. 1 the electrically non-conductive spaces 8a, 8b of the first electrically conductive layer 4 are not all identical, and in particular they do not have a same length along horizontal direction x parallel to the axis A of the consumable article 1. As visible in Fig. 2C in particular, first electrically non-conductive space 8a between electrodes 41 and 42 and third electrically non-conductive space 8a between electrodes 43 and 44 have an identical length that is longer than non-conductive space 8b between electrodes 42 and 43.
Similarly, electrodes 51, 52, 53, 54 of the second conductive layer 5 are separated from each other by electrically non-conductive spaces 9a, 9b. The electrically non-conductive spaces 9a, 9b of the second electrically conductive layer 5 are not all identical, and in particular they do not have a same length along horizontal direction x parallel to the axis A of the consumable article 1. As visible in Fig. 2C in particular, first electrically non-conductive space 9a between electrodes 51 and 52 and third electrically non-conductive space 9a between electrodes 53 and 54 have an identical length that is shorter size than that of non-conductive space 9b between electrodes 52 and 53. Preferably, the respective lengths of first non-conductive spaces 8a of the first electrically conductive layer 4 and second electrically non-conductive space 9b of the second electrically conductive layer 5 are substantially equal. Likewise, the respective lengths of electrically non-conductive spaces 9a of the second electrically conductive layer 5 and second electrically non-conductive space 8b of the first electrically conductive layer 4 are substantially equal.
All electrodes 41-42-43-44 of first electrically conductive layer 4 and all electrodes 51-52-53-54 of second electrically conductive layer 5 are similar to each other.
Electrode 41 of first electrically conductive layer 4 is powered at a negative tension. Electrode 44 of the first electrically conductive layer 4 is powered at a positive tension. Electrodes 42 and 43 of the first electrically conductive layer 4 are not powered at any tension. Electrodes 51 to 54 of the second electrically conductive layer 5 are not powered at any tension.
Electrons e^- flow (to the contrary of the electrical current), as is shown by the curved arrows, from one electrically conductive layer to the other and vice versa, through aerosol precursor material 1, progressing from negative tension (at left of figure 2C) toward positive tension (at right of figure 2C), mostly:

from electrode 41 to electrode 51, from first electrically conductive layer 4 toward second electrically conductive layer 5, because the first electrically non-conductive space 8 of the first electrically conductive layer 4 located between electrodes 41 and 42 of the first electrically conductive layer 4 is longer than the first electrically non-conductive space 9 of second first electrically conductive layer 5 located between electrodes 51 and 52 of the second electrically conductive layer 5, and because aerosol precursor material 1 is electrically conductive, the electrons following the path offering the lowest electrical resistance,
from electrode 51 to electrode 52,
from electrode 52 to electrode 42, for similar reason as before,
from electrode 42 to electrode 43,
from electrode 43 to electrode 53, for similar reason as before,
from electrode 53 to electrode 54,
from electrode 54 to electrode 44, for similar reason as before.

Fig. 3 shows a sectional view of an example of a heater H for an aerosol generating device according to a third embodiment of the invention to heat a consumable article 1 as described in reference to the 1^st and 2^nd embodiments to generate an inhalable aerosol. The heater H comprises a first heater part 2 and a second heater part 3 comprising each an electrically conductive layer 4, 5 forming a contacting surface of the first and second heater parts 2, 3.
The electrically conductive layers 4 comprises in this 3^rd embodiment three electrodes 41, 42, 43, which are separated from each other by an electrically non-conductive space 8. These electrodes 41, 42, 43 face at least partly the opposite electrically conductive layer 5 of the second heater part 3, which comprises only two electrodes 51, 52, which are separated from each other by an electrically non-conductive space 9. As visible in Fig. 3, the electrically non-conductive spaces 8 of the first electrically conductive layer 4 are offset, and preferably symmetrical to each other, with respect to a vertical median plan M of the heater H on which the electrically non-conductive space 9 of the second electrically conductive layer 5 is centered. The electrically non-conductive spaces 8, 9 of the first and second electrically conductive layer 4, 5 are all of the same dimensions in all directions X, Y, Z.
Electrode 41 of first electrically conductive layer 4 is powered at a negative tension. Electrode 43 of the first electrically conductive layer 4 is powered at a positive tension. Electrode 42 of the first electrically conductive layer 4 is not powered at any tension. Electrodes 51 and 52 of the second electrically conductive layer 5 are not powered at any tension. Electrodes 51 and 52 are of the same size as electrode 42 which is longer than electrodes 41 and 43.
Each electrode of the second electrically conductive layer 5 faces at least partially at least 2 electrodes of the first electrically conductive layer 5:

electrode 51 faces both electrodes 41 and 42,
electrode 52 faces both electrodes 42 and 43.

At least one electrode of the first electrically conductive layer 4 faces at least partially at least 2 electrodes of the second electrically conductive layer 5:

electrode 42 faces both electrodes 51 and 52.

Electrons e^- flow (to the contrary of the electrical current), as is shown by the curved arrows, from one electrically conductive layer to the other and vice versa, through aerosol precursor material 1, progressing from negative tension (at left of figure 3) toward positive tension (at right of figure 3), mostly:

from electrode 41 to electrode 51, from first electrically conductive layer 4 toward second electrically conductive layer 5, because electrode 41 faces electrode 51, with an electrically conductive layer 1 in between, whereas electrodes 41 and 42 are separated by the first electrically non-conductive space 8 of the first electrically conductive layer 4, the electrons following the path offering the lowest electrical resistance,
from electrode 51 to electrode 42, for similar reason as before,
from electrode 42 to electrode 52, for similar reason as before,
from electrode 52 to electrode 43, for similar reason as before.

Fig. 4 shows a sectional view of an example of a heater H for an aerosol generating device according to a fourth embodiment of the invention to heat a consumable article 1 as described in reference to all of the 1^st to 3^rd embodiments to generate an inhalable aerosol. The heater H comprises a first heater part 2 and a second heater part 3 comprising each an electrically conductive layer 4, 5 forming a contacting surface of the first and second heater parts 2, 3.
The electrically conductive layers 4 comprises 4 electrodes 41, 42, 43, 44, which are separated from each other by an electrically non-conductive space 8 and which all face partly a single electrode 51 of the second electrically conductive layer 5. The electrically non-conductive spaces 8 of the first electrically conductive layer 4 are all of the same dimensions in all directions X, Y, Z. First electrically conductive layer 4 is supported by first heater part 2.
Electrodes of the first electrically conductive layer 4 are powered alternatively (in space) at a negative tension and at a positive tension, i.e. electrodes 41, 43 are powered at a negative tension while electrodes 42, 44 are powered at a positive tension.
Electrons e^- flow (to the contrary of the electrical current), as is shown by the curved arrows, from one electrically conductive layer to the other and vice versa, through aerosol precursor material 1, progressing from negative tension (at left of figure 4) toward positive tension (in the middle of figure 4, more on the left), and then again progressing from positive tension (in the middle of figure 4, more on the left) toward negative tension (in the middle of figure 4, more on the right), and then further again progressing from negative tension (in the middle of figure 4, more on the right) toward positive tension (at right of figure 4), mostly:

from electrode 41 to electrode 51, from first electrically conductive layer 4 toward second electrically conductive layer 5, because electrode 41 faces electrode 51, with an electrically conductive layer 1 in between, whereas electrodes 41 and 42 are separated by the first electrically non-conductive space 8 of the first electrically conductive layer 4, the electrons following the path offering the lowest electrical resistance,
from electrode 51 to electrode 42, for similar reason as before,
from electrode 43 to electrode 51, for similar reason as before,
from electrode 51 to electrode 44, for similar reason as before.

Fig. 5A to 5C show an exploded view, a perspective view and a sectional view of a heater H for an aerosol generating device according to a fifth embodiment of the invention, in cooperation with a consumable article 1.
The heater H in that fifth embodiment is structurally identical to the one of the first embodiment of Fig. 1. It thus comprises a first heater part 2 and a second heater part 3 comprising each an electrically conductive layer 4, 5 forming a contacting surface of the first and second heater parts 2, 3. The first and second heater parts 2, 3 are arranged such that their respective electrically conductive layers 4, 5 are facing each other and are spaced apart from each other by a distance G, thereby defining a gap in between the electrically conductive layers 4, 5. The electrically conductive layers 4, 5 form respectively a first set of electrodes 41, 42, 43, 44 separated from each other by a non-electrically conductive space 8 and a second set of electrodes 51, 52, 53, 54 separated from each other by a non-electrically conductive space 9. The first set of electrodes 41, 42, 43, 44 is spaced apart from the second set of electrodes 51, 52, 53, 54 by distance G and the two sets of electrodes and their respective non-electrically conductive spaces 8, 9 are identical and facing each other symmetrically with respect to the longitudinal median axis A of the consumable article 1.
The consumable article 1 is identical to that described in relation to Fig. 1 to 4 and will not be described further in relation to that fifth embodiment of the heater H. The consumable article 1 comprises at least one layer of aerosol precursor material 1a that has a thickness T substantially equal to the distance G between the electrically conductive layers 4, 5 of the heater H. The consumable article is sandwiched in use between a first upper heater part 2 and second lower heater part 3. The first electrically conductive layer 4 which is located under the first upper heater part 2 goes toward the upper external surface 12 located on the aerosol precursor material 1a. The second electrically conductive layer 5 which is located on the second lower heater part 3 goes toward the lower external surface 12 located under the aerosol precursor material 1a. The thickness T of the aerosol precursor material 1a is along vertical direction y.
Electrode 41 of first electrically conductive layer 4 is powered at a negative tension. Electrode 51 of second electrically conductive layer 5 is powered at a negative tension. Electrode 44 of the first electrically conductive layer 4 is powered at a positive tension. Electrode 54 of the second electrically conductive layer 5 is powered at a positive tension. Electrodes 42 and 43 of the first electrically conductive layer 4 are not powered at any tension. Electrodes 52 and 53 of the second electrically conductive layer 5 are not powered at any tension.
Electrons e^- flow (to the contrary of the electrical current), as is shown by the curved arrows, rather along both electrically conductive layers, all across the thickness of the aerosol precursor material 1, and through the aerosol precursor material 1, rather progressing from negative tension (at left of figure 5C) toward positive tension (at right of figure 5C), mostly:

from electrode 41 to electrode 42 and then to electrode 43 and then to electrode 44,
from electrode 51 to electrode 52 and then to electrode 53 and then to electrode 54.

Electrodes placed in series in order to provide a longer electrical path through the aerosol precursor material 1 and therefore achieving more uniform heating of this aerosol precursor material 1: this corresponds to electrodes' configuration of figures 2C, 3, and 4.
Electrodes' configuration where there is one or more electrical conductors, however unpowered, on one side of the aerosol precursor material 1 and multiple segments of electrodes on the other side of the aerosol precursor material 1 allow for avoiding electrical wiring on one side of the aerosol precursor material 1: this corresponds to electrodes' configuration of figures 2C, 3, 4.
In all former embodiments related to figure 1 to figure 5C, each electrode 41 to 54 has been shown as being a single and flat surface.
Similarly, in all former embodiments related to figure 1 to figure 5C, each electrode 41 to 54 can also been shown as comprising two conductive strips shaped as two combs which are intricated within each other.
Similarly, in all former embodiments related to figure 1 to figure 5C, each electrode 41 to 54 can also been shown as comprising several conductive strips parallel to one another and equidistant from one another, these conductive strips being raised with respect to their common non-conductive flat support, these conductive strips being narrower than the spaces between these conductive strips.
Similarly, in all former embodiments related to figure 1 to figure 5C, each electrode 41 to 54 can also been shown as comprising several conductive strips parallel to one another and equidistant from one another, these conductive strips and their common non-conductive flat support making altogether a flat surface, these conductive strips being wider than the spaces between these conductive strips.
The invention has been described with reference to preferred embodiments. However, many variations are possible within the scope of the invention.

Claims

Heater for an aerosol generating device configured to operate with a consumable article (1) comprising an electrically conductive heating layer of aerosol precursor material (1), the heater comprising:
- two electrically conductive layers (4, 5) facing each other and spaced apart from each other so as to sandwich said electrically conductive heating layer of aerosol precursor material (1),
wherein:
- a first one (4) of the electrically conductive layers (4, 5) comprises at least one electrode (41 to 44),

- a second one (5) of the electrically conductive layers (4, 5) comprises at least two electrodes (51 to 54) which are separated from each other by an electrically non-conductive space (9) and which face at least partially one electrode (41 to 44) of said first electrically conductive layer (4).
Heater for an aerosol generating device according to claim 1, wherein each electrode (41 to 54) presents a surface configured to extend along an external surface (12) of the consumable (1) and be in contact with this external surface (12).
Heater for an aerosol generating device according to claim 2, wherein the electrodes (41 to 44, or 51 to 54)), taken altogether, extend along at least half the length (L) of an elongate aerosol precursor material (1).
Heater for an aerosol generating device according to any of preceding claims, wherein the electrodes (41 to 54) are flat electrodes extending along the external surface (12) of the aerosol precursor material (1).
Heater for an aerosol generating device according to any of preceding claims, wherein said first electrically conductive layer (4) comprises at least two electrodes (41 to 44) which are separated from each other by an electrically non-conductive space (8) and which face at least partially one electrode (51 to 54) of said second electrically conductive layer (5).
Heater for an aerosol generating device according to any of preceding claims, wherein:
- each electrode (51 to 54) of said second electrically conductive layer (5) faces at least partially at least 2 electrodes (41 to 44) of said first electrically conductive layer (4),

- and/or at least one electrode (41 to 44) of said first electrically conductive layer (4) faces at least partially at least 2 electrodes (51 to 54) of said second electrically conductive layer (5).
Heater for an aerosol generating device according to any of claims 1 to 6, wherein:
- all electrodes (41 to 44) of said first electrically conductive layer (4) are powered at a negative tension,

- all electrodes (51 to 54) of said second electrically conductive layer (5) are powered at a positive tension.
Heater for an aerosol generating device according to any of claims 1 to 6, wherein:
- no electrode of said second electrically conductive layer (5) is powered at any tension,

- one or more electrodes (41 to 44) of said first second electrically conductive layer (4) is or are powered at a negative tension,

- one or more electrodes (41 to 44) of said first electrically conductive layer (4) is or are powered at a positive tension.
Heater for an aerosol generating device according to claim 7, wherein:
- only one electrode (41) of said first electrically conductive layer (4) is powered at a negative tension,

- only one electrode (44) of said first electrically conductive layer (4) is powered at a positive tension,

- said negative tension powered electrode (41) and said positive tension powered electrode (44) of said first electrically conductive layer (4) are configured to face opposite ends of said consumable electrically conductive heating layer (1).
Heater for an aerosol generating device according to claim 9, wherein:
- all electrodes (41 to 44) of said first electrically conductive layer (4) are:
∘ powered at:
▪ either a negative predetermined tension,

▪ or a positive predetermined tension,

∘ and disposed relatively so that 2 electrodes (42, 44) powered at a positive tension are separated by an electrode (43) powered at a negative tension and/or so that 2 electrodes (41, 43) powered at a negative tension are separated by an electrode (42) powered at a positive tension.
Heater for an aerosol generating device according to any of claims 1 to 10, wherein each electrode (41 to 54) is a single and flat surface.
Heater for an aerosol generating device according to any of claims 1 to 10, wherein each electrode (41 to 54) comprises two conductive strips shaped as two combs which are intricated within each other.
Heater for an aerosol generating device according to any of claims 1 to 10, wherein:
- each electrode (41 to 54) comprises several conductive strips parallel to one another and equidistant from one another,
∘ these conductive strips being raised with respect to their common non-conductive flat support,

∘ these conductive strips being narrower than the spaces between these conductive strips.
Heater for an aerosol generating device according to any of claims 1 to 10, wherein:
- each electrode (41 to 54) comprises several conductive strips parallel to one another and equidistant from one another,
∘ these conductive strips and their common non-conductive flat support making altogether a flat surface,

∘ these conductive strips being wider than the spaces between these conductive strips.
Aerosol generating system comprising:
- a consumable article (1) comprising an electrically conductive heating layer of aerosol precursor material (1);

- an aerosol generating device comprising a heater according to any one of the preceding claims.