WO2024153758A1

WO2024153758A1 - Aerosol generating device configured to operate with an aerosol generating substrate

Info

Publication number: WO2024153758A1
Application number: PCT/EP2024/051184
Authority: WO
Inventors: Alec WRIGHT; Jaakko MCEVOY
Original assignee: JT International SA
Current assignee: JT International SA
Priority date: 2023-01-19
Filing date: 2024-01-18
Publication date: 2024-07-25
Anticipated expiration: 2025-07-19
Also published as: EP4651745A1; KR20250131799A

Abstract

The invention relates to an aerosol generating device configured to operate with a flat- shaped tobacco article (12) and comprising a flat-shaped heating chamber (50) extending along a device longitudinal axis (X'). The heating chamber (50) is configured to receive at least a tobacco portion (15) of the flat-shaped tobacco article (12) and comprises a continuous heating surface (72A) configured to be in contact with a first external surface of the tobacco portion (15). The area of the heating surface (72A)) is comprised between 35% and 99% of the area of the first external surface of the tobacco portion (15).

Description

Aerosol generating device configured to operate with an aerosol generating substrate

FIELD OF THE INVENTION

The present invention concerns an aerosol generating device configured to operate with an aerosol generating substrate.

Particularly, the aerosol generating device according to the invention is configured to operate with a tobacco article, for example a flat-shaped tobacco article, which comprises for example a solid substrate able to form aerosol when being heated. Thus, such type of aerosol generating devices, also known as heat-not-burn devices, is adapted to heat, rather than burn, the substrate by conduction, convection and/or radiation, to generate aerosol for inhalation.

BACKGROUND OF THE INVENTION

The popularity and use of reduced-risk or modified-risk devices (also known as vaporisers) has grown rapidly in the past few years as an aid to assist habitual smokers wishing to quit smoking traditional tobacco products such as cigarettes, cigars, cigarillos, and rolling tobacco. Various devices and systems are available that heat or warm vaporizable substances as opposed to burning tobacco in conventional tobacco products.

A commonly available reduced-risk or modified-risk device is the heated substrate aerosol generation device or heat-not-burn device. Devices of this type generate aerosol or vapour by heating an aerosol substrate that typically comprises moist leaf tobacco or other suitable vaporizable material to a temperature typically in the range 150°C to 350°C. Heating an aerosol substrate, but not combusting or burning it, releases aerosol that comprises the components sought by the user but not the toxic and carcinogenic by-products of combustion and burning. Furthermore, the aerosol produced by heating the tobacco or other vaporizable material does not typically comprise the burnt or bitter taste resulting from combustion and burning that can be unpleasant for the user and so the substrate does not therefore require the sugars and other additives that are typically added to such materials to make the smoke and/or vapour more palatable for the user. An aerosol generating device generally encloses at least one heating plate intended to heat the aerosol substrate. During operation, a heat transfer occurs between the heating plate and the aerosol substrate. However, heating plates come with a downside of consuming a lot of energy to be brought up to a predefined temperature and thus to heat the tobacco article to a target temperature. Hence, autonomy of the aerosol generating device is limited and a user needs to reload or to replace the power batteries of the device often.

SUMMARY OF THE INVENTION

One of the aims of the invention is to provide an aerosol generating device requiring less energy to heat and evaporate the vaporizable material from a tobacco article.

For this purpose, the invention relates to an aerosol generating device configured to operate with a flat-shaped tobacco article and comprising a flat-shaped heating chamber extending along a device longitudinal axis, the flat-shaped tobacco article extending along an article longitudinal axis and comprising a tobacco portion and a non-tobacco portion arranged successively along the article longitudinal axis, the tobacco portion defining a first external surface and a second external surface opposite to the first external surface ; the heating chamber being configured to receive at least the tobacco portion of the flat-shaped tobacco article and comprising a first heating plate forming partially a wall of the heating chamber, the first heating plate comprising a continuous first heating surface configured to be in contact with the first external surface of the tobacco portion ; wherein the area of the heating surface is comprised between 35% and 99% of the area of the first external surface of the tobacco portion.

The inventors have found that, surprisingly, the heating surface in contact with the external surface of the tobacco portion could be smaller than said external surface, while still providing sufficient heating to evaporate the vaporizable material.

Thanks to these features, it is possible to provide an aerosol generating device requiring less energy to heat and evaporate the vaporizable material from a tobacco article while heating the tobacco article in an optimal way. Particularly, thanks to its small size, the first heating surface enables to rapidly heat the tobacco article to a predetermined temperature and to maintain its temperature close to this predetermined temperature with little energy, as compared to larger heating plates.

Additionally, the first heating surface achieves a homogeneous heating during the whole vaping session, improving the user’s experience.

Furthermore, by providing a heating surface smaller than the external surface of the tobacco portion in which it is in contact, it is possible to not put the bottom part of the tobacco portion in contact with the heating surface, thus reducing vapour formed at the bottom end of the chamber that may leak, condensate and then require cleaning by the user.

According to some embodiments, the area of the first heating surface is comprised between 40% and 95%, preferably between 40% and 90%, more preferably between 45% and 85%, advantageously between 50% and 80%, advantageously between 50% and 75%, of the area of the first external surface of the tobacco portion.

Thank to these features, heating of the tobacco portion is further optimized in term of energy.

According to some embodiments, the heating chamber further comprises a second heating surface configured to be in contact with the second external surface of the tobacco portion.

Having a second heating surface allows a more homogenous heating of the tobacco article during the whole vaping session, by allowing a higher thermal penetration into the tobacco article, which enables to generate more vapour as compared to having only a first heating surface.

Consequently, a combination of two heating surfaces, with at least one being smaller than the external surface of the tobacco portion, enables to optimize the heating of the flatshaped tobacco article, while requiring less energy than in previous aerosol generating devices.

Furthermore, each heating surface may present different sizes, materials and/or physical properties, to ensure better operation of the aerosol generating device. For example, one of the heating surface may be heated more rapidly, allowing a quick preheating phase, while the other may store thermal energy and heat more homogeneously.

According to some embodiments, the area of the second heating surface is comprised between 35% and 99%, preferably between 40% and 95%, preferably between 40% and 90%, more preferably between 45% and 85%, advantageously between 50% and 80%, advantageously between 50% and 75%, of the area of the second external surface of the tobacco portion.

Thanks to these features, the energy required to heat the second heating surface to the predetermined temperature is also reduced. Less energy than in previous aerosol generating devices is required, thus improving the autonomy of the aerosol generating device.

According to some embodiments, the first and the second heating surfaces form same dimensions and are arranged opposite to each other aligned according to an elevation axis perpendicular to each of the surfaces.

Thanks to these features, the tobacco portion is sandwiched between the heating surfaces and is heated evenly from both sides. Higher thermal penetration is reached into the tobacco article, which enables to generate more vapour fast.

According to some embodiments, the first and the second heating surfaces are arranged opposite to each other according to an elevation axis perpendicular to each of the heating surfaces, the heating surfaces being in offset relative to each other according to an offset axis perpendicular to the elevation axis.

Hence, it is possible to better control the heating of the tobacco portion carried out by the heating surfaces. It is possible to create different heating areas in the tobacco portion, depending on their positions relative to the heating surfaces, in order to optimize the heating of the tobacco portion.

According to some embodiments, the first and the second heating surfaces are operated at different target temperatures. Thanks to these features, it is possible to control the heating of the tobacco portion carried out by different heating surfaces using different heating profiles. Each heating profile can be chosen for example based on the nature of the heating surface. Thus, the heating of the tobacco portion can be optimized according to the different heating plates.

The temperature at which each surface is heated can also be adjusted depending of the position of the heating surface relative to the tobacco portion. For example, a heating surface facing an abutting part of the tobacco portion may be heated at a lower temperature than a heating surface closer to the mouthpiece, reducing vapour formed at the bottom end of the chamber that would otherwise leak, condensate and then require cleaning by the user.

According to some embodiments, the or each heating surface forms a length measured according to the device longitudinal axis and comprised between 60% and 99% preferably between 70% and 95%, more preferably between 75% and 90%, of a length of the corresponding external surface of the tobacco portion, measured according to the article longitudinal axis

According to some embodiments, the or each heating surface forms a width measured according to a device transversal axis perpendicular to the device longitudinal axis and comprised between 60% and 99% preferably between 70% and 95%, more preferably between 75% and 90%, of a width of the corresponding external surface of the tobacco portion, measured according to an article transversal axis perpendicular to the article longitudinal axis.

Thanks to these features, sufficient heating of the tobacco portion is ensured.

According to some embodiments, the heating chamber comprises a first plate forming partially a wall of the heating chamber, the first heating plate comprising the first heating surface, the heating chamber preferably comprising a second heating plate comprising the second heating surface, the first heating plate and the second heating plate forming partially opposite walls of the heating chamber.

According to some embodiments, the or each heating plate includes a planar substrate and a resistive heating track embedded in or mounted on the planar substrate. According to some embodiments, the planar substrate of the or each heating plate comprises a rigid material. The rigid material is preferably chosen between ceramics and metal.

Metal and ceramics present both good physical properties to ensure the operation of the aerosol generating device according to the invention. For example, it is known that ceramics presents a greater value of heat capacity than metal. Metal heating plates can be heated more rapidly whereas ceramics heating plates can store more thermal energy and heat more homogeneously the tobacco portion.

The heating plates may be made of the same material or of different materials, depending of the thermal properties required.

Each heating plate can present a homogeneous body made from a same material, like as metal or ceramics.

For example, at least one heating plate may be made of oxide ceramic material, such as AI2O3, zirconia, silicon nitride or aluminum nitride.

In a variant, the planar substrate of the or each heating plate comprises a flexible, heat-resistant resin. The resin is preferably chosen between polyimide and fluororesin.

In a variant, the heating chamber comprises a long strip of flexible heater comprising two separate track patterns and wound around the heating chamber so those two patterns form the first and second heating surfaces respectively.

According to some embodiments, the or each heating surface is associated with a unique heating element.

In other words, each plate is made in one piece, providing a continuous heating surface. It allows a more homogeneous heating of the external surface of the tobacco portion, compared to a heating plate made of a plurality of heating elements.

BRIEF DESCRIPTION OF THE DRAWINGS The invention and its advantages will be better understood upon reading the following description, which is given solely by way of non-limiting example and which is made with reference to the appended drawings, in which:

- Figure 1 is a perspective view of an aerosol generating assembly, the aerosol generating assembly comprising an aerosol generating device according to the invention and a tobacco article usable with the aerosol generating device;

- Figure 2 is a perspective view of the tobacco article of Figure 1 ;

- Figure 3 is a partial cross-sectional view of the aerosol generating assembly of Figure 1 according to plane III; and

- Figure 4 is a partial perspective view of the aerosol generating assembly of Figure 1 , in which only the tobacco article and the first heating plate of the aerosol generating device have been represented.

DETAILED DESCRIPTION OF THE INVENTION

Before describing the invention, it is to be understood that it is not limited to the details of construction set forth in the following description. It will be apparent to those skilled in the art having the benefit of the present disclosure that the invention is capable of other embodiments and of being practiced or being carried out in various ways.

The expression “substantially equal to” is understood hereinafter as an equality at plus or minus 10% and preferably at plus or minus 5%.

As used herein, the term “aerosol generating device” or “device” may include a vaping device to deliver an aerosol to a user, including an aerosol for vaping, by means of a heater element explained in further detail below. The device may be portable. “Portable” may refer to the device being for use when held by a user. The device may be adapted to generate a variable amount of aerosol, e.g. by activating the heater element for a variable amount of time (as opposed to a metered dose of aerosol), which can be controlled by a trigger. The trigger may be user activated, such as a vaping button and/or inhalation sensor. The inhalation sensor may be sensitive to the strength of inhalation as well as the duration of inhalation to enable a variable amount of vapour to be provided (so as to mimic the effect of smoking a conventional combustible smoking article such as a cigarette, cigar or pipe, etc.). The device may include a temperature regulation control to drive the temperature of the heater and/or the heated aerosol generating substance (aerosol pre-cursor) to a specified target temperature and thereafter to maintain the temperature at the target temperature that enables efficient generation of aerosol.

As used herein, the term “aerosol” may include a suspension of vaporizable material as one or more of: solid particles; liquid droplets; gas. Said suspension may be in a gas including air. Aerosol herein may generally refer to/include a vapour. Aerosol may include one or more components of the vaporizable material.

As used herein, the term “vaporizable material” or “precursor” may refer to a smokable material which may for example comprise nicotine or tobacco and an aerosol former. Tobacco may take the form of various materials such as shredded tobacco, granulated tobacco, tobacco leaf and/or reconstituted tobacco. Suitable aerosol formers include: a polyol such as sorbitol, glycerol, and glycols like propylene glycol or triethylene glycol; a non-polyol such as monohydric alcohols, acids such as lactic acid, glycerol derivatives, esters such as triacetin, triethylene glycol diacetate, triethyl citrate, glycerin or vegetable glycerin. In some embodiments, the aerosol generating agent may be glycerol, propylene glycol, or a mixture of glycerol and propylene glycol. The substrate may also comprise at least one of a gelling agent, a binding agent, a stabilizing agent, and a humectant.

Figure 1 shows an aerosol generating assembly 10 comprising an aerosol generating device 1 1 and a tobacco article 12. The aerosol generating device 11 is intended to operate with the tobacco article 12 which is shown in more detail in Figure 2.

In the example of this Figure 2, the tobacco article 12 is a flat-shaped tobacco article presenting for example a flat-shaped cuboid extending along an article longitudinal axis X and having external dimensions L12xW12xD12. In a typical example, the length L12 of the article 12 according to the article longitudinal axis X equals substantially to 33 mm while its width W12 and depth D12 are substantially equal respectively to 12 mm and 1 ,2 mm. According to different examples, the values L12, W12 and D12 can be selected within a range of +/- 40%, for example. The depth D12 of the tobacco article 12 is formed by a pair of parallel walls 13A, 13B, called hereinafter narrow walls 13A, 13B, and the width W12 of the tobacco article 12 is formed by a pair of parallel walls 14A, 14B, called hereinafter wide walls 14A, 14B. In some embodiments, the edges between the wide and narrow walls 13A, 13B, 14A, 14B can be rounded. According to other embodiments of the invention, the tobacco article 12 can have any other suitable flat shape and/or external dimensions. According to still other embodiments, the tobacco article 12 can present any other suitable shape, as for example a stick shape. According to some embodiments, the wide walls 14A, 14B may present corrugations.

The tobacco article 12 comprises a tobacco portion 15 and a non-tobacco portion 16, also called mouthpiece portion 16, arranged along the article longitudinal axis X. The tobacco portion 15 may for example be slightly longer than the non-tobacco portion 16. The tobacco portion 15 is formed by parallel walls 15A, 15B which are parts of the wide walls 14A, 14B of the tobacco article 12. For example, the length L15 of the tobacco portion 15 according to the article longitudinal axis X may be substantially equal to 18 mm. The width W15 of the tobacco portion 15 is equal to the width W12 of the tobacco article 12. The length L16 of the mouthpiece portion 16 according to the article longitudinal axis X may be substantially equal to 15 mm. The tobacco portion 15 defines an abutting end 18 of the article 12 and the non-tobacco portion 16 defines a mouth end 20 of the article 12.

The tobacco portion 15 and the non-tobacco portion 16 may be fixed one to the other by a wrapper 21 extending around the article longitudinal axis X. The wrapper 21 forms the narrow and wide walls 13A, 13B, 14A, 14B of the tobacco article 12. In some embodiments, the wrapper 21 is formed from a same wrapping sheet. In some other embodiments, the wrapper 21 is formed by separate wrapping sheets wrapping separately the portions 15, 16 and fixed one to the other by any other suitable mean. The wrapper 21 may, for example, comprise paper and/or non-woven fabric and/or aluminium foil. The wrapper 21 may be porous or air impermeable and forms a plurality of airflow channels extending inside the article 12 between the abutting end 18 and the mouth end 20.

The non-tobacco portion 16 comprises a core 27 intended to act for example as a cooler to cool slightly the vapour before it is inhaled by the user. The core 27 may comprise for this purpose for example corrugated paper. Advantageously, the core 27 is arranged inside the non-tobacco portion 16 to be entirely in contact with the internal surface of the wrapper 21 delimiting this non-tobacco portion 16. The tobacco portion 15 comprises a vaporizable material and is intended to be heated by a heating chamber, as it will be explained in further detail below.

The tobacco portion 15 defines a first external surface 30 and a second external surface 32 opposite to the first external surface 30. In the example of Figure 2, the first and second external surfaces 30, 32 correspond to the external surface of the wide walls 14A, 14B.

Referring again to Figure 1 , the aerosol generating device 1 1 comprises a device body 40, extending along a device axis X’, and a mouthpiece 42. According to the example described below, the mouthpiece 42 and the device body 40 form two different pieces. Particularly, according to this example, the mouthpiece 42 is designed to be fixed on a fixing end of the device body 40.

As it is shown in Figure 3, the mouthpiece 42 comprises a central part 43 and a peripheral part 44 extending around the central part 43. The peripheral part 44 defines for example a collar covering partially an external surface of the device body 40 when the mouthpiece 42 is fixed on the fixing end of the device body 40. For example, the peripheral part 44 can be designed to cooperate with a gasket 45 arranged on the fixing end of the device body 40 in order to seal the space formed between the peripheral part 44 and the external surface of the device body 40. The central part 43 of the mouthpiece 42 defines a through-hole 46 adapted to receive at least partially the tobacco article 12. Particularly, the through-hole 46 can be adapted to receive at least a part of the non-tobacco portion 16 of the tobacco article 12 as it is shown in Figure 3. Advantageously, the through-hole 46 can be adapted to fit tightly the non-tobacco portion 16 of the tobacco article 12 so as to avoid or minimise flow leakage between a wall delimiting the through hole 46 and an external surface of the tobacco article 12. In some embodiments, the tobacco article 12 can be retained for example by friction in the through-hole 46. In this case, it is possible for example to insert first the mouthpiece portion 16 of the tobacco article 12 inside the through-hole 46 and when fix both elements on the fixing end of the device body 40. As it is also shown in Figure 3, an inner volume 47 is formed between an inner surface 48 of the mouthpiece 42 and the fixing end of the device body 40. This inner volume 47 is crossed by the tobacco article 12 when it is inserted inside the device body 40. For example, the tobacco article 12 can divide the inner volume 47 in two symmetric parts. The device body 40 delimits an internal space of the device 1 1 receiving various elements designed to carry out different functionalities of the device 1 1 . This internal space can for example receive a battery for powering the device 11 , a controller for controlling the operation of the device 11 , a flat-shaped heating chamber 50 (hereinafter “heating chamber 50”) for heating the tobacco portion 15 of the tobacco article 12, etc. Among these elements, only the flat-shaped heating chamber 50 will be explained in further detail in reference to Figure 3.

Particularly, as it is shown in Figure 3, the heating chamber 50 is configured to receive the tobacco article 12. The heating chamber 50 has a flat shape adapted to receive at least the tobacco portion 15 of the tobacco article 12. Similarly to the tobacco article 12, the heating chamber 50 may also form a cuboid shape extending along the device axis X’ and comprising a pair of parallel narrow walls (not visible) extending along the device axis X, a pair of parallel wide walls 54A, 54B extending also along the device axis X’ and a bottom wall 58 adjacent to each of said walls and extending perpendicularly to the device axis X. The bottom wall 58 forms thus a closed end of the chamber 50. Opposite to the bottom wall 58, the heating chamber 50 defines an opening configured to receive the tobacco article 12 so that the corresponding wide walls 14A, 14B of the tobacco article 12 face the corresponding wide walls 54A, 54B of the heating chamber 50, the corresponding narrow walls 13A, 13B of the tobacco article 12 face the corresponding narrow walls of the heating chamber 50 and the abutting end 18 of the tobacco article 12 faces the bottom wall 58. In the example of Figure 3, the abutting end 18 of the tobacco article 12 faces the bottom wall 58 without being in contact with it. Alternatively, the abutting end 18 of the tobacco article 12 abuts against the bottom wall 58. The facing wide walls 14A, 14B, 54A, 54B and the facing narrow walls 53A, 53B can be in contact one with the other or spaced one from the other.

In the example shown in Figure 3, the heating chamber 50 comprises a first heating plate 70A forming at least partially a wall of the heating chamber 50, more particularly a wide wall 54A of the heating chamber 50. The first heating plate 70A comprises a continuous heating surface 72A, advantageously a smooth heating surface 72A, configured to be in contact with an external surface 30, 32 of the tobacco portion 15. For example, as shown in Figure 3, the heating surface 72A of the first heating plate 70A is configured to be in contact with the first external surface 30 of the tobacco portion 15. In a variant (not shown), instead of heating plates, the heating chamber 50 comprises a long strip of flexible heater comprising two separate track patterns and wound around the heating chamber so those two patterns form the first and second heating surfaces 72A, 72B.

By “continuous” used in relation with a heating surface, it is meant that this surface has no discontinuous portions except its outer borders. In other words, a continuous heating surface extends continuously between its outer borders. Additionally, when a continuous heating surface is smooth, it has at least a first order derivative at each point except the outer borders.

Advantageously, as visible on Figure 3, the heating chamber 50 also comprises a second heating plate 70B arranged opposite to the first heating plate 70A. The first and the second heating plates 70A, 70B thus form at least partially opposite walls of the heating chamber 50, the second heating plate 70B forming a wide wall 54B of the heating chamber 50. The tobacco portion 15 is sandwiched between the two heating plates 70A, 70B. Said second heating plate 70B comprises a heating surface 72B configured to be in contact with the second external surface 32 of the tobacco portion 15. Advantageously, said heating surface 72B is also continuous and is advantageously smooth.

According to the invention, at least the heating surface 72A of the first heating plate 70A is designed to extend along only a partial area of the tobacco portion 15. In other words, the area of said heating surface 72A is comprised between 35% and 99% of the area of the first external surface 30 of the tobacco portion 15. In a preferred embodiment, the heating surface 72B of the second heating plate 70B is also designed to extend along only a partial area of the tobacco portion 15. In other words, the area of said heating surface 72B is comprised between 35% and 99%of the area of the second external surface 32 of the tobacco portion 15.

Advantageously, the area of the heating surface 72A, 72B of the first and/or second heating plate 70A, 70B is comprised between 40% and 95%, preferably between 40% and 90%, more preferably between 45% and 85%, advantageously between 50% and 80%, advantageously between 50% and 75%, of the area of the corresponding external surface 30, 32 of the tobacco portion 15. In other words, the tobacco portion 15 protrudes from at least one end of the first heating plate 70A and/or the second heating plate 70B. Advantageously, as shown in Figure 4, the length and the width of the first heating plate 70A and/or second heating plate 70B are smaller than the length L15 and width W15 of the tobacco portion 15, so that the tobacco portion 15 protrudes from both ends of the first heating plate 70A and/or second heating plate 70B.

Advantageously, the area of the heating surface 72A, 72B of the first and/or second heating plate 70A, 70B is comprised between 15% and 60%, preferably between 20% and 50%, advantageously between 25% and 40%, of the area of an external surface of the flatshaped tobacco article 12.

In the example shown in Figures 3 and 4, each heating plate 70A, 70B forms a flatshaped cuboid extending along the device longitudinal axis X’ and having external dimensions L70xW70xD70.

In the example of Figure 3, the heating plates 70A, 70B have substantially the same dimensions. Alternatively, the heating plates 70A, 70B have different dimensions.

Advantageously, the heating surface 72A, 72B of the or each heating plate 70A, 70B forms a length L70 measured according to the device longitudinal axis X’ and comprised between 60% and 99%, preferably between 70% and 95%, more preferably between 75% and 90%, of the length L15 of the corresponding external surface 30, 32 of the tobacco portion 15, measured according to the article longitudinal axis X.

Advantageously, the heating surface 72A, 72B of the or each heating plate 70A, 70B forms a width W70 measured according to a device transversal axis Y’ perpendicular to the device longitudinal axis X’ and comprised between 60% and 99% preferably between 70% and 95%, more preferably between 75% and 90%, of the width W15 of the corresponding external surface 30, 32 of the tobacco portion 15, measured according to an article transversal axis Y perpendicular to the article longitudinal axis X.

The depth D70 of the or each heating plate 70A, 70B may depend on the dimensions of the tobacco article 15. For example, the depth D70 of the or each heating plate 70A, 70B is greater or equal to 0,25 mm and less than or equal to 0,75 mm. In the embodiment of Figure 3, the first and the second heating plates 70A, 70B form same dimensions and are arranged opposite to each other, aligned according to an elevation axis Z perpendicular to each of the plates 70A, 70B.

According to another embodiment (not shown), the first and the second heating plates 70A, 70B are arranged opposite to each other according to the elevation axis Z, said plates 70A, 70B being in offset relative to each other according to an offset axis perpendicular to the elevation axis Z. In other words, the first and the second heating plates 70A, 70B are arranged to form in a central plane arranged between the heating plates 70A, 70B at least one first zone corresponding to an overlapping zone of orthogonal projections of the heating plates in the central plane and at least one second zone corresponding to a non-overlapping zone of said orthogonal projections.

The or each heating plate 70A, 70B can present a homogeneous body 75 made from a same material, like as metal (like copper), ceramics, etc. Preferably, at least one or each heating plate 70A, 70B is made from a ceramic substrate, for example made of AI2O3, zirconia, silicon nitride or aluminum nitride. In a variant, the or each heating plate 70A, 70B is made of a resin substrate layer, such as polyimide for example.

The heating plates 70A, 70B may be made of the same material or of different materials (as shown on Figure 3), depending of the desired thermal properties.

The or each heating plate 70A, 70B comprises a unique heating element presenting for example a resistive element. Such a resistive element forms for example a resistive heater track 80, embedded into the body of the heating plate 70A, 70B and connected to the controller, as known per se. In the further description, by powering a heating plate, it is understood powering of the resistive element associated with the respective heating plate 70A, 70B.

The controller (not shown) is configured to control the operation and particularly the powering of the or each heating surfaces 72A, 72B, in particular of the or each heating plate 70A, 70B, so that the or each heating surfaces 72A, 72B reaches a predetermined target temperature.

Said target temperature is for example comprises between 240°C and 320°C, for example equal to 280°C. The first and the second heating surfaces 72A, 72B may be operated at different target temperatures. Particularly, the controller may be configured to power the first heating plate 70A according to a first target temperature and the second heating plate 70B according to a second target temperature. Each target temperature can be chosen based on the nature of the heating plate and notably, based on the heat capacity of the heating plate and/or position of each heating plate 70A, 70B. Thus, the heating of the tobacco portion can be optimized according to the different heat capacity and/or position of the heating plates 70A, 70B.

It will be apparent to those skilled in the art that other embodiments may be carried out in various ways by combining different features of previously described embodiments.

Claims

1 . An aerosol generating device (11 ) configured to operate with a flat-shaped tobacco article (12) and comprising a flat-shaped heating chamber (50) extending along a device longitudinal axis (X’), the flat-shaped tobacco article (12) extending along an article longitudinal axis (X) and comprising a tobacco portion (15) and a non-tobacco portion (16) arranged successively along the article longitudinal axis (X), the tobacco portion (15) defining a first external surface (30) and a second external surface (32) opposite to the first external surface (30) ; the heating chamber (50) being configured to receive at least the tobacco portion (15) of the flat-shaped tobacco article (12) and comprising a continuous first heating surface (72A) configured to be in contact with the first external surface (30) of the tobacco portion (15); wherein the area of the heating surface (72A) is comprised between 35% and 99% of the area of the first external surface (30) of the tobacco portion (15).

2. The aerosol generating device (11 ) according to claim 1 , wherein the area of the first heating surface (72A) is comprised between 40% and 95%, preferably between 40% and 90%, more preferably between 45% and 85%, advantageously between 50% and 80%, advantageously between 50% and 75%, of the area of the first external surface (30) of the tobacco portion (15).

3. The aerosol generating device (11 ) according to claim 1 or 2, wherein the heating chamber (50) further comprises a second heating surface (72B) configured to be in contact with the second external surface (32) of the tobacco portion (15).

4. The aerosol generating device (11 ) according to claim 3, wherein the area of the second heating surface (72B) is comprised between 35% and 99%, preferably between 40% and 95%, preferably between 40% and 90%, more preferably between 45% and 85%, advantageously between 50% and 80%, advantageously between 50% and 75%, of the area of the second external surface (32) of the tobacco portion (15).

5. The aerosol generating device (11 ) according to claim 3 or 4, wherein the first and the second heating surfaces (72A, 72B) form same dimensions and are arranged opposite to each other aligned according to an elevation axis (Z) perpendicular to each of the surfaces (72A, 72B).

6. The aerosol generating device (11 ) according to claim 3 or 4, wherein the first and the second heating surfaces (72A, 72B) are arranged opposite to each other according to an elevation axis (Z) perpendicular to each of the heating surfaces (72A, 72B), the heating surfaces (72A, 72B) being in offset relative to each other according to an offset axis perpendicular to the elevation axis (Z).

7. The aerosol generating device (11 ) according to any one of claim 3 to 6, wherein the first and the second heating surfaces (72A, 72B) are operated at different target temperatures.

8. The aerosol generating device (1 1 ) according to any one of the preceding claims, wherein the or each heating surface (72A, 72B) forms a length (L70) measured according to the device longitudinal axis (X’) and comprised between 60% and 99% preferably between 70% and 95%, more preferably between 75% and 90%, of a length of the corresponding external surface (30, 32) of the tobacco portion (15), measured according to the article longitudinal axis (X).

9. The aerosol generating device (11 ) according to any one of the preceding claims, wherein the or each heating surface (72A, 72B) forms a width (W70) measured according to a device transversal axis (Y’) perpendicular to the device longitudinal axis (X’) and comprised between 60% and 99% preferably between 70% and 95%, more preferably between 75% and 90%, of a width of the corresponding external surface (30, 32) of the tobacco portion (15), measured according to an article transversal axis (Y) perpendicular to the article longitudinal axis (X).

10. The aerosol generating device (11 ) according to any one of the preceding claims, wherein the heating chamber (50) comprises a first plate (70A) forming partially a wall of the heating chamber (50), the first heating plate (70A) comprising the first heating surface (72A), the heating chamber (50) preferably comprising a second heating plate (70B) comprising the second heating surface (72B), the first heating plate (70A) and the second heating plate (70B) forming partially opposite walls of the heating chamber (50).

1 1. The aerosol generating device (1 1 ) according to claim 10, wherein the or each heating plate (70A, 70B) including a planar substrate and a resistive heating track (80) embedded in or mounted on the planar substrate.

12. The aerosol generating device (11 ) according to claim 1 1 , wherein the planar substrate of the or each heating plate (70A, 70B) comprises a rigid material, preferably chosen between ceramics and metal.

13. The aerosol generating device (11 ) according to claim 1 1 , wherein the planar substrate of the or each heating plate (70A, 70B) comprises a flexible, heat-resistant resin, preferably chosen between polyimide and fluororesin.

14. The aerosol generating device (11 ) according to any one of claims 1 to 9, wherein the heating chamber (50) comprises a long strip of flexible heater comprising two separate resistive track patterns and wound around the heating chamber (50) so the two separate resistive track patterns form the first and second heating surfaces (72A, 72B) respectively.

15. The aerosol generating device (11 ) according to any one of the preceding claims, wherein the or each heating surface (72A, 72B) is associated with a unique heating element.