Aerosol generating device including two heating plates and related control method

Abstract

The present 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), the heating chamber (50) configured to receive the flat shaped tobacco article (12) and comprising a first heating plate (70A) and a second heating plate (70B) forming at least partially opposing walls (54A, 54B) of the heating chamber (50), the heating plates (70A, 70B) being made of different materials having different thermal masses, the thermal mass of the second heating plate (70B) being greater than the thermal mass of the first heating plate (70A).

Description

[Technical field]

[0001] The present invention relates to an aerosol generating device that includes two different heating plates.

[0002] In particular, the aerosol generating device according to the invention is configured to operate with tobacco articles, e.g. flat shaped tobacco articles comprising a solid substrate capable of forming an aerosol when heated. Thus, such types of aerosol generating devices, also known as heat-non-combustion devices, are adapted to heat, by conduction, convection and / or radiation, rather than combusting, a substrate, to generate an aerosol for inhalation.

[0003] The present invention also relates to a method of controlling an aerosol generating device. [Background technology]

[0004] The popularity and use of risk reduction or risk modification devices (also known as vaporizers) has grown rapidly in recent years as an aid to support habitual smokers who wish to quit smoking traditional tobacco articles such as cigarettes, cigars, cigarillos and roll-up cigarettes. A variety of devices and systems are available that heat or warm a vaporizable substrate, as opposed to burning tobacco in traditional tobacco articles.

[0005] A commonly available risk reduction or risk modification device is a heat-to-burn substrate aerosol generating device or a heat-to-burn device. This type of device typically generates an aerosol or vapor by heating an aerosol substrate that includes moist tobacco or other suitable vaporizable material, typically to a temperature in the range of 150°C to 350°C. By heating the aerosol substrate but not burning or combusting it, an aerosol is released that contains the components desired by the user but that are not the toxic and carcinogenic by-products of combustion and burning. Furthermore, since the aerosol generated by heating tobacco or other vaporizable material typically does not contain the burnt or bitter taste that can result from burning and burning, which can be unpleasant to the user, the substrate therefore does not require the sugar and other additives that are typically added to such materials to make the smoke and / or vapor more palatable to the user.

[0006] Tobacco articles that can be used with such types of aerosol generating devices can take a variety of forms. Some of them can be elongated sticks or any other suitable shape, such as a flat shape. However, the design of a tobacco article is often a trade-off between its aesthetic value and heating efficiency.

[0007] Some of the known aerosol generating devices that operate with tobacco articles include a heater that raises the heater to a predetermined temperature and therefore consumes a lot of energy to heat the tobacco article to the target temperature. Summary of the Invention [Problem to be solved by the invention]

[0008] One object of the present invention is to provide an aerosol generating device that requires less energy to heat and vaporize vaporizable material from a tobacco article. [Means for solving the problem]

[0009] To this end, the present invention provides an aerosol generating device configured to operate with a flat-shaped tobacco article and including flat-shaped heating, comprising: the heating chamber is configured to receive a flat shaped tobacco article and includes a first heating plate and a second heating plate forming at least partially opposed walls of the heating chamber; The present invention relates to an aerosol generating device, wherein the heating plates are made of different materials having different thermal masses, the thermal mass of the second heating plate being greater than the thermal mass of the first heating plate.

[0010] These features make it possible to provide an aerosol generating device that requires less energy to heat and evaporate the vaporizable material from the tobacco article while heating the tobacco article in an optimal manner. In particular, the first heating plate, i.e. the heating plate with a smaller thermal mass, allows the tobacco article to be heated quickly with less energy, allowing for faster puffs by the user. The second heating plate with a higher thermal mass allows for homogeneous heating of the surface of the tobacco article during the entire inhalation session. In addition, the second heating plate ensures high heat penetration into the tobacco article, allowing for more vapor to be generated compared to the first heating plate. Thus, the user experience while using the aerosol generating device may be improved.

[0011] The use of heating plates with different thermal masses allows for less energy to be used to heat the tobacco article to a given temperature and to maintain it near the given temperature, compared to one or more heating plates with substantially the same thermal mass. In addition, these heating plates achieve homogeneous heating during the entire puff session. As a result, the combination of heating plates with different thermal masses allows for the optimization of heating of flat-shaped tobacco articles.

[0012] Each heating plate may represent a homogeneous body made of the same material, such as metal, ceramic, etc. In this case, by "thermal mass" is understood the property of this material that allows it to store heat. Thermal mass may be equivalent to thermal capacitance or heat capacity, which corresponds to the ability of a body to store thermal energy. Thermal mass may be measured in J / °C or J / K. In some cases, thermal mass may be directly proportional to the mass of the body. In this case, the proportionality factor is called the specific heat capacity.

[0013] In some embodiments, at least one heating plate presents a heterogeneous body made of different materials. This body may present, for example, a homogeneous mixture of different materials. In some embodiments, the mixture of materials may also be heterogeneous. This means that the different materials may be distributed heterogeneously along the heating plate. In the case of a heterogeneous body, by the "thermal mass" of such a body is understood the total value of the thermal mass of all materials forming this body. This total value may be determined, for example, according to the ratio of the materials forming the body or any other suitable method known per se.

[0014] Each heating plate may form or be connected to a resistive element designed to be powered by a power source, which may be controlled by a controller of the aerosol generating device.

[0015] According to some embodiments, each heating plate is positioned to contact or face the tobacco portion of a flat-shaped tobacco article.

[0016] For example, each heating plate may be in direct or indirect contact with the tobacco portion of the tobacco article. By "direct contact" it is understood that no intermediate element extends between the corresponding plate and the tobacco portion. By "indirect contact" it is understood that an intermediate element (such as a part wrapper) is interposed between the corresponding plate and the tobacco article. In either case, the tobacco portion of the tobacco article is heated by conduction.

[0017] According to other embodiments, each heating plate is positioned so as to only face the tobacco portion of the tobacco article without contacting it, in which case the tobacco portion of the tobacco article is heated by convection.

[0018] According to some embodiments, the first heating plate is made of metal and the second heating plate is made of ceramic.

[0019] Both metals and ceramics exhibit good physical properties to ensure the operation of the aerosol generating device according to the invention. For example, ceramics are known to exhibit a greater thermal mass value than metals. Thus, a metal heating plate can be heated more quickly, while a ceramic heating plate can store more thermal energy and heat the tobacco portion more homogeneously. Depending on the type of ceramic and metal, the ratio between the thermal capacity of the ceramic heating plate and the thermal mass of a metal heating plate having the same mass can be comprised between 1 and 5, advantageously between 1 and 3, possibly between 1 and 2.

[0020] According to some embodiments, the first heating plate forms a thin heating film.

[0021] These features allow the first heating plate to heat the tobacco portion very quickly to ensure a fast pre-heating phase, in which case the second heater can be made of any other material with a larger thermal mass, for example metal, ceramic, etc.

[0022] According to some embodiments, the system further includes a controller configured to power the first heating plate according to a first heating profile and to power the second heating plate according to a second heating profile that is different from the first heating profile.

[0023] These features make it possible to control the heating of the tobacco portion performed by the different heating plates using different heating profiles, each of which can be selected based on the properties of the heating plates, in particular on the thermal mass of each heating plate, so that the heating of the tobacco portion can be optimized according to the different thermal masses of the heating plates.

[0024] According to some embodiments, each heating profile includes an initial segment during which the corresponding heating plate is powered.

[0025] The initial segment may therefore include a pre-heating phase of the tobacco portion and, according to some embodiments, at least a part of the inhalation phase. During this initial segment, both heating plates may be powered according to a maximum power value. According to other embodiments, at least one heating plate may be powered according to a value less than the maximum power value during the initial segment. This value may, for example, be comprised between 10% and 90% of the maximum value.

[0026] According to some embodiments, the initial segment ends upon expiration of a predetermined time interval or upon achievement of a predetermined temperature by the second heating plate.

[0027] Thus, the boundary of the initial segment of the second heating plate may be formed by a time threshold or a temperature threshold.

[0028] The time threshold may be empirically determined. It may, for example, correspond to the total duration required for the second heating plate to achieve a predetermined temperature, the predetermined temperature corresponding to the temperature at which the tobacco portion begins to generate aerosol.

[0029] The temperature threshold may correspond to a predetermined temperature. The temperature of the second heating plate may be measured by a suitable temperature sensor located in the vicinity of the second heating plate. The temperature sensor may be directly connected to the controller.

[0030] After the end of the initial segment, the first heating profile may include, for example, decreasing the power supply of the first heating element until a substantially zero value is achieved. Thus, after the initial segment, only the second heating plate may be powered according to the second heating profile. In other words, after the initial segment, the first heating plate may be turned off and only the second heating plate may be used to heat the tobacco portion of the tobacco article.

[0031] According to some embodiments, the duration of the predetermined time interval is comprised between 50 and 70 seconds and substantially equal to 60 seconds, and the predetermined temperature is comprised between 260°C and 300°C and substantially equal to 280°C.

[0032] This duration is in particular adapted to ensure pre-heating of the second heating stage to a predetermined temperature, which, as mentioned above, may correspond to a temperature that allows aerosol generation by the tobacco portion of the tobacco article.

[0033] According to some embodiments, each heating profile further comprises a secondary segment: A secondary segment of the first heating profile includes turning off the power supply to the corresponding heating plate; and A secondary segment of the second heating profile includes powering a corresponding heating plate.

[0034] Thus, the secondary segment may correspond to a portion of the inhalation phase not included in the initial segment, the inhalation phase being performed to generate vapour while the user takes a puff.

[0035] As explained above, during the secondary segment, the first heating element can be turned off so that only the second heating element is powered. The larger thermal mass of the second heating plate allows the tobacco portion to be heated homogeneously during the inhalation phase. Thus, the aerosol is generated homogeneously during the entire inhalation phase and the entire outer area of ​​the tobacco portion can be heated. This avoids the waste of vaporizable substrate in underheated areas, which may correspond for example to the peripheral area of ​​a conventional aerosol generating device.

[0036] The invention also relates to a control method that includes heating each heating plate according to a heating profile determined based on the thermal mass of that heating plate.

[0037] The invention and its advantages will be better understood from reading the following description, given by way of non-limiting example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a perspective view of an aerosol generating assembly including an aerosol generating device according to the present invention and a tobacco article usable with the aerosol generating device. [Diagram 2] FIG. 2 is a perspective view of the tobacco article of FIG. 1. [Diagram 3] FIG. 2 is a partial cross-sectional view of the aerosol generation assembly of FIG. 1 taken along plane III. [Figure 4] 2 is a graph showing the operation of the aerosol generation assembly of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] Before the present invention is described, it is to be understood that the invention is not limited to the details of construction set forth in the following description. It will be apparent to one skilled in the art having the benefit of this disclosure that the invention is capable of other embodiments and of being practiced or carried out in various ways.

[0040] In the following, the expression "substantially equal" is understood to mean equal to plus or minus 10%, preferably to plus or minus 5%.

[0041] As used herein, the term "aerosol generating device" or "device" may include an inhalation device for delivering an aerosol to a user, including an aerosol for inhalation, using a heater element, which will be described in further detail below. The device may be portable. "Portable" may refer to a device for use when held by a user. The device may be adapted to generate a variable amount of aerosol, for example by activating a heater element for various amounts of time (as opposed to a fixed amount of aerosol), which may be controlled by a trigger. The trigger may be activated by a user, such as an inhale button and / or a draw sensor. The draw sensor may be sensitive to the duration of the draw as well as the intensity of the draw (to mimic the smoking effect of a conventional combustion smoking article, such as a cigarette, cigar, or pipe, etc.), to allow for the provision of a variable amount of vapor. The device may include a temperature regulation controller for driving the temperature of the heater and / or heated aerosol-generating substrate (aerosol precursor) to a specific target temperature and then maintaining the temperature at a target temperature that can efficiently generate aerosol.

[0042] As used herein, the term "aerosol" may include a suspension of vaporizable material as one or more of solid particles, liquid droplets, and gas. The suspension may be in a gaseous state, including air. Aerosol herein may generally refer to / include a vapor. Aerosol may include one or more components of vaporizable material.

[0043] As used herein, the term "vaporizable material" or "precursor" may refer to a smokable material that may include, for example, nicotine or tobacco and an aerosol-forming agent. The tobacco may take the form of various materials, such as cut tobacco, granulated tobacco, tobacco leaves, and / or reconstituted tobacco. Suitable aerosol-forming agents include polyols (e.g., glycols such as sorbitol, glycerol, and propylene glycol or triethylene glycol), non-polyols (e.g., 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 include at least one of a gelling agent, a binder, a stabilizer, and a humectant.

[0044] 1 shows an aerosol generating assembly 10 including an aerosol generating device 11 and a tobacco article 12. The aerosol generating device 11 is intended to operate with a tobacco article 12, which is shown in more detail in FIG.

[0045] In this example of Fig. 2, the tobacco article 12 is a flat-shaped tobacco article, for example, extending along the article axis X and presenting a flat cube with external dimensions L12xW12xD12. In a typical example, the length L12 of the article 12 according to the article axis X is substantially equal to 33 mm, while its width W12 and depth D12 are substantially equal to 12 mm and 1.2 mm, respectively. According to another example, the values ​​L12, W12 and D12 may be selected, for example, within a range of ±40%. The depth D12 of the tobacco article 12 is formed by a pair of parallel walls 13A, 13B, hereinafter referred to as narrow walls 13A, 13B, and the width W12 of the tobacco article 12 is formed by a pair of parallel walls 14A, 14B, hereinafter referred to as wide walls 14A, 14B. In some embodiments, the edges between the wide and narrow walls 13A, 13B, 14A, 14B may be rounded. According to other embodiments of the present invention, the tobacco article 12 may have any other suitable planar shape and / or external dimensions. According to still other embodiments, the tobacco article 12 may exhibit any other suitable shape, such as, for example, a stick shape.

[0046] The tobacco article 12 comprises a tobacco portion 15 and a mouthpiece portion 16 arranged along an article axis X. For example, the tobacco portion 15 may be slightly longer than the mouthpiece portion 16. The tobacco portion 15 is formed by parallel walls 15A, 15B that are part of the broad walls 14A, 14B of the tobacco article 12. For example, a length L15 of the tobacco portion 15 along the article axis X may be substantially equal to 18 mm. A width W15 of the tobacco portion 15 is equal to a width W12 of the tobacco article 12. A length L16 of the mouthpiece portion 16 along the article axis X may be substantially equal to 15 mm. The tobacco portion 15 defines an abutment end 18 of the article 12, and the mouthpiece portion 16 defines a mouth end 20 of the article 12. The tobacco portion 15 and the mouthpiece portion 16 may be fixed to each other by a wrapper 21 that extends around the substrate axis X. The wrapper 21 forms the narrow and broad walls 13A, 13B, 14A, 14B of the tobacco article 12. In some embodiments, the wrapper 21 is formed from the same wrapping sheet. In some other embodiments, the wrapper 21 is formed by separate wrapping sheets that separately wrap the portions 15, 16 and are secured together by any other suitable means. The wrapper 21 may comprise, for example, paper, and / or nonwoven fabric, and / or aluminum foil. The wrapper 21 may be porous or air impermeable and forms a plurality of air flow passages extending inside the article 12 between the abutment end 18 and the mouth end 20.

[0047] The mouthpiece portion 16 includes a core 27, which is intended to act as a cooler, for example to slightly cool the vapour before the user inhales it. The core 27 may for example consist of cardboard for this purpose. The core 27 may be formed into a stable shape via an extrusion and / or rolling process. Advantageously, the core 27 is arranged inside the mouthpiece portion 16 in full contact with the inner surface of the wrapper 21 which bounds said mouthpiece portion 16.

[0048] As will be explained in more detail below, tobacco portion 15 includes a vaporizable material and is intended to be heated by a heating chamber.

[0049] 1, the aerosol generating device 11 comprises a device body 40 extending along a device axis Y, and a mouthpiece 42. According to the following example, the mouthpiece 42 and the device body 40 form two distinct parts. In particular, according to this example, the mouthpiece 42 is designed to be fixed to a fixed end of the device body 40.

[0050] As shown in FIG. 3, the mouthpiece 42 includes a central portion 43 and a peripheral portion 44 extending around the central portion 43. The peripheral portion 44 defines, for example, a collar that partially covers the outer surface of the device body 40 when the mouthpiece 42 is fixed to the fixed end of the device body 40. For example, the peripheral portion 44 can be designed to cooperate with a gasket 45 disposed at the fixed end of the device body 40 to seal a space formed between the peripheral portion 44 and the outer surface of the device body 40. The peripheral portion 44 also defines, for example, an intermediate portion that extends transversely to the device axis Y and forms a transition between the central portion 43 of the mouthpiece 42 and the collar defined by the peripheral portion 44. The central portion 43 of the mouthpiece 42 defines a through hole 46 adapted to at least partially receive the tobacco article 12. Specifically, as shown in FIG. 3, the through hole 46 can be adapted to receive at least a portion of the mouthpiece portion 16 of the tobacco article 12. Advantageously, the through hole 46 may be adapted to fit securely with the mouthpiece portion 16 of the tobacco article 12 so as to avoid or minimize flow leakage between the walls defining the through hole 46 and the outer surface of the tobacco article 12. In some embodiments, the tobacco article 12 may be held within the through hole 46, for example, by friction. In this case, it is possible, for example, to first insert the mouthpiece portion 16 of the tobacco article 12 inside the through hole 46 while fastening both elements to the fixed end of the device body 40.

[0051] 3, an interior volume 47 is formed between an inner surface 48 of the mouthpiece 42 and the fixed end of the device body 40. This interior volume 47 is traversed by the tobacco article 12 when the tobacco article 12 is inserted inside the device body 40. For example, the tobacco article 12 may divide the interior volume 47 into two symmetrical portions.

[0052] The device body 40 defines an interior space of the device 11 that houses various elements designed to perform different functions of the device 11. This interior space may house, for example, 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. Of these elements, only the flat-shaped heating chamber 50 will be described in further detail with reference to FIG.

[0053] In particular, as shown in this Fig. 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 and optionally at least a portion of the mouthpiece portion 16 of the tobacco article 12. As the tobacco article 12, the heating chamber 50 may also form a cubic shape extending along the device axis Y and including a pair of parallel narrow walls 53A, 53B (shown in Fig. 4) extending along the device axis Y, a pair of parallel wide walls 54A, 54B also extending along the device axis Y, and a bottom wall 58 adjacent each of said walls and extending perpendicular to the device axis Y. The bottom wall 58 thus forms a closed end of the chamber 50. Opposite the bottom wall 58, the heating chamber 50 defines an opening configured to receive the tobacco article 12 such that the corresponding broad walls 14A, 14B of the tobacco article 12 face the corresponding broad walls 54A, 54B of the heating chamber 50, the corresponding narrow walls 13A, 13B of the tobacco article 12 face the corresponding narrow walls 53A, 53B of the heating chamber 50, and the abutting end 18 of the tobacco article 12 abuts the bottom wall 58 or at least a rib extending from the bottom wall 58. Alternatively, the abutting end 18 faces the bottom wall 58 without contacting the bottom wall 58. Thus, the flat shaped heating chamber 50 is configured to receive the tobacco article 12 such that the narrow wall 13A (respectively 13B) of the tobacco article 12 faces the narrow wall 53B (respectively 53A) of the heating chamber 50 and the wide wall 14A (respectively 14B) of the tobacco article 12 faces the wide wall 54B (respectively 54A) of the heating chamber 50. The opposing wide walls 14A, 14B, 54A, 54B and the opposing narrow walls 13A, 13B, 53A, 53B may be in contact with each other or may be spaced apart from each other.

[0054] In the example shown in FIG. 3, the heating chamber 50 includes a first heating plate 70A and a second heating plate 70B that form at least partially opposing walls of the heating chamber 50. The opposing walls are, for example, the broad walls 54A, 54B of the heating chamber 50. Each heating plate 70A, 70B is designed to contact or face the tobacco portion 15 of the tobacco article 12. In particular, each heating plate 70A, 70B is designed to contact or face the respective broad wall 15A, 15B of the tobacco article 15. In the example shown in FIG. 3, each heating plate 70A, 70B faces the respective broad wall 15A, 15B of the tobacco article 15, and a gap is defined between the heating plate 70A, 70B and the respective broad wall 15A, 15B of said tobacco article 12. The gap is, for example, 0.1 millimeter (mm) or less.

[0055] In the example of FIG. 3, the heating plates 70A, 70B have substantially the same dimensions. In addition, each heating plate 70A, 70B is designed to extend along the entire area of ​​the tobacco portion 15. In other words, the length of each heating plate 70A, 70B is at least equal to the length L15 of the tobacco portion 15, and the width of each heating plate 70A, 70B is at least equal to the width W15 of the tobacco portion 15. According to the embodiment shown in FIG. 3, the length of each heating plate 70A, 70B is greater than the length L15 of the tobacco portion 15. Thus, each heating plate 70A, 70B protrudes from both ends of the tobacco portion 15 defined along the device axis Y. This ensures proper heating of the ends of the tobacco portion 15 defined along the device axis Y. The depth of each heating plate 70A, 70B depends on the dimensions of the tobacco article 15. For example, the depth of each heating plate 70A, 70B is greater than or equal to 0.25 mm and less than or equal to 0.75 mm. As also shown in Figure 3, the tobacco portion 15 is sandwiched between two heating plates 70A, 70B.

[0056] According to another embodiment, the heating plates 70A, 70B have different dimensions.

[0057] According to the present invention, the heating plates 70A, 70B are made of different materials having different thermal masses, so that the thermal mass of the second heating plate 70B is greater than that of the first heating plate 70A. For example, the first heating plate 70A is made of a metal such as copper, and the second heating plate 70B is made of a ceramic. In addition, according to different embodiments, each heating plate 70A, 70B may form a resistive element itself or may be placed in contact with a resistive element. Such resistive elements may be connected to a controller and may form, for example, a thin heating film known as such. In further description, it will be understood that powering the heating plates powers the resistive elements associated with the respective heating plates 70A, 70B.

[0058] The controller is configured to control the operation, and in particular the power supply, of each heating plate 70A, 70B. In particular, the controller is configured to power the first heating plate 70A according to a first heating profile and to power the second heating plate 70B according to a second heating profile.

[0059] An example of these heating profiles is shown in Figure 4, where reference P1 represents a first heating profile and reference P2 represents a second heating profile. As shown in this figure, each heating profile P1, P2 includes an initial segment IS and a secondary segment SS.

[0060] According to one embodiment of the invention, the initial segment IS corresponds to the pre-heating phase of the aerosol generating device 11, and the secondary segment SS corresponds to the inhalation phase. According to another embodiment, the initial segment IS comprises the pre-heating phase and part of the inhalation phase. In other words, according to this last embodiment, the initial segment IS extends beyond the pre-heating phase. This last embodiment is shown in Fig. 4, where the pre-heating phase lasts for 10-20 seconds until the first heating plate 70A reaches a predetermined temperature (280 °C in the example of this figure), but the initial segment IS extends beyond the pre-heating phase.

[0061] As shown in Fig. 4, during the initial segment IS, both heating plates 70A, 70B are powered. According to different embodiments of the invention, these heating plates 70A, 70B can be powered according to their maximum power value or at least one of them is powered according to a reduced power value. The reduced power value can be comprised between 10% and 90% of the maximum power value.

[0062] The end of the initial segment can be determined either by a time threshold or by a temperature threshold. For example, the duration of the initial segment can be limited by a time threshold comprised between 50 and 70 seconds. This time threshold can, for example, be substantially equal to 60 seconds. Instead, a temperature threshold is used for the temperature of the tobacco portion or the temperature of the first heating plate or the temperature of the second heating plate. In the example of FIG. 4, a threshold for the temperature of the second heating plate is used. Thus, according to this embodiment, the end of the initial segment corresponds to the moment when the second heating plate 70B reaches a predetermined temperature. This predetermined temperature can, for example, be comprised between 260°C and 300°C and is substantially equal to 280°C. According to this embodiment, a temperature sensor can be arranged in the vicinity of the second heating plate 70B to measure the temperature of this heating plate 70B and can, for example, be directly connected to the controller.

[0063] According to other embodiments, any other parameter related to the operation of at least one of the heating plates 70A, 70B may be used to determine the end of the initial phase. Thus, for example, a parameter characterizing the current passing through at least one of the heating plates 70A, 70B may be used, such as the power consumption from the start of the initial segment IS.

[0064] As shown in Fig. 4, during the secondary segment SS, only the second heating plate 70B is powered to maintain its temperature near the predetermined temperature, while the first heating plate 70A is turned off. Thus, as shown in Fig. 4, the temperature of the first heating plate 70A is decreasing during the entire secondary segment SS. Instead, the first heating plate 70A may be turned on within at least some time intervals in the secondary segment SS. These time intervals may be defined at a given moment in the secondary segment SS or according to, for example, the temperature of the second heating plate 70B.

[0065] According to the invention, the method of controlling the aerosol generating device 11 comprises heating each heating plate 70A, 70B according to a corresponding heating profile. As mentioned above, for this purpose the controller of the device 11 controls the power supply of these heating plates 70A, 70B according to a corresponding heating profile.

Claims

1. An aerosol generating device (11) configured to operate with a flat tobacco article (12) and comprising a flat heating chamber (50), The heating chamber (50) is configured to receive the flat tobacco article (12) and includes a first heating plate (70A) and a second heating plate (70B) that form at least partially opposing walls (54A, 54B) of the heating chamber (50), The heating plates (70A, 70B) are made from different materials having different thermal masses, and the thermal mass of the second heating (70B) plate is greater than that of the first heating plate (70A), in the aerosol generating device (11).

2. The aerosol generating device (11) according to claim 1, wherein each heating plate (70A, 70B) is positioned to contact or face the tobacco portion (15) of the flat tobacco article (12).

3. The aerosol generating device (11) according to claim 1 or 2, wherein the first heating plate (70A) is made of metal, and the second heating plate (70B) is made of ceramic.

4. The aerosol generating device (11) according to claim 1 or 2, wherein the first heating plate (70A) forms a thin heating film.

5. The aerosol generating device (11) according to claim 1 or 2, further comprising a controller configured to supply power to the first heating plate (70A) according to a first heating profile and to supply power to the second heating plate (70B) according to a second heating profile different from the first heating profile.

6. The aerosol generating device (11) according to claim 5, wherein each heating profile includes an initial segment to which the corresponding heating plate is powered.

7. The aerosol generating device (11) according to claim 6, wherein the initial segment ends when a predetermined time interval has expired or when a predetermined temperature is achieved by the second heating plate (70B).

8. - The duration of the predetermined time interval is included in 50 to 70 seconds and is substantially equal to 60 seconds. - The aerosol generating device (11) according to claim 7, wherein the predetermined temperature is included in 260°C to 300°C and substantially equal to 280°C.

9. Each heating profile further includes a secondary segment, The secondary segment of the first heating profile includes turning off the power supply to the corresponding heating plate (70A), and The aerosol generating device (11) according to claim 6, wherein the secondary segment of the second heating profile includes supplying power to the corresponding heating plate (70B).

10. A method for controlling an aerosol generating device (11) according to claim 1 or 2, comprising heating each heating plate (70A, 70B) according to a heating profile determined based on the thermal mass of the heating plates (70A, 70B).

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