Heater for aerosol-generating device

Abstract

The present disclosure proposes a heater (2) adapted to be electrically connected to an aerosol-generating device (1) configured to generate an aerosol when heat is delivered to an aerosol-forming system (7), wherein the heater (2) comprises at least one heating element (201, 202), said heating element (201,202) comprising a heat diffusion element (210) thermally connected to at least two heat sources (212), each heat source (212) being electrically controlled to produce heat independently so that to create local controlled heated areas (6a, 6b, 6c) on an outer surface of the heat diffusion element (210).

Description

TECHNICAL FIELD

[0001] The present disclosure relates to aerosol-generating devices or aerosol-forming devices comprising an electrical heater for controlling the temperature and humidity conditions necessary for generating aerosols under the effect of heat. More particularly, the disclosure relates to an electrical heater comprising at least two heating zones, adapted to be controlled independently, to generate and to transfer heat to adjacent portions of aerosol-forming systems and to aerosol-generating devices adapted to use such heaters.BACKGROUND OF THE INVENTION

[0002] The generation of aerosols has become increasingly important in various fields such as medicine, chemistry, and environmental science. Aerosol generation typically involves heating or vaporizing a substance, which is then atomized to produce a uniform particle size distribution. This process is critical for applications such as inhalation therapy, chemical synthesis, and air quality monitoring.

[0003] Aerosol-generating devices such as e-cigarettes, typically comprise a heater element or heater designed to vaporize a substance - either a liquid also called e-liquids, or a solid, such as tobacco or nicotine salts - to form an inhalable aerosol. These devices often include a power source, such as a battery, and a heating element such as a coil or ceramic heater, which rapidly heats the substance without combusting it. To produce a nicotine containing aerosol with an electrical system, one usual solution is to generate the aerosol by heating an aerosol-generating substrate. In liquid-based systems, a reservoir holds a solution, often composed of nicotine, propylene glycol, glycerin, and flavorings, which is wicked into the heating chamber. In solid-based systems, like heat-not-burn tobacco products, a tobacco-containing article is inserted into the device, where it is heated just below the combustion point, releasing aerosolized compounds. The heated material generates an aerosol that the user inhales, delivering nicotine or other substances.

[0004] Existing heater designs have limitations that prevent them from effectively controlling temperature and humidity conditions necessary for optimal aerosol formation. For example, traditional heaters often rely on a single heating element or a simple thermostat, which can lead to inconsistent particle size distributions due to variations in temperature and humidity conditions and may not be designed to accommodate the specific requirements of different substances being heated or vaporized. This lack of flexibility can limit their usefulness in various applications where precise control over aerosol generation is critical.

[0005] Some heaters are made to use a plurality of heating elements organized in a longitudinal way to better mimic the conventional way of smoking, as illustrated in documents US 2014 / 0060554 or US 2020 / 0275693. Other solutions may comprise a plurality of heating elements in an array to heat an aerosol-generating substrate, as illustrated in US 2021 / 0401047.However, designing and manufacturing such array of heating elements to heat an aerosol-generating substrate present several challenges. These challenges include achieving the desired resolution and density of heating elements, controlling heat propagation between elements, selecting suitable technologies for construction, managing costs, and overcoming physical constraints in heating element organization.

[0006] A first challenge is the resolution - i.e. the total number of heating elements - and the density - i.e. the number of heating elements per unit of surface - of heating elements in the array to cover the heated zone in a homogeneous way and to form the desired shape for the heated area. A common concept for designing a multi-zone heater is to use a plurality of heating elements with a matrix organization, each heating element forming a dot in the matrix. This concept theoretically offers significant flexibility to configure and define a heated zone with a specific shape or geometry. However, this comes at the expense of implementing a high number of heating elements or dots to achieve sufficient resolution for creating the desired shapes. Increasing the resolution or quantity of heating elements in the matrix directly impacts the overall cost of the system.

[0007] A second challenge is controlling the heat propagation between the heating elements inside the array. It is desirable in terms of flexibility to combine enough heating elements in the same array to achieve sufficient resolution. Additionally, there is a constraint to keep the overall size of the array acceptable for integration into a handheld device resulting in reduced physical distance between each heating element. If the heating elements are physically too close, one heating element perturbs the others around it due to heat propagation effects, generating a sort of heat fuzziness. This reduces the efficiency and accuracy of the matrix definition, degrading the performance and interest of such type of arrangement.

[0008] Another challenge relates to the construction itself and the choice of suitable technologies regarding of the overall size and scalability of the array. For example, for an array with heating elements assembled on a semi-conductor or a ceramic base, building a large size array might be difficult and expensive to carry out. Conversely, for an array using resistive heating elements, achieving a small size array might be challenging.

[0009] An additional challenge is the cost of the heater array, which is linked to the number of individual elements being a function of the desired resolution and density of the array. The cost is also influenced by the technical solutions used to electrically and mechanically group, maintain all the heating elements together, as well as to reduce heat propagation effects.

[0010] Moreover, construction constraints are practically and physically restricting heating elements organisation to a longitudinal arrangement - i.e. an arrangement in a row - or to an array of heating elements - i.e. an arrangement in rows and columns. These configurations of heating elements similarly limit the configuration of aerosol-forming systems, as they need to match the layout of the heating elements to be close enough or adjacent to allow an efficient heat transfer.

[0011] These challenges highlight the need for innovative heater designs that can overcome these limitations while providing precise control over aerosol generation for various applications.SUMMARY

[0012] To overcome such challenges and drawbacks of the existing solutions, the present disclosure proposes a heater adapted to be electrically connected to an aerosol-generating device configured to generate an aerosol when heat is delivered to an aerosol-forming system, wherein the heater comprises at least one heating element said heating element comprising a heat diffusion element thermally connected to at least two heat sources, each heat source being electrically controlled to produce heat independently so that to create local controlled heated areas on an outer surface of the heat diffusion element.

[0013] According to another aspect of the present disclosure, the heating element may comprise a thermal insulation element adjacent to the heat sources and to the heat diffusion element.

[0014] According to another aspect of the present disclosure, the heating element may comprise a base plate.

[0015] According to another aspect of the present disclosure, the heater may comprise an internal controller unit adapted to be electrically connected to the at least one heating element.

[0016] According to another aspect of the present disclosure, the heater may comprise a memory unit adapted to store at least one parameter related to article-forming articles and / or to aerosol-forming systems to be used by said heater.

[0017] According to another aspect of the present disclosure, the heat diffusion element may have a thermal conductivity lower than 3 W / mK.

[0018] According to another aspect of the present disclosure, temperature gradients between two different heated zones may be higher than 10°C / cm at an outer surface of the heat diffusion element when one or more heat sources are activated so that to produce an aerosol.

[0019] According to another aspect of the present disclosure, the heat diffusion element may have a thickness below 1.5 mm.

[0020] According to another aspect of the present disclosure, a heat source may have an electrical power consumption lower than 100 Watt RMS.

[0021] According to another aspect of the present disclosure, the heat diffusion element of the at least one heating element has a surface area facing an aerosol-forming system, between 2 cm2 and 100 cm2.

[0022] The present invention also proposes an aerosol-generating device comprising said heater, an external control unit, an external power source unit, wherein said external control unit is adapted to identify at least one property of the heater.

[0023] According to another aspect of the present disclosure the memory unit of the heater may be adapted to be configured temporarily or permanently by the external controller unit once an electrical communication is established.

[0024] According to another aspect of the present disclosure, the memory unit or the external control unit may be adapted to store at least one parameter related to the aerosol-generation process in connection with one or more aerosol-forming systems intended to be thermally connected with the heater.

[0025] According to another aspect of the present disclosure, the external control unit may share with the memory unit said at least one parameter related to the aerosol-generation process in connection with one or more aerosol-forming systems intended to be thermally connected with the heater once an electrical connection is established.

[0026] According to another aspect of the present disclosure, the heater and / or the aerosol-generating device may comprise authentication and / or mistake-proofing means so that to be in use with compatible aerosol-forming systems only adapted for such devices.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG.1A illustrates a view of the aerosol-generating device according to the present invention showing the power distribution to the heater and heated zones 6a, 6b, 6c; FIG.1B illustrates a heater according to the present disclosure, wherein the heater comprises heating elements (only one is represented in this figure); FIG.2A illustrates a side view of a heating element; FIG.2B illustrates a side view of the heat diffusion element, wherein the thickness (mm) is illustrated in a transversal axis, with d1 being the effective thickness of the heat diffusion element thermally connected with two heat sources; FIG.2C illustrates a side view of the heating element according to an embodiment of the present invention with a base plate and electrical connections; FIG.3A, 3B and 3C illustrate examples of arrangements of resistive elements forming geometrical heat exchanges areas; 3A: Planar Serpentine resistive element with a rectangular shape for the heat exchange surface - 3B: Planar Serpentine resistive element with a Polygonal shape for the heat exchange surface - 3C: Planar Spiral coil; FIG.4A to 4G illustrate top views of the heat diffusion element in various examples of multi-spot heater arrangements, showing the different heat exchanges areas 6a and the heating zones 6d once activated as examples; FIG.5 illustrates a profile of the surface temperature distribution of the heat diffusion element along one longitudinal axis of the heat diffusion element of FIG.1A with two activated heat sources 212a, 212b and one inactivated heat source 212c and their respectively corresponding heated zones 6a, 6b; FIG.6 illustrates a view of an aerosol- forming article; FIG.7 illustrates an aerosol-forming system comprising two aerosol-forming articles 60a and 60b; FIG. 8A illustrates views showing the interaction of the heater and the aerosol-forming article according to an embodiment of the present invention; FIG.8B illustrates a side view of the heater equipped with a heating element, comprising a base plate and a thermal insulation layer, connected to a PCBA; FIG.9 illustrates temperature gradient examples for various heater applications. DETAILED DESCRIPTION

[0028] The present disclosure will now be described more fully hereinafter. This invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to thoroughly and completely convey the scope of the invention to those skilled in the art. It should be noted that, throughout this specification, singular forms such as "a," "an," and "the" include plural referents unless the context clearly indicates otherwise.

[0029] In the description that follows, two elements are considered "thermally connected" or in "thermal connection" when heat, or a portion thereof is transferred from one element to the other through any combination of conduction, convection, and radiation heat transfer mechanisms. This thermal connection can occur through direct physical contact between the elements or through intermediate materials or structures that facilitate heat transfer. The efficiency and rate of heat transfer between thermally connected elements may vary depending on factors such as the materials involved, the contact area, and the temperature differential between the elements. Understanding these thermal connections is crucial for analyzing the heat distribution and performance of the multi-zone heater described in this disclosure.

[0030] As shown in FIG.1A, is an aerosol-generating device 1 according to the present invention designed for producing inhalable aerosols for consumers. This device operates by heating a consumable item, referred to as an aerosol-forming system 7 which users insert into the device. The aerosol-forming system 7 is a key component that contains the substances or precursors necessary for aerosol generation when subjected to heat.

[0031] To facilitate the heating process, the aerosol-generating device 1 typically incorporates a designated slot or cavity. This feature allows users to insert the aerosol-forming system 7, positioning it in close proximity of an electrical heater 2. The heater 2 is a critical element of the device, responsible for generating the heat required to transform the constituents of the aerosol-forming system 7 into an inhalable aerosol.

[0032] The aerosol-generating device 1 is generally designed as a handheld device for user convenience. It comprises the aforementioned electrical heater 2 generating the heat needed to produce aerosols from consumable items, a source of electrical energy 5, - typically a rechargeable battery to ensure portability and repeated use, and a control system 4. The control system 4 serves multiple functions: it identifies the specific heater and its characteristics, enables user interactions, and manages device operations. It is important to note that while the control system 4 of the aerosol-generating device 1 does not configure the topology, shapes or number of heating zones of the heater- as these are fixed parameters of the heater design -, the aerosol-generating device 1 may be designed to accommodate different types of interchangeable heaters 2. This flexibility allows users to select heaters based on their specific needs or preferences, enhancing the device's versatility.

[0033] The interchangeability of heaters introduces a modular aspect to the aerosol-generating device 1. Users can potentially switch between heaters with different characteristics, such as varying numbers of heating zones or different heat distribution patterns, without needing to replace the entire device. This feature could allow for customization of the aerosol generation process to suit different types of aerosol-forming systems or to achieve different aerosol characteristics.

[0034] As illustrated in FIG.7, the aerosol-forming system 7 of the aerosol-generating device 1, designed to contain and deliver the substances necessary for aerosol production, comprises one or more discrete aerosol-forming articles 60a, 60b that can be of different types. In the example, as shown, the aerosol-forming system 7 combines two aerosol-forming articles 60a, 60b: article 60a is comprising three discrete portions of an aerosol precursor 61c made of a highly compressed tobacco foam and article 60b, is comprising a single aerosol precursor, for example a gel mixture of propylene glycol, vegetal glycerin and mint flavoring. This aerosol-forming system 7 allows the generation of a global aerosol that can have different characteristics such as different tastes or strengths by combining the effect of the individual aerosols generated by aerosol precursors.

[0035] An aerosol precursor is defined as a chemical substance or a chemical compound that, when subjected to heat from an electrical heating element, produces an aerosol consisting of gases and / or micro-droplets suspended in the air. These precursors can exist in various physical states - solid, liquid or semi-solid such as foam or gel, and may be deposited on or impregnated in a substrate or a carrier 62, as shown in FIG.6. Common examples of precursors comprise propylene glycol (PG), vegetal glycerin (VG), Nicotine, tobacco constituents - leafs - and extracts, and flavorants.

[0036] As discussed above, the aerosol-forming article 6, 60a, 60b may comprise one or more aerosol precursors 61a, 61b, 61c which can be identical or different substances. These precursors are mechanically tied together, either by attachment to a common carrier 62 (FIG.6) or by encapsulation within a container such as a cartridge as illustrated in the aerosol-forming articles 60a, 60b of the aerosol-forming system 7 of FIG.7.

[0037] When encapsulated in a cartridge, the precursors may be placed on the carrier 62 within a closed frame 63, equipped with an air inlet port 65 and an aerosol outlet port 64. This encapsulation method advantageously allows for the combination of aerosols produced by individual precursors, resulting in a combined aerosol that exits through the outlet port 64.

[0038] The aerosol-forming article 6 can comprise one or multiple discrete portions of aerosol precursors 61a, 61b, 61c, which may be present in varying quantities. Each precursor may have unique physical characteristics, including thermal properties, mechanical properties, topology etc., all of which are considered during the aerosol generation process.

[0039] To enhance consumers convenience, aerosol-generating devices and their associated aerosol-forming systems are designed with ergonomics in mind. The ideal design features a form factor and size that allows for easy handling, simple insertion and removal from the device, convenient everyday carry and storage.

[0040] The dimensions of the aerosol-forming systems 7 directly impact the size of both the heater 2 and the overall aerosol-generating device 1. For handheld devices, the optimal surface area for the heat diffusion element 210 of the heater 2 ranges between 2 cm2 and 100 cm2, with a preference for areas smaller than 25 cm2. Preferably the longitudinal dimension of the heater should not exceed 5 cm to maintain portability and ease of use.

[0041] The heater 2 as illustrated in FIG 1A, is adapted to be electrically connected to the aerosol-generating device 1 and configured to generate an aerosol when heat is delivered to aerosol-forming articles 6 of the aerosol-forming system 7. Aerosols are thus generated under the effect of the heat produced by the heating element 201. These chemical substances, conditioned in aerosol-forming articles are consumable items being replaced by consumers generally once depleted.

[0042] As illustrated in FIG.1A, the multi-zone heater 2 is electrically connected to an external control unit 4 for the control of the aerosol generation process.

[0043] According to the present disclosure, the heater 2 comprises at least one heating element 201 and an internal control unit 3.

[0044] As represented in FIG. 1A and 1B, the heater 2 comprises two heating elements 201, 202, with the heating element 202 not fully illustrated. The heat is transferred to the thermally connected aerosol-forming system 7 through the heating element 201, 202. Each element will be described hereinafter in the specification.

[0045] According to the present disclosure, one heating element 201 comprises a heat diffusion element 210, and at least two heat sources 212.

[0046] As shown in the embodiment of the FIG. 1A, the heating element 201 comprises three heat sources 212a, 212b and 212c while in the embodiment as shown in FIG. 1B, the heating element 201 comprises two heat sources 212a, 212b, or can be seen as the heater 2 of the FIG. 1A with the third source 212c not represented.

[0047] The heat diffusion element 210 is thermally connected to the at least two heat sources 212, each heat source 212 being electrically controlled to produce heat independently thus forming at least two independently, individually controlled heating zones. More precisely, the heating element 201, 202 is adapted to generate and to transfer heat from these at least two heating zones, controlled independently, to the thermally connected aerosol-forming system 7 that is physically adjacent. In FIG. 1A, each heat source 212a, 212b, 212c for example form three independently, individually controlled heating zones, and in FIG. 1B, the heat sources 212a, 212b form two independently, individually controlled heating zones.

[0048] In the following description, a heating zone is to be understood as a region of the heating element 201, 202 that can transfer heat to an aerosol-forming system or just a portion of it and that can be controlled independently from another heating zone. A heating zone 6a is thus associated with one electrical heat source, controlled independently from the other heat source(s) and is being formed by the corresponding heated portion or zone of the heat diffusion element. Therefore, in the context of this description, in regards of the heat diffusion element a "heating zone" or a "heated zone" are considered to be equivalent.

[0049] Due to the flexibility offered in term of implementation by this type of multi-zone heater, allowing to combine a plurality of heat sources for an optimal and consistent aerosol generation process and in order to ease the understanding of this description, heat sources may be referred to hereinafter in a generic way with the label "212" for general descriptions or for more detailed descriptions may be referred to as 212a, 212b, 212c etc... to reflect their plurality and to allow to differentiate them, both types of labelling are designating the same functional element.

[0050] The heater 2 is also called a multi-zone heater 2, and the heating element 201, 202 might be also called further in the description a multi-zone heating element.

[0051] The heat generated by the heater 2 is generated locally, in a specific area or region of the heating element 201, 202 the so-called heating zone. The heat generated by a heating zone is flowing to a corresponding and adjacent region of the aerosol-forming system 7 thermally connected with the multi-zone heating element 201.

[0052] In an embodiment, the multi-zone heater 2 comprises one unique multi-zone heating element 201 wherein the outer surface of its heat diffusion element 210 is adjacent to the aerosol-forming system 7.

[0053] In another embodiment, the multi-zone heater 2 comprise two multi-zone heating elements 201, 202- partially shown in FIG.1B - that are facing each other with an aerosol-forming article 6 that is positioned between them in a way that the aerosol-forming article 6 is being sandwiched between the two heating elements 201, 202.

[0054] The multi-zone heater 2 may be removable and interchangeable. This interchangeability advantageously may allow changing the number, layout and topology of the heating zones and consequently provides more flexibility in terms of aerosol-forming system compatibility.

[0055] In such case it may be advantageous to integrate a mechanism to prevent the use of the multi-zone heater 2 with incompatible aerosol-generating devices. This can be achieved by implementing a mechanical Poka-Yoke mechanism for example preventing installation of an incompatible multi-zone heater 2 in an aerosol-generating device 1 and / or by implementing an electrical solution, for example by checking an encoded hardware key or by accessing a software key stored in a memory unit. Poka Yoke, a Japanese term meaning "mistake-proofing" refers to design features that prevent incorrect assembly or use. In this context, it ensures that only compatible multi-zone heaters can be connected to the aerosol-generating device 1. This safety feature may involve mechanical keying of connectors, electrical encoding, or a combination of both to prevent the use of incompatible heaters that could potentially damage the device or produce unintended results.

[0056] The implementation of such a Poka Yoke mechanism in the electrical interface enhances user safety, protects the device from potential damage, and ensures that the aerosol-generating process occurs as intended with properly matched components. This attention to compatibility and safety underscores the sophisticated engineering considerations involved in designing effective and reliable aerosol-generating devices.

[0057] In the same way, it may be advantageous to integrate a mistake-proofing mechanism to prevent the use of non-compatible aerosol-forming systems with the multi-zone heater. Similarly, this may be a mechanical and / or an electrical mechanism as described above.

[0058] To allow the identification of an interchangeable multi-zone heater and for operation efficiency, it may be advantageous to integrate to the multi-zone heater a memory unit containing information related to its configuration and a list of parameters that can be accessed by a control unit, for example the external control unit 4, managing the aerosol generation process.

[0059] The multi-zone heating element 201, 202 is designed in a way to minimize thermal interactions between two adjacent heating zones. The multi-zone heating element 201, 202 is in thermal connection with the aerosol-forming system 7 and is designed to be thermally and chemically stable, moisture resistant and easy to clean. The multi-zone heating element 210,202 is preferably designed with an elongated shape and a large surface area adjacent to or facing the aerosol-forming system 7 in order to provide enough surface area to allow the implementation of a plurality of adjacent heating zones.

[0060] As explained, the at least two heat sources 212 are electrically independent and distant, while being both thermally connected to the same heat diffusion element 210 which allows these two heat sources 212 to transfer heat to the same common heat diffusion element 210.

[0061] Each heat source 212 can be activated and controlled individually by the internal control unit 3 - which will be described further below - either simultaneously or sequentially one after the other in any given order.

[0062] In the following description, an "activated" heat source may be understood as a heat source that is receiving electrical energy and that is converting it into heat. As a consequence, activating a heat source creates a corresponding activated heating zone or activated zone, i.e. a zone producing heat, in the multi-zone heater 2. Thus, the aerosol precursors of the aerosol-forming system 7 are positioned to be adjacent to activated heating zones of the multi-zone heater 2.

[0063] The internal control unit 3 manages the electrical power flowing through the heat sources 212 controlling the amount of heat generated by each of them. The heat produced by the activated heat sources at a given point of time advantageously generates a temperature distribution pattern inside the heat diffusion element 210.

[0064] As shown in FIG.5, is an example of temperature distribution along one longitudinal axis of the heat diffusion element with three heating zones and thermally connected to three heat sources 212a, 212b and 212c. As illustrated, the heat sources 212a and 212b are activated and produce heat independently in two different activated zones 6a and 6b of the aerosol-forming article 6, while the heat source 212c is not activated and thus does not produce heat to the aerosol-forming article 6.

[0065] As a non-limited example, one can use a heat diffusion element 210 flat and elongated, with a very good thermal conductivity, for example in a range comprised between 30 W / mK and 100 W / mK, and a small surface area less than 100 cm2. The heat from each activated heat sources 212 is elevating globally the temperature of the heat diffusion element 210 in a very uniform way and as a consequence the temperature distribution pattern in the heat diffusion element 210 is rather flat.

[0066] Advantageously, the heat diffusion element 210 has a low thermal conductivity, i.e. a thermal conductivity lower than 3 W / mK. This will be developed further in the specification. With such low thermal conductivity, the temperature distribution pattern inside the heat diffusion element 210 presents local peaks of temperature corresponding to the positions of the heat sources 212. Each heat source 212 may elevate the temperature locally rather than globally, in a specific zone adjacent to it. By using such heat diffusion element 210, the temperature distribution of the heat diffusion element 210 can be controlled by zones, adjacent to each heat source 212, creating a multi-zone heating element 201, 202.

[0067] The thermal conductivity of the heat diffusion element 210 is an important factor impacting the general design of the multi-zone heating element 201, 202. For a given thermal conductivity and thickness of the heat diffusion element 210, there is a trade-off between the distance between two adjacent heat sources 212 and their temperature differentiation, i.e. if the heat sources 212 are too close from each other, in the range of 1-3 mm for example, the temperature of their corresponding heated zones tend to be undifferentiated. On the opposite, if the heat sources 212 are very distant one from each other, in the range of 30-50 mm for example, the temperature differentiation between local zones is more important at the expense of the size of the heat diffusion element 210 and consequently the size of the corresponding aerosol-forming system that is becoming too large impacting the usability of the multi-zone heater 2.

[0068] In other words, for a given size and thermal conductivity of the heat diffusion element 210 and / or a given size of a compatible aerosol-forming systems, there is an optimal quantity, or density of heat sources 212 that can be integrated in the multi-zone heating element, in order to get the desired level of temperature differentiation between each zone. For ergonomic reasons, it is desirable that the maximal distance between two adjacent heat sources edge to edge is shorter than 50mm, and preferably shorter than 20mm.

[0069] In an embodiment, described as a non-limited example and not illustrated, a multi-zone heating element comprises eight heat sources 212, each of them having a heating surface area or heating exchange surface of less than 100 mm2. The heat sources are connected to a same heat diffusion element that is forming a flat plane. The eight heat sources are distributed in three rows equally distant along a transversal axis of the heat diffusion element. The first and third rows are integrating three heat sources equally distant in the longitudinal axis. The second row, in the middle is integrating two heat sources equally spaced. The shape of the heat diffusion element is a geometrical square with a side dimension of 45 mm.

[0070] It will be well understood that other configurations of a heating element 201, 202 are possible for creating a multi-zone heating element, based on the size, shape and thermal conductivity of the heat diffusion element 210, the number of heat sources used and their topology or spatial distribution. Different configurations are illustrated as examples in FIG. 4A, to FIG. 4G.

[0071] Heat sources 212 may be any type of electrical element that is receiving electrical energy and that is converting it, in a direct or indirect way, into heat. For example, a heat source based on a resistive element is directly converting electrical energy and producing heat by Joule effect. An indirect way to produce heat can be through the use of an induction heating element for example. Heat sources can be in the form of resistive elements, infrared (IR), Laser, inductive elements etc...

[0072] A very common approach to build electrical heat sources is to use resistive elements that are producing heat when an electrical current is flowing through them by Joule effect. There are many possibilities to build heat sources from resistive elements that are well known by persons skilled in the art. The examples provided hereafter are for illustration only and should not be considered as limiting examples.

[0073] A first example, resistive heat sources are heat sources that are built from metallic wires that are wound in different ways or directions forming coils. Coils can be three-dimensional (3-D) structures having a tubular shape for example or can be two-dimensional (2-D) flat structures such as planar coils.

[0074] Metallic wires used for such coils are generally made of Nichrome, Titanium, Tungsten material with a diameter usually ranging from 0.500 mm to 0.080 mm.

[0075] A second example of resistive heat sources are heat sources that are cut from a sheet of metal or a conductive film allowing to form planar coils. Metal sheets used for such coils can be made of stainless steel - SUS 304 for example - with a thickness ranging from 0.10 mm to 0.020mm. A resistive path is created in the metal sheet by creating a narrow serpentine conductive path that is heating when an electric current flows through it, this narrow serpentine path is formed by either a cutting, a drawing, an etching, a stamping process, or any kind of process allowing to cut a shape with high precision in a thin metal sheet. These methods are very convenient to create such a narrow resistive path that is arranged to form any sort of planar shapes.

[0076] A third example of resistive heat sources are heat sources that are made of a resistive conductor that is placed on a ceramic substrate. The resistive conductor can be printed, coated, die transferred or molded at the substrate surface.

[0077] The resistive path of planar coils can be arranged to form in any sort of shapes as illustrated in FIG.3A, 3B, 3C: either geometrical shapes - rectangular, linear, polygonal, circular...- or non-geometric shapes -curve, serpentine, patatoid - or very complex shapes. It is also possible to form shapes that have an empty space in their middle allowing to position an element inside. The shape of these planar coils examples can be easily understood considering FIG.4C, 4F and 4G.

[0078] Planar coils may be preferably used, as they allow more flexibility in terms of shapes, and may be easier and less expensive to manufacture, and may also reduce the cost for the electronic control. Moreover, a single planar coil having a large surface area can replace a large number of little dots in the matrix of a conventional and equivalent heater array.

[0079] The heat sources 212 may also be formed by a combination of multiple distinct electrical elements being controlled simultaneously and converting the electrical energy into heat.

[0080] A heater 2 with multiple heating elements 201, 202 may integrate different types of heat sources that are mixed together. In a preferred embodiment, all heat sources 212 are made of resistive elements.

[0081] The heat sources 212 are adjacent to the heat diffusion element 210. The distance between the heat sources 212 and the heat diffusion element 210 must be short in order to maximize the heat transfer between them.

[0082] If the heat diffusion element is in the form of a plane, all heat sources can be positioned in one or more planes parallel to it.

[0083] In a first embodiment, heat sources 212 are positioned in several planes or layers parallel to the heat diffusion element 210.

[0084] In a preferred embodiment, the heat diffusion element is a flat element and the heat sources 212 are positioned in a common single plane parallel to the heat diffusion element 210.

[0085] In this specification, a heat exchange surface area is defined hereinafter as a global surface area in mm2 or cm2 that is used to transfer heat to its surroundings and to the adjacent elements that are in thermal connection with it. This global surface area is not taking into consideration holes, slots, voids or spaces present in the heat source heat exchange surface. This global surface area is not taking into consideration either the surface of the electrical wiring of the heat source, even though the electrical wiring is transferring some amount of heat to the heat diffusion element.

[0086] In FIG.3A to 3C, are shown examples of arrangement of resistive elements 8 forming diverse geometrical heat exchange surface.

[0087] As illustrated in FIG.4A to FIG.4G, various configurations of multi-zone heating elements can be created by combining sizes and shapes of the exchange surface area of heat sources 212. Examples of multi-spot heater arrangements are illustrated in a top view of the heat diffusion element 210 to show the different heat exchange surfaces 6d and the heating zones 6a when activated. Heating areas or heating zones 6a and the heat exchanges surface areas 6d are illustrated, their corresponding heat sources 212 being not visible in this top view.

[0088] When selecting or dimensioning heat sources 212 for a multi-zone heating element 201, 202, it is important to consider the relative heat exchange surface area of these heat sources 212 compared to the surface area of the heat diffusion element 210. There is a trade-off to define between the surface area of the heat diffusion element 210, the quantity of heat sources 212 considering their heat exchange area, the distance between them and the temperature differentiation desired for each zone of the multi-zone heating element.

[0089] In an embodiment, eight heat sources 212 are used to build a heater 2 comprising one heating element 201, with a square shape of 45 x 45 mm and are made of resistive elements forming a serpentine shape, cut in a sheet of SUS 304 stainless steel material, having a thickness of 0.050 mm. They all present the same heat exchange surface area of 28 mm2. They are equally positioned at an edge-to-edge distance of 10 mm one from each other.

[0090] In another embodiment, five heat sources 212 are used to build a heater 2, with a square shape of 45 x 45 mm and are made of resistive elements formed by a flat spiral coil made of nichrome wire with a section of 0.30 mm. Four of them, in the corners, present the same apparent heat exchange surface area of 78mm2. The fifth and last heat source, in the center, has a bigger heat exchange surface area of 254mm2.

[0091] The heat diffusion element 210 comprise at least two heat exchange surfaces: one heat exchange surface thermally connected to one or more heat sources 212 - i.e. that heat exchange surface is adjacent and facing one or more heat sources 212 - and one exchange surface thermally connected to an aerosol-forming system 7 - i.e. the other heat exchange surface is adjacent to and facing an aerosol-forming system 7.

[0092] The heat exchange surfaces can have planar surfaces or curved surfaces, waved surfaces or any shape or combination of shapes allowing an effective heat transfer between the heat diffusion element 210 and both the aerosol-forming system 7 and the heat sources 212.

[0093] The heat diffusion element 210 outline can also be any type of geometrical, non-geometrical, or complex shapes as shown in FIG.4A to FIG. 4G: rectangular, linear, polygonal, circular, curve, serpentine, patatoid, etc.

[0094] The heat diffusion element 210, heat sources 212 and the one or more aerosol-forming articles 6 are positioned in a way such that the heat generated by the heat sources is transferred efficiently to the heat diffusion element and is allowing an efficient heat transfer from the heat diffusion element to the one or more aerosol-forming articles.

[0095] In one preferred embodiment, the heat diffusion element 210 is a flat element located between the heat sources 212a, 212b and the one or more aerosol-forming articles 6 in a way that it is sandwiched between them as illustrated in FIG.8A.

[0096] For energy efficiency purpose, it is desired, in a multi-zone heating element 201, 202, that the heat transfer through the heat diffusion element 210 between the heat sources 212 and the aerosol-forming system 7 is maximized in the transversal axis or direction in order to minimize the amount of electrical energy to be supplied to the heat sources.

[0097] Additionally, it may be desired that the heat generated in one zone of the multi-zone heating element 201, 202 does not significantly elevate the temperature of adjacent zones of the heat diffusion element 210, therefore, to avoid this the heat transfer in the longitudinal axis or longitudinal direction of the heat diffusion element may be minimized.

[0098] The transversal axis or direction may be defined here as the axis or direction from the heat sources 212 to the one or more aerosol-forming articles 6 through the heat diffusion element 210.

[0099] The longitudinal axis or direction may refer here to the axis from one heat source to the next ones.

[0100] The transversal and the longitudinal axes or directions of the heat diffusion element can have various orientations, which persons skilled in the art can readily identify without departing from the principles present of this disclosure.

[0101] To optimize the performance of the multi-zone heater, it is desirable to minimize heat transfer along the longitudinal direction while maximizing heat transfer in the transversal direction.

[0102] One approach to achieve this goal is to limit the electrical power of the heat sources 212. By restricting the power, the size of each heated zone can be controlled, reducing thermal interference between adjacent zones. Specifically, limiting the electrical power of individual heat sources to 100W RMS or less helps to maintain distinct heating zones and improves the overall temperature control process to heat the heat diffusion element.

[0103] This power limitation strategy offers an additional advantage: it enables the integration of multi-zone heaters 2 into low-power devices. Typically, these devices operate at less than 200 Watts total power, making them compatible with compact, lightweight power sources such as rechargeable batteries. This design consideration is particularly crucial for handheld aerosol-generating devices, where portability and user comfort are paramount.

[0104] By carefully balancing power limitations and heat distribution, the multi-zone heater 2 can achieve precise temperature control across different zones while remaining suitable for integration into portable, battery-powered devices. This approach enhances the versatility and practicality of aerosol-generating devices incorporating such heaters.

[0105] The heat diffusion element 210 plays an important role in the aerosol generation process, and its thermal properties significantly impact the device's performance. To optimize the aerosol production process, it is essential to design a heat diffusion element that can rapidly reach the desired temperature while minimizing energy consumption. This goal can be achieved by reducing the heat diffusion element's thermal inertia, which is the resistance of a material to temperature changes.

[0106] The heat diffusion element 210 with low thermal inertia offers several advantages. One advantage is a faster heating: the element can reach the target temperature more quickly, reducing the time required to initiate aerosol production. Another advantage is an improved energy efficiency: for example, reducing the thickness of the heat diffusion element, reduces its mass and consequently its thermal inertia, thus less energy is required to heat it, leading to reduced power consumption and potentially extended battery life in portable devices. Another advantage is an enhanced temperature control: with lower thermal inertia, the heating system can respond more rapidly to temperature adjustments, allowing for more precise control over the aerosol generation process. Another advantage is a quicker cooling: when the heating is stopped, a thinner element with lower thermal inertia will cool down faster, potentially improving safety and allowing for more rapid transitions between different heating zones or aerosol-forming articles.

[0107] It is still important to balance the reduction in thickness of the heat diffusion element with other design considerations, such as mechanical strength, durability, and heat distribution properties. The optimal thickness depends on the specific materials used, the desired temperature range, and the overall heater design. These factors are considered carefully to create a heat diffusion element that provides the best combination of rapid heating, energy efficiency, and reliable performance for the aerosol-generating device.

[0108] The heat diffusion element 210 shall be stable chemically and thermally, preferably non-porous to avoid contamination from article-forming systems, with a smooth surface to ease cleaning operations and must present a low thermal inertia and a low thermal conductivity.

[0109] The heat diffusion element 210 can be designed using multiple layers 210a, 210b to optimize its thermal and physical properties as illustrated for example in FIG.2A. In an exemplary embodiment, not illustrated here, the heat diffusion element 210 is made of one layer of mica, exhibiting a smooth surface and non-porous, forming the outer surface, combined with one layer of fiberglass placed underneath used to compensate the thermal conductivity of the mica layer by increasing the global thermal conductivity of the heat diffusion element 210 to shape the temperature distribution by smoothening temperature gradients and by enlarging the corresponding heated aera at the surface of the heat diffusion element 210.

[0110] When employing a multi-layered design, the individual layers may have varying thicknesses and thermal conductivities, allowing for fine-tuning of the element's overall performance. This layered structure can be tailored to achieve specific thermal characteristics that may not be possible with a single material.

[0111] For instance, one layer might be selected for its low thermal conductivity to minimize heat transfer between heating zones, while another layer could be chosen for its durability or ease of cleaning. The thickness of each layer can be adjusted to balance these properties and achieve the desired overall thermal behavior of the heat diffusion element.

[0112] To create a cohesive structure, these layers are typically joined together using various methods. Common techniques include adhesive bonding, where specialized high-temperature glues are used to attach the layers. Thermal bonding or welding may be employed for compatible materials, creating a seamless connection between layers. In some cases, mechanical fixtures such as clamps, screws, or rivets might be used, particularly if the layers need to be separable for maintenance or replacement.

[0113] The arrangement of these layers can be further optimized by grouping them. For example, two or more layers with complementary properties might be combined into a sub-unit within the overall heat diffusion element structure. This grouping approach allows for more complex thermal management strategies, such as creating localized areas with specific heat transfer characteristics within the larger heat diffusion element.

[0114] By carefully selecting materials, thicknesses, and bonding methods for each layer, engineers can create a heat diffusion element that meets the specific requirements of the aerosol-generating device, balancing factors such as thermal performance, durability, and manufacturability.

[0115] The heat diffusion element 210 is characterized by its low thermal conductivity., which is a critical property for the functioning of the multi-zone heater 2. In the context of this disclosure, "low thermal conductivity" may be defined by the element's thermal behavior when subjected to heat from a single activated heat source 212.

[0116] Specifically, when only one heat source 212 thermally connected to the heat diffusion element 210 is activated, it produces a significantly non-homogeneous temperature distribution along at least one longitudinal axis of the element's outer surface facing the aerosol-forming system 7. This non-uniform heating pattern results in the formation of distinct temperature gradients across the surface of the heat diffusion element.

[0117] The presence of these temperature gradients is a key indicator of the heat diffusion element's low thermal conductivity. It demonstrates that the heat generated by a single activated source remains largely localized, rather than spreading evenly across the entire element. This localization of heat is crucial for creating independently controlled heating zones within the multi-zone heater 2.

[0118] It's important to note that measuring and defining the thermal conductivity of a multi-layered structure like the heat diffusion element 210 can be challenging due to the complex interactions between different materials and layers. However, the observed thermal behavior - specifically, the formation of significant temperature gradients when a single heat source is activated - serves as a practical and functional definition of "low thermal conductivity" in the context of this heater design.

[0119] This non-homogeneous heating capability is essential for the multi-zone heater's ability to provide precise and localized heating to specific portions of the aerosol-forming system. It allows for the creation of distinct thermal zones, each of which can be independently controlled to optimize the aerosol generation process for different types of precursors or to create complex heating sequences.

[0120] The heating temperature range of 100°C to 350°C employed by most current aerosol-generating devices on the market is carefully selected to accommodate a wide variety of applications and precursors. This temperature spectrum is crucial for effectively vaporizing different substances without causing thermal degradation or unwanted chemical reactions.

[0121] For instance, water-based precursors, which are commonly used in medical inhalers and some recreational devices, have a boiling point around 100°C. This lower end of the temperature range ensures that aqueous solutions can be effectively aerosolized without excessive heat. Moving up the scale, cannabinoid precursors, which are increasingly utilized in both medical and recreational contexts, typically require temperatures between 160°C and 190°C to vaporize efficiently. This range allows for the extraction of active compounds from cannabis-derived materials without combustion.

[0122] In the realm of electronic cigarettes, a popular alternative to traditional smoking, Vegetable Glycerin (VG) is a key component of e-liquids. With a boiling point of 290°C, VG requires a higher temperature to produce a satisfactory vapor. This temperature is still well within the capabilities of most aerosol-generating devices, allowing for the creation of dense, flavorful vapor clouds that mimic the experience of traditional smoking.

[0123] At the upper end of the spectrum, tobacco-based precursors, used in heat-not-burn devices, necessitate temperatures around 350°C. This temperature is high enough to release nicotine and flavors from tobacco without initiating combustion, which occurs at higher temperatures and produces harmful by-products.

[0124] The diverse range of precursors and their corresponding optimal heating temperatures underscores the importance of versatility in aerosol-generating device design. Each type of precursor, whether it's for medical treatments, recreational use, or as an alternative to traditional tobacco products, demands specific heating conditions to ensure effective and safe aerosol generation.

[0125] Consequently, heaters for aerosol-generating devices are engineered with particular applications in mind. The design considerations include not only achieving the necessary temperature range but also maintaining precise temperature control, ensuring even heat distribution, and optimizing energy efficiency. For instance, a heater designed for a medical inhaler may prioritize lower temperatures and rapid heating to deliver quick, accurate doses of medication. In contrast, a heater for a recreational vaporizer might focus on sustaining higher temperatures for extended periods to maximize flavor extraction and vapor production.

[0126] The multi-zone heater described in this disclosure offers a significant advantage in this context. By providing independently controlled heating zones, it can accommodate different types of precursors within a single device, each with its own optimal heating temperature. This flexibility allows for the creation of more sophisticated aerosol-generating devices capable of producing complex aerosol mixtures or adapting to different user preferences and needs.

[0127] The design of an effective multi-zone heater requires careful consideration of several key parameters, particularly the temperature gradient and heating zone density. These factors are crucial in determining the heater's performance and suitability for specific applications.

[0128] The temperature gradient, a primary characteristic of the heater's design performance, is determined by two key factors: the edge-to-edge distance - or interdistance- between adjacent heating zones and the desired temperature gap between these zones. The interdistance is influenced by the heat diffusion element's dimensions, the number / quantity and size of heating zones, and serves as an indicator of heating zone density. The temperature gap refers to the difference in temperature between an activated heating zone (based on the boiling point of the precursors) and adjacent non-activated zones.

[0129] To categorize the diverse range of applications for multi-zone heaters in aerosol generation, a classification scheme based on heating zone density and temperature gap is proposed. Applications are classified as either "high density" (interdistance < 20mm) or "low density" (interdistance > 20mm). Similarly, temperature gaps are categorized as "high" (> 200°C) or "low" (roughly 100°C), with the latter suitable for precursors with boiling points between 100°C and 180°C.

[0130] As illustrated in FIG.9, a validity window for multi-zone heaters in aerosol-generating applications is defined considering practical limits for interdistances and temperature gaps.

[0131] FIG.9 is presenting the diverse range of applications for multi-zone heaters in the form of a two-dimensional graph considering interdistances between zones on the horizontal axis (x-axis) and temperature gaps on the vertical axis (y-axis). High density applications are found on the left of the x-axis while low density applications are on the right. Applications requiring high temperature gaps are found on the upper part of the y-axis and on the lower part for low density applications. Based on this representation, a temperature gradient can be identified for a specific application considering its specific requirements in term of heat sources interdistance and the desired temperature gap. In FIG.9 three temperature gradients are illustrated: one for a low density and low temperature gap application requiring a temperature gradient of 10°C / cm that could match requirements for water-based precursors for example, a second one for an application requiring a high temperature gap and a high density of heat sources with a temperature gradient of 350°C / cm that can be more appropriate for tobacco-based precursors and a third one, in between, with a temperature gradient of 100°C / cm for cannabinoid precursors for example.

[0132] Additionally in FIG.9, a validity window for multi-zone heaters is represented based on the maximum interdistance and the minimal temperature gap wherein multi-zone heaters are of particularly interest. More details about this validity window are provided below.

[0133] For handheld devices, the upper limit for interdistance is set at 50mm to constrain the heater's overall size. The lower limit for temperature gaps is 50°C, as smaller differences may not provide significant benefits. The upper limit for temperature gaps is constrained by precursor boiling points, while very high temperature gaps may not be achievable with very short interdistances due to material limitations.

[0134] With this validity window, the minimum temperature gradient for a multi-zone heater is established at 10°C / cm. Thus, temperature gradients between two different heated zones are higher than 10°C / cm at an outer surface of the heat diffusion element 210 when one or more heat sources are activated so that to produce an aerosol. However, multi-zone heaters are particularly advantageous for applications characterized by high heating zone density and high temperature gaps, ideally achieving temperature gradients greater than 100°C / cm.

[0135] A definition of a "low thermal conductivity" for a material is relative and application / context dependent. At ambient pressure and temperature conditions, the thermal conductivity of metals and metal alloys is roughly in the range of 7 W / mK to 400 W / m, the thermal conductivity of stones / rocks - excluding gemstones - are roughly in the range of 0.4 W / mK to 7 W / mK and the range for most types of glasses is from 0.5 up to 1.38 W / mK.

[0136] Metals and metal alloys are not suitable materials that can be used for the heat diffusion element as their thermal conductivity is too high and do not allow to form significant temperature variations at its outer surface when heated, therefore a low thermal conductivity in the context of this disclosure is below 7 W / mK. The heat diffusion element 210 requires specific material properties to function effectively. In this context, "low thermal conductivity" is defined as below 3 W / mK, with materials below 1 W / mK being preferable for applications requiring high temperature gradients. This low thermal conductivity is essential for creating significant temperature variations across the element's surface and minimizing heat flow between adjacent heating zones. Physically, the heat diffusion element 210 is typically designed as a thin elongated structure with a thickness less than 3 mm, preferably under 1.5 mm. It must be thermally stable within a service temperature range of 60°C to 350°C to accommodate various aerosol precursors. Chemical stability is also crucial to prevent degradation or contamination during the heater's lifetime.

[0137] To allow more flexibility in term of design and in term of heating scheme of aerosol-forming systems, it is advantageous to design a heat diffusion element that has a higher service temperature than the highest boiling point of the precursors intended to be integrated in aerosol-forming articles to compensate heat and thermal losses.

[0138] The surface of the heat diffusion element 210 facing the aerosol-forming system 7 should be smooth, uniform, and durable to facilitate cleaning and resist wear. Ideally, it should be resistant to common cleaning chemicals and mechanical scratches. The surface facing the heat sources should be non-electrically conductive for safety reasons.

[0139] Various materials can be used for the heat diffusion element comprising high temperature glass, ceramics, high temperature thermoplastics (PEEK, PEI, PAI), high temperature silicone, crystalline materials like mica sheets, etc. These materials can be layered, coated, or modified to achieve the desired thermal and physical properties.

[0140] Layers can for example be made of compounds or composite materials, which may comprise ceramics, or materials formed by particles - chips or grains - of amorphous or semi-crystalline / crystalline materials glued by a bonding agent - Silicone, epoxy etc...

[0141] Layers may be coated on one or both sides, the coating being applied either locally on a specific area or zone of the layer or on the whole surface. Applying a coating to a layer may change its physical properties such as its thermal or electrical conductivity, its mechanical, temperature or chemical resistance, its surface roughness for example.

[0142] Layers may comprise areas or zones with different thicknesses. By creating zones with a different geometry or thickness it is advantageously possible to modify locally the physical properties of a specific area or zone of the heat diffusion element 210.

[0143] A milling or drilling process can be applied to a layer of the heat diffusion element 210 to modify locally its thickness. Another way of forming layers with areas of different thicknesses is to stack two or more layers of the same material, some of them comprising holes, slots or empty areas.

[0144] By carefully considering these design parameters and material properties, multi-zone heaters can be optimized for a wide range of aerosol-generating applications, offering precise temperature control and efficient aerosol production.

[0145] The thermal conductivity values highlighted in the exemplary embodiments illustrate the careful selection of materials to achieve the desired heat transfer characteristics in the heat diffusion element 210. For example, in an embodiment, the heat diffusion element 210 has a square shape with a side dimension of 45mm made of three layers. The outer layer, facing the aerosol-forming articles 6 is a piece of fused silica glass (quartz) with a thickness 0.7 mm having a thermal conductivity of 1.55 W / mK facing the aerosol-forming system 7, combined with two layers made of fiberglass, with a thickness 0.3 mm having a thermal conductivity of 0.04 W / mK forming the surface facing the heat sources 212. Such outer layer of fused silica glass with a thermal conductivity of 1.55 W / mK provides a balance between heat distribution and localized heating while the inner layers of fiberglass, with a much lower thermal conductivity of 0.04 W / mK and a higher thermal inertia act as insulators to minimize heat transfer between adjacent heating zones and protect the outer layer from thermal shocks.

[0146] In another embodiment provided as example, the heat diffusion element 210 has a circular shape having a diameter of 45 mm, with a total thickness of 0.8 mm, formed of two layers of materials: one layer of PEEK with a thickness 0.5 mm having a thermal conductivity of 0.25 W / mK forming the surface facing the aerosol-forming system 7 and a layer made of fiberglass with a 0.3 mm thickness having a thermal conductivity of 0.04 W / mK forming the surface facing the heat sources 212. In this circular embodiment, the combination of PEEK (thermal conductivity 0.25 W / mK) and fiberglass (0.04 W / mK) creates a layered structure with varying thermal properties. The PEEK layer, facing the aerosol-forming system, offers a low heat conduction combined with a smooth surface and a very good chemical resistance, while the fiberglass layer provides a higher thermal insulation to maintain distinct heating zones.

[0147] In another exemplary embodiment, the heat diffusion element 210 has a square shape with a side dimension of 45mm and is formed of one layer of mica (muscovite) with a thickness 0.2 mm having a thermal conductivity of 0.71 W / mK facing the aerosol-forming system 7 on one side and facing the heat sources 212 on the opposite side.

[0148] The total thickness of 0.8 mm in the circular embodiment and the varying thicknesses in the other examples (0.7 mm for fused silica, 0.3 mm for fiberglass, 0.5 mm for PEEK) demonstrate the design considerations for balancing heat transfer, mechanical stability, and overall device compactness. These thin layers contribute to the low thermal inertia of the heat diffusion element 210, allowing for rapid temperature changes and precise control over the heating process.

[0149] The use of materials with thermal conductivities below 3 W / mK, such as mica (muscovite) with 0.71 W / mK, aligns with the earlier definition of "low thermal conductivity" for the heat diffusion element. These carefully selected materials and thicknesses enable the creation of distinct temperature gradients across the heat diffusion element's surface when individual heat sources are activated, facilitating the independent control of multiple heating zones within a compact design.

[0150] According to another embodiment of the present disclosure as illustrated in FIG.1A and FIG.1B, besides the at least two heat sources 212 physically distinct and thermally connected to the common heat diffusion element 210, the heating element 201, 202 also comprises a thermal insulation element 215, which serves multiple crucial functions in optimizing the heater's performance and efficiency.

[0151] The thermal insulation element 215 minimizes undesired heat exchanges, ensuring that the majority of the heat generated by the heat sources 212 is directed towards the heat diffusion element 210. This maximizes the amount of heat transferred to the intended target while reducing heat losses to the surrounding environment. By doing so, the thermal insulation element 215 significantly improves the overall energy efficiency of the heating system.

[0152] Furthermore, the thermal insulation element 215 acts as a protective heat barrier, effectively limiting the temperature exposure of adjacent components, structures, or layers near the heat sources 212. This thermal management is crucial for maintaining the integrity and longevity of the heater's components, especially in a compact design where various elements are in close proximity.

[0153] The design of the thermal insulation element 215 can be adapted to suit specific heating requirements. It may be implemented as a global insulation system, providing thermal isolation for multiple heating elements 201,202 or heating zones across the entire heat diffusion element 210. Alternatively, it can be segmented into distinct parts, each designed to insulate specific regions encompassing one or more heating elements 212 or heating zones of the heat diffusion element 210. This modular approach allows for precise thermal management across different areas of the heater.

[0154] In case where the thermal insulation element 215 is divided into multiple parts, these segments may possess varying thermal insulation properties, including differences in thermal conductivity, size and thickness. This variability enables fine-tuning of the thermal characteristics for each zone, potentially allowing for more complex and precise heating patterns across the heat diffusion element 210.

[0155] The thermal insulation element 215 is typically constructed from materials known for their low thermal conductivity. Options comprise advanced materials like aerogels, such as silica aerogel -, as well as more traditional insulators like fiberglass, mineral wool, and fiberglass wool etc. These materials can be arranged in single or multiple layers, either using throughout or creating a composite structure with layers of different materials, thicknesses, and thermal insulation properties. This layered approach allows for optimization of the insulation performance while potentially addressing other design considerations such as mechanical strength or manufacturability.To ensure durability and consistent performance, the thermal insulation element 215 is preferably designed to be moisture resistant to prevent the degradation of the insulation properties over time due to moisture absorption, which could otherwise lead to reduced efficiency and potential reliability issues in the heater's operation.

[0156] The incorporation of this thermal insulation element 215 allows to achieve precise and efficient heating capabilities of the multi-zone heater 2, contributing significantly to its ability to create controlled, localized heated areas on the outer surface of the heat diffusion element 210.

[0157] The thermal insulation element 215 plays an important role in optimizing the performance and efficiency of the multi-zone heating element 201, 202. In this embodiment, the thermal insulation element 215 is made of a layer of mineral wool and has a thickness of 5 mm, which provides sufficient insulation properties.

[0158] The thermal insulation element 215 is designed to match the size and outline of the heat diffusion element 210. This precise sizing ensures complete coverage and uniform insulation across the entire surface area of the heat diffusion element 210. By thermally insulating all the heat sources 212 of the multi-zone heating element 201, 202, the mineral wool layer serves multiple purposes: it may minimize unwanted heat transfer from the heat sources to the surrounding components, improving overall energy efficiency; it may help to maintain distinct temperature zones by reducing thermal interference between adjacent heating areas; it may protect sensitive components from excessive heat exposure, potentially extending the lifespan of the device, and it may contribute to the precise control of temperature gradients across the heat diffusion element's surface.

[0159] The use of mineral wool as the insulation material is particularly advantageous due to its low thermal conductivity, fire resistance, and durability. These properties ensure that the thermal insulation element 215 can withstand the high temperatures generated by the heat sources 212 while effectively containing and directing the heat towards the intended aerosol-forming system.

[0160] The mechanical integration of the heater 2 is an important aspect of its design and functionality. Two key factors must be carefully considered in this integration process: ensuring efficient heat transfer between the heat sources 212 and the heat diffusion element 210, and creating an assembly capable of withstanding the thermal stress and expansion of materials during operation.

[0161] To achieve this mechanical integration, different approached can be used. One method involves directly attaching the components to the heat diffusion element 210, for example, using a bonding agent. However, this approach may present challenges, particularly if the heat diffusion element 210 lacks sufficient structural integrity or rigidity. Additionally, the bonding agent would be subjected to significant temperature fluctuations, potentially compromising its effectiveness over time and reducing the heater's longevity.

[0162] An alternative solution involves the incorporation of one or more optional base plates 214 or base elements 214 into the multi-zone heater 2 design. These base plates serve as a structural foundation, supporting and mechanically unifying the various heater components. This comprises not only the heat sources 212 and heat diffusion element 210 but also auxiliary components such as electrical wires, temperature sensors 213, and electrical connectors.

[0163] It's important to note that the term "base plate" is used broadly to describe this structural element, regardless of its specific shape or form factor. This flexibility in terminology allows for various design configurations to be implemented while maintaining the core function of the component.

[0164] The use of a base plate 214 offers several advantages. It provides a stable platform for mounting components, which can be particularly beneficial if the heat diffusion element 210 is not sufficiently rigid on its own. The base plate can also act as a heat sink, helping to manage thermal distribution and potentially reducing stress on individual components. Furthermore, it can simplify assembly and maintenance processes, as components can be more easily attached to or removed from a solid base structure. When designing the base plate 214, materials are to be carefully selected to withstand the operational temperatures of the heater while also considering factors such as thermal expansion. The base plate 214 may incorporate features like mounting points, channels for wiring, or thermal management structures to enhance the overall performance and reliability of the heater assembly.

[0165] By utilizing a base plate 214, the multi-zone heater 2 can achieve a more robust and thermally stable configuration, potentially extending its operational life and improving its performance in generating controlled, localized heated areas for aerosol production.

[0166] The mechanical integration of components in the multi-zone heater 2 can be achieved through a combination of approaches. One method involves directly attaching certain elements to the heat diffusion element 210 while some others are secured to a base plate 214. This hybrid approach offers flexibility in component arrangement and thermal management.

[0167] The base plate 214 itself can be designed as a single continuous structure or divided into multiple distinct parts. These parts may be arranged in various configurations, such as parallel or perpendicular orientations, and may or may not lie in the same geometric plane. This modular approach to the base plate design allows for optimized component placement and thermal control within the heater assembly.

[0168] Despite the potential complexity and variety in base plate configurations, for the purposes of this disclosure, the term "base plate" refers to the entire structural support element, regardless of whether it consists of a single piece or multiple interconnected parts. This definition simplifies discussions of the heater's architecture while acknowledging the potential for complex internal structures.

[0169] The primary functions of the mechanical integration are twofold: to securely maintain the positions of all elements within the multi-zone heater 2 and to appropriately manage heat transfers between components. Depending on the specific design requirements, the heat diffusion element 210 can serve as the primary structure, or this role can be assigned to the base plate 214.

[0170] When the heat diffusion element 210 acts as the main support, it provides a direct thermal connection to the heat sources 212 while also serving as a structural backbone for the assembly. This configuration can be advantageous in designs where minimizing thermal resistance between heat sources and the heat diffusion surface is critical.

[0171] Conversely, using the base plate 214 as the primary support structure offers different benefits. It can provide a more rigid foundation for component mounting, potentially simplifying assembly and maintenance procedures. Additionally, a well-designed base plate can incorporate features for thermal management, such as heat sinks or insulating regions, to further optimize the heater's performance.

[0172] The choice between these approaches - or the decision to combine them - depends on factors such as the desired thermal characteristics, manufacturing considerations, and the specific requirements of the aerosol-generating application. By carefully considering these factors, it is advantageously possible to create a multi-zone heater 2 that effectively balances thermal performance, structural integrity, and overall system efficiency.

[0173] The base plate 214 serves as an optional structural component in the multi-zone heating element 201, 202, providing mechanical support and integration for various elements. Its primary function is to maintain the spatial relationships and connections between the heat sources 212, heat diffusion element 210, and other components, ensuring the overall integrity of the heating assembly.

[0174] In a preferred embodiment, the base plate 214 has an elongated and flat profile. This shape is specifically chosen to align with the heat diffusion element 210, with at least one of its longitudinal axes running parallel to it. This arrangement allows one side of the base plate 214 to directly face both the heat sources 212 and the heat diffusion element 210, optimizing the spatial organization of these critical components.

[0175] To enhance the performance of the multi-zone heating element, the base plate 214 is preferably made from materials with low thermal conductivity. This way, it helps to minimize unwanted heat transfer between adjacent heating zones. By limiting heat flow through its structure, the base plate 214 contributes to maintaining distinct temperature profiles in different areas of the heating element, which is important for precise control of aerosol generation. The material selection for the base plate often mirrors that the heat diffusion element 210, as both components benefit from similar thermal properties. This commonality in materials can simplify manufacturing processes and ensure compatibility between components. Moreover, the low thermal conductivity of the base plate allows it to function as a thermal insulation or heat barrier, complementing the role of the dedicated thermal insulation element 215.

[0176] To accommodate various assembly requirements, the base plate 214 may incorporate holes, slots or voids. These features serve multiple purpose, including facilitating the use of fasteners or fixtures to secure components of the multi-zone heating element 201; allowing for the integration of electrical connections between the heating elements and the internal control unit 3.

[0177] The base plate 214 's design can be further customized with regions of varying thicknesses or specialized slots. These modifications are particularly useful for positioning, supporting, or isolating electrical components within the heating element assembly, as shown in FIG.2B.

[0178] In some embodiments, the base plate 214 may feature a layered structure allowing for more complex integration of components and thermal management strategies. These layers can be individually shaped or modified using various industrial processes such as: etching, drilling, milling, cutting, engraving, stamping, forming or molding for example. Additionally, certain parts of the base plate may be manufactured using additive processes like 3D printing for example, offering even greater design flexibility.

[0179] Thermal stability is a critical requirement for the base plate 214, as it must withstand the thermal stresses induced by temperature fluctuations during the operational lifetime of the multi-zone heating element 201, 202. While the addition of a thermal insulation barrier 215 between the heat sources 212 and the base plate 214 can help mitigate these stresses, it remains important that the base plate's materials and structure are inherently capable of withstanding the expected thermal conditions.

[0180] To ensure long-term and safety, the base plate is preferably moisture-resistant and non-electrically conductive. These properties protect against potential degradation from environmental factors and prevent unwanted electrical interactions between components.

[0181] The integration of electrical components within the multi-zone heating element 201, 202 is facilitated by the inclusion of strategically placed holes or slots in the base plate 214. These openings allow for the passage of electrical connections as shown in FIG. 2C, linking various elements to the internal control unit 3, as illustrated in FIG.1A and FIG.1B. In some cases, the base plate may directly incorporate electrical elements such as wires and connectors to streamline the assembly process.

[0182] In a non illustrated embodiment, the base plate is made from a 4mm thick Calcium Silicate board, cut into a square shape with 55mm sides. This material choice is particularly advantageous due to its ability to withstand continuous temperatures above 650°C, far exceeding the service temperature requirements of a typical multi-zone heating element 201. Calcium Silicate also boasts a very low thermal conductivity - less than 0.2 - 0.3 W / mK- and is non-electrically conductive, making it an excellent choice for both thermal management and electrical isolation. The base plate in this embodiment is precision-machined to accommodate eight resistive heat sources, each made from 0.060mm thick SUS 304 metal sheet. Adjacent to each heat source is a 1.9mm thick temperature sensor. The integration of these components is achieved through carefully designed slots in the base plate. Additional holes are incorporated to facilitate electrical connections between the heat sources, temperature sensors, and the internal control unit.

[0183] This configuration shows how the base plate 214 can simultaneously fulfil multiple roles: providing mechanical support, maintaining component positioning, facilitating electrical connections, and acting as an effective thermal barrier. The combination of these functions in a single component streamlines the overall design of the multi-zone heating element 201, 202, potentially reducing complexity and improving reliability.

[0184] In conclusion, the design flexibility offered by the base plate 214 allows for the creation of multi-zone heating elements 201, 202 that can incorporate one or more heat barriers 215 and one or more base plates 214, depending on the specific requirements of the aerosol-generating device. This modular approach enables manufacturers to optimize the thermal, electrical, and mechanical properties of the heating assembly for different applications or product variations.

[0185] As described previously, during the aerosol generation process, the heat diffusion element 210 is thermally connected to at least one heat source 212 of the multi-zone heating element 201 and thermally connected to one or more aerosol-forming articles 6. The internal control unit 3 plays an important role in managing the complex thermal system formed by the multi-zone heating element 201. This internal control unit 3 is responsible for independently controlling each heat source 212, allowing for precise regulation of the heating zones on the heat diffusion element 210.The control unit 3 orchestrates the activation and deactivation of individual heat sources 212, effectively creating localized heated areas on the heat diffusion element's surface. This independent control is essential for achieving the desired temperature distribution across the heat diffusion element, which directly impacts the aerosol generation process.

[0186] The multi-zone heating element 210 thus forms a complex thermal system with multiple heat transfers wherein a first heat transfer is the transfer of the heat or a portion of the heat produced by a heat source 212 to the heat diffusion element 210; a second heat transfer is the heat that is flowing inside the heat diffusion element 210 in the longitudinal direction; a third heat transfer is the heat transferred from the heat diffusion element 210 to the aerosol-forming system 7 that is producing an aerosol under the effect of the transferred heat. All other heat transfers should be avoided because they are generating heat losses in the system leading to energy losses and electrical power inefficiencies, therefore they should be reduced as much as possible.

[0187] In the multi-zone heating element 201, 202, for energy efficiency reasons, it is desired to optimize the first and the third heat transfer in a way that a maximum amount of the heat produced by a heat source 212 can be transferred to the aerosol-forming system 7 minimizing heat losses. It is also preferable to control the heat generation by zones.

[0188] The desired effect is to be able to activate and to control a heating zone of the multi-zone heating element 201 independently from the others, i.e. where the second heat transfer, along the longitudinal direction, is impacting the performance of the system in term of differentiation between the heating zones.

[0189] By modulating the electrical current flowing through each heat source 212, the control unit 3 can fine-tune the heat generation in each zone. This capability is particularly important given the low thermal conductivity of the heat diffusion element 210, which results in localized temperature peaks aligned with the positions of active heat sources. More precisely, each heating zone is associated with a heat source 212 that is controlled by the control unit 3 independently from the other heat sources. When a heat source 212 is active, an electrical current is flowing through it, generating the heat that is transferred to the heat diffusion element 210 as discussed above. This heat is spreading through the heat diffusion element 210 generating a heat flow inside this element. As the heat diffusion element 210 has a low thermal conductivity, the heat is not evenly distributed inside the element - and rather presents a local distribution peak aligned with the physical position of the heat source 212 relative to the heat diffusion element 210. Thus, the heating zone of a multi-zone heating element 201, 202 is the corresponding portion and / or external surface area of the heat diffusion element 210 that is heated by a given heat source 212.

[0190] The desired effect for the multi-zone heating element 201, 202 is to create at least two differentiated heating zones at the surface of the heat diffusion element 210 that can be controlled independently one from each other as described above.

[0191] Two adjacent heating zones may overlap to some extent and therefore can be defined as "rather distinct" instead of being completely distinct. When two adjacent heat sources 212 are active, i.e. producing heat, simultaneously, the heat and consequently the temperature of the overlapping region is influenced by the two heat sources. In a similar way, when only one heat source 212 is active, this heat source is also heating a portion of the adjacent heating zones. The amount of overlapping between two adjacent heating zones and the temperature distribution or temperature behaviour in the overlapping regions is application dependent. Overlapping heating zones is advantageous for applications where heating zones are activated successively, one after the other and a pre-heating effect is desired. When a first heating zone is activated to heat only a portion of an aerosol-forming system 7, producing an aerosol, the overlap allows to pre-heat at the same time an adjacent portion of the aerosol-forming system aligned with the adjacent heating zone. When the adjacent heating zone will be activated, the pre-heating effect will allow reduce the time needed to generate the aerosol intended to be inhaled.

[0192] Heating zones will not overlap, or may have a low level of overlapping, in applications where precursors integrated in aerosol-forming systems 7 are subject to thermal degradation for example. If we consider an application where an aerosol-forming system 7 comprises two adjacent precursor portions that must be heated simultaneously at two different temperatures. For example if a first portion is heated by a first heating zone at 300°C and it is known that the second portion initiates a thermal degradation or decomposition at 230°C with a boiling point at 200°C, then for such case it is preferred that when the first portion is heated at 300°C and the second portion is being heated at 200°C, so that there are no overlapping regions in the second heating zone affected by temperature elevations above 230°C triggering thermal decomposition of the precursor in the aerosol-forming system 7.

[0193] It will be understood that a multi-zone heating element 201, 202 may comprise any combination of fully distinct zones and overlapping zones to get a controlled and desired effect on the aerosol to be generated.

[0194] In a nutshell, the control unit 3 thus balances several factors to optimize the heating process. It needs to maximize heat transfer from the heat sources 212 to the heat diffusion element 210, to minimize unwanted heat flow along the longitudinal direction of the heat diffusion element, to optimize heat transfer from the heat diffusion element 210 to the aerosol-forming system 7, and to manage potential overlap between adjacent heating zones. The internal control unit 3 implement various heating strategies to achieve specific effects. For example, it can activate heating zones sequentially to create a pre-heating effect in adjacent areas, potentially reducing the time required for aerosol generation. Alternatively, it can maintain distinct temperature zones to prevent thermal degradation of sensitive precursors in the aerosol-forming system 7.

[0195] The flexibility provided by the internal control unit 3 allows the multi-zone heating element 201, 202 to accommodate a wide range of aerosol-forming systems and user preferences. By precisely controlling the temperature distribution across the heat diffusion element 210, aerosols can be generated with specific characteristics, tailored to the requirements of different applications or user desires.

[0196] As shown in the figures FIG.1B, 2A to 2C, the heater 2 comprises temperature sensors 213. These sensors play an important role independently controlling each heating zone of the multi-zone heating element 201, 202, enabling the achievement of optimal temperature set point that align with the thermal characteristics of the corresponding heated portion 6a, 6b, 6c of the aerosol-forming article 6. An optimal temperature set point is defined as a temperature that is sufficiently high to vaporize the constituents in the exposed region of the aerosol-forming system while remaining low enough to minimize or prevent thermal degradation or decomposition of these constituents. This careful temperature control is essential to avoid or reduce the generation of unwanted by-products in the inhaled aerosol that may result from thermal degradation.

[0197] Temperature control for each heating zone can be implemented through various methods. A common and well-established approach involves using temperature sensor 213 to measure the temperature of the heating zone and adjusting it by regulating the electrical energy supplied to the corresponding heat source 212. This regulation is typically achieved using a Pulse Width Modulation (PWM) method, which allows for precise control of the power delivered to the heat source.

[0198] The temperature sensors 213 used in the multi-zone heater 2 may be of different types, for example can be Positive Temperature Coefficient (PTC) or Negative Temperature Coefficient (NTC) sensors. These sensors are widely available in various technologies, form factors, temperature ranges and measurement accuracies, allowing for flexibility in design and application.

[0199] It is important that the selected temperature sensors can withstand the service temperature of their corresponding heat source 212 or heating zone. While some NTC sensors are available as thin film sensors, which can be easily integrated between a resistive heat source 212 and the heat diffusion element 210, their operational temperature may be limited for certain high-temperature applications.

[0200] For applications requiring higher temperature capabilities, PT100 or Resistance Temperature Detector (RTD) sensors are preferred. These sensors consist of a resistive element printed on a ceramic substrate, with an electrical resistance that changes based on temperature. They offer several advantages, including service temperatures above 300 °C and a compact form factor, they are commonly available with a physical height of approximatively 2mm, facilitating easy mechanical integration into the heater 2.

[0201] The form factor of the temperature sensors 213 is an important consideration, as it should allow for good thermal connection with either the heat source(s) 212 and / or the heat diffusion element 210. Consequently, temperature sensors with a flat contact surface are often preferable, as they can provide better thermal contact and more accurate temperature readings.

[0202] By carefully selecting and integrating these temperature sensors, the multi-zone heater 2 can achieve precise and independent control over each heating zone, ensuring optimal aerosol generation while minimizing the risk of thermal degradation of the aerosol-forming substances.

[0203] The internal control unit 3 plays a crucial role in managing the multi-zone heater's operations. As illustrated in FIG.1A and 1B, this unit comprises several key components that work together to ensure precise control and efficient functioning of the heating system. The power switch unit 33 of the internal control unit 3 is responsible for controlling the distribution of electrical energy from the external power source to the individual heat sources 212 in the multi-zone heating element 201,202. It allows for independent activation and deactivation of each heating zone, enabling the creation of localized heated areas on the heat diffusion element's surface. The controller unit 32 serves as the brain of the internal control unit 3, coordinating the activities of other components and implementing the heating strategies based on input from sensors and pre-programmed parameters. It may operate with varying degrees of autonomy, either as a local master controlling the power channels based on information from the memory unit 34, or as a slave to the external control unit 4.

[0204] The memory unit 34 stores critical parameters and information related to the multi-zone heating element's configuration, electrical control requirements, safety limits, and aerosol generation processes. This information can be accessed by both the controller unit 32 and the external control unit 4, allowing for flexible and adaptive control of the heating process.

[0205] The sensors and signal conditioning unit 35 interfaces with various sensors throughout the system, including temperature sensors for each heating zone. It processes and routes these signals to the controller unit and / or external control unit, enabling real-time monitoring and adjustment of the heating process.

[0206] The electrical interface 31 facilitates communication and power transfer between the internal control unit 3, the external control unit 4, and the external power source unit 5. In designs where the multi-zone heater 2 is interchangeable, this interface may include connectors and safety features to ensure compatibility with the aerosol-generating device 1.

[0207] For practical implementation, the internal control unit 3 is typically constructed as a Printed Circuit Board Assembly (PCBA), as shown in FIG.8B. This compact and integrated design allows for efficient electrical connection to the multi-zone heating element 201, 202, while minimizing space requirements within the aerosol-generating device.

[0208] In embodiments utilizing heat sources 212 based on electrically resistive elements, the system can employ a direct measurement approach to monitor and control temperature. By measuring the electrical current flowing through the resistive element, the system can calculate its electrical resistance. With detailed knowledge of the resistive element material's characteristics, this resistance value can be used to accurately determine the element's temperature. This method provides a precise and responsive means of temperature control without the need for additional temperature sensors, potentially simplifying the design and reducing costs.

[0209] The multi-zone heating element 201, 202 can be connected to the control unit 3 in different ways depending on the design and intended use of the aerosol-generating device 1. In a preferred embodiment where the multi-zone heating element 201, 202 is permanently connected to the control unit 3, direct electrical wires or conductors are used. This approach provides a reliable and stable connection, minimizing potential issues related to loose contacts or wear over time.

[0210] However, in designs that feature replaceable and interchangeable multi-zone heating elements 201, 202, the use of electrical connectors is preferred. These connectors facilitate easy removal and replacement of the heating element while maintaining a secure electrical connection when in use. The choice of appropriate connectors is crucial, as they must withstand repeated insertion and removal cycles, resist degradation from heat exposure, and maintain low contact resistance to ensure efficient power transfer.

[0211] The internal control unit 3 may be distributed across multiple Printed Circuit Board Assemblies (PCBAs) in certain configurations, particularly when the multi-zone heater 2 comprises more than one multi-zone heating element 201. This distributed architecture offers several advantages. It may improve the thermal management: by separating control components from heat-generating elements, the risk of thermal damage to sensitive electronics is reduced. It may enhance the modularity: individual PCBAs can be more easily replaced or upgraded, potentially extending the device's lifespan and facilitating maintenance. It may optimize space utilization: distributing components across multiple boards can allow for more efficient use of available space within the device, potentially enabling a more compact overall design. It may increase flexibility: different heating elements or zones can be controlled by dedicated PCBAs, allowing for more precise and independent control of each heating zone. It may improve electromagnetic compatibility: separating power-handling components from sensitive control circuits can reduce electromagnetic interference and improve overall system reliability. This distributed approach to the internal control unit 3 functionality demonstrates the sophisticated engineering considerations involved in designing an efficient and reliable multi-zone heater for aerosol generation.

[0212] The internal control unit 3 is connected to the external power source unit 5 as shown in FIG:1A, providing the electrical energy for both the control unit 3 and the one or more multi-zone heating elements 201, 202. This connection is important for the operation of the entire aerosol-generating system, as it ensures a consistent and regulated power supply to all critical components.

[0213] The external power source unit 5 may take various forms, depending on the specific design requirements and intended use of the aerosol-generating device 1. Common options may comprise a lithium-ion battery known for its high energy density and rechargeable capabilities, this type of battery is widely used in portable electronic devices; a lithium-ion battery pack, consisting of multiple lithium-ion cells connected in series or parallel, this configuration can provide higher voltage or capacity as needed; a power supply as an AC adapter or other external power source, which might be suitable for stationary or larger aerosol-generating devices; any combination of the above, with some designs incorporating multiple power sources for redundancy or to meet varying power demands.

[0214] Regardless of the specific type, the external power source unit 5 is preferably designed with an output capacity less than 300W. This power limitation allows to balance performance requirements with safety considerations, energy efficiency, and the compact nature of many aerosol-generating devices. The 300W threshold allows for sufficient power to operate the heating elements and control systems while maintaining a reasonable size and weight for portable devices.

[0215] The choice of power source and its capacity directly impacts the overall performance, portability, and user experience of the aerosol-generating device 1. For instance, a higher capacity battery might allow for extended use between charges, while a lower-powered option might result in a more compact and lightweight device. The specific power requirements may be determined by factors such as the number or quantity of heating zones, their individual power consumption, and the desired duration of operation between recharges or power source replacements.

[0216] The external control unit 4 serves as a critical interface between the multi-zone heater 2 and the external environment, including both the physical surroundings and the users of the aerosol-generating system 1. This external control unit 4 typically comprises three key components: an external controller, a suite of sensors, and a user interface (UI). The external controller 4 manages the overall operation of the system, processing inputs from sensors and user commands to regulate the heater's performance. The collection of sensors monitors various parameters such as ambient conditions, device status, and potentially user interactions, providing real-time data to inform the system's operation. The user interface allows for direct interaction between the user and the device, enabling control over settings, modes of operation, and potentially displaying system status or other relevant information.

[0217] It is important to note that the physical implementation of the multi-zone heater 2 can vary significantly, with functionalities described in this disclosure potentially distributed or combined in different ways across various components or units. Consequently, the terms "internal" and "external" are employed primarily to facilitate understanding of the system's logical organization rather than to indicate strict physical boundaries.

[0218] This flexibility in design allows for optimized configurations based on specific product requirements, manufacturing considerations, or user needs. For instance, certain functions described as part of the external control unit might be integrated into the heater assembly itself in some implementations, while in others, they might be part of a separate module or even a connected external device such as a smartphone. This adaptable architecture enables the creation of aerosol-generating devices that can meet diverse performance, size, and usability criteria while maintaining the core functionality of the multi-zone heating system.

[0219] As illustrated in FIG.1A and FIG.1B, the power switch unit 33 serves as a critical interface between the external power source unit 5 and the multi-zone heating elements 201,202. This unit is responsible for managing and distributing electrical energy from the power source to the individual heat sources 212 within the heating element 201, 202. Its operation is controlled either by the controller unit 32,or the external control unit 4, with communication facilitated through the electrical interface 31.The power switch unit 33 comprises a collection of electrically operated switches and their associated circuitry. These switches can be electro-mechanical such as electrical relays, or electronic like transistors (IGBT, MOSFET) or a combination of both types. The switches are organized into power channels, with each channel controlling the electrical energy flow to a heat source 212 associated with a specific independent zone of the multi-zone heating element 201, 202.

[0220] This arrangement allows for precise, independent control of each heating zone. Each power channel may incorporate one or more electrically operated switches, depending on the complexity and power requirements of the associated heating zone. At a minimum, the power switch unit 33 comprises at least two independent power channels corresponding to the at least two independent heat sources 212 in a multi-zone heating element 201, 202. As illustrated in the embodiment of FIG.1A, the power switch unit 33 comprises three distinct power channels 331, 332, 333, each linked to a separate heat source 212a, 212b and 212c.

[0221] The controller unit 32 is important in managing these power channels. It is designed to drive the different channels within the power switch unit 33 activating or deactivating them as needed to control the flow of electrical energy to the heat sources 212. This capability allows the system to create localized, controlled heated areas 6a, 6b, 6c on the outer surface of the diffusion element as described above. By enabling such granular control over the heating elements, the power switch unit 33 and controller unit 32 work in tandem to facilitate the creation of complex heating patterns and sequences. This level of control is essential for optimizing aerosol generation across different zones of the heating element, allowing for precise temperature management and potentially accommodating various types of precursor materials contained in aerosol-forming articles or user preferences within a single device.

[0222] The controller unit 32, plays an important role in managing the multi-zone heater's operations, with its level of autonomy varying based on the specific implementation. In a highly autonomous configuration, the controller unit 32 functions as a local master, directly controlling the power channels using information stored in the memory unit 34. This autonomous setup typically uses a microcontroller or an equivalent electronic circuit, such as a microprocessor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC) or a Field-Programmable Gate Array (FPGA). These sophisticated components allow for complex, independent decision-making and control over the heating elements.

[0223] On another hand, in a less autonomous configuration, the controller unit 32 operates as a slave to the external control unit 4. In this scenario, the controller unit 32 may be implemented using simpler microcontroller peripheral circuits, relying on the external control unit 4 for higher-level decision-making and operational instructions.

[0224] An exemplary implementation demonstrates the flexibility of this architecture, where the controller unit 32 is realized as a multi-channel Pulse Width Modulation (PWM) driver peripheral circuit. This circuit is controlled by the external controller 4 via an Inter-Integrated Circuit (I2C) communication bus, allowing for precise and efficient control of multiple heating zones while maintaining a streamlined communication interface. The memory unit 34 of the internal control unit 3 serves as a repository for critical parameters related to the one or more multi-zone elements 201, 202. This memory can be accessed by the external control unit 4 through the electrical interface 31. To enhance security and protect proprietary information, the stored parameters may be encrypted. This encryption ensures that only authorized components can interpret and utilize the stored data, preventing unauthorized access or tampering.

[0225] The versatility of this memory and control architecture allows for efficient management of the multi-zone heater's operations, enabling dynamic adaptation to different aerosol-forming systems 7 and user preferences. By storing and accessing key parameters locally, the system can quickly adjust heating profiles and sequences without constant communication with the external control unit 4, potentially improving response times and overall system efficiency.

[0226] The memory unit 34 of the heater 2 stores various categories of parameters essential for its operation and integration with the aerosol-generating device. These parameters can be broadly classified into five categories.

[0227] The first category encompasses structural and identification information about the multi-zone heating elements 201, 202. This includes details such as the number or quantity of heating elements, their configuration, and topology. Specifically, it covers the number of heating zones within each heating element, their dimensions, and relative positions. Additionally, this category may comprise identification data like unique identifiers (IDs) for the multi-zone heater or individual heating elements, manufacturer references such as serial numbers, codes, or names. Importantly, it also contains information to identify compatible aerosol-generating devices, ensuring proper pairing and functionality.

[0228] The second category focuses on the electrical control aspects of the multi-zone heating element. This encompasses information about the types of heat sources associated with each heating zone and their respective electrical power requirements. It also comprises details about the control mode for each zone, the number, and types of sensors used, and their distribution across the heating element 201, 202. To facilitate precise temperature control, this category may comprise look-up tables, indexes, temperature set points, temperature ranges for various operating conditions.

[0229] The third category is dedicated to ensuring the reliability and safety of the multi-zone heating element over time. It comprises detailed specifications such as typical and maximum temperature settings, operational durations, and a comprehensive list of material used in construction. This category also covers limits and ranges for various properties, comprising thermal expansion coefficients, thermal inertia and thermal conductivity. It may also specify temperature and power limits, as well as heat exchange surface areas. all of which are crucial for maintaining safe and efficient operation throughout the heater's lifespan.

[0230] A fourth category of parameters relates to the aerosol generation process and the interaction between the multi-zone heater 2 and the aerosol-forming system 7. This extensive set of parameters may comprise lists or look-up tables of compatible aerosol-forming systems 7 and their detailed characteristics. It may also comprise information about aerosol-forming articles 6 and the properties of their precursors, such as identification data, quantity, topology, size, and heat exchange surface area. This category comprises parameters directly related to the aerosol generation process, including temperature requirements, heating durations, pause times, and specific heating profiles for different precursors. It may also comprise material-specific data like boiling points, thermal inertia, and thermal conductivity, as well as temperature limits and heat energy-related parameters. This comprehensive set of information enables the heater to optimize its performance for various types of precursor materials contained in aerosol-forming articles and user preferences.

[0231] A fifth category of parameters relates to users' preferences and manual adjustments or modification of parameters allowing them to customize the aerosol-generation process as per their own taste and usage.

[0232] By storing and utilizing these diverse categories of parameters, the multi-zone heater 2 can adapt its operation to different aerosol-forming systems 7, ensure safe and efficient performance, and provide a customizable user experience while maintaining compatibility with the broader aerosol-generating device ecosystem.

[0233] The memory unit 34 or the external control unit 4 may comprise detailed information regarding the activation modes for the various heating zones of the multi-zone heater 2. This information may comprise specific activation sequences that describe, for each multi-zone heating element 201, 202, which zones are to be activated, in what order, with what heating profile, and for what duration to produce heat. These activation sequences are important for optimizing the aerosol generation process and can be tailored to different aerosol-forming systems or user's preferences. In another embodiment, the management of the activation mode may be handled entirely by the external control unit 4, allowing for more dynamic control based on real-time inputs or changing conditions.

[0234] For multi-zone heaters 2 or individual multi-zone heating elements 201, 202 designed to be interchangeable, it is advantageous for the memory unit 34 to store additional compatibility information. This data ensures that the heater or the heating element can only be used with compatible aerosol-generating devices 1, preventing potential misuse or damage. Such information might comprise a comprehensive list of compatible devices, their specifications, and any specific operational parameters required for optimal performance.

[0235] The memory unit 34 may be in the form of a dedicated electrical element such as an Integrated Circuit (IC) implemented in the internal controller unit 3 or may be a part, a peripheral or a function of an electrical element implemented in the internal controller unit 3 and playing a more global role such as a microcontroller, a FPGA or an ASIC for example.

[0236] The memory unit 34 is preferably implemented as a programmable memory circuit, such as an Electrically Erasable Programmable Read-Only Memory (EEPROM). This type of memory allows for content modification by either the external control unit 4 or the controller unit 32. This programmability is an important feature, enabling the upgrade of multi-zone heater parameters through user-triggered or user-authorized processes. Such upgrades may comprise updates to heating profiles, the addition of new compatible aerosol-forming systems, or improvements to energy efficiency algorithms. This flexibility ensures that the multi-zone heater can adapt to new developments in aerosol generation technology or changes in user preferences without requiring hardware replacement.

[0237] The sensors and signal conditioning unit 35 serves as an interface for integrating a set of sensors into the multi-zone heater system. These sensors, while not directly involved in controlling the heat generation process of individual heating zones, play an important role in gathering comprehensive data about the heater's operational environment. This environment data can encompass a wide range of parameters, including, but not limited to information about the aerosol-forming system 7, such as its type, composition, or current state; information about ambient conditions like temperature or humidity, which can affect the aerosol generation process; reliability or safety indicators, such as the detection of the presence of an aerosol-forming system 7 or compatibility checks between the aerosol-forming system 7 with the multi-zone heater 2.

[0238] The sensors and signal conditioning unit 35 acts as a central hub for signal routing and processing. It manages various sensor inputs, including those important to the operation of the multi-zone heating elements 201, 202, such as temperature sensors 213 for individual heating zones. Additionally, it handles signals from sensors monitoring the broader heater environment. An important function of this unit is to convert raw sensor data into standardized analog or digital signals that can be readily interpreted by the controller unit 32 and / or the external control unit 4.

[0239] This signal conditioning process ensures accurate and reliable data transmission throughout the system. It may involve amplification, filtering, or analog-to-digital conversion, depending on the specific sensor types and the requirements of the receiving units. By centralizing these functions, the sensors and signal conditioning unit 35 streamlines the overall system architecture, enhancing efficiency and reducing the complexity of individual component interfaces.

[0240] The integration of this comprehensive sensing and signal processing capability enables the multi-zone heater to adapt to varying conditions, maintain optimal performance, and ensure user safety across a wide range of operational scenarios. It provides the control systems with real-time, accurate data necessary for precise regulation of the aerosol generation process, contributing significantly to the overall sophistication and effectiveness of the aerosol-generating device.

[0241] The electrical interface 31 serves as an important communication hub within the muti-zone heater system. It facilitates the interconnection between three main components: the internal control unit 3 the external control unit 4 and the external power source unit 5. This interface ensures seamless data exchange and power transfer, enabling coordinated operation of the entire aerosol-generating device.

[0242] The design of the electrical interface 31 may vary depending on the specific configuration of the multi-zone heater 2. In systems where the heater is permanently integrated into the device, the interface may provide fixed, hardwired connection between all components. This arrangement offers reliability and minimizes potential connection issues over time.

[0243] Alternatively, in designs featuring an interchangeable multi-zone heater 2, the electrical interface 31 comprises specialized electrical connectors. These connectors allow for easy removal and replacement of the heater 2 while maintaining robust electrical connections when in use. This modular approach enhances flexibility and potentially extends the device's lifespan by allowing heater upgrades or replacements.

[0244] In the case of interchangeable heaters, the electrical interface 31 may also integrate a Poka Yoke function.

[0245] The external control unit 4 orchestrates the aerosol generation process based on user inputs and system requirements. This unit offers flexibility in operation, allowing for fully automatic, semi-automatic or manual control modes to cater to different user preferences and usage scenarios.

[0246] The multi-zone heater 2 enables a sophisticated approach to aerosol generation, conceptualized as a sequence of activations across one or more heating zones. Each activation involves delivering a precise amount of electrical energy to a specific heat source, resulting in localized heat generation. This granular control over heating zones allows for complex and customizable aerosol production processes. The external control unit 4 is adapted to manage activation sequences that can be pre-programmed for an automatic operation, offering a standardized user experience. The activation sequences can be also user-created through an intuitive User Interface (Ul) for manual mode, allowing for personalized aerosol profiles. The activation sequences can also be based on pre-programmed sequences that can be dynamically modified in response to external conditions, user inputs, or a combination of both, enabling a semi-automatic mode that balances convenience with customization.

[0247] The external control unit 4 is adapted to select and initiate an appropriate activation sequence from a range of available options. This selection process takes into account the specific characteristics of the aerosol-forming system 7 that is thermally connected to the multi-zone heater 2, ensuring optimal performance and compatibility.

[0248] From a hardware perspective, the external control unit 4 can be implemented as a network of different devices: it can comprise one or more microprocessors, DSPs, ASICs, FPGAs or microcontrollers. These components are interconnected and communicate through various means, comprising physical wires, wireless protocols, or a combination of both. This flexible architecture is further enhanced by integration with a network of sensors, allowing the system to gather and respond to a wide range of inputs.

[0249] The external control unit 4 may establish communication and data exchange with external devices, such as smartphones, typically through wireless connections. In such configurations, the external device becomes an extension of the external control unit 4, potentially offering enhanced user interfaces, data analysis, or remote control capabilities.

[0250] Sensors can be carefully designed to collect a comprehensive set of information that can be related to environmental conditions (e.g., ambient temperature, humidity), user parameters (choices, selections), internal device state such as battery level, heater temperature, or characteristics and status of the aerosol-forming system. The external control unit 4 can thus make informed decisions about aerosol generation, adapt to changing conditions, and provide a highly responsive and personalized user experience. This sophisticated control system underscores the advanced nature of the multi-zone heater and its potential to deliver precisely tailored aerosol generation in various applications.

[0251] More details on the identification and activation processes, as well as the distributed architecture option are presented hereinafter: in an embodiment, the external control unit 4 is in the form of a microcontroller directly integrated in the aerosol-generating device 1, and is responsible for identifying the multi-zone heater 2. Upon successful identification, it initiates a compatible activation sequence tailored to the specific characteristics of the identified heater. This centralized approach allows for streamlined communication and control within the device. In another embodiment with a more distributed control system, the controller unit 32 functioning as a first controller, can take on the task of identifying the aerosol-forming system 7. Once identification is complete, it awaits a request from the external control unit 4, which acts as a second controller. Upon receiving this request, the controller unit 32 initiates an appropriate activation sequence based on the identified aerosol-forming system's characteristics. This dual-controller setup allows for more specialized handling of different system components.

[0252] In another embodiment, the architecture is highly distributed, leveraging external smart devices for enhanced functionality. The external control unit 4 is also a microcontroller and is adapted to identify the multi-zone heater 2. The external control unit 4 extends its capabilities by establishing wireless connection to a smartphone.

[0253] The smartphone, having more sensing and processing capabilities, can thus identify the aerosol-forming system 7 using an RFID (Radio-Frequency Identification) tag. Once identified, the smartphone communicates the characteristics back to the external control unit 4, which can then use this information to optimize the activation sequence.

[0254] In the following, the power requirements of these multi-zone heaters 2 will be described. Their overall design of being mostly intended to be integrated in small apparatus that are often handheld and rechargeable aerosol generator devices have an influence on the external power source unit 5 to be used for balancing high energy delivery with a compact and lightweight form factor. The external power source unit 5 has thus a dual purpose. It must provide sufficient electrical energy to power the one or more multi-zone heating elements 201, 202, which are the main components responsible for aerosol generation. Additionally, it supplies the electrical energy required by the internal control unit 3, ensuring that all control and monitoring functions can operate reliably. The power source must be capable of delivering short bursts of high energy to the heating elements while maintaining overall low power consumption to extend battery life and keep the device compact. This balance is important for creating a device that is both effective in aerosol generation and convenient for user portability and extended use between charges.

[0255] Additionally, the external power source unit 5 supplies the electrical energy required by the internal control unit 3, ensuring that all control and monitoring can operate reliably for example.

[0256] It is a common practice to use, for handheld devices, power sources in the form of rechargeable batteries, based on Lithium-Ion battery packs for example. These types of batterie packs can deliver a very high electrical current for several minutes, easily feeding a 200W heating system. Aerosol generator devices with an electrical power of 200W that are integrating a power source made of two 18650 Lithium-Ion battery cells are available on the market for many years. It will be well understood that the power limitation for handheld aerosol generator devices is usually a limitation of the size and weight of the device that is acceptable for consumers and not a technical limitation related to the amount of electrical power that it is available.

[0257] When designing multi-zone heaters 2, the dimensioning of the power source takes into account several critical factors: the number of heat sources 212 that are activated simultaneously, the individual electrical power consumption of each heat source 212, and the desired number of activations per battery charge. For example, a multi-zone heater 2 integrating two independent heat sources of 100W, providing two distinct heating zones, can be effectively powered by two 18650 lithium-Ion battery cells. However, it is desirable to increase the number or quantity of available heating zones while reducing the electrical power consumption of individual heat sources. This approach offers several advantages such as an enhanced control over temperature distribution across the heating element, an improved energy efficiency by activating only necessary zones, a potential for more complex and precise aerosol generation profiles, an extended battery life due to lower overall power consumption.

[0258] The controller unit 32, offers a wide range of activation sequence possibilities, from simple to highly complex. As its most basic, this unit 32 can generate a straightforward activation sequence by activating heating zones one after another, in a consecutive manner, for an equal duration. This type of sequence can be particularly useful for creating a controlled heating path across the surface of the multi-zone heating element 201, 202. By carefully selecting adjacent heating zones in a specific order, the controller can effectively "trace" a predetermined pattern, allowing for precise control over which areas of the aerosol-forming system 7 are heated and in what order.

[0259] The flexibility of the controller unit 32 extends beyond simple sequential activation. In more complex activation sequences, the controller unit 32 can activate multiple heating zones simultaneously at any point in the sequence. This parallel activation capability allows for more sophisticated heating patterns and potentially faster or more uniform heating of larger areas of the aerosol-forming system 7.

[0260] Furthermore, the activation parameters for each heating zone can be individually tailored within a sequence. The duration and temperature set-point for each zone's activation can be unique, differing from other zones and potentially varying over time within the same sequence. This granular control enables the creation of highly customized heating profiles tailored to specific aerosol-forming materials or desired aerosol characteristics.

[0261] Adding another layer of complexity, the controller unit 32 can implement dynamic temperature profiles for individual heating zones. Rather than maintaining a constant temperature throughout activation, a zone's temperature can be programmed to evolve over time. This feature allows for intricate heating sequences that can, for example, start with a rapid temperature rise for initial vaporization, followed by a controlled decrease to maintain optimal aerosol production without overheating the material.

[0262] These advanced activation capabilities of the controller unit 32 provide the multi-zone heater with exceptional versatility. By combining spatial control (which zones are activated), temporal control (when and for how long zones are activated), and thermal control (at what temperature and with what profile zones are heated), the system can generate a vast array of heating patterns. This flexibility allows the aerosol-generating device to optimize its performance for different types of aerosol-forming systems, accommodate various user preferences, and potentially create complex, multi-stage aerosol generation processes that were not possible with simpler heating systems.

[0263] Thanks to the independent control of the heating zones, very complex activation sequences can be generated by combining for example the effects of five different parameters. A first parameter is the spatial distribution: the specific the location of each activated heating zone on the multi-zone heating element's surface. A second parameter is the simultaneous activation: the number of heating zone activated concurrently at any given moment. A third parameter is the activation duration: the length of time each individual heating zone remains active. A fourth parameter is the inter-activation interval: the time period between consecutive activations of heating zones. A fifth parameter is the temperature control: the ability to set and maintain distinct temperatures for each individual heating zone.

[0264] Thanks to the low thermal conductivity of the heat diffusion element 210, each heating zone is well differentiated from the others in term of temperature behaviour. The controller unit 32 is able to precisely shape the temperature profile across the heat diffusion element's surface by applying carefully designed activation sequence. These sequences may be pre-programmed, dynamically modified based on user preferences or external conditions, or manually defined to suit specific requirements.

[0265] When an activation sequence is applied to a multi-zone heating element 201, 202 that is thermally connected to an adjacent aerosol-forming system 7, it becomes possible to generate a complex global aerosol stream. This stream comprises one or more individual aerosols, each produced by a separately or individually activated heating zone. This capability allows for unprecedented control over the aerosol generation process.

[0266] The heater's design enables each zone of the multi-zone heating element 201,202 to heat a corresponding adjacent portion or region of the thermally connected aerosol-forming system 7. Each of these portions is made of an aerosol precursor material, which produces an aerosol when heated. Importantly, these portions may contain either identical or different aerosol precursor material , allowing for the generation of uniform or varied aerosols from a single device.

[0267] Thanks to such advanced heaters, coupled with compatible aerosol-forming systems, the need for the aerosol-generating device to read or verify information from the aerosol-forming systems or articles to configure the heater is eliminated. Instead, the aerosol-generating device only needs to identify which specific heater is inserted or connected, significantly simplifying the user interaction process while maintaining a high degree of customization and control over the aerosol generation.

Claims

1. A heater (2) adapted to be electrically connected to an aerosol-generating device (1) configured to generate an aerosol when heat is delivered to an aerosol-forming system (7), wherein the heater (2) comprises at least one heating element (201, 202), said heating element (201,202) comprising a heat diffusion element (210) thermally connected to at least two heat sources (212), each heat source (212) being electrically controlled to produce heat independently so that to create local controlled heated areas (6a, 6b, 6c) on an outer surface of the heat diffusion element (210).

2. The heater (2) according to claim 1, wherein the heating element (201,202) comprises a thermal insulation element (215) adjacent to the heat sources (212) and to the heat diffusion element (210).

3. The heater (2) according to claim 2, wherein the heating element (201,202) comprises a base plate (214):

4. The heater (2) according to any of the preceding claims, wherein it comprises an internal controller unit (3) adapted to be electrically connected to the at least one heating element (201, 202).

5. The heater (2) according to any of the preceding claims, wherein it comprises a memory unit (34) adapted to store at least one parameter related to aerosol-forming articles (6) and / or to aerosol-forming systems (7) to be used by said heater (2).

6. The heater (2) according to any of the preceding claims, wherein the heat diffusion element (210) has a global thermal conductivity lower than 3 W / mK.

7. The heater (2) according to any of the preceding claims, wherein temperature gradients between two different heated zones are higher than 10°C / cm at an outer surface of the heat diffusion element (210) when one or more heat sources (212) are activated so that to produce an aerosol.

8. The heater (2) according to any of the preceding claims, wherein the heat diffusion element has a thickness below 1.5 mm.

9. The heater (2) according to any of the preceding claims, wherein a heat source (212) has an electrical power consumption lower than 100 Watt RMS.

10. The heater (2) according to any of the preceding claims, wherein the heat diffusion element (210) of the at least one heating element (201,202) has a surface area facing an aerosol-forming system (7), larger than 2 cm2 and lower than 100 cm2.

11. An aerosol-generating device (1) comprising the heater (2) according to the preceding claims, an external control unit (4), an external power source unit (5) wherein said external control unit (4) is adapted to identify at least one property of the heater (2).

12. The aerosol-generating device (1) according to claim 11, wherein the memory unit (34) of the heater (2) is adapted to be configured temporarily or permanently by the external controller unit (4) once an electrical communication is established.

13. The aerosol-generating device according to claims 11 and 12, wherein the memory unit (34) or the external control unit (4) are adapted to store at least one parameter related to the aerosol-generation process in connection with one or more aerosol-forming systems (7) intended to be thermally connected with the heater (2).

14. The aerosol-generating device (1) according to the preceding claim 13, wherein the external control unit (4) shares with the memory unit (34) said at least one parameter related to the aerosol-generation process in connection with one or more aerosol-forming systems (7) intended to be thermally connected with the heater (2) once an electrical connection is established.

15. The aerosol-generating device (1) according to any of the precedent claims, wherein the heater (2) and / or the aerosol-generating device comprises authentication and / or mistake-proofing means so that to be in use with compatible aerosol-forming systems only adapted for such devices.

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