Heater management

Abstract

An electrically operated aerosol generating system equipped with means for detecting harmful conditions such as a dry heater or an unapproved type of heater. [Solution] The system comprises an electric heater (30) having at least one heating element for heating an aerosol-forming substrate, a power supply (14), and an electrical circuit (16) connected to the electric heater and power supply and having memory, wherein the electrical circuit (16) determines a harmful condition when the ratio between the initial electrical resistance (R1) of the heater (30) and the change in electrical resistance from the initial resistance (R2-R1) is greater than a maximum threshold value stored in memory or less than a minimum threshold value, and if a harmful condition exists, limits the power supplied to the electric heater (30) or provides a display to the user. The system has the advantage of not requiring a pre-stored maximum resistance value, and thereby the system can use different heaters and can adapt to resistance variations due to manufacturing tolerances.

Description

Technical Field

[0001] The invention relates to heater management. Certain disclosed embodiments relate to heater management within an electrically heated aerosol generation system. Aspects of the present invention are directed to an electrically heated aerosol generation system and a method for operating an electrically heated aerosol generation system. Some of the described embodiments relate to a system capable of detecting abnormal changes in the electrical resistance of a heater element that may indicate a harmful state in the heater element. For example, a harmful state may indicate a depleted level of an aerosol-forming substrate within the system. In some of the described embodiments, this system may be effective for heater elements having different electrical resistances. In other embodiments, the detected characteristics of the electrical resistance may be used to determine or select how the system may be operated. Some aspects and features of the present invention have particular application to electrically heated smoking systems.

Background Art

[0002] International Patent Publication No. WO 2012 / 085203 discloses an electrically heated smoking system comprising a liquid storage portion for storing a liquid aerosol-forming substrate, an electric heater comprising at least one heating element for heating the liquid aerosol-forming substrate, and an electric circuit configured to determine depletion of the liquid aerosol-forming substrate based on the relationship between the power applied to the heating element and the resulting temperature change of the heating element. In particular, the electric circuit is configured to calculate the rate of temperature rise of the heating element, and a high rate of temperature rise indicates that the wick carrying the liquid aerosol-forming substrate to the heater has dried out. The system compares the rate of temperature rise to a threshold value stored in memory during manufacture. If the rate of temperature rise exceeds the threshold, the system may stop supplying power to the heater.

Summary of the Invention

Problems to be Solved by the Invention

[0003] The system described in International Patent Publication No. 2012 / 085203 can use the electrical resistance of the heater element to calculate the temperature of the heating element, which has the advantage of not requiring a dedicated temperature sensor. However, the system still requires the storage of a threshold that depends on the resistance of the heater element, and therefore the system is optimized for heater elements having a specific electrical resistance or range of resistance.

[0004] However, it is sometimes desirable to enable the system to operate with different heaters. Typically, in the type of system described in International Patent Publication No. 2012 / 085203, the heater is provided in a disposable cartridge along with a quantity of liquid aerosol-forming substrate. Heater elements in different cartridges may have different electrical resistances. This may be a result of manufacturing tolerances within the same type of cartridge, or because different cartridge designs are available for use in the system to provide different user experiences. The system in International Patent Publication No. 2012 / 085203 is optimized for heaters with known specific electrical resistances determined at the time of manufacture of the system used in this system.

[0005] In electric smoking systems, and especially in systems that can operate using different heaters, it is desirable to have alternative systems for determining when a heater has dried out or when other harmful conditions have occurred in the heater.

[0006] In an electrically heated aerosol generating system with both permanent components and consumable components, including aerosol-forming substrates, it is desirable that the manufacturer of the system be able to easily determine whether the consumable components are "genuine" parts or consumables that are considered compatible with the system. This applies to both systems where the heater is a consumable component and systems where the heater is part of a permanent component. [Means for solving the problem]

[0007] In the first embodiment, an electrically operated aerosol generating system is provided, which is, An electric heater comprising at least one heating element for heating an aerosol-forming substrate, Power supply and An electrical circuit connected to an electric heater and a power supply, and having memory, is configured to determine a harmful condition when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in memory outside of the expected period, and to control the power supplied to the electric heater based on whether a harmful condition exists, and to provide an indication based on whether a harmful condition exists.

[0008] The phrase "the ratio reaches a threshold value stored in memory outside of the expected period" clearly encompasses both situations: when the ratio reaches the threshold value earlier than expected, and when the ratio reaches the threshold value later than expected, or when it does not reach the threshold value at all.

[0009] One harmful condition in an aerosol generation system or aerosol generator is insufficient or depleted aerosol-forming substrate in the heater. Generally speaking, the less aerosol-forming substrate is delivered to the heater for vaporization, the higher the temperature of the heating element will be for a given applied power. For a given power, the evolution of the heating element temperature during heating cycles, or how that evolution changes over multiple heating cycles, can be used to detect whether the amount of aerosol-forming substrate in the heater is being depleted, and in particular whether there is insufficient aerosol-forming substrate in the heater.

[0010] Another harmful condition is the presence of counterfeit, incompatible, or damaged heaters in a system with replicable or disposable heaters. If the resistance of a heater element rises more quickly or more slowly than expected for a given applied power, this may be because the heater is counterfeit and has different electrical characteristics than the genuine heater, or because the heater is damaged in some way. In any case, the electrical circuit may be configured to prevent power from being supplied to the heater.

[0011] Another harmful condition is the presence of counterfeit, unsuitable, old, or damaged aerosol-forming substrates in the system. If the resistance of a heater element rises more quickly or more slowly than expected for a given applied power, this may be because the aerosol-forming substrate is counterfeit or old, and therefore its moisture content is higher or lower than expected. For example, if a solid aerosol-forming substrate is used, it may be dry if it is very old or has not been stored properly. If the substrate is drier than expected, less energy will be used for vaporization, and the heater temperature will rise more quickly. This will result in an unexpected change in the electrical resistance of the heater element.

[0012] By using the ratio of the initial resistance to the subsequent resistance, the system does not need to determine the actual temperature of the heating element, nor does it need to have any pre-stored knowledge of the heating element's resistance at a given temperature. This allows the use of different approved heaters within the system without triggering harmful conditions, and also allows for absolute resistance variations due to manufacturing tolerances of the same type of heater. This also enables the detection of unsuitable heaters.

[0013] Using the initial resistance measurement and subsequent resistance changes, it becomes possible to set thresholds more accurately to determine specific harmful conditions. The ratio of the resistance change to the initial resistance is independent of variations in heater size or shape due to manufacturing tolerances or variations in parasitic contact resistance within the system, but depends solely on the material properties of the heater and aerosol-forming substrate.

[0014] An electrical circuit does not necessarily have to calculate a ratio or change in electrical resistance and compare that ratio to a threshold value, but it may perform an equivalent comparison between the measured resistance value and one or more stored values ​​and a threshold value derived from one or more measured resistance values. For example, an electrical circuit may compare the electrical resistance of a heater element measured at a point after the initial power delivery from the power source to the electric heater with a value calculated from the initial electrical resistance and a threshold value stored in memory.

[0015] The electrical circuit may be configured to measure the initial electrical resistance of the heater element and the electrical resistance of the heater element after the initial power delivery from the power source to the electric heater. If the time between electrical resistance measurements is known or determined, the rate of change in resistance can be calculated for a given resistance coefficient of the heater element in relation to the rate of change in temperature. The system may always be configured to supply the heater with the same power, or the threshold(s) may depend on the power supplied to the heater.

[0016] The initial electrical resistance may be measured before the heater is first used. If the initial resistance is measured before the heater is first used, it can be assumed that the heater element is at or near room temperature. Since the expected change in resistance over time may depend on the initial temperature of the heater element, measuring the initial resistance at or near room temperature can narrow the range of expected behavior.

[0017] The initial resistance may be calculated by subtracting the assumed parasitic resistance from other electrical components and contacts in the system from the initially measured resistance.

[0018] The system may comprise a device and a cartridge detachably coupled to the device, with the power supply and electrical circuits located within the device and the electric heater and aerosol-forming substrate located within the detachable cartridge. As used herein, "detachably coupled" to the device means that the cartridge and the device can be coupled to and separated from each other without significant damage to either the device or the cartridge.

[0019] The electrical circuit may be configured to detect the insertion and removal of a cartridge from the device. The electrical circuit may be configured to measure the initial electrical resistance of the heater when the cartridge is first inserted into the device, but before significant heating occurs. The electrical circuit may compare the measured initial resistance to an acceptable range of electrical resistance stored in memory. If the initial resistance is outside the acceptable range, it may be considered a counterfeit, incompatible, or damaged product. In this case, the electrical circuit may be configured to prevent power supply until the cartridge is removed and replaced with a different cartridge.

[0020] The device may use cartridges with different characteristics. For example, the device may use two different cartridges with heaters of different sizes. Larger heaters may be used to deliver more aerosol for users with such personal preferences.

[0021] The cartridge may be refillable, or it may be configured to be discarded when the aerosol-forming substrate is depleted.

[0022] An aerosol-forming substrate is a substrate capable of releasing volatile compounds that can form aerosols. The volatile compounds may also be released by heating the aerosol-forming substrate.

[0023] The aerosol-forming substrate may contain plant-derived materials. The aerosol-forming substrate may contain tobacco. The aerosol-forming substrate may contain tobacco-containing materials that contain volatile tobacco-flavored compounds released from the aerosol-forming substrate upon heating. Alternatively, the aerosol-forming substrate may contain non-tobacco-containing materials. The aerosol-forming substrate may contain homogenized plant-derived materials. The aerosol-forming substrate may contain homogenized tobacco materials. The aerosol-forming substrate may contain at least one aerosol-forming body. The aerosol-forming body is any suitable known compound or mixture of compounds that facilitates the formation of a dense and stable aerosol in use and is substantially resistant to thermal decomposition at the operating temperature of the system. Suitable aerosol-forming materials are well known in the industry and include, but are not limited to, polyhydric alcohols (such as triethylene glycol, 1,3-butanediol, and glycerin), esters of polyhydric alcohols (such as glycerol monoacetate, diacetate, or triacetate), and aliphatic esters of monocarboxylic acids, dicarboxylic acids, or polycarboxylic acids (such as dimethyl dodecanediol and dimethyl tetradecanediol). Preferred aerosol-forming materials are polyhydric alcohols or mixtures thereof (such as triethylene glycol, 1,3-butanediol, and glycerin (most preferred)). The aerosol-forming substrate may also contain other additives and components (such as flavorings).

[0024] The cartridge may contain a liquid aerosol-forming substrate. For the liquid aerosol-forming substrate, certain physical properties of the substrate, such as vapor pressure or viscosity, are selected to be appropriate for use in an aerosol-generating system. The liquid preferably contains a tobacco-containing material that includes volatile tobacco flavor compounds released from the liquid when heated. Alternatively, or additionally, the liquid may contain a non-tobacco material. The liquid may contain water, ethanol, or other solvents, plant extracts, nicotine solutions, and natural or artificial flavors. The liquid preferably further contains an aerosol former. Examples of suitable aerosol formers are glycerin and propylene glycol.

[0025] The advantage of providing a liquid storage portion is that the liquid within the liquid storage portion is protected from the ambient air. In some embodiments, ambient light may also be prevented from entering the liquid storage portion so as to avoid the risk of photoinduced decomposition of the liquid. Furthermore, a high level of hygiene can be maintained.

[0026] The liquid storage portion is preferably arranged to hold liquid for a predetermined number of smoking sessions. If the liquid storage portion is not refillable and the liquid within the liquid storage portion has been used up, the user needs to replace the liquid storage portion. It is necessary to prevent contamination of the user by the liquid during such replacement. Alternatively, the liquid storage portion may be refillable. In that case, the aerosol-generating system may be replaced after a certain number of refills of the liquid storage portion.

[0027] Alternatively, the aerosol-forming substrate may be a solid substrate. The aerosol-forming substrate may contain a tobacco-containing material that includes volatile tobacco flavor compounds released from the substrate upon heating. Alternatively, the aerosol-forming substrate may contain a non-tobacco material. The aerosol-forming substrate may further contain an aerosol former. Examples of suitable aerosol formers are glycerin and propylene glycol.

[0028] If the aerosol-forming substrate is a solid aerosol-forming substrate, it may include one or more of the following: herb leaves, tobacco leaves, tobacco stem fragments, reconstituted tobacco, homogenized tobacco, extruded tobacco, cast leaf tobacco, and puffed tobacco, for example, one or more of the following: powder, granules, pellets, fragments, spaghetti, slivers, or sheets. The solid aerosol-forming substrate may be in an uncontained form, or a suitable container or cartridge may be provided. Optionally, the solid aerosol-forming substrate may contain additional tobacco or non-tobacco volatile flavor compounds released upon heating of the substrate. The solid aerosol-forming substrate may also contain, for example, capsules containing additional tobacco or non-tobacco volatile flavor compounds, which may melt during heating of the solid aerosol-forming substrate.

[0029] As used herein, “homogenized tobacco” means a material formed by agglomerating particulate tobacco. Homogenized tobacco may be in the form of a sheet. Homogenized tobacco material may have an aerosol-forming content of more than 5% by dry mass. Alternatively, homogenized tobacco material may have an aerosol-forming content of about 5 to about 30 weight percent by dry mass. Homogenized tobacco material sheets may be formed by agglomerating particulate tobacco obtained by crushing or otherwise subdividing one or both of tobacco leaf laminas and tobacco leaf stems. Alternatively, or additionally, homogenized tobacco material sheets may include, for example, one or more of tobacco dust, tobacco fines and other particulate tobacco by-products formed during tobacco processing, handling and transport. A homogenized tobacco material sheet may contain one or more inherent binders (i.e., tobacco endogenous binders), one or more exogenous binders (i.e., tobacco exogenous binders), or a combination thereof, to help aggregate particulate tobacco. Alternatively, or additionally, the homogenized tobacco material sheet may contain other additives, including but not limited to tobacco and non-tobacco fibers, aerosol-forming agents, wetting agents, plasticizers, flavoring agents, fillers, aqueous and non-aqueous solvents, and combinations thereof.

[0030] Optionally, the solid aerosol-forming substrate may be provided on or embedded within a thermally stable carrier. The carrier may take the form of a powder, granules, pellets, fragments, spaghetti, strips, or sheets. Alternatively, the carrier may be a tubular carrier having a thin layer of solid substrate disposed on its internal surface, its external surface, or both its internal and external surfaces. Such tubular carriers may be formed from, for example, paper or paper-like material, nonwoven carbon fiber mat, low-mass, coarse-mesh metal screen, or perforated metal foil or any other thermally stable polymer matrix.

[0031] The solid aerosol-forming substrate may be placed on the surface of a carrier in the form of, for example, a sheet, foam, gel, or slurry. The solid aerosol-forming substrate may be placed on the entire surface of the carrier, or alternatively, in a certain pattern to provide non-uniform flavor delivery during use.

[0032] The solid aerosol-forming substrate may be provided as a smoking article, such as a cigarette, for use in a device equipped with a heater, power supply, and electrical circuitry.

[0033] The electrical circuit may be configured to detect the insertion and removal of the aerosol-forming substrate from the device. The electrical circuit may also be configured to measure the initial electrical resistance of the heater when the aerosol-forming substrate is first inserted into the device, but before significant heating occurs. The electrical circuit may compare the measured initial resistance to an acceptable range of electrical resistance stored in memory. If the initial resistance is outside the acceptable range, the aerosol-forming substrate may be considered counterfeit, incompatible, or damaged. In this case, the electrical circuit may be configured to prevent power supply until the aerosol-forming substrate is removed and replaced.

[0034] An electric heater may have a single heating element. Alternatively, an electric heater may contain multiple heating elements, for example, two, three, four, five, six, or more. The heating elements (one or more) may be appropriately arranged to most effectively heat the liquid aerosol-forming substrate.

[0035] Preferably, at least one of the electric heating elements contains an electrically resistive material. Suitable electrically resistive materials include, but are not limited to, semiconductors such as doped ceramics, "conductive" ceramics (e.g., molybdenum disilide), carbon, graphite, metals, alloys, and composite materials made of ceramic and metallic materials. Such composite materials may contain doped or undoped ceramics. An example of a suitable doped ceramic is doped silicon carbide. Examples of suitable metals include titanium, zirconium, tantalum, and platinum group metals. Examples of suitable alloys include stainless steel, constantan, nickel-, cobalt-, chromium-, aluminum-titanium-zirconium-, hafnium-, niobium-, molybdenum-, tantalum-, tungsten-, tin-, gallium-, manganese-, and iron-containing alloys, as well as nickel, iron, cobalt, stainless steel-based superalloys, Timetal®, iron-aluminum alloys, and iron-manganese-aluminum alloys. Timetal® is a registered trademark of Titanium Metals Corporation. In composite materials, the electrically resistive material may be optionally embedded, encapsulated, or coated in an insulating material, or vice versa, depending on the required energy transfer dynamics and external physicochemical properties. The heating element may comprise a metallic, etched foil insulated between two layers of inert material. In this case, the inert material may include Kapton®, full-layer polyimide, or mica foil. Kapton® is a registered trademark of EI du Pont de Nemours and Company.

[0036] At least one electric heating element may take any suitable form. For example, at least one electric heating element may take the form of a heating blade. Alternatively, at least one electric heating element may take the form of a casing or substrate having different conductive parts or electrically resistant metal tubes. The liquid storage part may incorporate a disposable heating element. Alternatively, one or more heating needles or rods penetrating the liquid aerosol forming substrate may also be suitable. Alternatively, at least one electric heating element may include a flexible sheet of material. Other alternatives include heating wires or filaments, such as wires or heating plates made of Ni-Cr (nickel-chromium), platinum, tungsten, or alloys. Optionally, the heating element may be deposited in or on a rigid carrier material.

[0037] In one embodiment, the heating element includes a mesh, array, or cloth of conductive filaments. The conductive filaments may have defined gaps between them, and the width of these gaps may be 10 μm to 100 μm.

[0038] The conductive filaments may form a mesh of size 160 to 600 mesh US (±10%) (i.e., 160 to 600 filaments per inch (±10%)). The gap width is preferably 25 μm to 75 μm. The area ratio of the mesh openings, which is the ratio of the area of ​​the gaps to the total area of ​​the mesh, is preferably 25 to 56%. The mesh may be formed using different types of woven or lattice structures. Alternatively, the conductive filaments may consist of an array of filaments arranged parallel to each other.

[0039] The diameter of the conductive filament can be 10 μm to 100 μm, preferably 8 μm to 50 μm, and more preferably 8 μm to 39 μm. The filament may have a round cross-section or a flat cross-section.

[0040] The area of ​​the conductive filament mesh, array, or cloth can be small, up to 25 mm.2 It is preferable that the size is less than or equal to a handheld system, and that it is permissible to incorporate it into a handheld system. The conductive filament mesh, array, or cloth may be a rectangle with dimensions of, for example, 5 mm x 2 mm. It is preferable that the conductive filament mesh or array covers 10% to 50% of the area of ​​the heater assembly. It is more preferable that the conductive filament mesh or array covers 15% to 25% of the area of ​​the heater assembly.

[0041] The filaments may be formed by etching a sheet material (such as foil). This can be particularly advantageous when the heater assembly includes an array of parallel filaments. If the heating element includes a mesh or cloth of filaments, the filaments may be formed individually and then woven together.

[0042] Preferred materials for conductive filaments are 304, 316, 304L, and 316L stainless steel.

[0043] At least one heating element may heat the liquid aerosol-forming substrate by conduction. The heating element may be in at least partial contact with the substrate. Alternatively, heat from the heating element may be conducted to the substrate by means of a thermally conductive element.

[0044] During use, it is preferable that the aerosol-forming substrate comes into contact with the heating element.

[0045] The electrically operated aerosol generation system preferably further comprises a capillary material for transporting the liquid aerosol-forming substrate from the liquid storage section to the electric heater element.

[0046] It is preferable to position the capillary material so as to be in contact with the liquid in the liquid storage portion. It is preferable to extend the capillary core into the liquid storage portion. In this case, during use, the liquid is moved from the liquid storage portion to the electric heater by capillary action within the capillary core. In one embodiment, the capillary core has a first end and a second end, the first end extending into the liquid storage portion to be in contact with the liquid therein, and the electric heater is positioned to heat the liquid in the second end. When the heater is activated, the liquid at the second end of the capillary core is vaporized by at least one heating element of the heater to form supersaturated vapor. The supersaturated vapor is mixed with the airflow and carried in the airflow. As it flows, the vapor condenses to form an aerosol, which is carried toward the user's mouth. The liquid aerosol forming substrate has physical properties, including viscosity and surface tension, that allow the liquid to be carried through the capillary core by capillary action.

[0047] The capillary core may have a fibrous or spongy structure. Preferably, the capillary core contains a bundle of capillaries. For example, the capillary core may contain multiple fibers or threads, or other microtubules. The fibers or threads may generally be aligned along the long axis of the aerosol generating system. Alternatively, the capillary core may contain a spongy or foamy material formed into a rod shape. The rod shape may extend along the long axis of the aerosol generating system. The core structure forms multiple small holes or tubes through which liquid can be transported by capillary action. The capillary core may contain any suitable material or combination of materials. Examples of suitable materials are capillary materials, such as spongy or foamy materials, ceramic or graphite-based materials in the form of fibers or sintered powders, foamy metal or plastic materials, and fibrous materials made of spun or extruded fibers (such as cellulose acetate, polyester, or bonded polyolefins, polyethylene, terylene or polypropylene fibers, nylon fibers or ceramics). Capillary cores may have any suitable capillary and porosity for use with different liquid physical properties. Liquids have physical properties, including but not limited to viscosity, surface tension, density, thermal conductivity, boiling point, and vapor pressure, that allow them to be transported through capillary devices by capillary action.

[0048] The heating element may be in the form of a heating wire or filament surrounding and optionally supporting the capillary core. When there is a large amount of aerosol-forming substrate during normal use, the capillary properties of the core, combined with the properties of the liquid, ensure that the core remains consistently moist within the heated area.

[0049] Alternatively, as described, the heater element may include a mesh formed from multiple conductive filaments. Capillary material may extend into the gaps between the filaments. The heater assembly may draw a liquid aerosol-forming substrate into the gaps by capillary action.

[0050] The housing may contain two or more different capillary materials, where the first capillary material in contact with the heater element has a higher thermal decomposition temperature, and the second capillary material in contact with the first capillary material but not with the heater element has a lower thermal decomposition temperature. The first capillary material effectively acts as a spacer, separating the heater element from the second capillary material so that the second capillary material is not exposed to temperatures above its thermal decomposition temperature. As used herein, “thermal decomposition temperature” means the temperature at which a material begins to decompose and loses mass by generating gaseous byproducts. The second capillary material may advantageously occupy a larger volume than the first capillary material, and may also hold more aerosol-forming substrates than the first capillary material. The second capillary material may have better core performance than the first capillary material. The second capillary material may be less expensive or have higher filling capacity than the first capillary material. The second capillary material may be polypropylene.

[0051] The power source may be any suitable power source, such as a DC voltage source. In one embodiment, the power source is a lithium-ion battery. Alternatively, the power source may be a nickel-metal hydride battery, a nickel-cadmium battery, or a lithium-based battery, such as a lithium-cobalt battery, a lithium iron phosphate battery, a lithium titanate battery, or a lithium polymer battery. Alternatively, the power source may be another form of charge storage device, such as a capacitor. The power source may require recharging and may have a capacity that allows for sufficient energy storage for one or more smoking experiences. For example, the power source may have a capacity that allows for continuous aerosol generation for about 6 minutes, or a multiple of 6 minutes, corresponding to the typical time it takes to smoke one conventional cigarette. In another example, the power source may have a capacity that allows for a predetermined number of puffs or discontinuous heater activations.

[0052] The aerosol generating system preferably includes a housing. The housing is preferably elongated. The housing may contain any suitable material or combination of materials. Examples of suitable materials include metals, alloys, plastics, or composite materials containing one or more of these materials, or thermoplastics suitable for food or pharmaceutical applications, such as polypropylene, polyetheretherketone (PEEK), and polyethylene. The material is preferably lightweight and not brittle.

[0053] The aerosol generating system is preferably portable. The aerosol generating system may be an electrically heated smoking system and may be comparable in size to a conventional cigar or cigarette. The aerosol generating system may also be a smoking system. The total length of the smoking system may be approximately 30 mm to approximately 150 mm. The outer diameter of the smoking system may be approximately 5 mm to approximately 30 mm.

[0054] The electrical circuit preferably includes a microprocessor, and more preferably a programmable microprocessor. The system may include a data input port or a wireless receiver so that software can be uploaded onto the microprocessor. The electrical circuit may include additional electrical components. The system may include a temperature sensor.

[0055] If a harmful condition is detected, the system does nothing more than provide the user with an indication that a harmful condition has been detected. This may be done by providing a visual, auditory, or tactile warning. Alternatively, or additionally, when a harmful condition is detected, the electrical circuit may automatically limit or otherwise control the power supplied to the heater.

[0056] There are numerous possible ways in which electrical circuits can be configured to control the power supplied to an electric heater when a harmful condition is detected. If the aerosol-forming substrate delivered to the heating element is insufficient, or if the solid aerosol-forming substrate dries out, it may be desirable to reduce or stop the power supply to the heater. This may be both to ensure a consistent and enjoyable experience for the user and to mitigate the risk of overheating and the formation of undesirable compounds in the aerosol. Power to the heater may be stopped or limited for a short period or until the heater or aerosol-forming substrate is replaced.

[0057] The system may include a smoke extraction detector for detecting when the user is using the system, the smoke extraction detector being connected to an electrical circuit, the electrical circuit being configured to supply power from a power source to a heater element when smoke extraction is detected by the smoke extraction detector, and the electrical circuit being configured to determine whether there is a harmful condition between each smoke extraction.

[0058] The smoke extraction detector may be a dedicated smoke extraction detector that directly measures the airflow through the device, such as a microphone-based smoke extraction detector, or it may indirectly detect smoke extraction based, for example, on temperature changes within the device or changes in the electrical resistance of heater elements.

[0059] The electrical circuit may be configured to supply a predetermined power to the heater element for a period t1 following the initial detection of fume extraction or the initial supply of power to the heater, and the electrical circuit may be configured to determine the change in the electrical resistance of the heater element based on a measurement of the electrical resistance of the heater element during the period t1 between each fume extraction. The period t1 may be selected to be immediately after the initial detection of fume extraction or immediately after the heater is first powered. This is particularly advantageous if the circuit detects an incompatible or counterfeit heater or aerosol-forming substrate during the first use following the replacement of a consumable. For example, the duration of a typical fume extraction may be 3 seconds, and the response time of the fume extraction detector may be about 100 ms. Then, t1 may be selected to be 100 ms to 500 ms during the period of fume extraction before the heater temperature stabilizes. Alternatively, the period t1 may be selected to be the period during which the temperature of the heating element is expected to stabilize.

[0060] The electrical circuit may be configured to prevent the supply of power from the power source to the heater element if there are conditions that are harmful to a predetermined number of consecutive users inhaling smoke.

[0061] The electrical circuit may be configured to continuously determine whether a harmful condition exists, and if a harmful condition exists, to prevent or reduce the power supply to the heater, and to continue preventing or reducing the power supply to the heater element until the harmful condition is gone.

[0062] In liquid and wick-based systems, excessive smuggling can lead to wick drying because the liquid cannot be replaced quickly enough near the heater. In these situations, it is desirable to limit the power supply to the heater to prevent it from becoming too hot and to prevent the generation of undesirable aerosol components. Power to the heater may be cut off as soon as a harmful condition is detected, until subsequent user smuggling.

[0063] Similarly, excessive fume extraction may prevent the heater from cooling down as expected between fume extractions, resulting in a gradual and undesirable increase in heater temperature between fume extractions. This is true for systems based on liquid or solid aerosol-forming substrates. To monitor cooling between fume extractions, an electrical circuit may be configured to track a ratio over time, and if the difference between the maximum value of the ratio and the subsequent minimum value of the ratio does not exceed a threshold of difference stored in memory, the power supplied to the heater may be limited or an indication may be provided.

[0064] The electrical circuit may be configured to prevent the supply of power to the heater element for a predetermined period of time when a harmful condition is present.

[0065] The electrical circuit may be configured to prevent power from being supplied to the heater until the consumable part containing the aerosol-forming substrate or the heater is replaced.

[0066] Alternatively, or additionally, the electrical circuit may be configured to continuously calculate whether the ratio has reached a threshold value, compare the time taken for the ratio to reach the threshold value with a stored time value, and determine if there is a harmful condition if the time taken to reach the threshold value is less than the stored time value, or if the ratio does not reach the threshold value within the expected period, and to prevent or reduce the power supply to the heater. If the threshold value is reached faster than expected, this may indicate that the heater element or substrate is dry, or that the heater is unsuitable, counterfeit, or damaged. Similarly, if the threshold value is not reached within the expected period, this may indicate a counterfeit or damaged heater or substrate. This may allow for a quick determination of a counterfeit, damaged, or unsuitable heater or substrate.

[0067] As described, finding a harmful condition may indicate not only a dry condition in a heater element, but also a heater with electrical properties outside the expected characteristic range. This may be because the heater is defective, material accumulates on the heater over its product life, or it is an unapproved or counterfeit heater. For example, if a manufacturer uses stainless steel heater elements, those heater elements are expected to have an initial electrical resistance at room temperature within a certain range of electrical resistance. Furthermore, the ratio between the heater's initial electrical resistance and the change in electrical resistance from the initial resistance may be expected to be particularly valuable because it relates to the material of the heater element. For example, if a heater element made of Ni-Cr is used, the ratio will be lower than expected because the temperature resistance coefficient of Ni-Cr is much lower than that of stainless steel. Therefore, the electrical circuit may be configured to determine a harmful condition when the ratio between the heater's initial electrical resistance and the change in electrical resistance from the initial resistance is below a minimum threshold, and to limit the power supply to the heater based on the result. This prevents the use of some unapproved heaters. The electrical circuit may prevent power supply to the heater when the ratio is below a minimum threshold.

[0068] Multiple different thresholds may be used to produce different control strategies for different conditions. For example, a highest and lowest threshold may be used to set a boundary where the substrate heater needs to be replaced before further power is supplied. The electrical circuit may be configured to prevent power from being supplied to the heater until the heater or aerosol-forming substrate is replaced if the ratio exceeds the highest threshold or falls below the lowest threshold. One or more intermediate thresholds may be used to detect excessive fume extraction behavior that results in a dry condition in the heater. The electrical circuit may be configured to prevent power from being supplied to the heater for a certain period or until subsequent fume extraction by the user if the intermediate threshold is exceeded but the highest threshold is not. One or more intermediate thresholds can also be used to trigger an indication to the user that the aerosol-forming substrate is almost depleted and needs to be replaced soon. The electrical circuit may be configured to provide an indication, which may be visual, audible, or tactile, if the intermediate threshold is exceeded but the highest threshold is not.

[0069] One process for detecting counterfeit, damaged, or unsuitable heaters is to check the heater's resistance or the rate of change in the heater's resistance when the heater is first used or inserted into a device or system. The electrical circuit may be configured to measure the initial resistance of the heater element within a predetermined period after power has been supplied to the heater. The predetermined period may be short, ranging from 50 ms to 200 ms. For heaters with a mesh heating element, the predetermined period may be approximately 100 ms. Preferably, the predetermined period is between 50 ms and 150 ms. The electrical circuit may be configured to determine the rate of change in the initial resistance during the predetermined period. This may be done by taking multiple resistance measurements at different points in time during the predetermined period and calculating the rate of change in resistance based on the multiple resistance measurements. The electrical circuit may be configured to measure the heater's initial resistance or the rate of change in the heater's initial resistance, or to power the heater to heat an aerosol-forming substrate using much lower power as a separate routine, or to measure the heater's initial resistance for the first few minutes before significant heating occurs after the heater has started up. The electrical circuit may be configured to compare the initial resistance of the heater or the rate at which the initial resistance of the heater changes with respect to an acceptable range of values, and if the initial resistance or the rate at which the initial resistance changes with respect to respect is outside the acceptable range of values, it may prevent power from being supplied to the electric heater or provide an indication until the heater or aerosol-forming substrate is replaced.

[0070] If the initial resistance or the rate of change of the initial resistance is within an acceptable range, and the ratio of the heater's initial electrical resistance to the change in electrical resistance from the initial resistance is less than or greater than a maximum threshold value stored in memory, the electrical circuit may be configured to determine that the heater is acceptable and to control the power supplied to the electric heater based on whether it is acceptable, or to provide an indication if it is not an acceptable heater.

[0071] The electrical circuit may be configured to determine within one second of initially supplying power to the heater whether there is an acceptable heater.

[0072] In a second embodiment, a heater assembly is provided, which heater assembly is An electric heater having at least one heating element, An electrical circuit connected to an electric heater and having memory, the electrical circuit is configured to determine that a harmful condition exists when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in memory outside of an expected period, and to control the power supplied to the electric heater based on whether a harmful condition exists, or to provide an indication based on whether a harmful condition exists.

[0073] The heater assembly may be configured for use within an aerosol generation system, and may also be configured to heat the aerosol-forming substrate during use.

[0074] In a third embodiment, an electrically operated aerosol generator is provided, which is: Power supply and An electrical circuit connected to a power source and having memory, wherein the electrical circuit is connected to an electric heater when in use and is configured to determine a harmful condition when the ratio between the heater's initial electrical resistance and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in memory outside of the expected period, and to control the power supplied to the electric heater based on whether a harmful condition exists, or to provide an indication based on whether a harmful condition exists.

[0075] A fourth aspect of the present invention provides an electrical circuit for use in an electrically operating aerosol generator, which is connected to an electric heater and a power supply when in use, and which includes a memory, and which determines a harmful condition when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in the memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in the memory outside of an expected period, and which controls the power supplied to the electric heater based on whether a harmful condition exists, or provides an indication based on whether a harmful condition exists.

[0076] A fifth aspect of the present invention provides an electrical circuit for use in an electrically operated aerosol generator, which, when in use, is connected to an electric heater and a power supply for heating an aerosol-forming substrate, has memory, and is configured to measure the initial resistance of the heater or the rate of change of the initial resistance of the heater within a predetermined period after power has been supplied to the heater, compares the initial resistance of the heater or the rate of change of the initial resistance of the heater with an acceptable range of values, and if the initial resistance or the rate of change of the initial resistance is outside the acceptable range of values, prevents power supply to the electric heater or provides an indication until the heater or aerosol-forming substrate is replaced.

[0077] The predetermined period may be short, ranging from 50ms to 200ms. For heaters equipped with a mesh heating element, the predetermined period may be approximately 100ms. Preferably, the predetermined period is 50ms to 150ms. The electrical circuit may be configured to determine the rate of change of the initial resistance during the predetermined period. This may be done by taking multiple resistance measurements at different points in time during the predetermined period and calculating the rate of change of resistance based on the multiple resistance measurements.

[0078] If the initial resistance is within an acceptable range, the electrical circuit may be configured to determine the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance, and to compare the ratio with a maximum or minimum threshold value stored in memory. If the ratio is less than the maximum threshold value or greater than the minimum threshold value stored in memory, it may determine that the heater is acceptable and control the power supplied to the electric heater based on whether it is an acceptable heater, or provide an indicator based on whether it is an acceptable heater.

[0079] In a sixth aspect, a method is provided for controlling the power supply to a heater in an electrically operated aerosol generating system, the method comprising an electric heater having at least one heating element for heating an aerosol forming substrate, and a power source for supplying power to the electric heater, the method being

[0080] The system includes determining a harmful condition when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than or less than a maximum threshold value stored in memory, or when the ratio reaches a threshold value stored in memory outside of the expected period, and controlling the power supplied to the electric heater, or providing a display to the user depending on whether a harmful condition exists.

[0081] The method may include measuring the electrical resistance of the heater element initially and measuring the electrical resistance of the heater element at a point after the initial power delivery from the power source to the electric heater.

[0082] The method may include supplying a constant power to the heater when power is supplied. Alternatively, variable power may be supplied depending on other operating parameters. In this case, the threshold may depend on the power supplied to the heater.

[0083] The method may include determining the initial electrical resistance before the heater is first used. If the initial resistance is determined before the heater is first used, the heater element can be assumed to be around room temperature. Since the expected change in resistance over time may depend on the initial temperature of the heater element, measuring the initial resistance at or near room temperature can narrow the range of expected behavior.

[0084] The method may include calculating the initial resistance by subtracting the assumed parasitic resistance from other electrical components and electrical contacts in the system from the initially measured resistance.

[0085] An electrically operated aerosol generating system may be equipped with a smoke inhalation detector for detecting when a user inhales smoke from the system, and the method may include supplying power from a power source to a heater element when smoke inhalation is detected by the smoke inhalation detector, determining whether there is a harmful condition between each smoke inhalation, and preventing the supply of power from the power source to the heater element if there is a harmful condition for a predetermined number of consecutive user smoke inhalations.

[0086] The method may include preventing the supply of power from the power source to the heater element if harmful conditions are present.

[0087] The method may include continuously determining whether a harmful condition exists, and, if a harmful condition exists, preventing the supply of power to the heater and continuing to prevent the supply of power to the heater element until the harmful condition is gone.

[0088] The method may include preventing the supply of power to the heater element for a predetermined period of time when a harmful condition exists.

[0089] Alternatively, or additionally, the method may include continuously calculating whether the ratio exceeds a threshold and comparing the time taken to reach the threshold with a stored time value, and if the time taken to reach the threshold is less than the stored time value, determining a harmful condition and controlling the power supply to the heater.

[0090] In a seventh aspect, a method is provided for detecting an unsuitable or damaged heater in an electrically operated aerosol generating system, the system comprising an electric heater having at least one heating element for heating an aerosol-forming substrate, and a power supply for supplying power to the electric heater, wherein the method is

[0091] This includes determining an unsuitable or damaged heater when the ratio between the heater's initial electrical resistance and the change in electrical resistance from the initial resistance is greater than or less than the maximum threshold value stored in memory, or when the ratio reaches the threshold value stored in memory outside of the expected period.

[0092] The method may include preventing power from being supplied to the electric heater or providing a warning if it is determined that the heater is unsuitable, until the heater or aerosol-forming substrate is replaced.

[0093] The method further includes measuring the initial resistance of the heater, or the rate of change of the initial resistance of the heater, within a predetermined period after power has been supplied to the heater; comparing the initial resistance of the heater or the rate of change of the initial resistance of the heater with an acceptable range of values; and, if the initial resistance or the rate of change of the initial resistance is outside the acceptable range of values, preventing the supply of power to the electric heater until the heater or aerosol-forming substrate is replaced, or providing an indication.

[0094] The predetermined period may be short, and may be between 50ms and 200ms. For heaters equipped with a mesh heating element, the predetermined period may be approximately 100ms. Preferably, the predetermined period is between 50ms and 150ms.

[0095] Determining the rate of change of the initial resistance over a given period may be achieved by taking multiple resistance measurements at different points in time during that period and calculating the rate of change of resistance based on those measurements.

[0096] The method may further include detecting when a heater or aerosol-forming substrate is inserted into the system. The method may be performed immediately after it is detected that a heater or aerosol-forming substrate has been inserted into the system.

[0097] In an eighth aspect of the present invention, a method is provided for detecting an unsuitable or damaged heater in an electrically operated aerosol generating system, the system comprising an electric heater having at least one heating element for heating an aerosol-forming substrate, and a power supply for supplying power to the electric heater, wherein the method is

[0098] The method includes measuring the initial resistance of the heater, or the rate of change of the initial resistance of the heater, within a predetermined period after power has been supplied to the heater; comparing the initial resistance of the heater or the rate of change of the initial resistance with an acceptable range of values; and, if the initial resistance of the heater or the rate of change of the initial resistance is outside the acceptable range of values, preventing power supply to the electric heater until the heater or aerosol-forming substrate is replaced, or providing an indication.

[0099] The predetermined period may be short, and may be between 50ms and 200ms. For heaters equipped with a mesh heating element, the predetermined period may be approximately 100ms. Preferably, the predetermined period is between 50ms and 150ms.

[0100] Determining the rate of change of the initial resistance over a given period may be achieved by taking multiple resistance measurements at different points in time during that period and calculating the rate of change of resistance based on those measurements.

[0101] The method may further include detecting when a heater or aerosol-forming substrate is inserted into the system. The method may be performed immediately after it is detected that a heater or aerosol-forming substrate has been inserted into the system.

[0102] In the ninth aspect, a computer program product is provided that can be directly loaded into the internal memory of a microprocessor, which includes a software code portion, to perform the steps of the sixth, seventh, and eighth aspects when the computer program product is executed on a microprocessor in an electrically operating aerosol generating system, the system includes an electric heater having at least one heating element for heating an aerosol forming substrate, and a power supply for supplying power to the electric heater, and the microprocessor is connected to the electric heater and the power supply.

[0103] Computer program products may be provided as downloadable software or by being recorded on computer-readable storage media.

[0104] According to the tenth aspect, a computer-readable storage medium is provided on which a computer program according to the ninth aspect is stored.

[0105] Features described in relation to one aspect of the present invention may be applied to other aspects of the invention. In particular, features described in relation to the first aspect may be applied to the second, third, fourth, and fifth aspects of the present invention. Features described in relation to the first, second, third, fourth, and fifth aspects of the present invention are also applicable to the sixth, seventh, and eighth aspects of the present invention.

[0106] The present invention will be further described with reference to the accompanying drawings, which are merely illustrative examples. [Brief explanation of the drawing]

[0107] [Figure 1a] Figure 1a is a schematic diagram of a system according to an embodiment of the present invention. [Figure 1b] Figure 1b is a schematic diagram of a system according to an embodiment of the present invention. [Figure 1c] Figure 1c is a schematic diagram of a system according to an embodiment of the present invention. [Figure 1d] Figure 1d is a schematic diagram of a system according to an embodiment of the present invention. [Figure 2] Figure 2 is an exploded assembly diagram of the cartridge used in the system shown in Figures 1a to 1d. [Figure 3] Figure 3 is a detailed view of the heater filaments, showing the meniscus of the liquid aerosol-forming substrate between the filaments. [Figure 4] Figure 4 is a schematic diagram showing the change in heater resistance during user smoke extraction. [Figure 5] Figure 5 is an electrical circuit diagram showing a method for measuring the resistance of a heating element. [Figure 6] Figure 6 illustrates the control process that follows the detection of a harmful condition. [Figure 7] Figure 7 is a schematic diagram of the first alternative aerosol generation system. [Figure 8] Figure 8 is a schematic diagram of a second alternative aerosol generation system. [Figure 9] Figure 9 is a flowchart illustrating a method for detecting unapproved, damaged, or unsuitable heaters. [Modes for carrying out the invention]

[0108] Figures 1a to 1d are schematic diagrams of an aerosol generating system including a cartridge according to an embodiment of the present invention. Figure 1a is a schematic diagram of an aerosol generating device 10 and a separate cartridge 20, which together form the aerosol generating system. In this example, the aerosol generating system is an electrically operated smoking system.

[0109] Cartridge 20 contains an aerosol-forming substrate and is configured to be received in a recess 18 within the device. Cartridge 20 should be replaceable by the user when the aerosol-forming substrate provided in the cartridge is consumed. Figure 1a shows cartridge 20 immediately before insertion into the device, and arrow 1 in Figure 1a indicates the direction of cartridge insertion.

[0110] The aerosol generator 10 is portable and comparable in size to a conventional cigar or cigarette. The device 10 includes a main body 11 and a mouthpiece portion 12. The main body 11 contains a battery 14 (such as a lithium iron phosphate battery), an electrical circuit 16, and a recess 18. The electrical circuit 16 is equipped with a programmable microprocessor. The mouthpiece portion 12 is connected to the main body 11 by a hinged connector 21 and is movable between an open position shown in Figure 1 and a closed position shown in Figure 1d. The mouthpiece portion 12 is positioned in the open position to allow insertion and removal of the cartridge 20, and is positioned in the closed position when the system is used for aerosol generation. The mouthpiece portion includes a plurality of air intake ports 13 and outlet ports 15. When in use, the user inhales or breathes into the outlet ports to draw air from the air intake ports 13 through the mouthpiece portion to the outlet ports 15, and then into the user's mouth or lungs. An internal baffle 17 is provided to force the airflow through the mouthpiece portion 12 and through the cartridge.

[0111] The recess 18 has a circular cross-section and is sized to receive the housing 24 of the cartridge 20. An electrical connector 19 is provided on the side of the recess 18 to provide an electrical connection between the control electronic circuit 16 and the battery 14 and the corresponding electrical contacts of the cartridge 20.

[0112] Figure 1b shows the system of Figure 1a with the cartridge inserted into the recess 18 and the cover 26 removed. In this position, the electrical connector is positioned relative to the electrical contacts on the cartridge.

[0113] Figure 1c shows the system of Figure 1b with the cover 26 completely removed and the mouthpiece portion 12 moved to the closed position.

[0114] Figure 1d shows the system of Figure 1c with the mouthpiece portion 12 in the closed position. The mouthpiece portion 12 is held in the closed position by a latch mechanism. In the closed position, the mouthpiece portion 12 keeps the cartridge in electrical contact with the electrical connector 19, ensuring good electrical connection during use, regardless of the orientation of the system.

[0115] Figure 2 is an exploded assembly view of cartridge 20. Cartridge 20 includes a generally cylindrical housing 24 having a size and shape selected to fit within a recess 18. The housing contains capillary material 27, 28 immersed in a liquid aerosol-forming substrate. In this example, the aerosol-forming substrate contains 39 wt percent glycerin, 39 wt percent propylene glycol, 20 wt percent water and flavoring agent, and 2 wt percent nicotine. The capillary material is a material that actively carries the liquid from one end to the other and can be manufactured from any suitable material. In this example, the capillary material is formed from polyester.

[0116] It has an open end to which the heater assembly 30 is fixed. The heater assembly 30 includes a base 34 in which an opening 35 is formed, a pair of electrical contacts 32 fixed to the base and separated from each other by a gap 33, and a plurality of conductive heater filaments 36 fixed across the opening to the electrical contacts on the opposite side of the opening 35.

[0117] The heater assembly 30 is covered by a removable cover 26. The cover includes a liquid-impermeable plastic sheet that is bonded to the heater assembly but can be easily peeled off. Tabs are provided on the sides of the cover so that the user can grasp the cover when peeling it off. Although bonding is described as a method of securing the impermeable plastic sheet to the heater assembly, it will be apparent to those skilled in the art that other methods familiar to those skilled in the art, including heat sealing or ultrasonic welding, may also be used, as long as the cover can be easily removed by the consumer.

[0118] The cartridge in Figure 2 contains two separate capillary materials 27 and 28. The disc of the first capillary material 27 is provided to contact the heater elements 36 and 32 during use. The larger body of the second capillary material 28 is provided on the opposite side of the first capillary material 27 to the heater assembly. Both the first and second capillary materials hold a liquid aerosol-forming substrate. The first capillary material 27, which is in contact with the heater elements, has a higher thermal decomposition temperature (at least 160°C or higher, e.g., about 250°C) than the second capillary material 28. The first capillary material 27 effectively acts as a spacer separating the heater elements 36 and 32 from the second capillary material 28 so that the second capillary material is not exposed to temperatures above its thermal decomposition temperature. The thermal gradient across the entire first capillary material ensures that the second capillary material is exposed to temperatures below its thermal decomposition temperature. The second capillary material 28 can be selected to have superior core performance to the first capillary material 27, can hold more liquid per unit volume than the first capillary material, and may be less expensive than the first capillary material. In this example, the first capillary material is a heat-resistant element such as glass fiber or a glass fiber-containing element, and the second capillary material is a polymer such as a suitable capillary material. Exemplary suitable capillary materials include the capillary materials discussed herein, and alternative embodiments may include high-density polyethylene (HDPE) or polyethylene terephthalate (PET).

[0119] The capillary materials 27 and 28 are oriented to favorably transport the liquid to the heater assembly 30 within the housing 24. When the cartridge is assembled, the heater filaments 36, 37, and 38 may come into contact with the capillary material 27, so that the aerosol-forming substrate can be directly transported to the mesh heater. Figure 3 is a detailed view of the filaments 36 of the heater assembly, showing the meniscus 40 of the liquid aerosol-forming substrate between the heater filaments 36. It can be seen that the aerosol-forming substrate comes into contact with most of the surface of each filament so that most of the heat generated by the heater assembly enters the aerosol-forming substrate directly.

[0120] In this way, under normal operation, the liquid aerosol-forming substrate contacts a large portion of the surface of the heater filament 36. However, when most of the liquid substrate in the cartridge has been used, less liquid aerosol-forming substrate is delivered to the heater filament. With less liquid vaporizing, less energy is absorbed by the enthalpy of vaporization, and more of the energy supplied to the heating filament is directed to raise the temperature of the heating filament. When the heater element dries out in this way, the rate at which the heater element's temperature rises with respect to a given applied power increases. The heater element may dry out completely because almost all of the aerosol-forming substrate in the cartridge has been used up, or because the user performs very long or very frequent suctioning and cannot deliver the liquid to the heater filament as quickly as it vaporizes.

[0121] During use, the heater assembly operates by resistance heating. Current passes through the filament 36, based on the control of the control electronic circuit 16, heating the filament to a desired temperature range. The mesh or array of the filament has significantly higher electrical resistance than the electrical contacts 32 and electrical connector 19, so that high temperatures are localized on the filament. In this embodiment, the system is configured to generate heat by supplying current to the heater assembly in response to user fume extraction. In another embodiment, the system may be configured to generate heat continuously while the device is in the "on" state. Different materials for the filament may be suitable for different systems. For example, in a continuous heating system, Ni-Cr filament is suitable because it has a relatively low specific heat capacity and is compatible with low-current heating. In a system operated by fume extraction where heat is generated by short bursts using high-current pulses, stainless steel filament with a high specific heat capacity may be more suitable.

[0122] The system includes a smoke inhalation sensor configured to detect when the user inhales air through the mouthpiece. The smoke inhalation sensor (not shown) is connected to a control electronic circuit 16, which is configured to supply current to the heater assembly 30 only when it is determined that the user is smoking with the device. Any suitable airflow sensor, such as a microphone or pressure sensor, may be used as the smoke inhalation sensor.

[0123] To detect this increase in the rate of temperature change, the electrical circuit 16 is configured to measure the electrical resistance of the heater filament. In this embodiment, the heater filament is made of stainless steel and therefore has a positive temperature resistance coefficient. This means that as the temperature of the heater filament rises, its electrical resistance also rises.

[0124] Figure 4 is a schematic diagram of the change in heater resistance during user smoke extraction. The x-axis represents the time since the initial detection of user smoke extraction and the resulting power supply to the heater. The y-axis represents the electrical resistance of the heater assembly. It can be seen that the heater assembly has an initial resistance R1 before any heating occurs. R1 is obtained from the parasitic resistance RP from the electrical contacts 32 and electrical connector 19 and the contacts between them, and the resistance R0 of the heater filament. When power is applied to the heater during user smoke extraction, the temperature of the heater filament rises, and the electrical resistance of the heater filament increases. As shown, the resistance of the heater assembly at time t1 is R2. Therefore, the change in the electrical resistance of the heater assembly from the initial resistance to the resistance at time t1 is ΔR = R2 - R1.

[0125] In this embodiment, it is assumed that the parasitic resistance RP does not change even when the heater filament is heated. This is because RP is due to components that are not heated, such as the electrical contacts 32 and the electrical connector 19. It is assumed that the value of RP is the same for all cartridges, and the value is stored in the memory of the electrical circuit.

[0126] The relationship between the resistance of the heater filament and its temperature is given by the following equation. R2 = R0 * (1 + α * ΔT) + RP (1) In the equation, α is the temperature coefficient of the electrical resistance of the heater filament, and ΔT is the temperature change between the initial temperature before power is applied to the heater and the temperature at time t1.

[0127] The threshold value K is stored within the electrical circuit, and K is equal to α*ΔTmax. If the temperature rises more than ΔTmax at time t1, it may indicate that the heater is in a detrimental state, such as being dry.

[0128] From Equation 1: K = α * ΔTmax = ΔR / R0 (2)

[0129] Therefore, to detect a rapid rise in temperature indicating that the heater filament is dry, the ratio ΔR / R0 can be compared with the stored value of K. If ΔR / R0 > K, then the heater is dry.

[0130] This comparison can be performed by an electrical circuit, but the inequality signs can be rearranged to suit electronic processing operations, particularly to avoid the need to perform any division. In this embodiment, the software running on the microprocessor within the electrical circuit performs the following comparison derived from Equation 1. If R2 > (R1 * (K + 1) - K * RP), then a dry state exists in the heater. (3)

[0131] R2 and R1 are both measured values, and K and RP are stored in memory. Ideally, the value of R1 should be measured before any heating occurs, in other words, before the heater is first started, and that measured value should be used for all subsequent smoke extraction. This avoids any errors resulting from residual heat from previous smoke extraction. R1 may be measured only once for each cartridge, and the detection system may be used to determine it when a new cartridge is inserted, or R1 may be measured each time the system is switched on.

[0132] Other harmful conditions, besides a dry heater condition, may also be detected in this manner. If a cartridge with a heater made of a material with a different coefficient of thermal resistance is used in the system, the electrical circuit may be able to detect this and be configured not to supply power to it. In this embodiment, the heater filament is made of stainless steel. A cartridge with a heater made of Ni-Cr will have a lower coefficient of thermal resistance, which means that its resistance will rise more slowly with increasing temperature. Therefore, if a value of K2 equal to α*ΔTmin is stored in memory, this corresponds to the lowest temperature rise at the expected time t1 for the stainless steel heater element, and then if R2 < (R1*(K2+1)-K*RP), the circuit determines the harmful condition corresponding to an unapproved cartridge present in the system. Figure 9 illustrates the process of detecting an unsuitable heater.

[0133] In other words, the system may be configured to compare R2 or ΔR / R0, or even ΔR / R1, with a stored high threshold and a stored low threshold to determine a harmful condition. R1 may also be compared with a threshold(s) to check if it is within an expected range. These may even be multiple high stored thresholds, and different actions may be taken depending on which high threshold is exceeded. For example, if the highest threshold is exceeded, the circuit may prevent further power supply until the heater and / or substrate is replaced. This may indicate that the substrate is completely worn out, or that the heater is damaged or unsuitable. A lower threshold may be used to determine when the substrate is nearly worn out. If this lower threshold is exceeded but the higher threshold is not, the circuit may simply provide an indicator, such as an LED lighting up, to indicate that the substrate will soon need to be replaced.

[0134] The ratio of ΔR / R0 may be continuously monitored to determine whether the heater cools sufficiently between smoke extractions. If the ratio between smoke extractions does not fall below a cooling threshold due to the user's very frequent smoke extractions, the electrical circuit may prevent or limit the power supply to the heater until the ratio falls below the cooling threshold. Alternatively, a comparison may be made between the maximum value of the ratio during a smoke extraction and the minimum value of the ratio following a smoke extraction to determine whether sufficient cooling is occurring.

[0135] Furthermore, the ratio ΔR / R0 may be continuously monitored, and the time it takes to reach a threshold value may be compared to a time threshold. If ΔR / R0 reaches the threshold much faster or slower than expected, this may indicate a harmful condition, such as an unsuitable heater. The rate of change of ΔR can also be determined and compared to a threshold. If ΔR rises very rapidly or very slowly, this may indicate a harmful condition. These techniques may allow for very rapid detection of unsuitable heaters.

[0136] Figure 5 is a schematic electrical circuit diagram showing a way in which the resistance of a heating element can be measured. In Figure 5, the heater 501 is connected to a battery 503 that provides a voltage V2. The heater resistance measured at a specific point in time is R ヒーター An additional resistor 505 with a known resistance r is inserted in series with heater 501 and connected to voltage V1, which is midway between ground and voltage V2. Microprocessor 507 controls the resistance R of heater 501. ヒーター To measure this, both the current flowing through heater 501 and the voltage across heater 501 can be determined. Then, the resistance can be determined using the following well-known formula. JPEG2026050370000002.jpg6160

[0137] In Figure 5, the voltage across the heater is V2-V1, and the current flowing through the heater is I. Therefore JPEG2026050370000003.jpg16160

[0138] Using an additional resistor 505 whose resistance r is known, we again use (1) above to determine the current I. The current flowing through resistor 505 is I, and the voltage across resistor 505 is V1. Therefore, JPEG2026050370000004.jpg16160 Therefore, when (5) and (6) are combined, JPEG2026050370000005.jpg16160

[0139] Thus, the microprocessor 507 can measure V2 and V1, and since r is known when the aerosol generation system is in use, it can determine the heater resistance at different time points.

[0140] The electrical circuit can control the power supply to the heater in several different ways after a harmful condition is detected. Alternatively, or additionally, the electrical circuit may simply indicate to the user that a harmful condition has been detected. This may include a system LED or display, or a microphone, and these components may be used to alert the user of a harmful condition.

[0141] Figure 6a illustrates a first control process for a smoke-operated system. In the diagram illustrated in Figure 6a, the electrical circuit continues to supply power to the heater if ΔR / R0 exceeds a high threshold for a single smoke. Figure 6a shows three consecutive smokes, with the high threshold being exceeded in between. Power to the heater is cut off only if ΔR / R0 exceeds the high threshold for a specific number of consecutive smokes, e.g., three, four, or five smokes. A single instance of exceeding the threshold may result from a very long smoke by the user, while exceeding the high threshold in several consecutive smokes is more likely to be due to the cartridge being empty. At that point, the cartridge may be deactivated, for example, by blowing a fuse inside the cartridge, or the electrical circuit may cut off further power supply until the cartridge is replaced or refilled.

[0142] Figure 6b discloses an alternative control process that may be used as an alternative, or an additional control process may be added to the process described with reference to Figure 6b. In the control process of Figure 6b, the electrical circuit cuts off power to the heater until the end of user smoke inhalation as soon as it is determined that a high threshold has been exceeded. Power is supplied to the heater again when new user smoke inhalation is detected. This may be useful to prevent the heater from overheating, even when the user smokes excessively. As with cutting off power, it may be indicated that a threshold has been reached.

[0143] Figure 6c illustrates an alternative control process in which the electrical circuit immediately cuts off power to the heater as soon as it is determined that a high threshold has been exceeded. Power is also prevented from being supplied to subsequent user smoke extraction. To restore power to the heater, the user may need to replace the cartridge or perform a reset operation. This control process may be used in conjunction with the process described with reference to Figures 6a and 6b, but it uses a higher threshold than that used in the process described with reference to Figures 6a and 6b. A higher threshold may indicate a completely depleted aerosol-forming substrate, a defective heater, or an unsuitable heater.

[0144] Although the present invention has been described with reference to a cartridge-based system with a mesh heater, the same method for detecting harmful conditions can be used with other aerosol generating systems.

[0145] Figure 7 illustrates an alternative system according to the present invention, also using a liquid substrate and capillary material. In Figure 7, the system is a smoking system. The smoking system 100 in Figure 7 comprises a housing 101 having a mouthpiece end 103 and a body end 105. The body end is provided with a power source in the form of a battery 107 and an electrical circuit 109. A smoke detection system 111, which works in conjunction with the electrical circuit 109, is also provided. The mouthpiece end is provided with a liquid storage portion in the form of a cartridge 113 containing liquid 115, a capillary core 117, and a heater 119. Note that in Figure 7, the heater is shown schematicly only. One end of the capillary core 117 extends into the cartridge 113, and the other end of the capillary core 117 is surrounded by the heater 119. The heater is connected to the electrical circuit via a connector 121 (not shown in Figure 7) which may run along the outside of the cartridge 113. The housing 101 also includes an air intake port 123, an air outlet 125 at the end of the mouthpiece, and an aerosol forming chamber 127.

[0146] During use, the operation is as follows: Liquid 115 is carried by capillary action from cartridge 113 from one end of wick 117 extending into the cartridge to the other end of the wick surrounded by heater 119. When the user inhales the aerosol generating system at air outlet 125, ambient air is drawn in through air intake 123. In the configuration shown in Figure 7, the smoke detection system 111 detects smoke inhalation and activates heater 119. Battery 107 supplies electrical energy to heater 119, heating the end of wick 117 surrounded by the heater. The liquid at the end of wick 117 is vaporized by heater 119, producing supersaturated vapor. Simultaneously, the vaporized liquid is replaced by further liquid moving along wick 117 by capillary action. The generated supersaturated vapor is mixed with the airflow from air intake 123 and carried in the airflow. Within the aerosol formation chamber 127, the vapor condenses to form an inhalable aerosol, which is then carried toward the air outlet 125 and enters the user's mouth.

[0147] In the embodiment shown in Figure 7, the electrical circuit 109 and the smoke detection system 111 are programmable as shown in the embodiments of Figures 1a to 1d.

[0148] Capillary cores are preferably made from various porous or capillary materials that have known, predetermined capillary action. Examples include ceramic or graphite-based materials in the form of fibers or sintered powders. Different porous cores can be used to accommodate liquids with different physical properties such as density, viscosity, surface tension, and vapor pressure. The core must be suitable for delivering the required amount of liquid to the heater when there is sufficient liquid in the liquid storage section.

[0149] The heater comprises at least one heating wire or filament extending around a capillary core.

[0150] As illustrated with reference to Figures 1-3, the capillary material forming the wick may dry out near the heater wire if the liquid in the cartridge is used up or if the user performs very long and deep smuggling. As illustrated with reference to the systems in Figures 1-3, the change in the resistance of the heater wire between the first parts of each smuggling can be used to determine if there is a harmful condition such as a dry wick.

[0151] In the type of system illustrated in Figure 7, there may be considerable variation in heater resistance even among cartridges of the same type due to variations in the length of the heater wire surrounding the core. The present invention is particularly advantageous because the electrical circuit does not need to store a maximum heater resistance value as a threshold, but instead uses the increase in resistance relative to its initially measured resistance.

[0152] Figure 8 illustrates another aerosol generating system that can embody the present invention. The embodiment in Figure 8 is an electrically heated tobacco device in which a tobacco-based solid substrate is heated without combustion to generate an aerosol for inhalation. In Figure 8, the components of the aerosol generating device 700 are shown in a simplified form and the scale is not accurate. Elements not relevant to understanding this embodiment have been omitted in order to simplify Figure 8.

[0153] The electrically heated aerosol generator 200 comprises a housing 203 and an aerosol-forming substrate 210, such as a cigarette. The aerosol-forming substrate 210 is pressed into a recess 205 whose shape is determined by the housing 203, bringing it into thermal proximity with the heater 201. The aerosol-forming substrate 210 releases various volatile compounds at different temperatures. By controlling the operating temperature of the electrically heated aerosol generator 200 to be lower than the release temperature of some volatile compounds, the release or formation of these smoke components can be avoided.

[0154] Inside the housing 203 is a power source 207, such as a rechargeable lithium-ion battery. An electrical circuit 209 is connected to the heater 201 and the power source 207. The electrical circuit 209 controls the power supplied to the heater 201 to regulate its temperature. An aerosol-forming substrate detector 213 can detect the presence and characteristics of an aerosol-forming substrate 210 that is thermally close to the heater 201 and signals the presence of the aerosol-forming substrate 210 to the electrical circuit 209. Providing a substrate detector is optional. An airflow sensor 211 is provided inside the housing and connected to the electrical circuit 209 to detect the airflow velocity passing through the device.

[0155] In the described embodiment, the heater 201 is an electrically resistive track(s) deposited on a ceramic substrate. The ceramic substrate is in the form of a blade and is inserted into the aerosol-forming substrate 210 during use. The heater forms part of the apparatus and may be used to heat a number of different substrates. However, the heater may be an interchangeable component, and the electrical resistance of the alternative heaters may differ.

[0156] The type of system described in Figure 8 may be a continuously heating system in which the heater temperature is maintained at a target temperature while the system is on, or it may be a smoke-activated system in which the heater temperature is increased by supplying more power during the period when smoke extraction is detected.

[0157] In the case of a system operated by fume extraction, the operation is very similar to that described with reference to previous embodiments. When the substrate is dry near the heater, the heater resistance rises more rapidly with respect to a given applied power than when the substrate contains an aerosol-forming agent that can still vaporize at relatively low temperatures.

[0158] In the case of a continuously heated system, when the user inhales smoke in the system, there is initially a temperature drop in the heater due to the cooling effect of the airflow passing through the heater. When smoke inhalation is first detected, the heater resistance can be measured and recorded as R1, and in a similar manner to that described, when the system returns the heater to the target temperature, the subsequent resistance R2 can be measured at time t1 after the detection of smoke inhalation. Next, ΔR and R0 can be calculated as described above, and then the ratio of ΔR / R0 can be compared with the stored threshold as described above to determine whether the substrate is dry near the heater. The substrate may be dry because it is worn out from use, old or improperly stored, or counterfeit and its moisture content differs from that of a genuine aerosol-forming substrate.

[0159] The system in Figure 8 includes a warning LED 215 in the electrical circuit 209 that lights up when a harmful condition is detected.

[0160] Figure 9 is a flowchart illustrating a method for detecting an unauthorized, damaged, or incompatible heater. The first step, 300, detects the insertion of a cartridge containing a heater into the device. Next, step 300 measures the electrical resistance of heater R1. This is done after a predetermined period, such as 100 ms, following power supply to the heater. Step 320 compares the measured resistance R1 to an expected or acceptable resistance range. The acceptable resistance range takes into account manufacturing tolerances and variations between genuine heaters and substrates. If R1 is outside the expected range, the process proceeds to step 330, where it is considered incompatible with the device, and an indication, such as an audible alarm, is provided, and power to the heater is prevented. The process then returns to step 300, awaiting detection of the insertion of a new cartridge.

[0161] Alternatively, or additionally, in order to measure the initial resistance R1 in step 300, the rate of change of the initial resistance may be measured within a predetermined period after power has been supplied to the heater, for example, up to 100 ms. This may involve performing multiple resistance measurements at different points in time over the predetermined period, and then calculating the rate of change of the initial resistance from the multiple resistance measurements and the multiple points in time at which those measurements were taken. In the same manner, a particular design of a heater can be expected to have an initial resistance within an acceptable range of values, and a particular design of a heater can be expected to have an initial rate of change of resistance within an acceptable range of resistance rate values ​​for a given applied power. The calculated rate of change of the initial resistance can be compared to the acceptable range of resistance rate values, and if the calculated rate of change of resistance is outside the acceptable range, the process proceeds to step 330.

[0162] If it is determined in step 320 that R1 is within the expected resistance range, the process proceeds to step 340. In step 340, power is applied to the heater for a period t1, after which the ratio ΔR / R0 is calculated. Conveniently, t1 is chosen to be a short period before significant aerosol generation. In step 350, the value of the ratio ΔR / R0 is compared to an expected or acceptable range of values. The expected range of values, in this case as well, takes into account variations in the manufacturing of the heater and substrate assembly. If the value of ΔR / R0 is outside the expected range, the heater is considered unsuitable, and the process proceeds to step 330 as described above, and then returns to step 300. If the value of ΔR / R0 is within the expected range, the process proceeds to step 360, where power is supplied to the heater to generate aerosols as required by the user.

[0163] Although the present invention has been described with reference to three different types of electric smoking systems, it will be clear that the present invention is applicable to other aerosol generating systems.

[0164] It should also be clear that the present invention may be implemented within an existing aerosol generation system as a computer program product for execution on a programmable controller. The computer program product may be provided as one of the downloadable software programs or on a computer-readable medium such as a compact disc.

[0165] The exemplary embodiments described above are illustrative but not limiting. In light of the exemplary embodiments discussed above, other embodiments consistent with the exemplary embodiments will now be apparent to those skilled in the art.

Claims

1. An electrically operated aerosol generation system, An electric heater comprising at least one heating element for heating an aerosol-forming substrate, Power supply and An electrically operated aerosol generating system comprising: an electric heater and an electric power supply, and an electric circuit connected to the electric circuit and having a memory, wherein the electric circuit is configured to determine a harmful condition when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in the memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in the memory outside of an expected period, and if a harmful condition exists, to limit the power supplied to the electric heater or provide an indication.

2. The electrically operated aerosol generating system according to claim 1, wherein the system comprises a device and a removable cartridge, the power supply and the electrical circuit are located within the device, the electric heater is located within the removable cartridge, and the cartridge comprises a liquid aerosol forming substrate.

3. An electrically operated aerosol generating system according to claim 1 or 2, wherein the aerosol-forming substrate comes into contact with the heating element during use.

4. An electrically operated aerosol generating system according to any one of claims 1 to 3, comprising a smoke extraction detector for detecting when a user is inhaling smoke from the system, wherein the smoke extraction detector is connected to an electrical circuit, and the electrical circuit is configured to supply power from the power source to the heater element when smoke extraction is detected by the smoke extraction detector, and the electrical circuit is configured to determine whether there is a harmful condition between each smoke extraction.

5. The electrically operated aerosol generating system according to any one of claims 1 to 4, wherein the system is an electrically heated smoking system.

6. It is a heater assembly, An electric heater having at least one heating element, A heater assembly comprising: an electrical circuit connected to the electric heater and having a memory, wherein the electrical circuit determines that a harmful condition exists when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in the memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in the memory outside of an expected period, and controls the power supplied to the electric heater or provides an indication if a harmful condition exists.

7. An electrically operated aerosol generator, Power supply and An electrically operated aerosol generator comprising: an electrical circuit connected to the power supply and having a memory, wherein the electrical circuit is connected to an electric heater when in use and is configured to determine a harmful condition when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in the memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in the memory outside of the expected period, and to control the power supplied to the electric heater or provide an indication if a harmful condition exists.

8. An electrical circuit for use in an electrically operating aerosol generator, wherein the electrical circuit is connected to an electric heater and a power supply when in use, the electrical circuit includes a memory, and is configured to determine a harmful condition when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in the memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in the memory outside of an expected period, and further controls the power supplied to the electric heater based on whether a harmful condition exists, or provides an indication if a harmful condition exists.

9. An electrical circuit for use in an electrically operated aerosol generator, wherein, during use, the electrical circuit is connected to an electric heater and a power supply for heating an aerosol-forming substrate, the electrical circuit includes a memory and is configured to measure the initial resistance of the heater or the rate of change of the initial resistance within a predetermined period after power has been supplied to the heater, compares the initial resistance or the rate of change of the initial resistance of the heater with an acceptable range of values, and further prevents the power supply to the electric heater or provides an indication if the initial resistance or the rate of change of the initial resistance is outside the acceptable range of values ​​until the heater or the aerosol-forming substrate is replaced.

10. A method for controlling the power supply to a heater in an electrically operated aerosol generating system, wherein the system comprises an electric heater having at least one heating element for heating an aerosol forming substrate, and a power supply for supplying power to the electric heater, and the method is A method comprising determining a harmful condition when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in memory or less than a minimum threshold value, or when the ratio reaches a threshold value stored in memory outside of the expected period, and limiting the power supplied to the electric heater or providing a display to the user in response to the detection of a harmful condition.

11. The method according to claim 10, further comprising measuring the initial resistance of the heater or the rate of change of the initial resistance within a predetermined period after power has been supplied to the heater, comparing the initial resistance or the rate of change of the initial resistance of the heater with an acceptable range of values, and if the initial resistance or the rate of change of the initial resistance is outside the acceptable range of values, preventing the supply of power to the electric heater or providing an indication until the heater or the aerosol forming substrate is replaced.

12. The method according to claim 10 or 11, further comprising detecting when a heater or aerosol-forming substrate is inserted into the system.

13. A method for detecting an incompatible or damaged heater in an electrically operated aerosol generating system, wherein the system comprises an electric heater having at least one heating element for heating an aerosol-forming substrate, and a power supply for supplying power to the electric heater, the method being A method for determining an unsuitable or damaged heater when the ratio between the initial electrical resistance of the heater and the change in electrical resistance from the initial resistance is greater than a maximum threshold value stored in memory, or less than a minimum threshold value, or when the ratio reaches a threshold value stored in memory outside of the expected period.

14. A method for detecting an incompatible or damaged heater in an electrically operated aerosol generating system, wherein the system comprises an electric heater having at least one heating element for heating an aerosol-forming substrate, and a power supply for supplying power to the electric heater, the method being A method comprising: measuring the initial resistance of the heater, or the rate of change of the initial resistance, within a predetermined period after power has been supplied to the heater; comparing the initial resistance of the heater, or the rate of change of the initial resistance, with a range of acceptable values; and, if the initial resistance, or the rate of change of the initial resistance, is outside the range of acceptable values, preventing the supply of power to the electric heater until the heater or the aerosol-forming substrate is replaced, or providing an indication.

15. A computer program that can be directly loaded into the internal memory of a microprocessor comprising a software code portion to perform the steps described in any one of claims 10 to 14 when the computer program is executed on a microprocessor in an electrically operating aerosol generating system, wherein the system comprises an electric heater having at least one heating element for heating an aerosol forming substrate, and a power supply for supplying power to the electric heater, and the microprocessor is connected to the electric heater and the power supply.

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