Detection of aerosol-forming substrate in an aerosol generating device

European).

EP 2797446 B1

DETECTION OF SUBSTRATE FOR THE AEROSOL MANUFACTURE IN A DEVICE

AEROSOL MANUFACTURE

This description relates to aerosol generating devices, and in particular aerosol generating devices for user's inhalation, such as smoking devices. The description relates to a device and method for detecting the presence or properties of an aerosol-forming substrate in an aerosol generating device in a cost-effective and reliable manner.

Conventional lighted-end cigarettes provide smoke as a result of the burning of tobacco and wrapper, which occurs at temperatures that may exceed 800 degrees Celsius when puffed. At these temperatures, tobacco is thermally degraded by pyrolysis and combustion. The heat of combustion releases and generates various gaseous combustion products and distillates from tobacco. Products are drawn in by the cigarette and cooled and condensed to create smoke containing flavors and aromas associated with smoking. At combustion temperatures, not only flavors and aromas are generated, but also many unwanted compounds.

Electric heating smoking devices are known, which are primarily aerosol generating systems that operate cigarettes than conventional example of such lower temperatures with lit ends.

an electric smoking device is disclosed in WO2009 / 118085. WO2009 / 118085 discloses an electric smoking system in which an aerosol-forming substrate is heated by a heating element to generate an aerosol. The temperature of the heating element is controlled within a certain temperature range to ensure that unwanted volatile compounds are not generated and released from the substrate while other desired volatile compounds are released.

It is desirable to provide a function for detecting the substrate in an aerosol generating device, for example an aerosol generating device inexpensive and reliable. Detection of the substrate is useful, for example, to prevent activation of the heating element when the substrate is not present and prevents heating of unsuitable substrates.

In one embodiment, an aerosol generating device is provided comprising: a heating element configured to heat the aerosol generating substrate;

power source connected to the heating element; and a controller connected to the heating element and power supply, wherein the controller is configured to control the power supplied to the heating element from the power source to maintain the temperature of the heating element at the target temperature and is configured to compare the measurement of the power supplied to the heating element or energy supplied to the heating element from the power source for threshold power or energy measurement to detect the presence of an aerosol-forming substrate near the heating element or the properties of the aerosol-forming substrate near the heating element.

As used herein, an "aerosol generating device" refers to a device that interacts with an aerosol generating substrate to generate an aerosol. The aerosol-forming substrate may be part of an aerosol-forming article, e.g., part of a smoking article.

The aerosol generating device may be a smoking device that interacts with an aerosol generating substrate of an aerosol generating article to generate an aerosol that is directly inhaled into the user's lungs through the user's mouth. The aerosol generating device may be a handle.

The term "aerosol-forming substrate" as used herein refers to a substrate that can release volatile compounds that can form an aerosol. Such volatile compounds can be released by heating the aerosol-forming substrate. The aerosol-forming substrate may conveniently be part of an aerosol-forming article or smoking article.

The terms "aerosol article" and "smoking article" as used herein refer to an article containing an aerosol-forming substrate that can release volatile compounds that can form an aerosol. For example, the aerosol-forming article may be a smoking article that forms an aerosol that is directly inhaled into the user's lungs through the user's mouth. An aerosol generating device may be disposable. The term "smoking article" is generally further used. The smoking article may or may include a tobacco rod.

Measurement of power or energy can be any measurement of power or energy, including average power over a predetermined period of time or a predetermined number of cycles, rate of change of power or energy or cumulative measurement of power or energy delivered over a predetermined period of time or a predetermined number of cycles .

In one embodiment, the energy measurement is normalized energy over a predetermined period of time.

In another embodiment, the energy measurement is the rate of reduction of normalized energy over a predetermined period of time.

The amount of power or energy needed to reach and maintain the heating element at the target temperature depends on the speed of heat loss from the heating element. It strongly depends on the environment surrounding the heating element. If the substrate is close to or in contact with the heating element, this affects the rate of heat loss from the heating element compared to when there is no substrate near the heating element. In one embodiment, the device is configured to obtain an aerosol-forming substrate in contact with the heating element. The heating element then loses heat to the substrate by conduction. The device can be configured such that the substrate surrounds the heating element during use.

The controller can be configured to reduce power supply to the heating element from the power source to zero if the power or energy measurement is less than the power or energy threshold measurement. If the amount of energy needed to maintain the heating element temperature at the target temperature is less than expected, perhaps because the aerosol-forming substrate is not present in the device or it may be because an unsuitable substrate, such as the previously used substrate is in the device. The previously used substrate will usually have a lower water content and lower aerosol content than the new substrate, and thus less energy from the heating element. In both cases, it is usually desirable to stop the power supply to the heater.

This allows detection without the need for use

The power source may be any suitable power source, for example a DC voltage source such as a battery. 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 bacterium, or a lithium-based battery, such as a lithium cobalt, lithium iron phosphate or lithium polymer battery. Power can be supplied to the heating element as a pulse signal. The amount of power supplied to the heating element can be adjusted by changing the duty cycle factor or pulse width of the power signal.

The controller can be configured to monitor the temperature of the heating element based on measuring the electrical resistance of the heating element.

heating element temperature of additional measuring equipment.

The heater temperature can be monitored at predetermined intervals, such as every few milliseconds. This can be done continuously or during periods when power is supplied to the heating element.

The device may include an output data center and a controller configured to provide a register of detected presence of an aerosol-forming substrate near the heating element or the properties of an aerosol-forming substrate near the heating element for the output means. Substrate detection records can be helpful in preventing misuse of data during clinical trials. For example, an aerosol generating device may comprise a wireless transmission module connected to the controller or a universal serial bus (USB) connected to the controller. Alternatively, the aerosol generating device may be configured to be able to transfer data from memory to an external memory in the battery charging device each time the aerosol generating device is recharged via appropriate data links. For this purpose, the device can be equipped with special contacts.

The device may also contain non-volatile memory. The controller can be configured to store substrate detection registers in memory. The memory can be a temporary data storage for registers before they are transferred to a larger, more durable external memory or directly to a data processing device.

In one embodiment, the controller is configured to provide a register of the detected presence of an aerosol-forming substrate near the heating element or the property of the aerosol-forming substrate near the heating element for the output means during the power source loading procedure. The device can be connected to a charging device having more memory for long-term storage of substrate detection registers.

The device may be an electric smoking device. The aerosol generating device may be an electric heating smoking device comprising an electric heater. The term "electric heater" refers to one or more electric heating elements.

An electric heater may contain a single heating element. Alternatively, the electric heater may contain more than one heating element. The heating element or heating elements may be arranged to heat the aerosol-forming substrate most efficiently.

An electric heater may contain material that creates electrical resistance.

electric

Suitable include materials that provide resistance without limitation:

semiconductors such as doped ceramics, electrically conductive ceramics (such as, for example, molybdenum disilica), carbon, graphite, metals, metal alloys and composite materials made of ceramic material and metallic material. Such composite materials may contain doped or undoped ceramics. Examples of suitable doped ceramics include doped silicon carbides. Examples of suitable metals include titanium, zirconium, tantalum and platinum group metals. Examples of suitable metal alloys include stainless steel, nickel, cobalt, chromium, aluminum, titanium, zirconium, hafnium, niobium, molybdenum, tantalum, tungsten, tin, gallium, manganese, gold and iron and nickel, iron, cobalt-based alloys , stainless steel, Timetal® and iron-manganese-aluminum based alloys. In composite materials, the electrical resistance material can optionally be embedded, encapsulated or coated with insulating material, or vice versa, depending on the energy transfer kinetics and required external physicochemical properties. Alternatively, the electric heater may comprise an infrared heating radiator of the heating element, a photon source or an induction heating element.

The electric heater may have any suitable form. For example, the electric heater may be in the form of a heating blade. Alternatively, the electric heater may be in the form of a sheath or substrate having various electrically conductive parts or a metallic tube that causes electrical resistance. Alternatively, there may also be one or more heating pins or rods that run through the center of the aerosol-forming substrate as already described. Alternatively, the electric heater may be a disk heater (terminated with a disk) or a combination of a disk heater with heating pins or rods. Other options include a heating wire or fiber, for example made of Ni-Cr (nickel-chromium), platinum, gold, silver, tungsten or an alloy wire or heating plate. Optionally, the heating element may be embedded in or on the rigid carrier material. In one such embodiment, the electric resistance heater can be formed using a metal with a specific relationship between temperature and resistivity. In such an exemplary device, the metal may be in the form of a strip of suitable insulating material, such as ceramic, and then pressed into another insulating material, such as glass. Heaters formed in this way can be used to both heat and monitor the temperature of heaters during operation.

At least one electric heater may include a heat sink or heat accumulator containing material that can absorb and accumulate heat, and then release heat into the aerosol-forming substrate over time. The heat sink may be made of any suitable material, such as a suitable metal or ceramic material. In one embodiment, the material has a high heat capacity (material with palpable heat accumulation) or is a material that can absorb and then release heat in a reversible process, such as a high temperature phase change. Suitable materials with palpable heat accumulation include silica gel, clay, carbon, glass mat, fiberglass, minerals, metal or alloy such as aluminum, silver or lead and cellulosic material such as paper. Other suitable materials that release heat in a reversible phase transition include paraffin, sodium acetate, naphthalene, wax, polyethylene oxide, metal, metal salt, mixture of eutectic salts or alloy.

The heat sink or heat accumulator may be arranged to be in direct contact with the aerosol-forming substrate and be able to transfer the accumulated heat directly to the substrate. Alternatively, the heat stored in the heat sink or heat accumulator may be transferred to the aerosol-forming substrate by means of a heat conductor, such as a metallic tube.

An electric heater may heat the aerosol-forming substrate by conduction. During use, the electric heater may be at least partially in contact with the substrate or support on which the substrate is mounted. Alternatively, heat from the electric heater can be conducted to the substrate via a heat conducting element.

covering discussed above.

In one embodiment, power is supplied to the electric heater before the heating element or heating elements electrically reach a temperature between approximately 250 ° C and 440 ° C. Any suitable temperature sensor and control circuit can be used to control the heating of the heating element or elements to achieve a temperature between approximately 250 ° C and 440 ° C dual use of the heating element This is in contrast to traditional cigarettes, in which tobacco burning and cigarette wrapper can reach 800 ° C.

The controller may include a programmable microprocessor. In another embodiment, the controller may include a specially designed electronic chip, such as based on a directly programmable gate matrix (FPGA) or an integrated circuit designed to perform a predetermined task (ASIC). Generally, any device capable of providing a signal capable of controlling heating elements may be used in accordance with the embodiments described herein. In one embodiment, the controller is configured to monitor the difference between the temperature of the heating element and the target temperature to detect a change in the airflow next to the heating element indicating a user's inspiration.

An aerosol-forming substrate may be included in the smoking article. In operation, the smoking article comprising the aerosol-forming substrate may be completely contained in the aerosol-forming device. In this case, the user may puff through the mouthpiece of the aerosol generating device. The mouthpiece can be any part of an aerosol generating device that a user inserts into the mouth to directly inhale the aerosol generated by the aerosol generating device or the aerosol generating device. The aerosol is transferred to the user's mouth through the mouthpiece. Alternatively, in operation, the smoking article comprising the aerosol-forming substrate may be partially contained in the aerosol-forming device. In this case, the user can puff directly through the mouthpiece of the smoking article.

The smoking article may have a substantially cylindrical shape. The smoking article may be substantially elongated. The smoking article may have a length and a circumference substantially perpendicular to the length. The aerosol-forming substrate may have a substantially cylindrical shape. The aerosol-forming substrate can be substantially elongated. The aerosol-forming substrate may also have a length and a circumference substantially perpendicular to the length. An aerosol-forming substrate may be received in a sliding reservoir of the aerosol-forming device such that the length of the aerosol-forming substrate is substantially parallel to the air flow direction of the aerosol-forming device.

The total length of the smoking article may be between approximately 30 mm and approximately 100 mm. The outside diameter of the smoking article may be between approximately 5 mm and approximately 12 mm. The smoking article may include a filter plug. The filter plug may be located in the bottom end of the smoking article. The filter plug may be a cellulose acetate filter plug.

In one embodiment, the length of the filter plug is approximately 7 mm, but its length can be between approximately 5 mm and approximately 10 mm.

In one embodiment, the total length of the smoking article is approximately 45 mm. The outer diameter of the smoking article may be approximately 7.2 mm. In addition, the aerosol-forming substrate may have a length of about 10 mm. Alternatively, the length of the aerosol-forming substrate may be approximately 12 mm. In addition, the diameter of the aerosol-forming substrate may be between approximately 5 mm and approximately 12 mm. The smoking article may contain an outer paper. In addition, the smoking article may include a separation between the aerosol-forming substrate and the filter plug. The separation may be approximately 18 mm, but may be in the range of approximately 5 mm to approximately 25 mm.

The aerosol-forming substrate may be a solid aerosol-forming substrate. Alternatively, the aerosol-forming substrate may contain both solid and liquid components. The aerosol-forming substrate may contain tobacco-containing material containing volatile tobacco aromatic compounds that are released from the substrate when heated. Alternatively, the aerosol-forming substrate may contain tobacco-free material. The aerosol-forming substrate may also contain an aerosol former that facilitates the formation of a dense and stable aerosol. Examples of suitable aerosol forming agents are glycerin and propylene glycol.

If the aerosol-forming substrate is a solid aerosol-forming substrate, the solid aerosol-forming substrate may contain, for example, one or more: powder, granules, pellets, scraps, threads, strips or sheets containing one or more: plant leaf, tobacco leaf, tobacco vein fragments, reconstituted tobacco, homogenised tobacco, extruded tobacco and expanded tobacco. The solid aerosol-forming substrate may be in a loose form or may be provided in a suitable container or cartridge. Optionally, the solid aerosol-forming substrate may contain additional tobacco or tobacco-free volatile aromatics that will be released when the substrate is heated. The solid aerosol-forming substrate may also contain capsules, which, for example, include additional tobacco or tobacco-free volatile aromatic compounds, and such capsules may melt when heating the solid aerosol-forming substrate.

Homogenised tobacco as used herein refers to material produced by agglomeration of molecular tobacco. Homogenised tobacco may be in the form of a sheet. The content of the aerosol former in the homogenised tobacco material may be greater than 5% by weight based on dry weight. The content of the aerosol former in the homogenised tobacco material may alternatively be between 5% and 30% by weight based on dry weight. Sheets of homogenised tobacco can be made by agglomeration of molecular tobacco obtained by grinding or crushing by other means of tobacco leaf blades or tobacco leaf veins or both leaf blades and veins. Alternatively or additionally, sheets of homogenised tobacco material may contain one or more forms of tobacco, such as tobacco dust, fine

Preferably, the assembled tobacco particles and other solid waste products of tobacco products arose during, for example, the handling, storage and transport of tobacco. Sheets of homogenised tobacco material may contain one or more internal binders, that is, endogenous tobacco binders, one or more external tobacco binding agents, that is, exogenous tobacco binding agents or combinations thereof to facilitate molecular agglomeration; alternatively or additionally, sheets of homogenised tobacco material may contain other additives including but not limited to tobacco and tobacco-free fibers, aerosol forming agents, humectants, plasticizers, flavorings fillers, aqueous and anhydrous solvents and combinations thereof.

In a particularly preferred embodiment, the aerosol-forming substrate comprises a collected corrugated sheet of homogenised tobacco material. As used herein, the term "corrugated sheet" means a sheet having a plurality of substantially parallel edges or corrugations. when the aerosol-forming article is essentially parallel edges or corrugations extend along or parallel to the longitudinal axis of the aerosol-forming article. This advantageously facilitates the collection of a sheet of corrugated homogenized tobacco material to form an aerosol-forming substrate. However, it is understood that corrugated sheets of homogenised tobacco material for incorporation into an aerosol generating article may alternatively or additionally have a plurality of substantially parallel edges or corrugations disposed at an acute or obtuse angle to the longitudinal axis of the aerosol producing article after assembling the aerosol producing article. In some embodiments, the aerosol-forming substrate may comprise a collected sheet of homogenised tobacco material that is substantially uniformly textured over its substantially entire surface. For example, the aerosol-forming substrate may comprise a collected corrugated sheet of homogenised tobacco material containing a plurality of substantially parallel edges or corrugations that are substantially evenly spaced apart over the entire width of the sheet.

Optionally, a solid aerosol-forming substrate may be provided on a thermally stable carrier or may be incorporated into it. The carrier may be in the form of powder, granules, pellets, fragmented sections, threads, strips or sheets. Alternatively, the support may be a tubular support having a thin layer of a solid substrate applied on its internal surface or on its external surface, or on both its internal and external surface. Such a tubular support may be formed, for example, of paper or paper-like material, carbon fiber nonwoven mat, low weight open mesh metallic screen or perforated metallic foil or any other thermally stable polymer matrix.

A solid aerosol-forming substrate may be applied to the surface of the carrier in the form of, for example, a sheet, foam, gel or suspension. A solid aerosol-forming substrate may be deposited over the entire surface of the carrier or alternatively may be embedded in a pattern to provide uneven aroma delivery during use.

Despite the above reference to solid aerosol-forming substrates, it is obvious to one of ordinary skill in the art that other forms of the aerosol-forming substrate may be used in other embodiments. For example, the aerosol-forming substrate may be a liquid aerosol-forming substrate. If liquid is provided

<td>substrate for</td><td colspan="2">aerosol production, it</td><td>device</td><td>down</td>

<td>preparation</td><td>aerosol</td><td>preferably contains</td><td>items</td><td>down</td>

<td>maintaining</td><td>fluid.</td><td>For example liquid</td><td>substratum</td><td>down</td>

<td>preparation</td><td>aerosol</td><td>can be maintained</td><td colspan="2">in the container.</td>

Alternatively or additionally, the liquid aerosol-forming substrate may be absorbed by the porous carrier material. The porous support material can be made of any suitable absorbent plug or mass, for example foamed metal or plastic, polypropylene, terylene, nylon fibers or ceramics. the aerosol-forming liquid substrate may be held in the porous carrier material prior to use of the aerosol-forming device or alternatively the liquid aerosol-forming substrate material may be released into the porous carrier material during use or immediately before. For example, a liquid aerosol-forming substrate may be provided in a capsule. The capsule shell preferably melts when heated and releases a liquid aerosol-forming substrate into the porous carrier material. The capsule optionally may contain a solid in combination with a liquid. Alternatively, the carrier may be a nonwoven or fiber bundle in which tobacco components have been incorporated. The nonwoven or fiber bundle may contain, for example, carbon fibers, natural cellulose fibers or cellulose derivative fibers.

The aerosol generating device may additionally comprise an air inlet. The aerosol generating device may additionally comprise an air outlet. The aerosol generating device may additionally comprise a condensation chamber through which the aerosol will have the desired characteristics.

The aerosol generating device is preferably a manual aerosol generating device that the user can conveniently hold between the fingers of one hand. The aerosol generating device may have a substantially cylindrical shape. An aerosol generating device may have a polygonal cross section and a protruding button formed on one of the surfaces: in this embodiment, the outer diameter of the aerosol-forming device may be between about 12.7 mm and about 13.65 mm measured from a flat surface to the opposite flat surface; between about 13.4 mm and about 14.2 mm measured from the edge to the opposite edge (i.e. from the intersection of two surfaces on one side of the aerosol former to the corresponding intersection on the other side); and between about 14.2 mm and about 15 mm measured from the top of the button to the opposite lower flat surface. The length of the aerosol generating device may be between about 70 mm and 120 mm.

In another embodiment, a method is provided for detecting the presence of an aerosol-forming substrate near a heating element or the properties of an aerosol-forming substrate material in an aerosol generating device, the aerosol generating device comprises a heating element configured to heat the aerosol generating substrate while a power source is connected to the heating element, wherein the method includes: controlling power supplied to the heating element from a power source to maintain the temperature of the heating element at a target temperature including measuring the power delivered to the heating element or energy supplied to the heating element from the power source for measuring the power or energy threshold to detect the presence of an aerosol-forming substrate near the element heating or the properties of the aerosol-forming substrate material near the heating element based on the result of the comparison step.

Measurement of power or energy can be any measurement of power or energy, including average power over a predetermined period of time or a predetermined number of cycles, rate of change of power or energy or cumulative measurement of power or energy delivered over a predetermined period of time or a predetermined number of cycles .

In one embodiment, the energy measurement is normalized energy over a predetermined period of time. In another embodiment, the energy measurement is the rate of reduction of normalized energy over a predetermined period of time.

The method may further include the step of reducing the power supply to the heating element from the power source to zero if the power or energy measurement is less than the power or energy threshold measurement. If the amount of energy needed to reach and maintain the heating element temperature at the target temperature is less than expected, perhaps because the aerosol-forming substrate is not present in the device or it may be because an unsuitable substrate such as the previously used substrate is in the device . In both cases, it is usually desirable to stop the power supply to the heater.

The method may include the step of monitoring the temperature of the heating element based on measuring the electrical resistance of the heating element.

In another embodiment, a computer program is provided that, when run on a computer or other suitable processing device, performs the method described above. The description includes embodiments that can be implemented as software suitable for activating an aerosol generating device having a programmable controller as well as other required hardware components.

The embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which:

Fig. 1 schematically shows the main components of an aerosol generating device according to one embodiment; Fig. 2 is a schematic diagram showing the controls of one embodiment;

Fig. 3 is a graph showing the different normalized energy needed to deliver to a heating element to maintain the temperature at the target level for new, old or no substrate next to the heating element; and

Fig. 4 shows the control sequence to determine if the correct substrate is in the device.

Fig. 1 shows in a simplified way the interior of an embodiment of an electrically heated aerosol generating system 100. In particular, the elements of the aerosol generating system 100 are not drawn to scale. Elements that are not essential for understanding the system are omitted for simplicity. Fig.1.

The electrically heated aerosol-forming system 100 includes a housing 10 and an aerosol-forming substrate 2, e.g. a cigarette. The aerosol-forming substrate 2 is pressed into the housing 10 so that it is in thermal proximity to the heater 20. The aerosol-forming substrate 2 will release a set of volatile compounds at different temperatures.

Some of the volatile compounds released from the aerosol-forming substrate 2 are produced only by the heating process. Each volatile compound is released above the characteristic release temperature. Controlling the highest temperature at which the aerosol generating system 100 operates so that it is lower than the temperature at which some volatile compounds are released, avoids the formation or release of these smoke constituents.

In addition, the housing 10 includes an electric power supply 40, e.g. a lithium-ion battery. The controller 30 is connected to the heating element 20, power supply 40, puff detector 32 and graphical user interface 36, e.g. a display.

The controller 30 controls the user interface 36 to display information about the system, e.g., battery power, temperature, status of the aerosol-forming substrate 2, other messages or combinations of the foregoing.

The puff detector 32 is an optional item and detects the airflow in the device indicates a user puff. The puff detector signals this puff to the controller 30.

The controller 30 additionally controls the maximum operating temperature of the heating element 20. The temperature of the heating element can be detected by a specially designed temperature sensor. But in this embodiment, the temperature of the heating element is determined by monitoring its electrical resistivity. The electrical resistivity of a wire length depends on its temperature. The resistivity increases with increasing temperature. The characteristics of the actual resistivity will vary depending on the exact composition of the alloy and the geometric configuration of the heating element 20 and the empirically determined compound that can be used in the controller. Thus, knowledge of the resistivity p at a given time can be used to derive the actual operating temperature of the heating element 20.

Heating element resistance R = V / I; where V is the voltage flowing through the heating element and I is the current flowing through the heating element 20. The resistance R depends on the configuration of the heating element 20 as well as on the temperature and is expressed by the following relationship:

R = p (T) * L / S equation 1

Where p (T) is the temperature dependent on the resistivity, L is the length, S the cross-sectional area of ​​the heating element 20. L and S are constant for the given configuration of heating element 20 and can be measured. Thus, for a given heating element, the formula R is proportional to p (T). The heating element resistivity can be expressed as a polynomial as follows:

p (T) = after * (1 + a1 T + a, 2 T²) equation 2

Where po is the resistivity at the reference temperature To and a1 and a2 are polynomial coefficients.

In this way, knowing the length and cross-section of the heating element 20, it is possible to determine the resistance R and thus the resistivity p at a given temperature by measuring the heating element voltage V and the current I. The temperature can be obtained directly from the table of values ​​of the function LUT of the characteristic resistivity versus the temperature ratio for the heating element used or by assessing the polynomial equation (2) above. In one embodiment, this process can be simplified by presenting the resistivity p depending on the temperature curve for one or more, preferably two linear approximations in the temperature range that applies to tobacco. This makes it easier to assess the temperature, which is desirable in a controller 30 having limited computing resources.

Fig. 2 is a block diagram illustrating the controls of the device of Fig. 1. Fig. 2 also shows the connection of the aerosol generating device to the external device

58. The controller 30 comprises a measuring unit 50 and a control unit 52. The measuring unit is configured to determine the resistance R of the heating element 20. The measuring unit 50 undergoes resistance measurements to the control unit 52. The control unit 52 controls the supply of power from the battery 40 to the heating element 20 via a toggle switch 54. The controller may contain a microprocessor as well as separate electronic components.

When preparing the temperature control, the target operating temperature of the aerosol generating system 100 is selected. The selection is based on the release temperature of volatile compounds that should and should not be released. This predetermined value is then stored in the control unit 52. The control unit 52 contains a non-volatile memory 56.

The controller 30 controls the heat of the heating element 20 by controlling the supply of electricity from the battery to the heating element 20. By activating the switch 54, the power is supplied as a pulse signal. The pulse width or signal duty cycle can be modulated by the control unit 52 to change the amount of energy supplied to the heating element.

In use, the controller 30 measures the resistivity p of the heating element 20. The controller 30 then transforms the resistance of the heating element 20 to the actual value of the operating temperature of the heating element by comparing the measured resistivity p with the LUT (Look-up Table) value table. This can be done by the measuring unit 50 or by the control unit 52. In a next step, the controller 30 compares the actual calculated operating temperature with the target operating temperature. If the actual operating temperature is below the target operating temperature, then the control unit 52 provides additional heating energy to the heating element 20 to increase the actual operating temperature of the heating element 20. If the actual operating temperature is above the target operating temperature, the control unit 52 reduces the electricity supplied to the heating element 20 to lower the actual operating temperature back to the target operating temperature.

The control unit can implement any suitable control technique to control the temperature, such as a simple thermostatic feedback loop or a proportional, integral, differential (PID) control technique.

The amount of energy needed to reach the target temperature and keep the heating element at the target temperature depends on the presence or absence of substrate material 2 close to the heating element 20 and the properties of the substrate. Fig. 3 shows the evolution of normalized energy delivered to the heating element as a function of time. Curve 60 is normalized energy when a new substrate is present in the device and curve 61 is normalized energy when there is no substrate in the device. Normalized energy is the energy delivered over a constant period of time normalized to the initial energy measurement. Standardized energy measurement minimizes the impact of environmental conditions such as ambient temperature, airflow and humidity.

It can be seen that in both cases, the power supplied to the heating element monotonically decreases over the course of the initial high power period to bring the heating element to the target temperature. However, Fig. 3 shows that at T = 10 seconds the amount of energy supplied with the new substrate in the device is about twice as much as the amount of energy supplied when no substrate is present in the device. The difference in energy supplied between the new and previously heated substrate is smaller, but still detectable. In one embodiment, the difference in normalized energy can be measured at T = 5 seconds and accurately determined whether a substrate is present or not. The controller is able to calculate the normalized energy delivered to the heating element for a predetermined time, and then is able to determine whether the expected or correct substrate is in the device.

Fig. 4 shows an example of a control process that can be carried out by the control unit 52 to determine if the substrate is in the device or not. The process is a loop process and starts at step 400. In step 410, the round number is increased. At the beginning of the process, the round number is set to zero. Each time the control loop passes through, the round number is increased in step 410. At step 420, the process branches depending on the round value. In the initial loop, when the round number is one, the process goes to step 430. At step 430, the initial energy, i.e. the energy supplied to this heater is set as energy. Initial energy is used to normalize subsequent energy measurements. The process then proceeds to step 440 and back to step 410. Subsequent roundings pass directly from step 420 to step 440 until the decision rounding is reached. Each rounding can be carried out at a fixed time interval, for example every two seconds. The decision rounding corresponds to the time during which the controller is configured to compare normalized energy with the expected or threshold value to determine if a substrate is present or not. The normalized energy threshold value is represented by the dashed line 64 in Fig. 3. In this example, the decision rounding is round 5, and occurs 10 seconds after turning on the device. In the decision rounding, the process proceeds from step 420 to step 450. At step 450, normalized energy is calculated as the energy supplied since the device was turned on, divided by the initial energy product and the number of decision rounding (in this example five). The calculated normalized energy is then compared to the threshold in step 460. If the normalized energy exceeds the threshold value, the control unit determines whether the appropriate substrate is present and the device can still be used. If the normalized energy does not exceed the threshold, the control unit determines if no substrate (or unsuitable substrate) is present and the control unit provides power to the heating element by opening switch 54.

The process shown in Fig. 4 is just one example of a process for determining whether a suitable substrate is present in an aerosol generating device. Other measurements of power or energy supplied to the heating element may be used and normalized or non-normalized data may be used. The time at which the determination is made is also a matter of choice. The advantage of a quick determination to take early action, if necessary, must be balanced with the need to obtain a reliable result.

Measurement of power or energy can be compared to many thresholds. This can be useful to distinguish between different types of substrate or between the wrong substrate and the absence of any substrate.

Just as useful for dynamically controlling an aerosol generating device, the substrate detection data determined by the controller 30 may be useful for analysis purposes. Fig. 2 shows the connection of the controller 30 to the external device 58. Substrate detection data may be exported to external device 58 (along with any other captured data) and may be forwarded from device 58 to other external processing or storage devices. The aerosol generating device may contain any suitable output means. For example, an aerosol generating device may comprise a wireless transmission module connected to controller 30 or 56 memory or on a universal serial bus (USB) connected to the controller 30 or 56 memory. Alternatively, the aerosol generating device may be configured to be able to transfer data from memory to an external memory in the battery charging device each time the aerosol generating device is recharged via appropriate data links. The battery charging device can provide more memory for long-term storage of puff data and can then be connected to a suitable data processing device or to a communication network.