JP7817244B2 - Smoking device with heating profile based on puff frequency - Google Patents

Description

The present disclosure relates to an aerosol generating device, a computer-readable medium for use in an aerosol generating device, an aerosol generating device, and a method of operating an aerosol generating system.

Aerosol-generating devices configured to generate an aerosol from an aerosol-forming substrate, such as a tobacco-containing substrate, are known in the art. Typically, an inhalable aerosol is generated by the transfer of heat from a heat source to a physically separate aerosol-forming substrate or material, which may be located within, around, or downstream of the heat source. The aerosol-forming substrate may be a liquid substrate contained within a reservoir. The aerosol-forming substrate may be a solid substrate. The aerosol-forming substrate may be a component of a separate aerosol-generating article configured to engage with the aerosol-generating device to form an aerosol. During consumption, volatile compounds are released from the aerosol-forming substrate by heat transfer from the heat source and are entrained in the air drawn through the aerosol-generating article. As the released compounds cool, they condense to form an aerosol, which is inhaled by the consumer.

Some aerosol generating devices are configured to provide a user experience of finite duration. The duration of a usage session may be limited, for example, to approximate the experience of consuming a traditional cigarette. Some aerosol generating devices are configured to be used with a separate consumable aerosol-generating article. Such aerosol-generating articles include an aerosol-forming substrate capable of releasing volatile compounds capable of forming an aerosol. The aerosol-forming substrate is typically heated to form the aerosol. As the volatile compounds in the aerosol-forming substrate are used up, the quality of the aerosol produced may deteriorate. Therefore, some aerosol generating devices are configured to limit the duration of a usage session to help prevent the generation of lower-quality aerosol from the aerosol-forming substrate of a substantially depleted aerosol-generating article. A user inhales aerosol from such known aerosol generating devices by applying one or more puffs to the device during a usage session. Some known aerosol generating devices may limit the duration of a usage session based on when the number of puffs applied to the device during a session reaches a predetermined limit.

It is known to provide power to a heat source to heat an aerosol-forming substrate with a thermal profile that varies over the duration of a use session. In practice, such known thermal profiles define the temperature fluctuations for the heat source as a function of time elapsed in the use session. As the aerosol-forming substrate becomes more depleted during a use session, more energy is required to extract the remaining volatile compounds from the substrate that form the aerosol. Therefore, it is known to use a thermal profile that increases the target operating temperature for the heat source over the second half of the use session. The known thermal profile used to operate the heat source is based on an ideal, hypothetical use session. The ideal use session may be characterized by a predetermined length for the use session. The ideal use session may additionally be based on the user's assumed or ideal puff behavior, for example, assuming that continuous puffs are applied at a predetermined rate over a finite period of time. However, if the actual use session deviates from the assumptions inherent in the ideal use session, the use of such a known thermal profile to control the temperature of the heat source may lead to inefficient extraction of aerosol from the substrate and may be detrimental to the overall user experience. As an example, if a user applies puffs at a rate faster than expected for a known heat profile, this may result in the use session terminating earlier than would be expected during an ideal use session. As a result, the temperature of the heat source may never reach the level required later in the use session to efficiently extract the aerosol from the substrate.

It is therefore desirable to overcome the deficiencies and limitations outlined above.

According to a first aspect of the present invention, there is provided a method of operating an aerosol generating device to generate an aerosol from an aerosol-forming substrate during a use session, the aerosol generating device comprising a power supply arranged to provide power to a heater during the use session. The method comprises:

Associating puffs applied during a use session with a corresponding target operating temperature of the heater based on a cumulative number of puffs applied during the use session;
For the applied puff, controlling the power supply from the power source to adjust the temperature of the heater to a target operating temperature associated with the applied puff.

By correlating applied puffs with a corresponding target operating temperature of the heater based on the cumulative number of puffs, it is possible to adjust the target operating temperature of the heater to take into account an individual user's specific puff characteristics. This contrasts with the known devices and thermal profiles discussed above, in which the heater temperature varies as a function of time elapsed in a use session. The ability to adjust the heater's target operating temperature according to an individual user's specific puff characteristics may enable more efficient extraction of aerosol from the aerosol-forming substrate. Efficient aerosol extraction from the substrate may be achieved regardless of (or with reduced dependence on) the rate at which an individual user applies puffs to the aerosol-generating device. Thus, a user may be able to extract substantially all of the aerosol from the substrate without being limited to applying puffs at a predetermined rate. These advantages may also provide the user with an enhanced user experience over a use session.

As used herein, the term "aerosol-generating device" refers to a device that interacts with an aerosol-forming substrate to generate an aerosol. The aerosol-forming substrate may be part of an aerosol-generating article, such as part of a smoking article. The aerosol-generating device may include one or more components that are used to provide energy from a power source to the aerosol-forming substrate to generate an aerosol. For example, the aerosol-generating device may be a heated aerosol-generating device. The aerosol-generating device may be an electrically heated aerosol-generating device or a gas-heated aerosol-generating device. The aerosol-generating device may also be a smoking device that interacts with the aerosol-forming substrate of the aerosol-generating article to generate an aerosol that can be inhaled directly into the user's lungs through the user's mouth.

As used herein, the term "aerosol-forming substrate" refers to a substrate capable of releasing volatile compounds capable of forming an aerosol. Such volatile compounds may be released by heating the aerosol-forming substrate. The aerosol-forming substrate may be solid or liquid, or may contain both solid and liquid components. The aerosol-forming substrate may be adsorbed, coated, impregnated, or otherwise loaded onto a carrier or support. The aerosol-forming substrate may conveniently be part of an aerosol-generating article or a smoking article.

The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise tobacco, e.g., a tobacco-containing material containing volatile tobacco flavor compounds that are released from the aerosol-forming substrate upon heating. In a preferred embodiment, the aerosol-forming substrate may comprise homogenized tobacco material, e.g., cast leaf tobacco. The aerosol-forming substrate may comprise at least one aerosol-forming agent, such as propylene glycol or glycerin.

As used herein, the term "use session" refers to a period of time during which a user applies a series of puffs to extract an aerosol from an aerosol-forming substrate.

As used herein, the term "cumulative puffs" refers to the number of puffs taken by a user during a use session relative to the start of that use session.

Advantageously, the aerosol generating device may store a predetermined thermal profile defining the variation of heater temperature over a predetermined distribution of puffs, wherein the target operating temperature associated with an applied puff is the temperature of the predetermined thermal profile for puffs in the predetermined distribution of puffs corresponding to the cumulative number of puffs applied. In this way, the temperature of the predetermined thermal profile is linked to the number of puffs. This is in contrast to the known devices mentioned above, in which the thermal profile temperature is linked only to the elapsed time in a usage session.

The predetermined thermal profile may be stored within a controller used to control the power supply. Alternatively, the predetermined thermal profile may be stored in a memory module accessible to such a controller.

Advantageously, the predetermined thermal profile may include a predetermined relationship between a puff parameter and a predetermined puff distribution. The method further includes determining whether a value of the puff parameter for either or both of the applied puff and previous puffs applied during the use session differs from a value of the puff parameter for a corresponding puff of the predetermined puff distribution; using the determined difference in the value of the puff parameter to modify a temperature of the predetermined thermal profile for the puff at the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puffs; and using the modified temperature of the predetermined thermal profile as a target operating temperature associated with the applied puff. In this manner, the predetermined thermal profile may be dynamically adapted during a use session in response to characteristics of the puffs applied by individual users during the use session.

As described in more detail below, the puff parameters used to modify the thermal profile may include one or more of: i) the time interval between successive puffs; ii) the intensity of the puffs; and iii) the volume of aerosol generated from the aerosol-forming substrate in response to the puffs.

Preferably, the time interval between successively applied puffs is determined by the controller based on the detection of each puff. The controller may include control electronics configured to measure the time interval. Puff detection may be performed directly, such as by using an airflow sensor. However, preferably, puff detection is performed indirectly based on detecting a change in heater temperature that is expected to accompany any applied puff. Determining the heater temperature may be performed directly through the use of a temperature sensor. However, preferably, the heater temperature is determined indirectly based on a change in one or more operating parameters of the aerosol generating device. For example, the heater temperature may be determined based on the heater's electrical resistance, which is particularly relevant when the heater is a resistive heater. In another example, where the heater takes the form of a susceptor that is heated by an inductor in use, the susceptor temperature may be determined based on a change in current supplied to the inductor from a power supply.

The volume of aerosol generated in response to an applied puff may be determined directly or indirectly. The volume may be determined directly, such as by using an airflow sensor. However, the volume is preferably determined indirectly through the use of a parameter indicative of aerosol generation during a use session. The parameter indicative of aerosol generation may itself be an indication of the power supplied by the power source during a use session. For example, the current, voltage, or both current and voltage supplied to the heater may be parameters representing power. For example, the power source may provide power to maintain the heater at a predetermined temperature during a use session. When a user takes a puff on the aerosol generating device to generate aerosol, the heater cools down, requiring more power to maintain the heater at the predetermined temperature. Thus, by monitoring a parameter indicative of the power supplied by the power source, a value indicative of real-time aerosol generation may be recorded.

Advantageously, there may be a predetermined threshold limit for the thermal profile, above which the temperature of the thermal profile cannot be altered. By way of example, temperature changes within the thermal profile may be limited to a temperature change not exceeding a predetermined threshold limit temperature of ±10%, or ±7.5%, or ±5%, or ±3% of the unchanged temperature. Providing a threshold limit for altering the temperature of the thermal profile helps to avoid excessive temperature fluctuations in the heater (and substrate) between successively applied puffs. Additionally or alternatively, the predetermined threshold limit may include an absolute temperature limit. The value of this absolute temperature limit may be set to avoid ignition and combustion of the aerosol-forming substrate and the release of harmful compounds from the substrate. By way of example, the absolute temperature limit may be set to a value of 400°C, or 375°C, or 350°C.

Correlating an applied puff with a corresponding target operating temperature of the heater may additionally be based on the time interval between the applied puff and the preceding puff applied during the use session. In this manner, the target operating temperature of the heater may be a function of both i) the cumulative number of puffs applied and ii) the time interval between the applied puff and the preceding puff. This correlation provides the ability to adjust the target operating temperature of the heater during a use session to account for the rate at which puffs are applied by individual users during a session. This maintains efficient extraction of aerosol from the substrate throughout the use session, regardless of (or with low reliance on) the time interval between successively applied puffs. Preferably, the preceding puff is the puff immediately preceding the applied puff during the use session.

Each puff applied by a user is itself of finite duration. Preferably, the time interval between an applied puff and the preceding puff in a use session is the time interval between the start of the applied puff and the start of the preceding puff. However, alternatively, the time interval between an applied puff and the preceding puff in a use session may be the time interval between the end of the applied puff and the end of the preceding puff.

As described above, the aerosol generating device may store a predetermined thermal profile defining the variation of heater temperature for a predetermined puff distribution. Preferably, the predetermined thermal profile includes a predetermined time interval between successive puffs of the predetermined puff distribution. The method may further include determining whether the time interval between the applied puff and the preceding puff differs from the predetermined time interval between corresponding puffs of the predetermined puff distribution, using this time difference to modify the temperature of the predetermined thermal profile for the puff at the predetermined puff distribution corresponding to the cumulative number of applied puffs, and using the modified temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. In this manner, the temperature of the predetermined thermal profile may be modified based on actual real-time puffing behavior by the user to maintain efficient aerosol extraction from the substrate. As described above, the predetermined thermal profile may be stored in a controller used to control the power supply. Alternatively, the predetermined thermal profile may be stored in a memory module accessible to such controller. The predetermined time interval may be uniform across the predetermined puff distribution.

A non-limiting example of the use and modification of a predetermined thermal profile using such a "predetermined time interval" between successive puffs of a predetermined puff profile is as follows: A predetermined puff profile of a thermal profile may have successive puffs separated from one another by a time interval Δt _predet . Thus, puff "n" is separated in time from its subsequent puff "n+1" in the thermal profile by Δt _predet . Conveniently, the time interval Δt _predet is 30 seconds. However, other values of the time interval Δt _predet may be selected according to the rate at which an ideal or hypothetical user is assumed to apply puffs over the course of a use session. In this example, the thermal profile defines the heater temperatures of puffs "n" and "n+1" as T _n and T _n+1 , respectively. In the thermal profile, T _n and T _n+1 are different from one another and are separated from one another by a time interval Δt _predet .

Two scenarios are possible in which an actual user applies puffs to the device during a use session. In the first scenario, the user applies puffs according to the predetermined time intervals of the thermal profile, meaning that each puff is separated from its preceding puff by Δt _predet . In this first scenario, the target operating temperature of the heater for applied puff "n+1" simply corresponds to temperature T _n+1 and requires no modification to the thermal profile. In the second scenario, the same user applies puffs at a faster or slower rate than expected in the thermal profile. In this second scenario, the temperature of the thermal profile for puff "n+1" is modified depending on whether the user applies puff "n+1" earlier or later than expected in the thermal profile, i.e., whether applied puffs "n" and "n+1" are separated in time by a shorter or longer time interval than Δt _predet . Preferably, the temperature of the thermal profile corresponding to puff "n+1" is modified depending on how early or late puff "n+1" is applied after puff "n" relative to the time interval Δt _predet . Advantageously, the temperature of the thermal profile corresponding to puff "n+1" is altered after puff "n" in proportion to how early or late puff "n+1" is applied compared to Δt _predet .

Correlating an applied puff with a corresponding target operating temperature of the heater may additionally be based on the intensity of previous puffs applied during the use session. In this way, the target operating temperature of the heater may consequently be a function of both i) the cumulative number of applied puffs and ii) the intensity of the previous puff. Optionally, the target operating temperature may additionally be a function of the time interval between the applied puff and the previous puff, as described in the previous paragraph. The intensity of the puff may affect both the depletion of the aerosol-forming substrate and the temperature of the substrate. The greater the intensity of the puff applied by the user, the greater the aerosol generated in response to that puff, and the greater the substrate's depletion of compounds necessary for aerosol formation. Furthermore, puffs of higher intensity than expected may cause the substrate to cool below the level necessary to ensure effective aerosol extraction from the substrate. As the substrate becomes more depleted, more energy is required to extract the remaining compounds necessary for aerosol formation, resulting in a higher heater temperature. Thus, correlating an applied puff with a corresponding target operating temperature of the heater additionally based on the intensity of a prior puff provides the benefit of allowing the target operating temperature to be adjusted to counteract substrate depletion caused by the intensity characteristics of the puff applied by an individual user. This maintains efficient aerosol extraction from the substrate regardless of (or less dependent on) the intensity of the puff applied by the user. Preferably, the prior puff immediately precedes the puff applied during the use session.

The intensity of a given puff may be characterized in various ways. As one example, the intensity of a puff may be characterized by the volume of aerosol generated from the substrate in response to that puff. Thus, the method may further include determining the volume of aerosol generated from the aerosol-forming substrate in response to a previous puff, and using the determined volume to determine the intensity of the previous puff.

As described above, the aerosol generating device may store a predetermined thermal profile defining the variation of heater temperature for a predetermined puff distribution. Preferably, the predetermined thermal profile includes a predetermined intensity for each puff of the predetermined puff distribution. The method may further include determining whether the intensity of a preceding puff differs from the predetermined intensity for the corresponding puff of the predetermined puff distribution, using this intensity difference to modify the temperature of the predetermined thermal profile for the puff at the predetermined puff distribution corresponding to the cumulative number of applied puffs, and using the modified temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. In this manner, the predetermined thermal profile may be adapted in real time according to the puff intensity characteristics of an individual user to maintain efficient aerosol extraction from the substrate. As described above, the predetermined thermal profile may be stored in a controller used to control the power supply. Alternatively, the predetermined thermal profile may be stored in a memory module accessible to such controller. The predetermined intensity may be uniform throughout the predetermined puff distribution.

A non-limiting example of the use and modification of a predetermined thermal profile using such a "predetermined intensity" for each predetermined puff distribution is now described. In this example, the volume of aerosol generated in response to a puff is used as a measure of the intensity of the puff, as follows: For a predetermined thermal profile, the predetermined puff distribution consists of a predetermined number N of puffs applied over the course of a hypothetical use session. The thermal profile also defines a predetermined total volume V of aerosol generated from the aerosol-forming substrate over the course of a hypothetical use session. For purposes of this example, the predetermined total aerosol volume V is assumed to be generated equally for each of the N puffs. Thus, for a predetermined thermal profile, each puff of the "N" puffs will generate the same volume v of aerosol, where v = V/N. In this example, the volume v corresponds to the "predetermined intensity."

Two scenarios are considered in which an actual user applies puffs to the device during a use session. In the first scenario, the user applies puffs according to a predetermined puff distribution in the thermal profile. This means that each puff applied by the user during a use session has an intensity that matches the thermal profile, i.e., each applied puff results in the generation of an aerosol volume v. In this first scenario, no changes to the thermal profile occur; the heater's target operating temperature for each applied puff simply tracks the corresponding temperature in the thermal profile for puffs in the predetermined puff distribution at a number corresponding to the cumulative number of applied puffs. However, in the second scenario, the user may apply puffs with a different intensity (and therefore aerosol volume generated) than assumed in the thermal profile. In this second scenario, two consecutive puffs applied by the user, namely puffs "n" and "n+1," are monitored. If the applied puff "n" is stronger than assumed in the thermal profile, the aerosol volume _v resulting from puff "n" will be greater than the ideal volume v of the thermal profile. A higher than expected intensity (aerosol volume v _n ) of puff "n" will result in greater than expected depletion of the substrate in response to puff "n". To compensate for the greater than expected depletion, the target operating temperature of the next puff "n+1" may need to be higher than defined in the predetermined thermal profile. Alternatively, if the applied puff "n" is weaker than assumed in the thermal profile, the aerosol volume v _n of puff "n" will be smaller than the ideal volume v of the thermal profile. A lower than expected intensity (aerosol volume v _n ) of puff "n" will result in less than expected depletion of the substrate in response to puff "n". To compensate for the lower than expected depletion, the target operating temperature of the next puff "n+1" may need to be lower than defined in the predetermined thermal profile. The change in temperature of puff "n+1" in a predetermined thermal profile may be expressed as follows:

During the ceremony:
is the temperature initially defined in the thermal profile for puff "n+1".

is the modified temperature of the thermal profile for puff "n+1".

α is the actual "intensity" of puff "n"
is a correction factor applied to account for the aerosol volume _vn generated in response to an applied puff "n" being greater than or less than the ideal volume v.

In one example, the correction coefficient α may be expressed as follows:

During the ceremony:
δ is a scale factor, whose value is determined by the initially defined temperature
v _n may be chosen to have a different increasing or decreasing effect than v when changing

The association between an applied puff and a corresponding target operating temperature of the heater may additionally be based on the volume of aerosol generated from the aerosol-forming substrate in response to a previous puff applied during the use session. In this manner, the target operating temperature of the heater may consequently be a function of both i) the cumulative number of applied puffs and ii) the volume of aerosol generated in response to the previous puff. Optionally, the target operating temperature may additionally be a function of one or more of i) the time interval between the applied puff and the previous puff (as described in the previous paragraph) and ii) the intensity of the previous puff (as described in the previous paragraph). This may be understood to be closely related to the situation described above, where the target operating temperature is a function of the intensity of the puff, and the volume of aerosol generated in response to the puff is one suitable means of characterizing the intensity of the puff. The greater the volume of aerosol generated in response to the puff, the greater the depletion of the substrate. As substrate depletion increases, more energy is required to extract the remaining compounds necessary for aerosol formation, resulting in a higher heater temperature. Thus, correlating an applied puff with a corresponding target operating temperature of the heater, additionally based on the volume of aerosol generated in response to a prior puff, provides the benefit of allowing the target operating temperature to be adjusted to counteract substrate depletion caused by the characteristics of the puff applied by an individual user. Preferably, the prior puff immediately precedes the puff applied during the use session.

As described above, the aerosol-generating device may store a predetermined thermal profile defining the variation in heater temperature for a predetermined puff distribution. Preferably, the predetermined thermal profile includes a predetermined volume of aerosol generated from the aerosol-forming substrate for each puff of the predetermined puff distribution. The method may further include determining whether the volume of aerosol generated for a previous puff differs from the predetermined volume for the corresponding puff of the predetermined puff distribution, using this volume difference to modify the temperature of the predetermined temperature profile for the puff at the predetermined puff distribution corresponding to the cumulative number of applied puffs, and using the modified temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. In this manner, the predetermined thermal profile can be adapted according to the puffing characteristics of an individual user, thereby facilitating the maintenance of efficient extraction of aerosol from the substrate over a usage session. As described above, the predetermined thermal profile may be stored in a controller used to control the power supply. Alternatively, the predetermined thermal profile may be stored in a memory module accessible to such a controller. The predetermined volume may be uniform across the predetermined puff distribution. The non-limiting examples outlined in the previous paragraph with reference to Equations 1 and 2, which describe the use and modification of a predetermined thermal profile using a "predetermined intensity" for each puff of each predetermined puff distribution, are also applicable to the variant of the predetermined thermal profile described in this paragraph that uses a "predetermined volume" of generated aerosol.

Advantageously, the target operating temperature varies within a range of 320°C to 350°C over a use session. Such operating temperatures have been found to be particularly suitable for generating aerosols from aerosol-forming substrates that are solid and include tobacco. However, the present disclosure is not limited to the use of solid aerosol-forming substrates, but may also apply to the use of liquid aerosol-forming substrates. It may also be desirable to limit the maximum target operating temperature over a use session to avoid ignition and combustion of the substrate and the release of harmful compounds from the substrate; by way of example, this limit may be set at 400°C, 375°C, or 350°C. The specific range and limit of the target operating temperature over a use session may be set according to the heating characteristics of the particular aerosol-forming substrate used, as well as the energy capacity of the power source used.

The method may include detecting the applied puff by monitoring a change in heater temperature in response to the applied puff. By way of example, the heater temperature may be detected as described in the preceding paragraph.

The method may further include terminating the use session when either i) the cumulative number of puffs applied during the use session reaches a predetermined puff limit, or ii) the use session reaches a predetermined maximum duration, whichever occurs first. By way of example, the predetermined puff limit may be 12 puffs, and the predetermined maximum duration may be 6 minutes. However, other values for the puff limit and maximum duration may be established, and their selection is influenced by several factors. These factors may include the amount and composition of the aerosol-forming substrate used and the amount of power available from the power source in a given use session. The aerosol-generating device is preferably portable, having a size and mass suitable for the device to be held in a user's hand. These preferences, in turn, affect the size and energy capacity of the aerosol-generating device's power source, thereby affecting the values established for the puff limit and maximum duration.

According to a second aspect of the present invention, there is provided a computer-readable medium for use in an aerosol generating device, the computer-readable medium comprising instructions for carrying out the method of the first aspect and any of its variants, as described above. The computer-readable medium may include computer memory. The computer-readable medium may be provided within a controller for use to control the power supply. Alternatively, the computer-readable medium may be a distinct component separate from but accessible to such controller. Preferably, the computer-readable medium is readable and writable during use, thereby providing the benefit of allowing the thermal profile stored within the computer-readable medium to change over the course of a use session.

According to a third aspect of the present invention there is provided an aerosol-generating device for generating an aerosol from an aerosol-forming substrate during a session of use, the aerosol-generating device comprising:
a power source arranged to power the heater during a session of use;
The aerosol generating device
Associating the puffs applied during the use session with a corresponding target operating temperature of the heater based on a cumulative number of puffs applied during the use session;
For an applied puff, the device is configured to control the supply of power from the power source to adjust the temperature of the heater to a target operating temperature associated with the applied puff.

This third aspect generally provides an aerosol generating device capable of carrying out the methods of the first aspect and its variants described above. For completeness, different variants of the aerosol generating device are briefly outlined below.

As described above in relation to the first aspect, the aerosol generating device may store a predetermined thermal profile defining the variation of heater temperature over a predetermined puff distribution, and the aerosol generating device is configured such that the target operating temperature associated with an applied puff is a temperature in the predetermined thermal profile for a puff at the predetermined puff distribution corresponding to the cumulative number of puffs applied.

As described above in relation to the first aspect, the predetermined thermal profile may be stored within a controller used to control the power supply. Alternatively, the predetermined thermal profile may be stored in a memory module accessible to such a controller.

As described above in relation to the first aspect, the predetermined thermal profile may include a predetermined relationship between a puff parameter and a predetermined puff distribution. Furthermore, the aerosol generating device is preferably configured to determine whether the value of the puff parameter for either or both of the applied puff and the preceding puff differs from the value of the puff parameter for the corresponding puff in the predetermined puff distribution, use this difference in the value of the puff parameter to modify the temperature of the predetermined thermal profile for the puff at the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puffs, and use the modified heater temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff.

As described in the first aspect, the puff parameters may include one or more of the time interval between successive puffs, the intensity of the puffs, and the volume of aerosol generated from the aerosol-forming substrate in response to the puffs.

Providing predetermined threshold limits for the thermal profile described in the first aspect is equally applicable to the aerosol generating device of this third aspect of the present invention.

The aerosol generating device may also be configured to determine a time interval between the applied puff and the preceding puff, and to associate the applied puff with a corresponding target operating temperature of the heater additionally based on the determined time interval.

As previously mentioned, the aerosol generating device may store a predetermined thermal profile defining the variation in heater temperature for a predetermined puff distribution. Preferably, the predetermined thermal profile includes a predetermined time interval between successive puffs of the predetermined puff distribution, and the aerosol generating device is configured to determine whether the determined time interval between the applied puff and the preceding puff differs from the predetermined time interval between corresponding puffs of the predetermined puff distribution, use this time difference to modify the temperature of the predetermined thermal profile for the puff at the predetermined puff distribution corresponding to the cumulative number of puffs applied, and use the modified temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. The examples described in the previous paragraph (with respect to the method of the first aspect) for using and modifying the predetermined thermal profile using a "predetermined time interval" between successive puffs of the predetermined puff distribution are equally applicable to providing an understanding of the configuration of the device outlined in this paragraph.

The aerosol-generating device may also be configured to determine the intensity of a preceding puff applied during a use session, and to associate the applied puff with a corresponding target operating temperature of the heater additionally based on the determined intensity of the preceding puff. As discussed in the previous paragraph for the first aspect, the intensity of a given puff may be characterized in various ways. As an example, the intensity of a puff may be characterized by the volume of aerosol generated from the substrate in response to that puff. Thus, the aerosol-generating device may be configured to determine the volume of aerosol generated from the aerosol-forming substrate in response to the preceding puff, and use the determined volume to determine the intensity of the preceding puff.

As described above, the aerosol generating device may store a predetermined thermal profile defining the variation of heater temperature for a predetermined puff distribution. Preferably, the predetermined thermal profile includes a predetermined intensity for each puff of the predetermined puff distribution, and the aerosol generating device is configured to determine whether the determined intensity of a preceding puff differs from the predetermined intensity for the corresponding puff of the predetermined puff distribution, use this intensity difference to modify the temperature of the predetermined thermal profile for the puff at the predetermined puff distribution corresponding to the cumulative number of applied puffs, and use the modified temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. The examples described in the previous paragraph (with respect to the method of the first aspect) for using and modifying the predetermined thermal profile using the "predetermined intensity" of each puff of the predetermined puff distribution are equally applicable to providing an understanding of the configuration of the device outlined in this paragraph.

The aerosol-generating device may also be configured to determine the volume of aerosol generated from the aerosol-forming substrate in response to a previous puff applied during a use session, and to associate the applied puff with a corresponding target operating temperature of the heater additionally based on the volume determined for the previous puff. As noted in the previous paragraph, this may be understood to be closely related to the situation described above, where the target operating temperature is a function of the intensity of the puff, and the volume of aerosol generated in response to the puff is one suitable means of characterizing the intensity of the puff.

As described above, the aerosol generating device may store a predetermined thermal profile defining the variation in heater temperature for a predetermined puff distribution. Preferably, the predetermined thermal profile includes a predetermined volume of aerosol generated from the aerosol-forming substrate for each puff of the predetermined puff distribution, and the aerosol generating device is configured to determine whether the determined volume of aerosol generated for a preceding puff differs from a predetermined volume for a corresponding puff of the predetermined puff distribution, use this volume difference to modify the temperature of the predetermined temperature profile for a puff at the predetermined puff distribution corresponding to the cumulative number of puffs applied, and use the modified temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff.

In the same manner and with the same reasoning as discussed in the previous paragraph for the method of the first aspect, the aerosol generating device may be configured so that the target operating temperature is limited to vary within the range of 320°C to 350°C.

The aerosol generating device may be configured to detect an applied puff by monitoring a change in heater temperature in response to an applied puff.

In the same manner and with the same reasoning as discussed in the previous paragraph with respect to the method of the first aspect, the aerosol generating device may be configured to terminate a use session upon either i) the cumulative number of puffs applied during said use session reaching a predetermined puff limit, or ii) the use session reaching a predetermined maximum duration, whichever occurs first.

The aerosol-generating device may include a heater. By way of example, the heater may be a resistive heating element intended to fit around or within the aerosol-forming substrate. Alternatively, the heater may be separate and distinct from the device. For example, the heater may be a susceptor forming part of an article separate from the device, in which the article houses the aerosol-forming substrate. In such an embodiment, the aerosol-generating device may include an inductor, and the power supply is configured to supply power to the inductor such that, upon use of the device with the article, the inductor induces eddy currents in the susceptor, thereby resulting in heating of the susceptor.

In a fourth aspect, there is provided an aerosol generation system, the system comprising an aerosol generation device according to the third aspect described above, and any variant thereof, wherein the aerosol-generating article comprises a heater and an aerosol-forming substrate, and the aerosol-generating device is configured to receive the aerosol-generating article.

By way of example, the heater may be in the form of a susceptor, and the aerosol-generating device includes an inductor coupled to a power source. The aerosol-generating article and device are preferably configured such that, when the article is received by the device, the inductor and susceptor are positioned relative to one another such that power supplied from the power source to the inductor induces eddy currents in the susceptor, thereby causing heating of the aerosol-forming substrate.

The present invention is defined in the claims. However, the following provides a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of any other example, embodiment, or aspect described herein.

[Example 1]
1. A method of operating an aerosol-generating device to generate an aerosol from an aerosol-forming substrate during a session of use, the method comprising:
a power source arranged to power the heater during a session of use;
The method comprises:
Associating puffs applied during the use session with a corresponding target operating temperature of the heater based on a cumulative number of puffs applied during the use session;
For the applied puff, controlling the supply of power from the power source to adjust the temperature of the heater to a target operating temperature associated with the applied puff.

[Example 2]
A method according to example 1, wherein the aerosol generating device stores a predetermined thermal profile defining the variation of heater temperature over a predetermined puff distribution, and the target operating temperature associated with the applied puff is the temperature of the predetermined thermal profile for a puff at the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puff.

[Example 3]
the predetermined thermal profile comprises a predetermined relationship between a smoke puff parameter and a predetermined smoke puff distribution, and the method comprises:
determining whether the value of a puff parameter for either or both of the applied puff and a preceding puff applied during the use session differs from the value of the puff parameter for a corresponding puff of the predetermined puff distribution;
using the determined difference in values of the puff parameters to modify the temperature of a predetermined thermal profile for the puffs in a predetermined puff distribution corresponding to the cumulative number of puffs applied;
The method according to example 2, further comprising: using the altered temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff.

[Example 4]
The smoke absorption parameter is
the time interval between successive puffs;
Strong smoking and
a volume of aerosol generated from the aerosol-forming substrate in response to a puff.

[Example 5]
The method of any one of Examples 1 to 4, wherein the association between the applied puff and the corresponding target operating temperature of the heater is additionally based on the time interval between the applied puff and the preceding puff applied during the use session.

[Example 6]
A method according to Example 5, wherein the preceding puff is the puff immediately preceding the puff applied during the use session.

[Example 7]
the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff profile, the predetermined thermal profile including a predetermined time interval between successive puffs of the predetermined puff profile;
The method is
determining whether a time interval between the applied puff and the preceding puff differs from a predetermined time interval between corresponding puffs of a predetermined puff profile;
using this time difference to modify the temperature of a predetermined thermal profile for the puffs in a predetermined puff distribution corresponding to the cumulative number of puffs applied;
The method according to any one of Examples 5 or 6, further comprising: using the altered temperature of the predetermined thermal profile as a target operating temperature associated with the applied puff.

[Example 8]
The method according to example 7, wherein the predetermined time intervals are non-uniform across the predetermined puff distribution.

[Example 9]
The method of any one of examples 1 to 8, wherein the association between the applied puff and the corresponding target operating temperature of the heater is additionally based on the intensity of the previous puff applied during the use session.

[Example 10]
A method according to Example 9, wherein the preceding puff is the puff immediately preceding the applied puff.

[Example 11]
the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff distribution, the predetermined thermal profile including a predetermined intensity for each puff of the predetermined puff distribution;
The method is
determining whether the intensity of the preceding puff differs from a predetermined intensity for a corresponding puff of a predetermined puff distribution;
using the intensity difference to modify the temperature of a predetermined thermal profile for the puffs in a predetermined puff distribution corresponding to the cumulative number of puffs applied;
The method according to any one of examples 9 or 10, further comprising: using the altered temperature of the predetermined thermal profile as a target operating temperature associated with the applied puff.

[Example 12]
The method according to example 11, wherein the predetermined intensity is non-uniform across the predetermined puff distribution.

[Example 13]
The method is
The method according to any one of Examples 9 to 12, further comprising determining the volume of aerosol generated from the aerosol-forming substrate in response to the preceding puff, and using the determined volume to determine the intensity of the preceding puff.

[Example 14]
The method according to any one of Examples 1 to 13, wherein the association between the applied puff and the corresponding target operating temperature of the heater is additionally based on the volume of aerosol generated from the aerosol-forming substrate in response to a previous puff applied during a use session.

[Example 15]
A method according to Example 14, wherein the preceding puff is the puff immediately preceding the applied puff.

[Example 16]
the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff distribution, the predetermined thermal profile including a predetermined volume of aerosol generated from the aerosol-forming substrate for each puff of the predetermined puff distribution;
The method is
determining whether the volume of aerosol generated for the preceding puff differs from a predetermined volume for a corresponding puff of a predetermined puff profile;
using this volume difference to modify the temperature of a predetermined temperature profile for the puffs at a predetermined puff distribution corresponding to the cumulative number of puffs applied;
The method according to any one of examples 14 or 15, further comprising: using the altered temperature of the predetermined thermal profile as a target operating temperature associated with the applied puff.

[Example 17]
The method according to example 16, wherein the predetermined volume is non-uniform across the predetermined puff distribution.

[Example 18]
The method according to any one of examples 1 to 17, wherein the target operating temperature varies within a range of 320°C to 350°C over the use session.

[Example 19]
The method according to any one of examples 1 to 18, comprising detecting an applied puff by monitoring a change in heater temperature in response to the applied puff.

[Example 20]
The method is
The method according to any one of Examples 1 to 19, further comprising terminating the use session upon the earlier occurrence of: i) the cumulative number of puffs applied during the use session reaches a predetermined puff limit; or ii) the use session reaches a predetermined maximum duration.

[Example 21]
21. A computer-readable medium for use in an aerosol generating device, the computer-readable medium comprising instructions for performing a method according to any one of Examples 1 to 20.

[Example 22]
1. A method of operating an aerosol-generating device to generate an aerosol from an aerosol-forming substrate during a session of use, the method comprising:
a power source arranged to power the heater during a session of use;
The aerosol generating device
Associating the puffs applied during the use session with a corresponding target operating temperature of the heater based on a cumulative number of puffs applied during the use session;
An aerosol generating device configured to control the supply of power from the power source to adjust, for an applied puff, the temperature of the heater to a target operating temperature associated with the applied puff.

[Example 23]
An aerosol generating device according to Example 22, wherein the aerosol generating device stores a predetermined thermal profile defining the variation in heater temperature over a predetermined distribution of puffs, and the aerosol generating device is configured such that the target operating temperature associated with an applied puff is the temperature of the predetermined thermal profile for a puff in the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puffs.

[Example 24]
24. An aerosol generating apparatus according to example 23, wherein the predetermined thermal profile stored by the aerosol generating apparatus comprises a predetermined relationship between puff parameters and a predetermined puff distribution, wherein the aerosol generating apparatus comprises:
determining whether the value of a puff parameter for one or both of the applied puff and the preceding puff differs from the value of the puff parameter for a corresponding puff of the predetermined puff distribution;
using this difference in the values of the puff parameters to modify the temperature of a predetermined thermal profile for the puffs in a predetermined puff distribution corresponding to the cumulative number of puffs applied;
The aerosol generating device is configured to use the altered heater temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff.

[Example 25]
The smoke absorption parameter is
the time interval between successive puffs;
Strong smoking and
a volume of aerosol generated from the aerosol-forming substrate in response to a puff.

[Example 26]
The aerosol generating device
determining a time interval between the applied puff and the preceding puff;
An aerosol generating device according to any one of Examples 22 to 25, configured such that the association between the applied puff and the corresponding target operating temperature of the heater is additionally based on the determined time interval.

[Example 27]
the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff profile, the predetermined thermal profile including a predetermined time interval between successive puffs of the predetermined puff profile;
The aerosol generating device
determining whether the determined time interval between the applied puff and the preceding puff differs from a predetermined time interval between corresponding puffs of a predetermined puff profile;
Using this time difference to modify the temperature of a predetermined thermal profile for the puffs in a predetermined puff distribution corresponding to the cumulative number of puffs applied;
27. The aerosol generating device of Example 26, configured to use the altered temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff.

[Example 28]
The aerosol generating device
An aerosol generating device according to any one of Examples 22 to 27, configured to determine the intensity of a preceding puff applied during a usage session, and wherein the association of the applied puff with the corresponding target operating temperature of the heater is additionally based on the determined intensity of the preceding puff.

[Example 29]
the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff distribution, the predetermined thermal profile including a predetermined intensity for each puff of the predetermined puff distribution;
The aerosol generating device
determining whether the determined intensity of the preceding puff differs from a predetermined intensity for a corresponding puff of the predetermined puff distribution;
using the intensity difference to modify the temperature of a predetermined thermal profile for the puffs in a predetermined puff distribution corresponding to the cumulative number of puffs applied;
29. An aerosol generating device according to example 28, configured to use the altered temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff.

[Example 30]
The aerosol generating device
determining a volume of aerosol generated from the aerosol-forming substrate in response to a preceding puff;
30. An aerosol generating device according to any one of Examples 28 or 29, configured to use the determined volume in determining the intensity of the preceding puff.

[Example 31]
The aerosol generating device
An aerosol generating device according to any one of Examples 22 to 30, configured to determine a volume of aerosol generated from the aerosol-forming substrate in response to a previous puff applied in a use session, and wherein the association of the applied puff with a corresponding target operating temperature of the heater is additionally based on the volume determined for the previous puff.

[Example 32]
the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff distribution, the predetermined thermal profile including a predetermined volume of aerosol generated from the aerosol-forming substrate for each puff of the predetermined puff distribution;
The aerosol generating device comprises:
determining whether the determined volume of aerosol generated for the preceding puff differs from a predetermined volume for a corresponding puff of the predetermined puff distribution;
using this volume difference to modify the temperature of a predetermined temperature profile for the puffs in a predetermined puff distribution corresponding to the cumulative number of puffs applied;
An aerosol generating device according to example 31 configured to use the altered temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff.

[Example 33]
The aerosol generation device according to any one of Examples 22 to 32, wherein the aerosol generation device is configured such that the target operating temperature is constrained to vary within the range of 320°C to 350°C.

[Example 34]
An aerosol generating device according to any one of Examples 22 to 33, wherein the aerosol generating device is configured to detect an applied puff by monitoring a change in heater temperature in response to the applied puff.

[Example 35]
The aerosol generating device
An aerosol generating device according to any one of Examples 22 to 34, configured to terminate a use session when either i) the cumulative number of puffs applied during the use session reaches a predetermined puff limit, or ii) the use session reaches a predetermined maximum duration, whichever occurs first.

[Example 36]
The aerosol generating device according to any one of Examples 22 to 35, wherein the aerosol generating device comprises a heater.

[Example 37]
An aerosol generation system comprising an aerosol-generating device according to any one of claims 22 to 35 and an aerosol-generating article, the aerosol-generating article comprising a heater and an aerosol-forming substrate, the aerosol-generating device configured to receive the aerosol-generating article.

Now, the example will be further explained with reference to the figures.

FIG. 1 is a schematic side view of an aerosol generating device. FIG. 2 is a schematic top view of the aerosol generating device of FIG. FIG. 3 is a schematic cross-sectional side view of the aerosol generating device of FIG. 1 and an aerosol-generating article for use in the device. FIG. 4 shows a prior art thermal profile used in the operation of known aerosol generating devices. FIG. 5 illustrates the variation in target operating temperature of the heater of an aerosol generating device resulting from the use of the prior art thermal profile of FIG. 4 in a scenario in which a user applies successive puffs spaced 15 seconds apart. FIG. 6 illustrates the variation in target operating temperature of the heater of an aerosol generating device resulting from the use of the prior art thermal profile of FIG. 4 in a scenario in which a user applies successive puffs spaced 11 seconds apart. FIG. 7 illustrates a method according to the present disclosure in which the target operating temperature of the heater is adjusted as a function of the number of puffs. FIG. 8 illustrates a thermal profile according to the present disclosure in which the target operating temperature of the heater is defined as a function of the number of puffs. FIG. 9 is a diagram illustrating how the target operating temperature of the heater varies when using the thermal profile of FIG. 8 in a scenario where the user applies puffs at uniform intervals. FIG. 10 is a diagram illustrating how the target operating temperature of the heater changes when using the thermal profile of FIG. 8 in a scenario where the user applies puffs at varying (i.e., non-uniform) intervals.

The exemplary aerosol generating device 10 is a handheld aerosol generating device and has an elongated shape defined by a housing 20 that is substantially circular and cylindrical in shape (see FIGS. 1, 2, and 3). The aerosol generating device 10 includes an open cavity 25 located at the proximal end 21 of the housing 20 for receiving an aerosol-generating article 30 having an aerosol-forming substrate 31. The aerosol generating device 10 includes a battery 26, control electronics 27, and a memory module 28 located within the housing 20. The memory module 28 is readable and writable during use. An electrically operated heater 40 is disposed within the device 10 for heating at least the aerosol-forming substrate portion 31 of the aerosol-generating article 30 when the aerosol-generating article is received within the cavity 25. The memory module 28 stores a thermal profile accessible to the control electronics 27 during use of the device 10. The thermal profile defines how the target operating temperature for the heater 40 changes over a use session.

The aerosol-generating device is configured to receive a consumable aerosol-generating article 30. The aerosol-generating article 30 is in the form of a cylindrical rod and includes an aerosol-forming substrate 31 (see FIG. 3). The aerosol-forming substrate 31 is a solid aerosol-forming substrate that includes tobacco. The aerosol-generating article 30 further includes a mouthpiece, such as a filter 32, disposed within the cylindrical rod in coaxial alignment with the aerosol-forming substrate 31. The aerosol-generating article 30 has a diameter substantially equal to the diameter of the cavity 25 of the device 10 and a length greater than the depth of the cavity 25, such that when the article 30 is received within the cavity 25 of the device 10, the mouthpiece 32 extends outside the cavity 25 and may be withdrawn by the user in the same manner as a conventional cigarette.

During use, a user inserts the article 30 into the cavity 25 of the aerosol-generating device 10 and turns on the device 10 by activating the heater 40 by pressing the user button 50 (see FIG. 1) to begin a use session. The heater 40 heats the aerosol-forming substrate 31 of the article 30, causing volatile compounds in the aerosol-forming substrate to be released and atomized to form an aerosol. The user draws on the mouthpiece of the article 30 and inhales the aerosol generated from the heated aerosol-forming substrate 31. After activation, the temperature of the heater 40 is increased from ambient temperature to a predetermined temperature to heat the aerosol-forming substrate. The predetermined temperature is defined in a thermal profile stored in memory 28. After activation and during the course of a use session, the control electronics 27 of the device 10 accesses the thermal profile stored in the memory module 28 to control the power supply from the battery 26 to the heater 40 and regulate the heater temperature according to the thermal profile. The heater 40 continues to heat the aerosol-generating article 30 until the end of the use session, at which point the heater is deactivated and allowed to cool. In certain embodiments, the heater 40 may be a resistive heating element. In certain embodiments, the heater 40 may be a susceptor disposed within a varying magnetic field so as to be heated by induction.

At the end of the usage session, the item 30 may be removed from the device 10 for disposal, and the device 10 may be connected to an external power source to charge the device 10's battery 26.

The aerosol-generating article 30 for use with the device 10 has a finite amount of aerosol-forming substrate 31, and therefore, a use session must have a finite duration to prevent a user from attempting to generate aerosol when the aerosol-forming substrate is depleted. A use session is configured to have a maximum duration determined by the longest period from the start of the use session. A use session is also configured to have a duration shorter than the maximum period if a user interaction parameter recorded during the use session reaches a threshold before the longest period has elapsed. In a specific example, the user interaction parameter represents the cumulative number of puffs the user applies to the device during the use session, and a threshold of 14 puffs is defined for the cumulative number of puffs. Thus, for this specific example, the aerosol-generating device 10 is configured so that each use session has a maximum duration defined by either i) six minutes from activation of the use session or ii) the application of a total of 14 puffs during the use session, whichever occurs first.

In prior art devices, the thermal profile used to regulate the temperature of the heater 40 is a predetermined temperature profile that varies the heater's target operating temperature solely as a function of elapsed time in a use session. FIG. 4 illustrates such a prior art thermal profile. Prior art thermal profiles are based on ideal or hypothetical user behavior and define a temperature profile for the heater 40 that varies the heater's target operating temperature solely as a function of elapsed time. The prior art thermal profile of FIG. 4 is constructed based on the assumption that the user applies each successive puff to the device 10 at 30-second intervals, resulting in a use session having a duration of six minutes (360 seconds). These hypothetical or ideal puffs are represented by the dashed lines in FIG. 4.

The operation of the device 10 using the prior art thermal profile of Figure 4 will now be described in three different scenarios.

In the first scenario, the user activates the device 10 by pressing the user button 50, initiating a use session with an unused article 30, and then applies a series of 12 consecutive puffs spaced 30 seconds apart from each other. When the user applies puffs at a rate consistent with the assumptions made for the thermal profile of FIG. 4, the battery 26 (under the control of the control electronics 27) will provide power to the heater 40 for a 6-minute use session corresponding to 12 puffs spaced 30 seconds apart. Essentially, the heater 40 is regulated according to the thermal profile shown in FIG. 4. As a result, the aerosol-forming substrate 31 is substantially depleted of aerosol.

In the second scenario, the user activates the device 10 by pressing the user button 50, initiating a use session with an unused article 30. However, in contrast to the first scenario, after taking the first puff 30 seconds into the use session, the user applies all subsequent puffs only 15 seconds apart from each other. This high puff rate results in the device 10 prematurely terminating the use session because the threshold limit of 14 puffs has been reached before six minutes (360 seconds) have elapsed in the use session. The effect of increasing puff rate on heater temperature over the course of this shortened use session can be seen in FIG. 5, with each applied puff represented by a dashed line. Because the thermal profile in this second scenario assumes that successive puffs are applied at 30-second time intervals, the effect of a real-world user applying puffs at a faster rate of one every 15 seconds would be that the heater 40 would never achieve the temperature required to extract all of the aerosol from the aerosol-forming substrate 31 during the latter half of the use session.

In the third scenario, the user activates the device 10 by pressing the user button 50, initiating a use session with a fresh article. However, in contrast to the second scenario, after taking the first puff 30 seconds into the use session, the user applies all subsequent puffs only 11 seconds apart from each other. As shown in FIG. 6, this higher puff rate results in the device 10 terminating the use session even earlier than in the second scenario. Again, the early termination of the use session occurs because the threshold limit of 14 puffs was reached before 6 minutes (360 seconds) had elapsed in the use session. The effect of increasing puff rate on heater temperature over the course of this shortened use session can be seen in FIG. 6, with each applied puff represented by a dashed line. As can be seen from FIG. 6, the consequences of insufficient heating of the aerosol-forming substrate 31 by the heater 40 are even more severe in this third scenario than in the second scenario of FIG. 5.

Thus, Figures 5 and 6 can illustrate the problem of using a known thermal profile for a heater that simply varies the target operating temperature of the heater 40 as a function of elapsed time.

FIG. 7 schematically illustrates a method 100 according to the present disclosure. Method 100 is performed by the aerosol generating device 10 of the present disclosure when a user applies a series of puffs to the aerosol generating device 10 during a use session. In step 101, the applied puffs are associated with a corresponding target operating temperature of the heater 40 based on the cumulative number of puffs applied during the use session. In step 102, for each applied puff, power supply from the battery 26 is controlled by the control electronics 27 to adjust the temperature of the heater 40 to the target operating temperature associated with the applied puff.

Steps 101, 102 of method 100 are performed for each puff applied by the user during a use session until the end of the use session, thereby enabling method 100 to adjust the temperature of heater 40 as a function of the cumulative number of puffs in the use session.
Method 100 is implemented by a combination of control electronics 27 and a thermal profile stored in memory module 28. During the course of a use session, control electronics 27 will access memory module 28 to read the thermal profile and then control the supply of power from power supply 26 to regulate the temperature of heater 40 according to the instructions provided in the thermal profile. However, the thermal profile used by method 100 differs from the prior art thermal profiles described above in connection with FIGS. 4-6 .

FIG. 8 illustrates an example thermal profile for use in practicing method 100 with aerosol generating device 10. However, in contrast to the prior art thermal profiles discussed above, the thermal profile of FIG. 8 defines a target operating temperature for heater 40 as a function of the number of puffs. Thus, for the thermal profile of FIG. 8, each puff of a use session is associated with a given target operating temperature for heater 40. The thermal profile of FIG. 8 defines a target operating temperature for each puff of a predetermined distribution of 12 puffs. As discussed above, the thermal profile is stored in memory module 28 of aerosol generating device 10. As the user applies each puff of the series of puffs to device 10, control electronics 27 accesses memory 28 to read the thermal profile. Control electronics 27 then controls the supply of power from battery 26 to heater 40 to adjust the target operating temperature of the heater according to the thermal profile of FIG. 8 and the cumulative number of puffs for each applied puff.

9 and 10 show two examples of how the target operating temperature of the heater 40 varies over time when using the thermal profile of FIG. 8 for a use session in which a user applies successive puffs to the aerosol generating device 10. FIG. 9 shows the temperature fluctuations when the user applies puffs at uniform intervals, in this case 15 seconds apart. FIG. 10 shows the temperature fluctuations when the user applies puffs spaced apart by uneven time intervals. By examining FIGS. 9 and 10, it can be seen that use of the thermal profile of FIG. 8 results in the target operating temperature being adjusted based on the cumulative number of puffs applied in the use session, rather than being adjusted solely as a function of elapsed time in the use session. Essentially, the target operating temperature of the heater 40 is adjusted by tracking the number of puffs applied with reference to the thermal profile of FIG. 8 stored in memory module 28. Thus, in contrast to use of the prior art thermal profile of FIG. 4, the thermal profile of FIG. 8 allows the target operating temperature to be increased over the latter half of a use session, regardless of the puff rate and timing applied by the user.

In another example, associating an applied puff with a corresponding target operating temperature of the heater may additionally be a function of the time interval between the applied puff and the preceding puff applied during the use session. In this example, a second thermal profile corresponding to the profile shown in FIG. 8 is used. However, this second thermal profile also includes a "predetermined time interval" Δt _predet . In this example, Δt _predet has a value of 30 seconds. The predetermined time interval Δt _predet represents a hypothetical or ideal time interval between successive puffs in the thermal profile. In this example, the temperature in the thermal profile corresponding to the applied puff is itself modified depending on whether the actual time interval Δt between the applied puff and the preceding puff differs from the predetermined time interval Δt _predet . In the thermal profile, heater temperatures T _n , T _n+1 are defined for successively applied puffs "n" and "n+1". When a user applies a puff to the device during a use session, if the time interval Δt between the applied puff "n+1" and the preceding puff "n" is shorter or longer than a predetermined time interval Δt _predet , the temperature in the thermal profile of puff "n+1" is altered in proportion to the difference between Δt and Δt _predet . Expressed mathematically, the temperature in the thermal profile of puff "n+1" is:
Changes to temperature as follows:

However, temperature changes in the thermal profile are subject to predetermined threshold limits of ±3% of the unchanged temperature. Additionally, temperature changes in the thermal profile are also subject to an absolute temperature limit of 350°C. In other embodiments, different values may be set for the threshold limits and percentage of the absolute temperature limit.

For this second thermal profile, when a user applies successive puffs to the aerosol generating device 10 during a use session, the time interval between the applied puff and the preceding puff is first determined. Next, the temperature in the thermal profile corresponding to the puff number of the applied puff (e.g., for puff "n+1") is altered according to the method discussed above (see Equation 3). The altered temperature of the thermal profile is then used as the target operating temperature for the applied puff, and the control electronics 27 controls the power supply to the heater 40 to achieve this target operating temperature for the applied puff. If the user happens to apply puffs at intervals equal to the "predetermined time interval" Δt _predet , no temperature alteration in the thermal profile occurs for those puffs.

In yet another example, relating an applied puff to a corresponding target operating temperature may also be a function of the intensity of the preceding puff in the use session. In this example, the intensity of the puff is characterized by the volume of aerosol generated in response to the puff. In this example, a third thermal profile corresponding to the profile shown in FIG. 8 is used. However, this third thermal profile also contains a "predetermined intensity," which in this example is in the form of a predetermined volume. The predetermined intensity (or volume) can be thought of as representing an ideal or assumed volume of aerosol generated by each puff in the thermal profile. In this example, the thermal profile has a predetermined number of puffs, N, that are assumed to be applied over the use session. The thermal profile also has a predetermined total volume, V, of aerosol generated over the course of the use session. In this example, the predetermined total aerosol volume, V, is assumed to be generated uniformly for each of the N puffs. Thus, in this thermal profile, each puff in the "N" puffs is assumed to generate the same volume, v, of aerosol, where v = V/N. This volume, v, is the predetermined intensity (or volume).

In the thermal profile, heater temperatures _Tn , Tn ₊₁ are defined for successively applied puffs "n" and "n+1." If the applied puff "n" is stronger than assumed in the thermal profile, the aerosol volume _vn of puff "n" will be larger than the predetermined volume v. The higher-than-expected intensity (aerosol volume _vn ) of puff "n" will result in a larger-than-expected depletion of the substrate in response to puff "n." To compensate for the larger-than-expected depletion, the target operating temperature of the next puff "n+1" may need to be higher than defined in the predetermined thermal profile. Alternatively, if the applied puff "n" is weaker than assumed in the thermal profile, the aerosol volume _vn of puff "n" will be smaller than the ideal volume v of the thermal profile. The lower-than-expected intensity (aerosol volume _vn ) of puff "n" will result in a smaller-than-expected depletion of the substrate in response to puff "n." To compensate for lower than expected depletion, the target operating temperature of the next puff "n+1" may need to be lower than defined in the predetermined thermal profile. The change in temperature of puff "n+1" in a predetermined thermal profile can be expressed as shown in equations 1 and 2 listed above, which are repeated below for completeness:

During the ceremony:
is the temperature initially defined in the thermal profile for puff "n+1".

is the modified temperature of the thermal profile for puff "n+1".

α is the actual "intensity" of puff "n"
is a correction factor applied to account for the difference between the ideal volume v and the volume _vn of aerosol generated in response to an applied puff "n". The correction factor α varies depending on whether the volume vn of aerosol generated in response to an applied puff "n" is greater than or less than the ideal volume v.

The correction coefficient α may be expressed as follows:

During the ceremony:
δ is a scale factor whose value is the temperature initially defined for puff "n+1" of the thermal profile.
When changing v _n may be chosen to have a different increasing or decreasing effect than v.

For this third thermal profile, as the user applies successive puffs to the aerosol generating device 10 over a use session, the volume of aerosol generated by each puff is determined. The temperature in the thermal profile corresponding to the number of puffs applied (e.g., for puff "n+1") is then altered according to the method discussed above. The altered temperature of the thermal profile is then used as the target operating temperature for the applied puffs, and the control electronics 27 controls the power supply to the heater 40 to achieve this target operating temperature for the applied puffs. If the user applies puffs over an entire use session that each generate a volume of aerosol equal to volume v, no temperature alteration of the thermal profile occurs. However, there will be variation in the volume of aerosol generated by each successive puff, and it is more likely that some or all of the applied puffs will generate a volume of aerosol different from volume v.

For purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, and the like should be understood in all instances to be modified by the term "about." Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein. Accordingly, in this context, the number "A" should be understood as "A" ± 10%. Within this context, the number "A" can be considered to include a numerical value that is within the usual standard error for the measurement of the property that the number "A" modifies. In some instances, the number "A," as used in the appended claims, may deviate by the percentages recited above, provided that the amount by which "A" deviates does not materially affect the basic and novel characteristics of the claimed invention. Also, all ranges include the disclosed maximum and minimum points, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims (15)

1. A method of operating an aerosol generating device to generate an aerosol from an aerosol-forming substrate during a session of use, said aerosol generating device comprising:
a power source arranged to power the heater during said session of use;
The method uses control electronics of the aerosol generating device to:
associating puffs applied during the use session with a corresponding target operating temperature of the heater based on a cumulative number of puffs of the applied puffs during the use session and based on a time interval between the applied puff and a preceding puff applied during the use session;
10. The method of claim 9, further comprising: controlling the power supply from the power source to adjust, for the applied puff, the temperature of the heater to the target operating temperature associated with the applied puff. The method of claim 1, wherein the aerosol generating device stores a predetermined thermal profile defining the variation of heater temperature over a predetermined puff distribution, and the target operating temperature associated with the applied puff is a temperature of the predetermined thermal profile for the puff at the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puff. the predetermined thermal profile comprises a predetermined relationship between a puff parameter and the predetermined puff distribution, and the method further comprises:
determining whether values of the puff parameters for either or both of the applied puff and a previous puff applied during the use session differ from values of the puff parameters for a corresponding puff of the predetermined puff profile;
using the determined difference in values of the puff parameters to modify the temperatures of the predetermined thermal profile for the puffs in the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puffs;
3. The method of claim 2, further comprising: using the altered temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. The smoke draw parameters are:
the time interval between successive puffs;
The strength of the smoke and
a volume of aerosol generated from said aerosol-forming substrate in response to a puff. The method of any one of claims 1 to 4, wherein the preceding puff is the puff immediately preceding the applied puff during the use session. the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff profile, the predetermined thermal profile including a predetermined time interval between successive puffs of the predetermined puff profile;
The method comprises:
determining whether the time interval between the applied puff and the preceding puff differs from the predetermined time interval between corresponding puffs of the predetermined puff profile;
using this time difference to modify the temperature of the predetermined thermal profile for the puffs in the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puffs;
6. The method of claim 1, further comprising: using the altered temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. The method of any one of claims 1 to 6, wherein the association between the applied puff and the corresponding target operating temperature of the heater is additionally based on the intensity of a previous puff applied during the use session. the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff distribution, the predetermined thermal profile including a predetermined intensity for each puff of the predetermined puff distribution;
The method comprises:
determining whether the intensity of the preceding puff differs from a predetermined intensity for the corresponding puff of the predetermined puff profile;
using this intensity difference to modify the temperature of the predetermined thermal profile for the puffs in the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puffs;
8. The method of claim 7, further comprising: using the altered temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. The method of any one of claims 1 to 8, wherein the method includes detecting the applied puff by monitoring a change in heater temperature in response to the applied puff. The method comprises:
10. The method of any one of claims 1 to 9, further comprising terminating the use session upon the earlier occurrence of: i) the cumulative number of puffs applied during the use session reaches a predetermined puff limit; or ii) the use session reaches a predetermined maximum duration. A computer-readable medium for use in an aerosol-generating device, the computer-readable medium containing instructions for executing the method of any one of claims 1 to 10 on the aerosol-generating device when the computer-readable medium interacts with an aerosol-forming substrate. 1. An aerosol-generating device for generating an aerosol from an aerosol-forming substrate during a session of use, said aerosol-generating device comprising:
a power source arranged to power the heater during said session of use;
control electronics;
The control electronics of the aerosol generating device
determining a time interval between a puff applied during said use session and a preceding puff during said use session ;
Associating the puffs applied during the use session with a corresponding target operating temperature of the heater based on a cumulative number of puffs applied during the use session and the determined time interval;
An aerosol generating device configured to control the power supply from the power source to adjust the temperature of the heater to the target operating temperature associated with the applied puff for the applied puff. 13. The aerosol generating device of claim 12, wherein the aerosol generating device stores a predetermined thermal profile defining the variation of heater temperature over a predetermined puff distribution, and the aerosol generating device is configured such that the target operating temperature associated with the applied puff is a temperature of the predetermined thermal profile for the puff at the predetermined puff distribution that determines the time interval between the applied puff and the preceding puff and the cumulative puffs of the applied puff. the aerosol generating device stores a predetermined thermal profile defining a variation in heater temperature over a predetermined puff profile, the predetermined thermal profile including a predetermined time interval between successive puffs of the predetermined puff profile;
The aerosol generating device comprises:
determining whether the determined time interval between the applied puff and the preceding puff differs from the predetermined time interval between corresponding puffs of the predetermined puff profile;
using this time difference to modify the temperature of the predetermined thermal profile for the puffs in the predetermined puff distribution corresponding to the cumulative number of puffs of the applied puffs;
14. An aerosol generating device as claimed in any one of claims 12 or 13, configured to use the altered temperature of the predetermined thermal profile as the target operating temperature associated with the applied puff. The aerosol generating device comprises:
15. An aerosol generating device according to any one of claims 12 to 14, further configured to determine a volume of aerosol generated from the aerosol-forming substrate in response to a previous puff applied during the use session, and wherein the association of the applied puff with a corresponding target operating temperature of the heater is additionally based on the determined volume for the previous puff.