Smoking device having dynamic heating profile - Patents.com

Abstract

A method is provided for operating an aerosol generating device for generating an aerosol from an aerosol-forming substrate during a use session, the aerosol generating device comprising a power supply arranged to supply power to a heater and control electronics for controlling a temperature of the heater during a use session, the method comprising the steps of determining a target operating temperature of the heater, the target operating temperature being determined with reference to a) accumulated values ​​of a user interaction parameter monitored during the use session and b) time elapsed since a trigger event, and using the target operating temperature to control the temperature of the heater.

Description

[Technical field]

[0001] The present disclosure relates to an aerosol generating device, a computer readable medium for use with an aerosol generating device, an aerosol generating device, and a method of operating an aerosol generating system. [Background technology]

[0002] 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 transferring heat from a heat source to a physically separate aerosol-forming substrate or material that may be located within, around, or downstream of the heat source. The aerosol-forming substrate may be a liquid substrate contained in a reservoir. The aerosol-forming substrate may be a solid substrate. The aerosol-forming substrate may be a component part 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 that is inhaled by the consumer.

[0003] Some aerosol generating devices are configured to provide a user experience having a finite duration. The duration of a usage session may be limited to approximate the experience of consuming a traditional cigarette, for example. Some aerosol generating devices are configured to be used with a separate consumable aerosol generating article. Such an aerosol generating article includes an aerosol-forming substrate(s) capable of releasing a volatile compound capable of forming an aerosol. The aerosol-forming substrate is typically heated to form an aerosol. As the volatile compounds in the aerosol-forming substrate are depleted, the quality of the aerosol generated may deteriorate. Therefore, some aerosol generating devices are configured to limit the duration of a usage session to help prevent the generation of a lower quality aerosol from a substantially depleted aerosol-forming substrate of the aerosol generating article. A user inhales an 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.

[0004] It is known to provide power to a heat source in order to heat an aerosol-forming substrate according to different thermal profiles over the duration of a use session. Indeed, such known thermal profiles define the temperature variation of the heat source as a function of the time elapsed in the use session. As the aerosol-forming substrate becomes more depleted during the use session, more energy is required to extract the remaining volatile compounds of the substrate that form the aerosol. It is therefore known to use thermal profiles that increase the target operating temperature of the heat source over the second half of the use session. The known thermal profiles used to operate the heat source are based on an ideal hypothetical use session. The ideal use session may be characterized by a predefined length of the use session. The ideal use session may additionally be based on an assumed or ideal puff behavior of the user, for example on the assumption that continuous puffs are applied at a predefined rate over a finite period of time. However, if the real use session deviates from the assumptions inherent in the ideal use session, the use of such known thermal profiles to control the temperature of the heat source may lead to inefficient extraction of the aerosol from the substrate, which may be detrimental to the overall user experience. For example, if a user applies a puff at a rate faster than expected by a known thermal profile, this may result in the use session terminating earlier than would be expected in 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. Summary of the Invention

[0005] According to a first aspect of the invention, there may be provided a method of operating an aerosol generating device for generating an aerosol from an aerosol-forming substrate during a use session. The aerosol generating device may comprise a power supply arranged to supply power to the heater for controlling the temperature of the heater during the use session, and control electronics. The method may comprise the step of determining a target operating temperature of the heater. The target operating temperature may be determined with reference to a) an accumulated value of a user interaction parameter monitored during the use session, and b) an elapsed time from a trigger event. The target operating temperature may be used to control the temperature of the heater. The target operating temperature is preferably determined to have an initial value upon detection of the trigger event. The target operating temperature may vary from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, and the target operating temperature may vary from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold.

[0006] In a preferred embodiment, the aerosol generating device comprises a power source arranged to supply power to the heater to control the temperature of the heater during a session of use and control electronics, and the method comprises the steps of determining a target operating temperature of the heater, the target operating temperature being determined with reference to a) an accumulated value of a user interaction parameter monitored during the session of use and b) an elapsed time since a trigger event, and using the target operating temperature to control the temperature of the heater, the target operating temperature being determined to have an initial value upon detection of a trigger event, the target operating temperature changing from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, and the target operating temperature changing from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold.

[0007] In a further preferred embodiment, the method may be a method of operating an aerosol generating device to generate an aerosol from an aerosol-forming substrate during a use session, the use session having a use session start and a use session end, the aerosol generating device comprising a power supply arranged to supply power to a heater for controlling a temperature of the heater during the use session, and control electronics including at least one microprocessor and at least one memory, the control electronics configured to detect and record user puffs taken during the use session, the method comprising the step of determining a target operating temperature of the heater, the target operating temperature being determined with reference to a) an accumulated number of user puffs detected during the use session, and b) a time elapsed since a trigger event. determining that a target operating temperature is determined to have an initial value upon detection of the trigger event, the operating temperature changing from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, the operating temperature changing from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold, and optionally the operating temperature changing from the initial value at a third rate of change different from the second rate of change during a third period of elapsed time, the third period extending between the second time threshold and a third threshold occurring after the first time threshold.

[0008] Hence, the target operating temperature may be determined for any instant during a use session. The target operating temperature changes over the duration of the use session. The target operating temperature may be described as an instantaneous target operating temperature or a dynamic target operating temperature. The target operating temperature depends on both the value of the user interaction parameter (e.g., the number of user puffs taken at that point during the use session) and the time elapsed since a trigger event (e.g., the time elapsed since the last user puff). By controlling the power supply to the heater so that the temperature of the heater is maintained at the target operating temperature, or as close to the target operating temperature as possible, during the duration of the use session, the heater, and consequently the aerosol-forming substrate, may be maintained at an optimal temperature for aerosol generation, regardless of whether the user takes closely spaced puffs or more widely spaced puffs.

[0009] By relating a user interaction parameter (e.g., applied puffs) to a corresponding target operating temperature of the heater based on that user interaction parameter (e.g., cumulative puffs), it is possible to adjust the target operating temperature of the heater to take into account the specific puff characteristics of an individual user. This is in contrast to the known devices and thermal profiles discussed above, where the temperature of the heater varies depending on the time elapsed in a usage session. The ability to adjust the target operating temperature of the heater according to the specific puff characteristics of an individual user may enable more efficient extraction of aerosol from the aerosol-forming substrate. Efficient aerosol extraction from the substrate may be achieved regardless of (or less dependent on) the speed at which an individual user applies puffs to the aerosol generating device. Thus, a user may be able to extract substantially all aerosol from the substrate without being limited to applying puffs at a given rate. These advantages may also provide the user with an enhanced user experience over a usage session.

[0010] Benefits may arise if the change in the target operating temperature is based solely on user interaction parameters. For example, if each puff detected during a use session acts as a triggering event that triggers a change in the target operating temperature, the thermal profile applied to the aerosol-forming substrate over the course of the use session will be dynamically adjusted to the particular use during that use session. However, differences in aerosol delivery may occur depending on whether the user takes a subsequent puff quickly or slowly following the previous puff. For example, if the user's puff acts as a triggering event that increases the target operating temperature by 10° C., the quality of the aerosol delivered during the subsequent puff will be different depending on whether the subsequent puff is taken 5 seconds later or 35 seconds later. Following the increase in the target operating temperature, the power supply of the device may be controlled to increase the actual temperature of the heater to the new target operating temperature as quickly as possible. Although there is a certain inertia inherent to the heater, the temperature will rise quickly to reach the new target operating temperature. Once at the new target operating temperature, it may take a few more seconds before the aerosol-forming substrate is also heated to the new temperature. After about 5 seconds, the heater and substrate are likely to have reached a sufficient temperature for a subsequent puff to result in an optimized delivery of aerosol. If the heater temperature is maintained at this temperature, satisfactory delivery is likely to occur if the user puffs within a time window of, for example, 5 to 20 seconds, from the triggering event (i.e., the previous puff). However, if there is a long delay between puffs, the aerosol-forming substrate may have been maintained at the target operating temperature for too long. The aerosol may begin to deplete and there may be condensation of aerosol within the aerosol-generating system. As the time elapsed from the triggering event increases, for example beyond 20 seconds, the quality of the aerosol delivered in the subsequent puff may decrease. To take this into account, the target operating temperature is varied with reference to the time elapsed from the triggering event, such that the temperature of the heater and the temperature of the aerosol-forming substrate are preferably maintained at the optimal temperature, no matter how much time has elapsed between the previous puff and the subsequent puff.

[0011] The method may also be described as a method for optimizing the heating of an aerosol-forming substrate during a use session, for example a method for applying a dynamic heating profile to the aerosol-forming substrate based on user interaction and the passage of time during a use session.

[0012] The term "aerosol-generating device" as used herein 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 a smoking article. The aerosol-generating device may comprise 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 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 lungs of a user through the user's mouth.

[0013] The term "aerosol-forming substrate" as used herein refers to a substrate capable of releasing a volatile compound capable of forming an aerosol. Such a volatile compound 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.

[0014] The aerosol-forming substrate may comprise nicotine. The aerosol-forming substrate may comprise tobacco, e.g., a tobacco-containing material containing volatile tobacco flavour 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 former, such as propylene glycol or glycerin.

[0015] 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. A use session may have a defined start point and a defined end point.

[0016] As used herein, the term "cumulative puffs" refers to the number of puffs applied by a user during a use session relative to the start of that use session.

[0017] The user interaction parameter may be a parameter selected from the list consisting of a user puff, a volume of aerosol generated, an intensity of a user puff, and energy delivered from the power source to the heater. Preferably, the user interaction parameter is a user puff. The aerosol generating device is preferably configured to monitor and detect user puffs and to record user puffs taken during a use session. Thus, the cumulative value of the user interaction parameter may be either a cumulative number of user puffs taken during a use session, or a cumulative volume of aerosol generated during a use session, or a cumulative energy delivered from the power source to the heater during a use session.

[0018] The user interaction parameter may be a combination of parameters. For example, the target operating temperature may be determined with reference to both the user puffs and the intensity of those user puffs (or the user puffs and the volume of aerosol generated by those puffs). In this way, the target operating temperature of the heater may be a function of both, for example, i) the cumulative number of puffs applied, and ii) the intensity of the preceding puffs. The intensity of the puff can affect both the depletion of the aerosol-forming substrate and the temperature of the substrate. The more intense the puff applied by the user, the more aerosol will be generated in response to that puff, and the substrate will be more depleted of compounds necessary for aerosol formation. Furthermore, puffs of higher intensity than expected may cause the substrate to cool below the level required to ensure effective aerosol extraction from the substrate. The greater the substrate depletion, the more energy is required to extract the remaining compounds necessary for aerosol formation, resulting in a higher heater temperature. Thus, determining the target operating temperature of the heater additionally based on the intensity of the preceding puff provides the benefit of allowing the target operating temperature to be adjusted to counter substrate depletion caused by the intensity characteristics of the puff applied by an individual user. This thus allows efficient aerosol extraction from the substrate to be maintained regardless of (or less dependent on) the intensity of the puff applied by the user. Preferably, the preceding puff immediately precedes the puff applied during the use session.

[0019] The intensity of a given puff can be characterized in a variety of ways. By way of example, the intensity of a puff may be characterized by the volume of aerosol generated from the substrate in response to the puff.

[0020] Thus, the method may further comprise determining the volume of aerosol generated from the aerosol-forming substrate in response to a preceding puff, and determining the intensity of the preceding puff using the determined volume.

[0021] A use session may have a use session start and a use session end, and a use session may have a use session duration extending between the use session start and the use session end. The duration of a use session may be determined with respect to a threshold of time elapsed from the use session start, or a threshold of a user interaction parameter, such as a threshold of the number of user puffs taken during the use session. Preferably, the duration of a use session may be determined with respect to both a threshold of time elapsed from the use session start and a threshold of a user interaction parameter, such as a threshold of the number of user puffs taken during the use session. As an example, a use session may have a maximum duration determined by a time threshold that occurs first from the start of the use session, and a maximum number of user puffs taken during the use session.

[0022] The trigger event is preferably a user puff. For example, the trigger event may be a previous user puff applied during a use session. The trigger event may result in a new value of the target operating temperature of the heater. The time elapsed since the trigger event is monitored. There may be one, two, three, four or more time thresholds associated with the time elapsed since the trigger event. The time elapsed since the trigger event may pass one, two, three, four or more time thresholds unless a subsequent puff results in a new trigger event or the end of the use session. The or each or time threshold may mark a change in the target operating temperature. The or each or time threshold may mark a change in the rate of change of the target operating temperature. The first period of elapsed time may be a period defined between the trigger event and the first time threshold. The second period of elapsed time may be a period defined between the first and second time thresholds. The third period of elapsed time may be a period defined between the second and third time thresholds. The fourth period of elapsed time may be a period defined between the third and fourth time thresholds. More than four periods may be defined.

[0023] The trigger event may be the start of a detected user puff or the end of a detected user puff. The trigger event may be determined to be a predetermined time after the start of a detected user puff or a predetermined time after the end of a detected user puff. A subsequent user puff preferably acts as a new trigger event. For example, the start of a detected subsequent user puff or the end of a detected subsequent user puff may be This may act as a new triggering event resulting in a new target operating temperature and the start of a new period of time elapsed since the triggering event.

[0024] Although a trigger event associated with the number of puffs by a user may be convenient, there may be other trigger events, for example a trigger event may be a threshold in the cumulative volume of aerosol generated during a use session.

[0025] The trigger event may be the start of a detected use session if no puffs have been taken, a user puff if at least one puff has been taken, or a threshold of cumulative aerosol volume.

[0026] Thus, a use session may be initiated, and the initiation of the use session may also be a first trigger event that results in a first initial value of the target operating temperature being determined. The controller may then control the power provided to the heater such that the temperature moves towards and is maintained at the target operating temperature. Time elapses from the first trigger event, and the target operating temperature may change at a first rate of change. The first rate of change may result in the target operating temperature increasing, decreasing or remaining the same. If the target operating temperature remains the same, the rate of change during that period of elapsed time is zero. The first rate of change may be linear or non-linear. If no user puffs are taken, the elapsed time from the first trigger event may reach a first time threshold. The time between the first trigger event and the first time threshold is a first period of elapsed time. A second period of elapsed time may start at the first time threshold and extend to a second time threshold. During the second period, the target operating temperature changes at a second rate of change. The second rate of change is different from the first rate of change. If the user takes a puff at any time after the trigger event, a second trigger event occurs. For example, the second trigger event may be the end of a detected user puff. Upon detection of the second trigger event, a second initial value for the target operating temperature is determined. The second initial value may be the same as the first initial value or may be different from the first initial value. After the second trigger event, the target operating temperature is varied as described above until a third trigger event is detected. The process is repeated upon detection of each subsequent trigger event, for example at the end of each detected user puff, until the end of the usage session. Throughout the usage session, the target operating temperature varies with respect to the number of user puffs taken and the amount of time that elapses between subsequent user puffs. The power supplied to the heater is preferably controlled to maintain the temperature of the heater as close as possible to the target operating temperature, with the user experience being optimized for each puff.

[0027] The control electronics preferably includes at least one microprocessor and at least one memory. The control electronics is preferably arranged to monitor and record user interaction parameters. The control electronics is preferably arranged to detect a trigger event. The control electronics is preferably arranged to determine a target operating temperature. The control electronics is preferably arranged to control the supply of power from a power source to control the temperature of the heater.

[0028] The target operating temperature may be redetermined periodically or continuously. For example, the target operating temperature may be redetermined every 0.1 milliseconds to every 100 milliseconds, such as every 0.2 milliseconds to every 50 milliseconds, or every 0.5 milliseconds to every 10 milliseconds.

[0029] The target operating temperature may change from the initial value at a third rate of change different from the second rate of change during a third period of elapsed time after the triggering event, the third period of time extending between the second time threshold and a third time threshold occurring after the second time threshold.

[0030] There are many possibilities for the rate of change variation after a detected trigger event. For example, the target operating temperature may change linearly or non-linearly during a first period of elapsed time. The target operating temperature may change linearly or non-linearly during a second period of elapsed time. The target operating temperature may change linearly or non-linearly during a third (or any subsequent) period of elapsed time.

[0031] In some embodiments, one of the first rate of change or the second rate of change is zero. In some embodiments, at least one of the first rate of change and the second rate of change is a positive rate of change. In some embodiments, at least one of the first rate of change and the second rate of change is a negative rate of change. In some embodiments, at least one of the first rate of change and the second rate of change (preferably both the first rate of change and the second rate of change) is a parabolic rate of change.

[0032] There may be a third period of elapsed time after the trigger event. Thus, in some embodiments, one of the first rate of change, or the second rate of change, or the third rate of change is zero. In some embodiments, at least one of the first rate of change, the second rate of change, and the third rate of change is a positive rate of change. In some embodiments, at least one of the first rate of change, the second rate of change, and the third rate of change is a negative rate of change. In some embodiments, at least one of the first rate of change, the second rate of change, and the third rate of change (preferably at least the second rate of change and the third rate of change) is a parabolic rate of change. In some embodiments, the first rate of change is zero and the second rate of change and the third rate of change are negative.

[0033] The trigger event may be a first trigger event. There may be multiple trigger events over the duration of the usage session. In some embodiments, the first period of time elapsed from the trigger event or each trigger event to the first time threshold may be between 1 second and 20 seconds, such as between 5 seconds and 15 seconds, such as between 8 seconds and 12 seconds, such as about 10 seconds. The second period of time elapsed from the first time threshold to the second time threshold may be between 1 second and 20 seconds, such as between 5 seconds and 15 seconds, such as between 8 seconds and 12 seconds, such as about 10 seconds. If there is a third period following the trigger event or each trigger event, the third period of time elapsed from the second time threshold to the third time threshold may be between 1 second and 40 seconds, such as between 5 seconds and 30 seconds, such as between 10 seconds and 20 seconds. If there is a fourth period following the trigger event or each trigger event, the fourth period of time elapsed from the third time threshold to the fourth time threshold may be between 1 second and 40 seconds, such as between 5 seconds and 30 seconds, such as between 10 seconds and 20 seconds. If there is a fifth period of time following the or each trigger event, the fifth period of time elapsed from the fourth time threshold to the fifth time threshold may be between 1 second and 40 seconds, such as between 5 seconds and 30 seconds, for example between 10 and 20 seconds.

[0034] Upon detection of a subsequent trigger event, the target operating temperature is preferably assigned a new initial value. For example, if the trigger event is a first trigger event and the initial value of the target operating temperature is a first initial value, upon detection of a second trigger event occurring after the first trigger event, the instantaneous operating temperature is determined to have a second initial value. In this embodiment, the target operating temperature preferably changes from the second initial value at a first rate of change during a first period of elapsed time, the first period of time extending between the second trigger event and the first time threshold, and the target operating temperature changes from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period of time extending between the first time threshold and a second time threshold occurring after the first time threshold.

[0035] A use session preferably has a maximum duration determined by a maximum time threshold and a maximum puff threshold. A use session preferably terminates when a first of the maximum time thresholds of the maximum puff threshold is reached. A use session may have a maximum number of allowed puffs, n. Each puff from puff n=1 to puff n=n-1 may provide a trigger event that resets the initial value of the target operating temperature to a new value. Thus, each of the first, second, third and subsequent user puffs taken during a use session may be associated with a corresponding first, second, third and subsequent initial value of the target operating temperature.

[0036] The aerosol generating device may store a predefined thermal profile defining the variation of heater temperature over a predefined distribution of puffs, and an initial value of the target operating temperature associated with each applied puff is the temperature of the predefined thermal profile for puffs at the predefined distribution of puffs corresponding to the cumulative number of puffs applied. The target operating temperature may vary over a usage session within a range of 280°C to 380°C, such as 300°C to 370°C, for example 320°C to 350°C.

[0037] In an advantageous embodiment, the target operating temperature varies within the range of 320°C to 350°C over a usage session. Such an operating temperature range has 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 be applied to use with liquid aerosol-forming substrates. It may also be desirable to limit the maximum value of the target operating temperature over a usage session to avoid ignition and combustion of the substrate and release of harmful compounds from the substrate; by way of example, the upper limit of the target operating temperature may be set at 400°C or 375°C or 350°C. The specific range and limits of the target operating temperature over a usage 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.

[0038] Determining the temperature of the heater may be performed directly by use of a temperature sensor. However, it is preferred that the temperature of the heater is indirectly determined based on a change in one or more operating parameters of the aerosol generating device. For example, the temperature of the heater may be determined based on the electrical resistance of the heater, which is particularly relevant when the heater is a resistive heater. In another embodiment, where the heater takes the form of a susceptor that is heated in use by an inductor, the temperature of the susceptor may be determined based on a change in the current supplied to the inductor from the power source. The method may require detection of a user puff. The puff may be detected by means such as an airflow sensor or a heat sensor to detect the airflow associated with the user puff. The method may include detecting the applied puff by monitoring a change in heater temperature in response to the applied puff.

[0039] The use session may have a finite duration.The method may further include terminating the use session upon the earlier occurrence of i) a cumulative number of puffs applied during the use session reaching a predetermined puff limit, or ii) the use session reaching a predetermined maximum duration.

[0040] If a fault condition is detected, the use session may further be terminated. By way of example, the predetermined puff limit or puff threshold for a use session may be between 10 and 14 puffs, e.g., 12 puffs, and the predetermined maximum duration or threshold may be between 4.5 and 6.5 minutes, e.g., 6 minutes. However, other values ​​for the puff limit and maximum duration may be set, the selection of which is influenced by several factors. These factors may include the amount and composition of the aerosol-forming substrate used, as well as the amount of power available from the power source in a given use session. It is preferred that the aerosol generating device be portable and have a size and mass suitable for the device to be held by the user's hand. These preferences in turn affect the size and energy capacity of the power source of the aerosol generating device, which will therefore affect the values ​​set for the puff limit and the maximum duration of the use session.

[0041] According to a second aspect of the invention, there is provided a computer readable medium for use with 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 comprise a computer memory. The computer readable medium may be provided in a controller used to control the power supply. Alternatively, the computer readable medium may be a separate component separate from but accessible to such controller. Preferably, the computer readable medium is readable and writeable in use, thus providing the benefit of allowing the thermal profile stored in the computer readable medium to be altered over the course of a usage session. A computer readable medium for use with or incorporated in an aerosol generating device may comprise instructions for carrying out a method according to any aspect described herein.

[0042] According to a third aspect of the invention, there may be provided an aerosol generating device for generating an aerosol from an aerosol-forming substrate during a use session. The aerosol generating device may comprise a power supply arranged to supply power to a heater for controlling a temperature of the heater during a use session, and control electronics. The control electronics is preferably configured to determine a target operating temperature of the heater, the target operating temperature being determined with reference to a) an accumulated value of a user interaction parameter monitored during the use session, and b) an elapsed time since a trigger event, and the control electronics is preferably configured to use the target operating temperature to control the temperature of the heater. The target operating temperature may be determined to have an initial value upon detection of the trigger event. The target operating temperature may vary from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, and the target operating temperature may vary from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time; The second period of time extends between the first time threshold and a second time threshold occurring after the first time threshold. An aerosol generating device may comprise a computer readable medium according to the second aspect of the invention.

[0043] The aerosol-generating device may comprise 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 separate from the device. For example, the heater may be a susceptor forming part of an article separate from the device, in which the article contains the aerosol-forming substrate. In one such embodiment, the aerosol-generating device may comprise 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.

[0044] The aerosol generating device is preferably configured to carry out the methods as set out in any embodiment described herein.

[0045] According to a fourth aspect of the present invention, an aerosol generating system may be provided. The system may comprise an aerosol generating device according to the third aspect of the present invention and an aerosol-generating article. The aerosol-generating article preferably comprises an aerosol-forming substrate, the aerosol-generating device being configured to receive the aerosol-generating article. The aerosol-forming substrate may be any suitable substrate, for example a fixed substrate or a liquid substrate. The substrate may have both liquid and solid components.

[0046] In some embodiments, the aerosol-generating article comprises both a heater and an aerosol-forming substrate.

[0047] In some embodiments, the aerosol-generating article comprises a susceptor. For example, a heater, or a heating element of a heater, may be the susceptor, and the aerosol-generating device may further comprise an inductor, the inductor being controlled by the control electronics to control the temperature of the susceptor.

[0048] The present invention is defined in the claims. However, below is provided 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. EXAMPLES

[0049] Example i. 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 a use session, and control electronics; The method using control electronics comprises: determining a target operating temperature of the heater during a use session, the target operating temperature at a particular instant during the use session being based on both the value of a cumulative user puff parameter and a time interval since the previous user puff applied during the use session; and controlling a supply of power from a power source during the course of a user session to maintain a temperature of a heater at a target operating temperature, wherein during a first period of a time interval, the target operating temperature changes at a first average rate of change and during a second period of a time interval subsequent to the first period of the time interval, the target operating temperature changes at a second average rate of change different from the first average rate of change.

[0050] Example ii. 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 supply power to a heater for controlling a temperature of the heater during a use session, and control electronics; The method is determining a target operating temperature of the heater, the target operating temperature being determined with reference to a) a cumulative value of a user interaction parameter monitored during a usage session, and b) an elapsed time since a trigger event; and using the target operating temperature to control the temperature of the heater.

[0051] Example iii. 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 supply power to a heater for controlling a temperature of the heater during a use session; and control electronics; The method is determining a target operating temperature of the heater, the target operating temperature being determined with reference to a) accumulated values ​​of a user interaction parameter monitored during a usage session, and b) an elapsed time since a trigger event; and using the target operating temperature to control the temperature of the heater; A target operating temperature is determined to have an initial value upon detection of a trigger event, the operating temperature being: changing from an initial value at a first rate of change during a first period of elapsed time and at a second rate of change different than the first rate of change during a second period of elapsed time.

[0052] Example 1. 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 for controlling a temperature of the heater during a use session; and control electronics; The method is determining a target operating temperature of the heater, the target operating temperature being determined with reference to a) accumulated values ​​of a user interaction parameter monitored during a usage session, and b) an elapsed time since a trigger event; and using the target operating temperature to control the temperature of the heater; 11. A method of claim 10, wherein a target operating temperature is determined to have an initial value upon detection of a trigger event, the operating temperature changing from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, and the operating temperature changing from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold.

[0053] [Example 1A] The method of Example i, Example ii, Example iii, or Example 1, wherein the target operating temperature can be described as a dynamic target operating temperature or an instantaneous target operating temperature.

[0054] [Example 2] A method according to any of Examples i to 1, wherein the method is for optimizing heating of the aerosol-forming substrate during a use session, for example for applying a dynamic heating profile to the aerosol-forming substrate based on user interactions during a use session.

[0055] [Example 3] A method as described in any of Examples i to 2, wherein the user interaction parameter is a parameter selected from the list consisting of a user puff, an intensity of the user puff, a volume of the generated aerosol, and an energy delivered from the power source to the heater.

[0056] [Example 3A] A method according to any of Examples i to 3, wherein the user interaction parameter is a combination of the user puff and the intensity of the user puff or the volume of aerosol generated during the user puff.

[0057] [Example 4] The method described in Example 3, wherein the cumulative value of the user interaction parameter is either the cumulative number of user puffs taken during the use session, or the cumulative volume of aerosol generated during the use session, or the cumulative energy delivered from the power source to the heater during the use session.

[0058] [Example 5] A method as described in any of Examples i to 4, wherein the usage session has a usage session start and a usage session end, and the usage session has a usage session duration extending between the usage session start and the usage session end.

[0059] [Example 6] The method of any of Examples i to 5, wherein the trigger event is a user puff, such as the most recent user puff applied during a usage session.

[0060] [Example 7] The method described in Example 6, wherein the trigger event is the start of a detected user puff or the end of a detected user puff.

[0061] [Example 8] The method described in Example 6 or Example 7, wherein a subsequent user puff acts as a new trigger event.

[0062] [Example 9] A method as described in any of Examples i to 5, wherein the trigger event is a threshold in the cumulative volume of aerosol generated during a usage session.

[0063] [Example 10] A method as described in any of Examples i to 9, wherein the trigger event is a detected start of a usage session if no puffs have been taken, and a threshold in user puffs or cumulative volume of aerosol if at least one puff has been taken.

[0064] [Example 11] A method described in any of Examples i to 10, wherein the control electronics includes at least one microprocessor and at least one memory, and preferably the control electronics is arranged to monitor and record user interaction parameters, detect trigger events, determine a target operating temperature, and control the power supply from the power source to control the temperature of the heater.

[0065] [Example 12] The method according to any of Examples i to 11, wherein the target operating temperature is periodically or continuously redetermined.

[0066] [Example 13] The method described in Example 12, wherein the target operating temperature is redetermined at a frequency between every 0.1 milliseconds and every 10 milliseconds.

[0067] [Example 14] A method as described in any of Examples i to 13, wherein the operating temperature changes from the initial value at a third rate of change different from the second rate of change during a third period of elapsed time, the third period extending between the second time threshold and a third time threshold occurring after the second time threshold.

[0068] [Example 15] The method of any of Examples i-14, wherein the operating temperature varies linearly during the first period of elapsed time.

[0069] [Example 16] The method of any of Examples i-14, wherein the operating temperature varies non-linearly during the first period of elapsed time.

[0070] [Example 17] The method of any of Examples i-16, wherein the operating temperature varies linearly during the second period of elapsed time.

[0071] [Example 18] The method of any of Examples i-16, wherein the operating temperature varies non-linearly during the second period of elapsed time.

[0072] [Example 19] The method of any of Examples i-18, wherein the operating temperature is varied linearly during a third or subsequent period of elapsed time.

[0073] [Example 20] The method of any of Examples i-19, wherein the operating temperature varies non-linearly during a third or subsequent period of time.

[0074] [Example 21] The method according to any one of Examples i to 20, wherein one of the first rate of change or the second rate of change is zero.

[0075] [Example 22] The method according to any one of Examples i to 21, wherein at least one of the first rate of change and the second rate of change is a positive rate of change.

[0076] [Example 23] The method according to any one of Examples i to 22, wherein at least one of the first rate of change and the second rate of change is a negative rate of change.

[0077] [Example 24] The method described in any of Examples i to 23, wherein at least one of the first rate of change and the second rate of change, preferably both the first rate of change and the second rate of change, is a parabolic rate of change.

[0078] [Example 25] A method according to any one of Examples i to 24, when dependent on Example 14, in which one of the first rate of change, the second rate of change, or the third rate of change is zero.

[0079] [Example 26] A method according to any one of Examples i to 25, depending on Example 14, in which at least one of the first rate of change, the second rate of change, and the third rate of change is a positive rate of change.

[0080] [Example 27] A method according to any one of Examples i to 26, depending on Example 14, in which at least one of the first rate of change, the second rate of change, and the third rate of change is a negative rate of change.

[0081] [Example 28] The method according to any of Examples i to 27 when dependent on Example 14, wherein at least one of the first rate of change, the second rate of change, and the third rate of change, preferably at least the second rate of change and the third rate of change, is a parabolic rate of change.

[0082] [Example 29] The method according to any one of Examples i to 28, when dependent on Example 14, wherein the first rate of change is zero, and the second rate of change and the third rate of change are negative.

[0083] [Example 30] A method of operating an aerosol generating device to generate an aerosol from an aerosol-forming substrate during a use session, the use session having a use session start and a use session end, the aerosol generating device comprising: a power source arranged to provide power to the heater to control a temperature of the heater during a use session; control electronics including at least one microprocessor and at least one memory, the control electronics configured to detect and record user puffs taken during a use session; The method is determining a target operating temperature of the heater, the target operating temperature being determined with reference to a) a cumulative number of user puffs detected during a session of use, and b) the time elapsed since a trigger event, the trigger event being the immediately preceding user puff; using the target operating temperature to control the temperature of the heater; The method of any of Examples i-29, wherein the operating temperature is determined to have an initial value upon detection of a trigger event, the operating temperature changing from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, the operating temperature changing from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold, and optionally the operating temperature changing from the initial value at a third rate of change different from the second rate of change during a third period of elapsed time, the third period extending between the second time threshold and a third time threshold occurring after the first threshold.

[0084] [Example 31] A method as described in any of Examples i to 30, wherein a first period of elapsed time from a trigger event to a first time threshold is between 1 second and 20 seconds, for example between 5 and 15 seconds, for example between 8 and 12 seconds, for example about 10 seconds.

[0085] [Example 32] The method described in any of Examples i to 31, wherein the second period of time elapsed from the first time threshold to the second time threshold is between 1 second and 20 seconds, such as between 5 and 15 seconds, such as between 8 and 12 seconds, for example about 10 seconds.

[0086] [Example 33] A method as described in any of Examples i-32, wherein the operating temperature changes from the initial value at a third rate of change different from the second rate of change during a third period of elapsed time, the third period of time extending between the second time threshold and a third time threshold occurring after the second time threshold, and the third period of elapsed time from the second time threshold to the third time threshold is between 1 second and 40 seconds, for example between 5 seconds and 30 seconds, for example between 10 and 20 seconds.

[0087] [Example 34] The method of any of Example 33, wherein the operating temperature changes from the initial value at a fourth rate of change different from the third rate of change during a fourth period of elapsed time, the fourth period of time extending between a third time threshold and a fourth time threshold occurring after the third time threshold, and the fourth period of elapsed time from the third time threshold to the fourth time threshold is between 1 second and 40 seconds, e.g., between 5 seconds and 30 seconds, e.g., between 10 and 20 seconds.

[0088] [Example 35] The method of any example 34, wherein the operating temperature changes from the initial value at a fifth rate of change different from the fourth rate of change during a fifth period of elapsed time, the fifth period of time extending between a fourth time threshold and a fifth time threshold occurring after the fourth time threshold, and the fifth period of elapsed time from the fourth time threshold to the fifth time threshold is between 1 second and 40 seconds, e.g., between 5 seconds and 30 seconds, e.g., between 10 and 20 seconds.

[0089] [Example 36] The method of any of Examples i to 35, wherein upon detection of a subsequent trigger event, the target operating temperature is assigned a new initial value.

[0090] [Example 37] The trigger event is a first trigger event, the initial value of the target operating temperature is a first initial value, and upon detection of a second trigger event occurring after the first trigger event, the operating temperature is determined to have a second initial value; The method of any of Examples i-36, wherein the target operating temperature changes from a second initial value at a first rate of change during a first period of elapsed time, the first period extending between a second trigger event and a first time threshold, and the target operating temperature changes from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold.

[0091] [Example 38] A method as described in any of Examples i to 37, wherein the use session has a maximum duration determined by a maximum time threshold and a maximum puff threshold, and the use session ends when a first of the maximum time thresholds of the maximum puff threshold is reached.

[0092] [Example 39] A method described in any of Examples i to 38, wherein a usage session has a maximum allowable number of puffs of n, and each puff from puff n=1 to puff n=n-1 provides a trigger event that resets the initial value of the target operating temperature to a new value.

[0093] [Example 40] A method described in any of Examples i to 39, wherein each of the first, second, third and subsequent user puffs taken during a usage session is associated with a corresponding first, second, third and subsequent initial value of the target operating temperature.

[0094] [Example 41] A method as described in Example 39 or Example 40, wherein the aerosol generating device stores a predetermined thermal profile defining the variation of heater temperature over a predetermined puff distribution, and an initial value of the target operating temperature associated with each 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 puffs.

[0095] [Example 42] The method of any of Examples i to 41, wherein the target operating temperature varies over a usage session within a range of 280°C to 380°C, such as 300°C to 370°C, such as 320°C to 350°C.

[0096] [Example 43] A method according to any of Examples i-42, wherein the method comprises detecting an applied puff by monitoring a change in heater temperature in response to the applied puff.

[0097] [Example 44] The method comprises: The method of any of Examples i-43, further comprising terminating the use session upon either i) the cumulative number of puffs applied during the use session reaching a predetermined puff limit, or ii) the use session reaching a predetermined maximum duration, whichever occurs first.

[0098] [Example 45] A computer-readable medium for use in an aerosol generating device, the computer-readable medium comprising instructions for carrying out the method described in any one of Examples i to 44.

[0099] [Example 46] An aerosol generating device for generating an aerosol from an aerosol-forming substrate during a use session, the aerosol generating device comprising: a power source arranged to provide power to a heater to control a temperature of the heater during a use session; and a control electronic device, the control electronic device comprising: determining a target operating temperature for the heater, the target operating temperature being determined with reference to a) an accumulated value of a user interaction parameter monitored during a usage session, and b) an elapsed time since a trigger event, and the control electronics configured to use the target operating temperature to control the temperature of the heater; An aerosol generating device, wherein a target operating temperature is determined to have an initial value upon detection of a trigger event, the operating temperature changes from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, and the operating temperature changes from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold.

[0100] [Example 47] An aerosol generating device as described in Example 46, wherein the device is configured to carry out a method as set forth in any of Examples 1 to 44.

[0101] [Example 48] An aerosol generating system comprising an aerosol generating device as described in Example 46 or Example 47 and an aerosol generating article, wherein the aerosol generating article includes an aerosol-forming substrate and the aerosol generating device is configured to receive the aerosol generating article.

[0102] [Example 49] An aerosol generating system as described in Example 48, wherein the aerosol generating article comprises a heater and an aerosol-forming substrate.

[0103] [Example 50] An aerosol generating system as described in Example 48 or Example 49, wherein the aerosol generating article comprises a susceptor, e.g., the heater is the susceptor, the aerosol generating device comprises an inductor, and the inductor is controlled by the control electronics to control the temperature of the susceptor. [Brief description of the drawings]

[0104] The embodiments will now be further described with reference to the following figures:

[0105] [Figure 1] 1 illustrates a schematic side view of an aerosol generating device. [Diagram 2] 2 illustrates a schematic top view of the aerosol generating device of FIG. 1. [Diagram 3] 2 shows a schematic cross-sectional side view of the aerosol generating device of FIG. 1 and an aerosol-generating article for use in the device. [Figure 4] 1 illustrates a prior art thermal profile used in the operation of a known aerosol generating device; [Diagram 5] 5 illustrates the variation in target operating temperature of the heater of an aerosol generating device resulting from use of the prior art thermal profile of FIG. 4 in a scenario in which a user applies successive puffs, each spaced 15 seconds apart. [Figure 6] 5 illustrates the variation in target operating temperature of the heater of an aerosol generating device resulting from use of the prior art thermal profile of FIG. 4 in a scenario in which a user applies successive puffs, each spaced 11 seconds apart. [Figure 7] 1 illustrates how the target operating temperature of the heater is adjusted as a function of the number of puffs. [Figure 8] 1 illustrates a thermal profile in which the target operating temperature of the heater is defined as a function of the number of puffs. [Figure 9] 9 illustrates 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 uniform intervals. [Figure 10]9 illustrates 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 (ie, non-uniform) intervals. [Figure 11] 1 illustrates how the target operating temperature of the heater varies with both the puff taken and the time after the user puffs. [Figure 12] 1 illustrates a further example showing how the target operating temperature of the heater varies with both the puff taken and the time after the user puffs. [Figure 13] 1 illustrates a further example showing how the target operating temperature of the heater varies with both the puff taken and the time after the user puffs. [Figure 14] 1 illustrates a further example showing how the target operating temperature of the heater varies with both the puff taken and the time after the user puffs. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0106] The exemplary aerosol generating device 10 is a handheld aerosol generating device and has an elongated shape defined by a substantially circular cylindrical housing 20 (see Figures 1, 2 and 3). The aerosol generating device 10 comprises an open cavity 25 located at a proximal end 21 of the housing 20 for receiving an aerosol-generating article 30 comprising an aerosol-forming substrate 31. The aerosol generating device 10 has 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 of the heater 40 changes over a usage session.

[0107] 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 comprises an aerosol-forming substrate 31 (see FIG. 3). The aerosol-forming substrate 31 is a solid aerosol-forming substrate comprising tobacco. The aerosol-generating article 30 further comprises a mouthpiece, such as a filter 32, disposed in coaxial alignment with the aerosol-forming substrate 31 within the cylindrical rod. 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 a user in the same manner as a conventional cigarette.

[0108] In use, a user inserts the article 30 into the cavity 25 of the aerosol-generating device 10 and turns on the device 10 by pressing a user button 50 (see FIG. 1 ) to activate the heater 40 to begin a usage session. The heater 40 heats the aerosol-forming substrate 31 of the article 30, which causes 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 generated aerosol 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 the memory 28. After activation and during the course of a usage session, the control electronics 27 of the device 10 accesses the thermal profile stored in the memory module 28 to control the supply of power from the battery 26 to the heater 40 to 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 usage session, at which point the heater is deactivated and cools down. In some specific embodiments, the heater 40 may be a resistive heating element. In some specific embodiments, the heater 40 may be a susceptor disposed within a varying magnetic field so that it is heated by induction.

[0109] At the end of a usage session, the article 30 is removed from the device 10 for disposal, and the device 10 may be coupled to an external power source for charging the battery 26 of the device 10.

[0110] 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 needs to 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 since the start of a use session. A use session may also be If the user interaction parameter recorded during a use session reaches the threshold value before the maximum period has elapsed, it is configured to have a duration shorter than the maximum period. In one particular embodiment, the user interaction parameter represents the cumulative number of puffs applied to the device by the user during the use session, and a threshold of 14 puffs is defined for the cumulative number of puffs. Thus, in this particular embodiment, the aerosol generating device 10 is configured such that each use session has a maximum duration defined by i) six minutes from activation of the use session, or ii) a total of 14 puffs applied during the use session, whichever occurs first.

[0111] In prior art devices, the thermal profile used to regulate the temperature of the heater 40 is a predefined temperature profile that changes the target operating temperature of the heater only as a function of elapsed time of 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 changes the target operating temperature of the heater 40 only 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 6 minutes (360 seconds). These hypothetical or ideal puffs are represented by the dashed lines in FIG. 4.

[0112] Operation of the apparatus 10 using the prior art thermal profile of FIG. 4 will now be described in three different scenarios.

[0113] In a first scenario, the user activates the device 10 by pressing the user button 50, initiating a use session of 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 that conforms to 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. In essence, the heater 40 will be regulated according to the thermal profile shown in FIG. 4. As a result, the aerosol-forming substrate 31 will be substantially depleted of aerosol.

[0114] In the second scenario, the user activates the device 10 by pressing the user button 50, beginning a use session of 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 use session being terminated early by the device 10 because the threshold limit of 14 puffs has been reached before 6 minutes (360 seconds) have elapsed in the use session. The effect of increasing puff rate on heater temperature over the course of this shortened length use session can be seen in FIG. 5, with each applied puff represented by a dashed line. In this second scenario, the thermal profile is: Since it is assumed that successive puffs are applied at 30 second time intervals, the consequence of a real user applying puffs at a rate faster than one every 15 seconds would be that the heater 40 would not achieve the temperature required to extract all of the aerosol from the aerosol-forming substrate 31 later in the use session.

[0115] In the third scenario, the user activates the device 10 by pressing the user button 50, beginning a use session of an unused article. However, in contrast to the second scenario, after the first puff is taken 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 has been reached before 6 minutes (360 seconds) have elapsed in the use session. The effect of further increases in puff rate on heater temperature over the course of this shortened length 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.

[0116] 5 and 6 can thus be seen as illustrating the problem of using a known thermal profile of a heater to vary the target operating temperature of the heater 40 simply as a function of elapsed time.

[0117] 7 illustrates a method 100 in which the target operating temperature changes over the course of a user session with respect to the number of puffs taken. The method 100 is implemented 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, an applied puff is 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 an applied puff, the 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.

[0118] 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. Method 100 thus makes it possible to regulate the temperature of heater 40 as a function of the cumulative number of puffs in a use session.

[0119] Method 100 may be 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 source 26 to regulate the temperature of heater 40 according to the instructions provided in the thermal profile. The thermal profile used by method 100 differs from the prior art thermal profiles described above in connection with FIGS.

[0120] FIG. 8 illustrates an example of a thermal profile for use in implementing the method 100 with the aerosol generating device 10. However, in contrast to the thermal profiles of the prior art discussed above, the thermal profile of FIG. 8 defines an initial target operating temperature of the heater 40 as a function of the number of puffs. Thus, for the thermal profile of FIG. 8, each puff of a usage session is associated with a given initial target operating temperature of the heater 40. The thermal profile of FIG. 8 defines an initial target operating temperature of each puff of a given distribution of 12 puffs. As described above, the thermal profile is stored within the memory module 28 of the aerosol generating device 10. As the user applies each puff of the series of puffs to the device 10, the control electronics 27 accesses the memory 28 to read the thermal profile. The control electronics 27 then controls the supply of power from the battery 26 to the 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 of each applied puff.

[0121] 9 and 10 show two examples of how the initial target operating temperature of the heater 40 changes over time when using the thermal profile of FIG. 8 for a usage session in which a user applies successive puffs to the aerosol generating device 10. FIG. 9 illustrates the temperature variation when the user applies each puff at uniform intervals (in this case 15 seconds apart). FIG. 10 illustrates the temperature variation when the user applies each puff at non-uniform time intervals. In consideration of FIGS. 9 and 10, it can be seen that the use of the thermal profile of FIG. 8 results in an adjustment of the initial target operating temperature based on the cumulative number of puffs applied in the usage session, rather than being adjusted solely as a function of elapsed time in the usage session. In essence, 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 the memory module 28. Thus, in contrast to the 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 the usage session, independent of the puff rate and timing applied by the user.

[0122] Although improvements in the thermal profile result from relating the target operating temperature to the number of puffs rather than time, there are situations in which the user experience may still not be optimal. For example, if the user takes a long time between successive puffs, the aerosol-forming substrate may begin to deplete due to evaporation of volatile components. Aerosols formed while the substrate is maintained at temperature may also begin to condense within the system, for example, within the aerosol-generating article. To remedy this situation, it may be desirable to include a time-dependent component in the target operating temperature profile. Such a profile is illustrated in FIG. 11.

[0123] FIG. 11 illustrates a portion of a temperature-time curve 1101 showing the evolution of the target operating temperature curve over three consecutive puffs of a use session. Although the puffs are referred to as puff 1, puff 2, and puff 3, it is clear that they could be any three consecutive puffs in a use session. After puff 1 is taken, the target operating temperature shifts to an initial target operating temperature 1110 (initial TOT puff 1) according to a predefined thermal profile, for example the thermal profile illustrated in FIG. 8. In this case, puff 1 acts as a triggering event and the initial target operating temperature associated with puff 1 is performed. After puff 1, the target operating temperature is reduced 1115 at a rate of 0.2° C. / sec. This continues until puff 2 is taken. If puff 2 is taken 30 seconds after puff 1, the target operating temperature will have decreased by 6° C. from the initial target operating temperature 1110 associated with puff 1 by the time puff 2 is taken. This decrease in temperature as a function of time elapsed after Puff 1 reduces substrate depletion and condensation that could occur if the target operating temperature remained at the initial target operating temperature for the entire period between when Puff 1 and Puff 2 are taken.

[0124] Puff 2 acts as a new triggering event and the initial target operating temperature 1120 associated with Puff 2 is executed. After Puff 2, the target operating temperature is decreased at a rate of 0.2°C / sec. This continues until Puff 3 is taken. If Puff 3 is taken 10 seconds after Puff 2, the target operating temperature will have decreased by 2°C from the initial target operating temperature 1120 associated with Puff 2 by the time Puff 3 is taken.

[0125] Puff 3 acts as a new trigger event and the initial target operating temperature 1130 associated with puff 3 is executed. The process outlined above is repeated until the use session ends, for example after a threshold number of puffs have been taken or a threshold time since the start of the use session has been reached.

[0126] One potential problem with the thermal profile illustrated in FIG. 11 is that if the user takes long pauses between subsequent puffs, the target operating temperature may become too low. For example, if the initial target operating temperature is decreased at a rate of 0.2° C. until subsequent puffs are taken, the target operating temperature will decrease by 10° C. if the user takes 50 seconds between successive puffs. Such a decrease in operating temperature may reduce the temperature of the aerosol-forming substrate too much to form a suitable aerosol. To help avoid this situation, the device may be configured to change the target operating temperature from the initial target operating temperature at a first rate of change for a first period of time after the trigger event, and at a second rate of change different from the first rate of change for a second period of time after the first period of time. An example of such a thermal profile is illustrated in FIG. 12.

[0127] Similar to FIG. 11, FIG. 12 illustrates a portion of a temperature-time curve 1201 showing the evolution of a target operating temperature curve over three successive puffs of a use session.

[0128] Similar to the profile of FIG. 11, each of the three puffs taken is associated with its own initial target operating temperature, and the target operating temperature changes dynamically with the time elapsed since each puff until a subsequent puff is taken.

[0129] Therefore, after puff 1 is taken, the target operating temperature shifts to an initial target operating temperature 1210 (Initial TOT Puff 1) according to a predefined thermal profile, for example the thermal profile illustrated in FIG. 8. In this case, puff 1 acts as a triggering event and the initial target operating temperature associated with puff 1 is executed. After puff 1, the target operating temperature is decreased 1215 at a rate of 0.2° C. / sec. This continues for a first period of time until a first time threshold 1216 associated with puff 1 is reached. The first time threshold occurs after a predefined period of puff 1, for example 20 seconds after puff 1. At a rate of change of 0.2° C. / sec, the target operating temperature has decreased 4° C. at the first time threshold. The rate at which the target operating temperature is now changed such that the target operating temperature is decreased 1217 at a rate of 0.1° C. / sec until a subsequent puff is taken. If puff 2 is taken 30 seconds after puff 1, the target operating temperature will be reduced by 5° C. from the initial target operating temperature 1210 associated with puff 1 by the time puff 2 is taken.

[0130] Puff 2 acts as a new trigger event and the initial target operating temperature 1220 associated with puff 2 is executed. After puff 2, the target operating temperature is decreased at a rate of 0.2°C / sec over a first period of time until the time threshold associated with the second puff. If puff 3 is taken 10 seconds after puff 2, the time elapsed since puff 2 never reaches the time threshold (set at 20 seconds after puff 2). Therefore, the target operating temperature is decreased by 2°C from the initial target operating temperature 1220 associated with puff 2 by the time puff 3 is taken.

[0131] Puff 3 acts as a new trigger event and the initial target operating temperature 1230 associated with puff 3 is executed. The process outlined above is repeated until the use session ends, for example after a threshold number of puffs have been taken or a threshold time since the start of the use session has been reached.

[0132] One advantage of the thermal profile illustrated in Figure 12 is that any adverse effects on the target operating temperature after long pauses between puffs are ameliorated. For example, if a user takes 50 seconds between successive puffs, the profile of Figure 12 (a first rate of change of 0.2 degree / sec for 20 seconds, followed by 0.1 degree / sec until the subsequent puff) will result in only an 8 degree drop in temperature from the initial target operating temperature.

[0133] It is clear that the change from the initial target operating temperature after puffing need not be a negative deviation only. 13 illustrates a portion of a temperature-time curve 1301 showing the evolution of the target operating temperature curve over three successive puffs of a use session. Similar to the profile of FIG. 11, each of the three puffs taken is associated with its own initial target operating temperature, and the target operating temperature changes dynamically with the time elapsed since each puff until the subsequent puff is taken.

[0134] Therefore, after puff 1 is taken, the target operating temperature shifts to an initial target operating temperature 1310 (initial TOT puff 1) according to a predefined thermal profile, for example the thermal profile illustrated in FIG. 8. In this case, puff 1 acts as a triggering event and the initial target operating temperature associated with puff 1 is performed. After puff 1, the target operating temperature changes 1315 at a rate of 0° C. / sec. That is, the target operating temperature does not change for a first period of time until it reaches a first time threshold 1316 associated with puff 1. The first time threshold occurs after a predefined period of puff 1, for example 20 seconds after puff 1. The rate at which the target operating temperature now changes such that the target operating temperature decreases 1317 at a rate of 0.2° C. / sec until the subsequent puff is taken. If puff 2 is taken 30 seconds after puff 1, the target operating temperature will decrease by 2° C. from the initial target operating temperature 1310 associated with puff 1 by the time puff 2 is taken.

[0135] Puff 2 acts as a new trigger event and the initial target operating temperature 1320 associated with puff 2 is executed. After puff 2, the target operating temperature is decreased at a rate of 0°C / sec over a first period of time until the time threshold associated with the second puff. If puff 3 is taken 10 seconds after puff 2, the time elapsed since puff 2 never reaches the time threshold (set at 20 seconds after puff 2). Therefore, the target operating temperature remains at the initial target operating temperature 1320 associated with puff 2 until the time puff 3 is taken.

[0136] Puff 3 acts as a new trigger event and the initial target operating temperature 1330 associated with puff 3 is executed. The process outlined above is repeated until the use session ends, for example after a threshold number of puffs have been taken or a threshold time since the start of the use session has been reached.

[0137] For simplicity, the example thermal profiles illustrated in Figures 11, 12, and 13 involve a linear rate of change of the target operating temperature. Non-linear changes in the target operating temperature are also contemplated, and one such example is illustrated in Figure 14.

[0138] Figure 14 illustrates a portion of a temperature-time curve 1401 showing the evolution of the target operating temperature curve over three successive puffs of a use session. Similar to the profile of Figure 11, each of the three puffs taken is associated with its own initial target operating temperature, and the target operating temperature changes dynamically with the time elapsed since each puff until the subsequent puff is taken.

[0139] Therefore, after Puff 1 is taken, the target operating temperature shifts to an initial target operating temperature 1410 (Initial TOT Puff 1) according to a predetermined thermal profile, for example the thermal profile illustrated in FIG. 8. In this case, Puff 1 acts as a triggering event and the initial target operating temperature associated with Puff 1 is executed. After Puff 1, the target operating temperature decreases 1415 in a non-linear manner. For example, the target operating temperature may decrease according to a parabolic curve. After a first time threshold 1416 is reached (for example, a time threshold of 20 seconds from the puff), the target operating temperature may have decreased at an average rate of 0.2° C. / s. With an average rate of change of 0.2° C. / s, the target operating temperature has decreased by 4° C. at the first time threshold. The rate of change of the target operating temperature continues to decrease after the first time threshold. Therefore, the average rate of change of the target operating temperature is different during the period after the first time threshold compared to the period before the first time threshold.

[0140] Puff 2 acts as a new triggering event and the initial target operating temperature 1420 associated with puff 2 is executed. After puff 2, the target operating temperature decreases again along a parabolic curve.

[0141] Puff 3 acts as a new trigger event and the initial target operating temperature 1430 associated with puff 3 is executed. The process outlined above is repeated until the use session ends, for example after a threshold number of puffs have been taken or a threshold time since the start of the use session has been reached.

[0142] For simplicity, the examples presented above utilized only a single rate of change of the target operating temperature. It may be advantageous for the thermal profile to include multiple changes in operating temperature between successive puffs. For example, a device or system as described above may be operated using a thermal profile that follows the following logic:

[0143] Detection of a user puff during a use session acts as a triggering event that sets the target operating temperature to an initial value of the target operating temperature associated with that puff. The initial value of the target operating temperature may, for example, be as illustrated in Figure 8. The power supply of the device is controlled such that the actual temperature of the heater of the device matches the target operating temperature as quickly as possible.

[0144] During a first period between the detection of a user puff and a first time threshold, the target operating temperature does not change. This may be expressed as the target operating temperature changing at a rate of zero from the initial target operating temperature. The first period may have a length of, for example, 10 seconds, during which the target operating temperature deviates from the initial target operating temperature by 0°C.

[0145] For a second time period extending between the first time threshold and the second time threshold, the target operating temperature is decreased at a rate of 1° C. / second. The period may last for 5 seconds, in which case the target operating temperature is reduced by 5 degrees compared to the initial target operating temperature.

[0146] For a third time period extending between the second and third time thresholds, the target operating temperature is decreased at a rate of 0.4° C. / sec. The third time period may last for 10 seconds, in which case the target operating temperature is decreased an additional 4 degrees, for a total decrease of 9 degrees compared to the initial target operating temperature.

[0147] For a fourth time period extending between the third and fourth time thresholds, the target operating temperature is decreased at a rate of 0.15° C. / sec. The fourth time period may last for 20 seconds, in which case the target operating temperature is decreased an additional 3 degrees, for a total decrease of 12 degrees compared to the initial target operating temperature.

[0148] For a fifth time period extending between the fourth and fifth time thresholds, the target operating temperature is decreased at a rate of 0.1° C. / sec. The fifth time period may last for 20 seconds, in which case the target operating temperature is decreased an additional 2 degrees, for a total decrease of 14 degrees compared to the initial target operating temperature.

[0149] After the fifth period, further periods may be defined with further different rates of change of the target operating temperature. Alternatively, a lowest stable temperature may be reached at which the target operating temperature remains until the user takes a puff or the use session times out.

[0150] For the 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 as modified by the term "about." Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein. Thus, in this context, the number "A" is understood as "A" ± 10%. Within this context, the number "A" may be considered to include a numerical value that is within the general standard error for the measurement of the property that the number "A" modifies. The number "A" may, in some cases as used in the appended claims, deviate by the percentages recited above, provided that the amount by which "A" deviates does not materially affect the basic and novel property(ies) of the claimed invention. Also, all ranges include the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically recited herein.

Claims

1. 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 supply power to the heater to control the temperature of the heater during the use session; and control electronics; The method comprises: determining a target operating temperature of the heater, the target operating temperature being determined with reference to a) cumulative values ​​of a user interaction parameter monitored during the use session, and b) time elapsed since a trigger event; and using the target operating temperature to control the temperature of the heater; the target operating temperature is determined to have an initial value upon detection of the trigger event, the target operating temperature changing from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, and the target operating temperature changing from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold.

2. The method of claim 1, wherein the method is a method for optimizing heating of an aerosol-forming substrate during the use session, for example a method for applying a dynamic heating profile to the aerosol-forming substrate based on user interactions during the use session.

3. 3. The method of claim 1 or 2, wherein the user interaction parameter is a parameter selected from the list consisting of a user puff, the intensity of the user puff, the volume of the aerosol generated, and the energy delivered to the heater from the power source.

4. 3. The method of claim 1 or 2, wherein the cumulative value of the user interaction parameter is either the cumulative number of user puffs taken during the use session, or the cumulative volume of aerosol generated during the use session, or the cumulative energy delivered to the heater from the power source during the use session.

5. The method of claim 1 or 2, wherein the trigger event is a user puff, such as the most recent user puff applied during the use session.

6. The method of claim 1 or 2, wherein the trigger event is the start of a detected user puff or the end of a detected user puff.

7. 3. The method of claim 1 or 2, wherein a subsequent user puff acts as a new trigger event.

8. 3. The method of claim 1 or 2, wherein the trigger event is a detected start of a use session if no puffs have been taken, or a threshold value for a user puff or cumulative aerosol volume if at least one puff has been taken.

9. 3. The method of claim 1 or 2, wherein the control electronics includes at least one microprocessor and at least one memory, and preferably the control electronics is arranged to monitor and record the user interaction parameters, detect the trigger event, determine the target operating temperature, and control the power supply from the power source to control the temperature of the heater.

10. The method of claim 1 or 2, wherein the target operating temperature is periodically or continuously redetermined.

11. The method of claim 10, wherein the target operating temperature is redetermined at a frequency between every 0.1 milliseconds and every 10 milliseconds.

12. 3. The method of claim 1 or 2, wherein the operating temperature changes from the initial value at a third rate of change different from the second rate of change during a third period of the elapsed time, the third period extending between the second time threshold and a third time threshold occurring after the second time threshold.

13. 3. The method of claim 1, wherein the first period of time elapsed from the trigger event to the first time threshold is between 1 second and 20 seconds, such as between 5 and 15 seconds, such as between 8 and 12 seconds, such as about 10 seconds.

14. 3. The method of claim 1 or 2, wherein the aerosol generating device stores a predetermined thermal profile defining the variation of heater temperature over a predetermined puff distribution, and the initial value of the target operating temperature associated with each applied puff is 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.

15. 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 supply arranged to supply power to the heater to control the temperature of the heater during the use session; and control electronics, the control electronics comprising: the control electronics configured to determine a target operating temperature of the heater, the target operating temperature being determined with reference to a) cumulative values ​​of a user interaction parameter monitored during the use session, and b) time elapsed since a trigger event, and to use the target operating temperature to control the temperature of the heater; An aerosol generating device, wherein the target operating temperature is determined to have an initial value upon detection of the trigger event, the target operating temperature changes from the initial value at a first rate of change during a first period of elapsed time, the first period extending between the trigger event and a first time threshold, and the target operating temperature changes from the initial value at a second rate of change different from the first rate of change during a second period of elapsed time, the second period extending between the first time threshold and a second time threshold occurring after the first time threshold.

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