Method for powering an aerosol generating device and aerosol generating device

Abstract

The present invention concerns a method (100) for powering an aerosol generating device comprising an aerosol-generating unit configured to generate an aerosol from a vaporizable material and a control unit configured to process data from a puff sensor and to supply a power profile to the aerosol generating unit, the method comprising: determining (110) a puff duration from data provided by the puff sensor; computing (110) a reference puff duration based on the puff duration; comparing (112) the reference puff duration to a predefined threshold duration; setting (114) a power profile based on the comparison; and supplying (116) power to the aerosol generating unit according to the set power profile; wherein the control unit is configured to set the power profile so that an amount of power supplied to the aerosol generating unit in a given period of the next power profile decreases as the reference puff duration increases.

Description

[0001] METHOD FOR POWERING AN AEROSOL GENERATING DEVICE AND AEROSOL GENERATING DEVICE

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method for powering an aerosol generating device to control aerosol generation based on the vaping behavior of a user.

[0004] The present invention also concerns an aerosol generating device configured to implement such a method.

[0005] BACKGROUND OF THE INVENTION

[0006] Different types of aerosol generating devices are already known in the art. Generally, such devices comprise a storage portion for storing a vaporizable material, which can comprise for example a liquid or a solid. A heating system is formed of one or more electrically activated resistive heating elements arranged to heat said vaporizable material to generate the aerosol. The aerosol is released into a flow path extending between an inlet and outlet of the device. The outlet may be arranged as a mouthpiece, through which a user inhales for delivery of the aerosol.

[0007] Different types of heating systems can be used to heat the vaporizable material in such devices. For example, in case of a liquid vaporizable material, a heating system may be formed by a resistance arranged in the flow path and wound around a wick in communication with the liquid vaporizable material. Thus, carried by the wick, the vaporizable material can be evaporated by the resistance arranged in the flow path.

[0008] Depending on preferences or breath characteristics of a user, the duration of a puff can vary not only between different users but also for a same user during a vaping session. As the amount of aerosol generated for each puff greatly influences the user experience, it is desirable to control and tailor the aerosol delivered to the user during a puff. This can be done by controlling the power delivery to the aerosol generating unit or heater in such devices.

[0009] For devices having predetermined aerosol generation settings, some users such as user having longer puff lengths than average may notice a cut-off of the aerosol generating unit and a stop of the aerosol generation, which negatively affects their vaping experience. Therefore, a need exists for aerosol generating devices having improved aerosol generation properties while keeping power consumption to a minimum.

[0010] SUMMARY OF THE INVENTION

[0011] One of the aims of the present invention is to provide a method for powering an aerosol generating device, which allows to improve aerosol generation properties of said device while keeping power consumption to a minimum.

[0012] For this purpose, the invention relates to a method for powering an aerosol generating device comprising an aerosol generating unit configured to generate an aerosol from a vaporizable material and a control unit configured to process data from a puff sensor and to supply a power profile to the aerosol generating unit.

[0013] The method comprises:

[0014] • determining a puff duration from data provided by the puff sensor;

[0015] • computing a reference puff duration based on the puff duration of the previous step;

[0016] • comparing the reference puff duration of the previous step to a predefined threshold duration;

[0017] • setting a power profile based on a result of the comparison; and

[0018] • supplying power to the aerosol generating unit according to the set power profile; wherein the control unit is configured to set the power profile so that an amount of power supplied to the aerosol generating unit in a given period of the next power profile decreases as the reference puff duration increases.

[0019] The method reduces the amount of power supplied to the aerosol generating unit in a given period of the next (or the following) power profile if a user inhales longer puffs. The method therefore allows to maintain power supply to the aerosol generation unit to generate aerosol for longer puffs. The method may also prevent an excess energy consumption of the aerosol device if users inhale longer puffs than average users. The method may allow to supply an appropriate power profile to the aerosol generating unit for aerosol generation in response to the user behaviour, in a puff-by-puff manner. In particular, the method allows to determine an optimal power profile for a puff number n + 1 in response to the duration of a previous puff number n. A reference puff duration may be computed as a parameter representing duration(s) of previous puff(s). The reference puff duration may be the measured duration of puff n, or a moving average of durations of previous puffs. For example, if the reference puff duration computed at puff n is smaller than a first threshold duration, a power profile may be supplied to the aerosol generating unit for the next puff n + 1 . If the reference duration computed at puff n is higher than the first threshold duration, another power profile is supplied to the aerosol generating unit for the next puff n + 1. In particular, in response to an increasing reference puff duration, the method allows to reduce the amount of power supplied to the aerosol generating unit in a given period of a subsequent power profile while still generating a satisfactory amount of aerosol. These power profiles may be stored in a memory of the control unit in advance, or may be set by an equation taking into account the reference puff duration. The given period may be the entire power profile, or a part of the power profile.

[0020] In addition, as a consequence of applying the method of the invention, the consumption of vaporizable material comprised in the device is also optimized.

[0021] The power profile may be divided into a first part and a second part. Preferably, the given period is only in the second part of the power profile among the first and the second part of the power profile. Before powering on the aerosol generating device, the aerosol generating unit is generally in a state in which aerosol cannot be generated. The first part of the power profile may work to transit the aerosol generating unit to a state in which aerosol can be generated. If the aerosol generating unit comprises a heater to heat the vaporizable material, the first part of the power profile may work as preheating of the vaporizable material. In view of usability, it is preferable that the waiting time until aerosol is generated is as short as possible. If the above-mentioned given period is in the first part, the waiting time is impacted and it may significantly affect usability. Arranging the given period in the second part may lead to provide a same usability even if the puff duration is varied. Due to same reason, the control unit is preferably configured to set the first part of the power profile irrespective of the reference puff duration, and / or is preferably configured to set the first part of the power profile as constant.

[0022] The given period, during which the amount of power supplied to the aerosol generating unit is adapted based on duration(s) of previous puff(s), is preferably included into the power profile so that the user experience is kept at a same level. The given period is preferably included into the second part of the power profile. Preferably, a temperature of the heater is stable or substantially constant in the second part of the power profile, if the aerosol generating unit comprises the heater. Accordingly, the given period is included in the power profile while satisfactory amount of aerosol is generated. Thus, the user may taste the aerosol even if the given period is included. If the given period is included after the user tasted the aerosol to some extent, user experience will be also improved. Thus, in preferable embodiment, the temperature of the heater becomes stable or substantially constant in the first part of the power profile before transition to the second part. For avoiding variation of amount of generated aerosol during a single puff, the second part of the power profile directly follows the first part of the power profile.

[0023] In some embodiments, the set power profile induces an essentially equal volume of generated aerosol per puff, if the user inhales a puff having same duration as the reference puff duration. In some embodiments, the volume of generated aerosol differs between puffs by about 80% or less, by about 85% or less, by about 90% or less, or by about 95% or less. In some embodiments, the selected power profile induces generation of between about 3 mg and about 5 mg of aerosol per puff.

[0024] In some embodiments, the set power profile induces a consumption of an essentially equal quantity of vaporizable material per puff, if the user inhales a puff having same duration as the reference puff duration. In some embodiments, the consumed quantity of vaporizable material differs between puffs by about 80% or less, by about 85% or less, by about 90% or less, or by about 95% or less. In some embodiments, the selected power profile induces a consumption of between about 3 mg and about 5 mg of vaporizable material per puff.

[0025] In some embodiments, the selected power profile provides an essentially equal energy per puff to the aerosol generating unit, if the user inhales a puff having same duration as the reference puff duration. In some embodiments, the energy provided to the aerosol generating unit differs between puffs by about 80% or less, by about 85% or less, by about 90% or less, or by about 95% or less. In some embodiments, the selected power profile provides between about 10 joule and about 15 joule of energy to the aerosol generating unit. Accordingly, in some embodiments, the selected power profile is configured to deliver an essentially equal power to the aerosol generating unit for each puff.

[0026] Preferably, parameters relative to aerosol properties described herein are measured according to Coresta Recommended Method (CRM) no. 81. Having a consistency between each puffs, as described in the above embodiments, allows to improve the consumption management of energy and vaporizable material in the aerosol generating device during use.

[0027] In some embodiments, the data provided by the puff sensor comprises a puff start signal and a puff end signal. Either one of a microphone sensor, a temperature sensor (e.g., a thermistor), and a flow sensor may be used as the puff sensor, for example.

[0028] As describes above, in some embodiments, although the first threshold duration is key for setting the power profile in the method of the invention, more threshold values can be defined and used to further fine-tune the power profiles to be set in response to puffs lasting longer than the first threshold duration. Accordingly, in some embodiments, the predefined threshold duration may be a set of threshold durations comprising 1 , 2, 3, 4 or more threshold durations. Each of the predefined threshold durations can be comprised between about 1 and about 5 seconds. Preferably, the predefined threshold durations differ from each other. Preferably, the predefined set of threshold durations comprises a first threshold duration, a second threshold duration and a third threshold duration. In some embodiments, the first threshold duration is comprised between 2 and 2.5 seconds, the second threshold duration is comprised between 2.6 and 3.0 seconds and / or the third threshold duration is comprised between 3.1 and 3.5 seconds. In preferred embodiments, the first threshold duration equals 2.3 seconds, the second threshold duration equals 2.8 seconds, and / or the third threshold duration equals 3.3 seconds. In some embodiments, the predefined set of threshold durations is stored in the control unit of the device.

[0029] In some embodiments, a plurality of power profiles can be set based on the comparison of the reference puff duration with the predefined threshold duration or set of threshold durations. In some embodiments, data relative to the power profiles is stored in the control unit of the device.

[0030] A power profile shall generally refer to any pattern of power suitable for being supplied to the aerosol generation unit. In some embodiments, a power profile is generated by supplying a voltage to the aerosol generating unit. Therefore, in some embodiments, the power profile can be determined from a voltage profile. If a current flowing through the heater is fixed by any type of electronics (e.g., a constant current source), a voltage profile may be used instead of the power profile. If a voltage applied to the heater is fixed by any type of electronics (e.g., voltage regulator or converter), a current profile may be used instead of the power profile.

[0031] In some embodiments, the power profile may provide between 1 W and 10 W and / or has a duration comprised between 1 and 3 seconds. Preferably, the power profile provides 6.5 W for 2 seconds.

[0032] In some embodiments, the first part of the power profile may provide between 1 W and 10 W and / or may have a duration comprised between 1 and 3 seconds. Preferably, the first part may provide 6.5 W for 1.5 seconds.

[0033] In some embodiments, the second part of the power profile may comprise one or more high power density and one or more low power density blocks. An amount of power supplied to the aerosol generating unit in the high power density block is higher than the low power density block. Preferably, a plurality of alternating high power density and low power density blocks may be comprised in the second part. In some embodiments, the second part comprises high power density blocks and low power density blocks alternating with high power density blocks. The amount of power supplied to the aerosol generating unit in a low power density block may be zero. The control unit may realize such a low power density block by shutting off the supply of power to the aerosol generating unit, thus it may lead to avoid the complication of control algorithm and / or electrical circuit. The amount of power supplied to the aerosol generating unit in at least one of the low power density blocks may be greater than zero. This may lead to reduce variation of supplied power at transitions between the high and low power density blocks, and as a result the aerosol generation in the second part may be stable. The amount of power supplied to the aerosol generating unit in the low power density blocks may decrease in accordance with progress of the power profile. In a single puff, flavour tasted by the user tends to be concentrated into an early stage of the puff. This control scheme of the low power density blocks follows such user sensation and allows to flexibly adapt to various durations of puffs in a natural way.

[0034] In the method of the invention, characteristics of the power profiles such as profile length and power intensity can be adapted to provide preferred power profiles in response to the threshold durations-based selection rationale. In some embodiments, the second part of the power profile may have a duration of between about 0.5 and about 1.5 seconds when the reference puff duration is equal to or higher than the first threshold duration and lower than the second threshold duration. In a preferred embodiment, the second part may have a duration of 1 second when the reference puff duration is equal to or higher than the first threshold duration and lower than the second threshold duration. In a further preferred embodiment, the second part may have a duration of 1 second when the reference puff duration is equal to or higher than 2.3 seconds and lower than 2.8 seconds. In some embodiments, the second part may have a duration of between about 1 and about 2 seconds when the reference puff duration is equal to or higher than the second threshold duration and lower than the third threshold duration. In a preferred embodiment, the second part may have a duration of 1.5 seconds when the reference puff duration is equal to or higher than the second threshold duration and lower than the third threshold duration. In a further preferred embodiment, the second part may have a duration of 1 .5 second when the reference puff duration is equal to or higher than 2.8 seconds and lower than 3.3 seconds.

[0035] Each of the high power density and low power density block of a second part of the power profile may have a duration independently selected from a value comprised between 1 msec and 100 msec. This allows for fine-tuning of the aerosol generation during the second part. In addition or in alternative, each of the high power density block of a second part of the power profile may provide a power value independently selected from a value comprised between 1 W and 10 W. Preferably, the power value may be kept equal for each high power density block and may be fixed at about 6.5 W. In addition or in alternative, each of the low power density block of a second part of the power profile may provide a power value independently selected from a value comprised between 0 W and 5 W.

[0036] In some embodiments, the duration ratio of high power density blocks to low power density blocks is constant in the second part. In a more specific embodiment, the second part comprises a succession of 50 msec high power density blocks and 50 msec low power density blocks. It may lead to provide a simplified control algorithm and / or electrical circuit. In some alternative embodiments, the duration ratio of high power density blocks to low power density blocks is higher in a first half of the second part than in a second half of the second part. In said alternative embodiments, a more progressive reduction of aerosol generation is obtained, allowing to satisfy the trend of the user sensation as described above. In a more specific embodiment, the second part may comprise the following pattern of blocks: 3 occurrences of (75 msec high power density block + 25 msec low power density block) followed by 4 occurrences of (50 msec high power density block + 50 msec low power density block) followed by 3 occurrences of (25 msec high power density block + 75 msec low power density block), which totals to a second part of 1 second. As mentioned above, such second part can beneficially allow for aerosol generation at an essentially similar maximal aerosol generation rate compared to a power profile defined as a constant power across the first and the second part while limiting energy consumption thanks to the presence of low power density blocks in the profile. In some embodiments, the second part may have a duration comprised between 1 and 3 seconds.

[0037] In some embodiments of the method, the maximum power output of the first part is essentially equal to the maximum power output of the second part. In some embodiments of the method, the maximum aerosol generation rate in the first part is essentially equal to the maximum aerosol generation rate in the second part. In some embodiments, the temperature of the heater comprised in the aerosol generating unit is maintained essentially constant throughout the second part. These may lead to realize a stable aerosol generation even if a non-constant second part is employed.

[0038] In some embodiments, the set power profile may be a constant profile defined by a constant power across the first and second part when the reference puff duration is smaller than the first threshold duration or when no puff data is received for a predetermined duration, wherein said predetermined duration may be of at least 30 seconds.

[0039] The invention also relates to an aerosol generating device comprising an aerosol generating unit configured to heat vaporizable material and a control unit configured to process data from a puff sensor and to supply a power profile to the aerosol generating unit using a method as defined above. Accordingly, in some embodiments, said device further comprises vaporizable material, a puff sensor and a battery.

[0040] BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The invention and its advantages will be better understood upon reading the following description, which is given solely by way of non-limiting example and which is made with reference to the appended drawings, in which:

[0042] - Figure 1 is a schematic diagram showing an aerosol generating device comprising a control unit and configured to implement the method according to the invention.

[0043] - Figure 2 is a block diagram of steps of the method implemented by the device of Figure 1. - Figure 3 is a block diagram representing the method of Figure 2 applied for a series of three puffs.

[0044] - Figure 4 shows parameter details of the method of Figure 2 applied during a vaping session of nine puffs.

[0045] - Figure 5 shows power profiles in function of puff duration resulting from the implementation of the method of Figure 2.

[0046] - Figure 6 represents two alternative second parts of a power profile of Figure 5.

[0047] DETAILED DESCRIPTION OF THE INVENTION

[0048] Before describing the invention, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description. It will be apparent to those skilled in the art having the benefit of the present disclosure that invention is capable of other embodiments and of being practiced or being carried out in various ways.

[0049] As used herein, the term “aerosol generating device” or “device” may include an inhaling device (inhaler) to deliver an aerosol to a user. The inhaling device includes an aerosol precursor, an aerosol generating unit (e.g. a heater or atomizer) which generates vapor from the aerosol precursor, an air flow channel condenses the generated vapor into an aerosol, and a mouthpiece being fluidly connected to the air flow channel and provided at an outlet of the device. The device may be portable. The term “portable” may refer to the device being for use when held by a user. The device may be adapted to generate a variable amount of aerosol, e.g. by activating an atomizer for a variable amount of time (as opposed to a metered dose of aerosol), which can be controlled by a trigger. The trigger may be user activated, such as a vaping button and / or inhalation sensor. The device may include a temperature regulation control to drive the temperature of the heater and / or the heated aerosol generating substance (aerosol pre-cursor) to a specified target temperature and thereafter to maintain the temperature at the target temperature regardless of the amount of substrate (pre-cursor) available at the aerosol generating unit and regardless of the strength with which a user inhales. As used herein, the term “control unit” refers to a component configured to be part of the aerosol generating device for controlling according to the invention. The control unit is configured to control the operation of the device according to a determined operation configuration. Thus, the control unit can control the operation of the heater and / or the power provided for example by a battery and / or the pressure of the precursor or the air. The control unit may be realized by single integrated chip (e.g., MCU or MPU), or a combination of multiple integrated chips, or a combination of at least one integrated chip and peripherals. A whole of a printed circuit board assembly comprising a circuit board and aggregation of electronics may be deemed as the control unit.

[0050] As used herein, the term “aerosol” may include a suspension of precursor as one or more of: solid particles; liquid droplets; gas. Said suspension may be in a gas including air. Aerosol herein may generally refer to / include a vapor. Aerosol may include one or more components of the precursor.

[0051] As used herein, the term “vaporizable material” or “precursor” or “aerosol-forming substance” or “substance” may refer to one or more of a: liquid; solid; gel; mousse; other substance. The precursor may be processable by an atomizer of the device to form an aerosol. The precursor may comprise one or more of: nicotine; caffeine or other active component. The active component may be carried with a carrier, which may be a liquid. The carrier may include propylene glycol or glycerin. A flavoring may also be present. The flavoring may include Ethylvanillin (vanilla), menthol, Isoamyl acetate (banana oil) or similar. A solid aerosol forming substance may be in the form of a rod, which contains processed tobacco material, a crimped sheet or oriented strips of reconstituted tobacco (RTB).

[0052] Referring to Figure 1 , an aerosol generating device 10 used in different embodiments of the invention is first described.

[0053] Particularly, the aerosol generating device 10 comprises an aerosol-generating unit 12 configured to generate an aerosol from a vaporizable material 16, a control unit 14 configured to supply a power profile to the aerosol generating unit 12 and a puff sensor 18 configured to generate data characterizing user puffs. The aerosol generating device 10 may further comprise other components performing different functionalities of the device 10, such as a battery 20 for powering the device 10. It is to be understood that Figure 1 is just a schematic drawing, and appearance of the aerosol generating device 10, arrangements of the vaporizable material 16, the aerosol generating unit 12, the control unit 14, the puff sensor 18 and the battery 20 can be modified.

[0054] The battery 20 is for example a known battery designed to be charged using a power supply furnished by an external charger and to provide a direct current of a predetermined voltage (e.g., lithium-ion secondary battery). The battery 20 may be charged by at least one of wired manner and wireless manner, the control unit 14 may be configured to control the charging of the battery 20, and the aerosol generating device 10 may further comprises a power receiving port (e.g., USB receptacle and / or receiving coil) in accordance with charging manner. If the aerosol generating device 10 itself is designed as disposable type, charging mechanism (incl. power receiving port and / or charging circuit) may be omitted. In such the disposable type, a primary battery, which does not support charging, may be used as the battery 20.

[0055] The vaporizable material 16 may be stored in a compartment suitable for storing a vaporizable material, preferably a liquid vaporizable material. Such a compartment can be fixed with respect to the body of the aerosol generating device 10 or removable from it. In the first case, the compartment can be refilled with vaporizable material. In the second case, the vaporizable material 16 may be stored in a replaceable cartridge (e.g., a pod or capsule containing e-liquid) that can be removed and replaced by another one when the vaporizable material 16 is no longer available. In some embodiments, the replaceable cartridge can be also refilled with the vaporizable material.

[0056] The aerosol generating unit 12 may comprise a heater designed to be in contact with the vaporizable material 16. Powered by the battery 20 and controlled by the control unit 14, the aerosol generating unit 12 is configured to heat the vaporizable material 16 comprised in device 10 to generate aerosol. Either one of a resistive heater, an inductive heater, or combination thereof may be employed as the heater. The aerosol generating unit 12 is not limited to the heater. A spray, an ultrasonic transducer or any type of mechanism to generate the aerosol from the vaporizable material 16 may be used.

[0057] The control unit 14 may comprise a processor embodied as various hardware-based processing means such as a micro processing unit (MPU), a coprocessor, a microcontroller unit (MCU) or various other computing or processing devices including integrated circuits. In some embodiments, the processor may be configured to execute instructions that may be stored in a memory and / or that may be otherwise accessible to the processor. As such, whether configured by hardware or by a combination of hardware and software, the processor may be capable of performing operations according to various embodiments, depending on configuration. The memory may be configured to store control software, configuration settings, and / or other data, programs, and / or the like that may be used to control operation of the aerosol generating device 10. In particular, the control unit 14 is configured to process data from the puff sensor 18 and to supply a power profile to the aerosol generating unit 12, as further explained in relation to the method of the invention.

[0058] The puff sensor 18 may be an inhalation sensor and is capable of sensing puff start and puff end signals. Accordingly, the puff sensor 18 is configured to at least communicate puff start and puff end signals to the control unit 14. Based on data from the puff sensor 18, the control unit 14 is configured to compute various puff-event-related operations such as puff duration and time interval between puffs. Alternatively, the puff sensor 18 itself may output the puff duration to the control unit 14. The puff sensors 18 may comprise either one of a microphone sensor, a temperature sensor (e.g., a thermistor), and a flow sensor.

[0059] An embodiment of the method according to the invention is now described with reference to Figure 2.

[0060] In Figure 2, a method 100 for powering an aerosol generating device 10 of Figure 1 is shown. The method 100 comprises a first step 110, a second step 112, a third step 114 and a fourth step 116. The method 100 may be mainly performed by the control unit 14.

[0061] In the first step 110, the control unit 14 may determine a puff duration from data provided by the puff sensor 18. If the puff sensor 18 is configured to output puff start and puff end signal, the control unit 14 may determine the puff duration by subtracting a time when the puff start signal is inputted from a time when the puff end signal is inputted. Otherwise, the control unit 14 initiates a timer upon input of the puff start signal, stops the timer upon input of puff end signal, and subsequently use a value of the timer as the puff duration. Else if the puff sensor 18 itself outputs the puff duration, the control unit 14 may directly use a value inputted from the puff sensor 18 as the puff duration. In the first step 110, the control unit 14 may further compute a reference puff duration based on the puff duration. The reference puff duration may be the latest puff duration itself, or moving average of a series of the puff durations. If the control unit 14 computes the moving average, the series of the puff durations may be stored in the memory. The moving average may be a simple moving average or a weighted moving average. In the second step 112, the control unit 14 compares the reference puff duration computed in step 110 to a predefined set of threshold durations.

[0062] In the third step 114, the control unit 14 sets a power profile based on the comparison performed in step 112. Further details about the threshold and selection rationale are provided below with reference to Figure 4.

[0063] In the fourth step 116, the control unit 14 supplies power to the aerosol generating unit 12 according to the power profile set in step 114. Further details about the power profiles are provided below with reference to Figures 5-6.

[0064] An example of the method 100 as implemented by the aerosol generating device 10 is further shown in Figure 3, where a series of a first puff 21 , a second puff 22 and a third puff 23 are symbolically represented by boxes.

[0065] The first puff 21 is drawn by a user following a sufficiently long rest period during which the device 10 was inactive, such as an initial puff from a vaping session. In such cases, upon detection of a first puff start signal by the puff sensor 18, the control unit 14 controls the aerosol generating unit 12 according to on a default power profile P0 to generate the aerosol of the first puff 21. In addition, the control unit 14 computes a first reference puff duration dt1 based on data from the puff sensor 18 in step 110, compares dt1 to a set of threshold durations in step 112, sets a power profile P0 in step 114 for the next (second) puff based on the comparison in step 112 and supplies power to the aerosol generating unit 12 in step 116 according to the profile P0 for the second puff 22 upon detection of a second puff start signal.

[0066] During the second puff 22, the control unit 14 controls the aerosol generating unit 12 according to the profile P0 to generate aerosol of the second puff 22 upon detection of a second puff start signal. The control unit 14 further computes a second reference puff duration dt2 based on data from the puff sensor 18 in step 110, compares dt2 to the threshold durations in step 112, sets a power profile P0 in step 114 for the next (third) puff based on the comparison in step 112 and supplies power to the aerosol generating unit 12 in step 116 according to the profile P0 for the third puff 23 upon detection of a third puff start signal. The process is repeated in third puff 23. The control unit 14 controls the aerosol generating unit 12 according to the profile PO to generate the aerosol of third puff 23 upon detection of a third puff start signal. The control unit 14 further computes a third reference puff duration dt3 based on data from puff sensor 18 in step 110, compares dt3 to the set of threshold durations in step 112, sets the power profile P1 in step 114 for the next (fourth) puff based on the comparison in step 112. As no fourth puff is detected, the control unit 14 does not supply power to the aerosol generating unit 12 according to the power profile P1 set in the third puff 23 and the power profile P1 may be discarded.

[0067] As mentioned above relative to Figure 3, the power profile for a puff (number n+1) is determined based on the duration of the previous puff (number n). The setting of a power profile for puff number n+1 results from a comparison of the reference puff duration computed at puff number n to a set of predetermined threshold durations. These setting criteria are further described by referring to Figure 4. The exemplary puffs 21 , 22 and 23 of Figure 3 correspond to a subset of the 3 first puffs presented in Figure 4.

[0068] In Figure 4 and Table 1 , specific parameters used in the method 100 described in Figure 2 and 3 are provided. An exemplary vaping session 30 consisting of 9 puffs is represented in a tabular view in Figure 4, wherein each puff corresponds to a line of the table. For each puff, the applied power profile as resulting from step 116 of the method 100, the reference puff duration (dt1 to dt9) as resulting from step 110 of the method 100 and the set power profile (i.e., a next power profile) as resulting from steps 112 and 114 of the method 100 are shown. The predetermined threshold values used in step 112 and the rationale used in the power profile setting of step 114 are shown in the left column of Table 1 , in which threshold 1 is 2.3 sec, threshold 2 is 2.8 sec and threshold 3 is 3.3 sec. Definitions of corresponding power profiles are shown in the right column of Table 1.

[0069] Table 1 In the method 100, the control unit 14 is further configured to set in step 114, for a puff number n + 1 , a default power profile, such as default power profile P0 shown in Figures 3 and 4, in case the time interval between the previous puff number n and the puff number n + 1 exceeds a predetermined duration. In other words, the control unit 14 is also configured to keep track of time elapsed between puffs, based on signals inputted from the puff sensor 18.

[0070] Total number of power profiles may be any integer number greater than 1. If only the default power profile P0 and the power profile P1 are prepared, the skilled person in the art will understand that a single threshold is sufficient to set the power profile.

[0071] Power profiles delivered to the aerosol generating unit 12 in step 116 of the method 100 are described with reference to Figures 5 and 6. Figure 5 shows the default power profile P0 (plot 1), the power profile P1 (plot 2) and the power profile P2 (plot 3) of Table 1 supplied to the aerosol generating unit 12. A power supplied to the aerosol generating unit 12 (vertical axis) can be described as a function of a lapsed time (horizontal axis). A constant power phase is commonly employed from 0 second. In general, the aerosol generating unit 12 needs time to transit to a state in which aerosol can be generated. The corresponding waiting time may be understood as a preheating time if the aerosol generating unit 12 comprises a heater. The constant power phase may lead to shorten the waiting time. Thus, a value of power in the constant power phase is preferably as high as possible while avoiding accelerated degradation of the battery 20. For example, the rated power of the battery 20 may be used as a value of power in the constant power phase. The power profiles last for a few seconds, so it may be divided into a first part and a later part, as shown in plots 2 and 3. The first part may be from 0 second to 1.5 second, and the second part may start at 1.5 second. The power profile during the first part may be kept identical so that the above-mentioned waiting time is shortened as much as possible. On the other hand, the power profile during the second part may be adjustable based on the puff duration (or reference puff duration) in the previous puff. In Figure 5, the second part of the default power profile P0 is constant and the same as in the first part, but the second part of the power profiles P1 and P2 has an intermittent shape.

[0072] If a current flowing through the heater is fixed by any type of electronics (e.g., a constant current source), a voltage profile may be used instead of the power profile. If a voltage applied to the heater is fixed by any type of electronics (e.g., voltage regulator or converter), a current profile may be used instead of the power profile. A skilled person in the art will understand that the voltage profile and the current profile have same or similar shape compared to the power profiles in Figure 5.

[0073] In each case, maximal aerosol generating rate is reached after approximately 1 second supplying power to the aerosol generating unit 12. The aerosol generation rate [ml / s] or [mg / s] may be defined as a volume [ml] or weight [mg] of aerosol generated from the vaporizable material per a unit of time. A volume or weight of the generated aerosol may be considered equivalent to a volume or weight of the generated vapor before condensation, respectively. Alternatively, a hypothetical value resulting from subtracting a loss representing the condensation from vapor volume or weight, or a volume or weight of the aerosol dispersed from the mouthpiece of the aerosol generating device 10 may be considered as a volume or weight of the generated aerosol. Intermittent power segments in the second part comprise alternating power on and power off blocks. Thanks to a heat capacity of the heater in the aerosol generating unit 12, aerosol generation may not be stopped even during power off blocks. In plot 2 showing the power profile P1 , the intermittent power segment comprises alternating 50 msec power on and off blocks alternating during a total of 1 second. In plot 3 showing the power profile P2, the intermittent power segment comprises alternating 75 msec power on and off blocks alternating during a total of 1 .5 second. Accordingly, in step 116 of the method 100, power profiles P0, P1 or P2 can be used to control the aerosol generating unit 12.

[0074] In power profiles P1 and P2, supplying power to the aerosol generating unit 12 is completely paused in power off blocks which may be realized by turning off a switch (e.g., MOSFET) connected between the battery 20 and the aerosol generating unit 12. In alternative embodiments, a high power density block and a low power density block may be respectively used instead of power on block and power off blocks. In the low power density block, supplying power to the aerosol generating unit 12 is maintained, but the amount of power supplied to the aerosol generating unit 12 in the high power density block is much higher than in the low power density block. Using such low power density blocks may lead to a more stable aerosol generation in the second part. Values of power in the low power density blocks may be same, or may decrease in accordance with lapsed time. In a single puff, flavour tasted by the user tends to be concentrated into an early stage of the puff. This control scheme of the low power density block follows such user sensation and may allow to flexibly adapt to various durations of puffs in a natural way. As will be understood by the skilled person in the art, particular threshold duration values and power profile properties used in the above embodiment and shown in Table 1 are of exemplary nature only. These parameters can be adapted if required by the circumstances. Examples of two alternative intermittent power profiles applicable in the method 100 are further described with reference to Figure 6.

[0075] Figure 6 shows two intermittent power segments 40 and 42, each having a duration of 1 second. Segment 40 corresponds to the intermittent power segment of power profile P1 shown in Figure 5, which comprises alternating power on and power off blocks (or high power density and low density blocks, respectively) of 50 msec each. In segment 42, a gradual decrease of the length of each power on block (or high power density block) and a corresponding increase of the length of each power off block (or low power density) over the 1 -second segment is shown. In more details segment 42 comprises 3 occurrences of (75 msec power-on (or high power density) block + 25 msec power-off (or low power density block) followed by 4 occurrences of (50 msec power-on block (or high power density block) + 50 msec power-off block (or low power density block)) followed by 3 occurrences of (25 msec power-on block (or high power density block) + 75 msec power-off block (or low power density block)). Segment 42 leads to a more progressive decrease of aerosol generation.

[0076] The control unit 14 may control the supply of power from the battery 20 to the aerosol generating unit 12 according to the power profile by manipulating electronic components arranged between the battery 20 and the aerosol generating unit 12. For example, the control unit 14 may adjust a duty ratio applied to a switch arranged between the battery 20 and the aerosol generating unit 12 according to the power profile. If a higher power is required, the control unit 14 outputs a duty signal having high duty ratio to the switch, or vice versa. Such switch outputs power with pulse waves, so smoothing capacitors may be optionally connected to smooth the wave shape.

[0077] The power profile may be generated by calculation. For example, if total energy [J] supplied to the aerosol generating unit 12 is predetermined, an energy supplied to the aerosol generating unit 12 in the second part is computed by subtracting an energy supplied to the aerosol generating unit 12 in the first part from the total energy. The power profile in the second part may be generated by dividing the allocated energy supplied to the aerosol generating unit 12 in the second part across the second part.

Claims

CLAIMS1. A method (100) for powering an aerosol generating device (10) comprising an aerosolgenerating unit (12) configured to generate an aerosol from a vaporizable material (16) and a control unit (14) configured to process data from a puff sensor (18) and to supply a power profile to the aerosol generating unit (12); the method comprising:• determining (110) a puff duration from data provided by the puff sensor (18);• computing (110) a reference puff duration based on the puff duration of the previous step;• comparing (112) the reference puff duration of the previous step to a predefined threshold duration;• setting (114) a power profile based on a result of the comparison; and• supplying (116) power to the aerosol generating unit (12) according to the set power profile; wherein the control unit (14) is configured to set the power profile so that an amount of power supplied to the aerosol generating unit (12) in a given period of the next power profile decreases as the reference puff duration increases, wherein the given period is in only the second part of the power profile among a first and a second part of the power profile, wherein the second part comprises high power density blocks and low power density blocks alternating with the high power density blocks; and an amount of power supplied to the aerosol generating unit (12) in the high power density blocks is higher than in the low power density blocks.

2. The method according to claim 1 , wherein the control unit (14) is configured to set the first part of the power profile irrespective of the reference puff duration.

3. The method according to claim 1 or 2, wherein the control unit (14) is configured to set the first part of the power profile as constant.

4. The method according to any one of claims 1 to 3, wherein the aerosol generating unit (12) comprises a heater configured to heat the vaporizable material (16), and a temperature of the heater is stable or substantially constant in the second part of the power profile.

5. The method according to claim 4, wherein the temperature of the heater becomes stable or substantially constant in the first part of the power profile before transition to the second part.

6. The method according to any one of claims 1 to 5, wherein the second part of the power profile directly follows the first part of the power profile.

7. The method according to any one of claims 1 to 6, wherein the amount of power supplied to the aerosol generating unit (12) in the low power density blocks is zero.

8. The method according to any one of claims 1 to 6, wherein the amount of power supplied to the aerosol generating unit (12) in at least one of the low power density blocks is greater than zero.

9. The method according to claim 8, wherein the amount of power supplied to the aerosol generating unit (12) in the low power density blocks decreases in accordance with progress of the power profile.

10. The method according to any one of claims 1 to 9, wherein the duration ratio of the high power density blocks to the low power density blocks is constant in the second part.

11. The method according to any one of claims 1 to 10, wherein the duration ratio of the high power density blocks to the low power density blocks is higher in a first half of the second part than in a second half of the second part.

12. The method according to any one of the preceding claims, wherein the maximum power output of the first part is essentially equal to the maximum power output of the second part.

13. An aerosol generating device (10) comprising an aerosol generating unit (12) configured to generate an aerosol from a vaporizable material (16), a puff sensor (18) and a control unit (14) configured to process data from the puff sensor (18) and to supply a power profile to the aerosol generating unit (12) using a method according to any one of the preceding claims.

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