Note: Descriptions are shown in the official language in which they were submitted.
WO 2022/049157 PCT/EP2021/074184
1
SMOKING DEVICE WITH HEATING PROFILE BASED ON PUFF FREQUENCY
The present disclosure relates to a method of operating an aerosol-generating
device, a
computer-readable medium for use in an aerosol-generating device, an aerosol-
generating
device, as well as an aerosol-generating system.
Aerosol-generating devices configured to generate an aerosol from an aerosol-
forming
substrate, such as a tobacco-containing substrate, are known in the art.
Typically, an inhalable
aerosol is generated by the transfer of heat from a heat source to a
physically separate aerosol-
forming substrate or material, which may be located within, around or
downstream of the heat
source. An aerosol-forming substrate may be a liquid substrate contained in a
reservoir. An
aerosol-forming substrate may be a solid substrate. An aerosol-forming
substrate may be a
component part of a separate aerosol-generating article configured to engage
with an 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
entrained in air drawn
through the aerosol-generating article. As the released compounds cool, they
condense to form
an aerosol that is inhaled by the consumer
Some aerosol-generating devices are configured to provide user experiences
that have a
finite duration. The duration of a usage session may be limited, for example,
to approximate the
experience of consuming a traditional cigarette. Some aerosol-generating
devices are configured
to be used with separate, consumable, aerosol-generating articles. Such
aerosol-generating
articles comprise an aerosol-forming substrate or substrates that are capable
of releasing volatile
compounds that can form an aerosol. Aerosol-forming substrates are commonly
heated to form
an aerosol. As the volatile compounds in an aerosol-forming substrate are
depleted, the quality
of the aerosol produced may deteriorate. Thus, some aerosol-generating devices
are configured
to limit the duration of the usage session to help prevent generation of a
lower quality aerosol
from a substantially depleted aerosol-forming substrate of an aerosol-
generating article. A user
would inhale aerosol from such a known aerosol-generating device by the
application of one or
more puffs to the device during the usage session. Some known aerosol-
generating devices may
limit the duration of the usage session based upon when a number of puffs
applied to the device
in the session reaches a predetermined limit.
It is known to provide power to a heat source to heat an aerosol-forming
substrate in
accordance with a thermal profile which varies over the duration of a usage
session. In effect.
such known thermal profiles define a temperature variation for the heat source
as a function of
the time elapsed in the usage session. As an aerosol-forming substrate becomes
more depleted
during a usage session, more energy is required to extract the remaining
volatile compounds of
the substrate which form the aerosol. Thus, it is known to use a thermal
profile which increases
a target operating temperature for the heat source over the second half of a
usage session.
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Known thermal profiles used in the operation of a heat source are based on an
idealised,
hypothetical usage session. The idealised usage session may be characterised
by a
predetermined length for the usage session. The idealised usage session may
additionally be
based upon an assumed or idealised puffing behaviour of a user; for example,
on an assumption
that successive puffs are applied at a predetermined rate over a finite period
of time. However,
when a real-life usage session departs from the assumptions inherent in the
idealised usage
session, the use of such known thermal profiles to control the temperature of
the heat source can
lead to inefficient extraction of aerosol from the substrate and be
detrimental to the overall user
experience. By way of example, if a user applied puffs at a faster rate than
assumed in the known
thermal profile, this could result in the usage session being terminated
earlier than anticipated in
the idealised usage session. Consequently, the temperature of the heat source
may never reach
the levels required in the second half of the usage session to efficiently
extract aerosol from the
substrate.
It is therefore desired to overcome the deficiencies and limitations outlined
above.
According to a first aspect of the present invention, there is provided a
method of operating
an aerosol-generating device for generating aerosol from an aerosol-forming
substrate during a
usage session, the aerosol-generating device comprising a power supply
arranged to supply
power to a heater during the usage session. The method comprises:
associating a puff applied in the usage session with a corresponding target
operating
temperature for the heater based on a cumulative puff count of the applied
puff in the usage
session; and
for the applied puff, controlling the supply of power from the power supply in
order to
adjust a temperature of the heater to the target operating temperature
associated with the
applied puff
By associating an applied puff with a corresponding target operating
temperature for the
heater based on cumulative puff count, it is possible to adjust the target
operating temperature
of the heater to take account of the specific puff characteristics of an
individual user. This
contrasts with known devices and thermal profiles discussed above, in which
the temperature of
the heater is varied as a function of 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 allow for more efficient extraction of aerosol from the
aerosol-forming
substrate. Efficient aerosol extraction from the substrate may be achieved
regardless of (or with
less dependence on) the rate at which an individual user applies puffs to the
aerosol-generating
device. Therefore, a user may be able to extract substantially all aerosol
from the substrate
without being limited to applying puffs at a predetermined rate. These
advantages may also
provide the user with an enhanced user experience over the usage session.
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As used herein, the term "aerosol-generating device" refers to a device that
interacts
with an aerosol-forming substrate to generate an aerosol. The aerosol-forming
substrate may
be part of an aerosol-generating article, for example part of a smoking
article. An aerosol-
generating device may comprise one or more components used to supply energy
from a power
supply to an aerosol-forming substrate to generate an aerosol. For example, an
aerosol-
generating device may be a heated aerosol-generating device. An aerosol-
generating device
may be an electrically heated aerosol-generating device or a gas-heated
aerosol-generating
device. An aerosol-generating device may be a smoking device that interacts
with an aerosol-
forming substrate of an aerosol-generating article to generate an aerosol that
is directly
inhalable into a user's lungs through the user's mouth.
As used herein, the term "aerosol-forming substrate" refers to a substrate
capable of
releasing volatile compounds that can form an aerosol. Such volatile compounds
may be
released by heating the aerosol-forming substrate. An aerosol-forming
substrate may be solid
or liquid or comprise both solid and liquid components. An aerosol-forming
substrate may be
adsorbed, coated, impregnated or otherwise loaded onto a carrier or support.
An aerosol-
forming substrate may conveniently be part of an aerosol-generating article or
smoking article.
An aerosol-forming substrate may comprise nicotine. An aerosol-forming
substrate may
comprise tobacco, for example may comprise a tobacco-containing material
containing volatile
tobacco flavour compounds, which are released from the aerosol-forming
substrate upon
heating. In preferred embodiments an aerosol-forming substrate may comprise
homogenised
tobacco material, for example cast leaf tobacco. An aerosol-forming substrate
may comprise at
least one aerosol-former, such as propylene glycol or glycerine.
As used herein, the term "usage session" refers to a period in which a series
of puffs are
applied by a user to extract aerosol from an aerosol-forming substrate
As used herein, the term "cumulative puff count" refers to the number of puffs
applied by
a user in a usage session, relative to the start of that usage session.
Conveniently, the aerosol-generating device may store a predetermined thermal
profile
defining a variation in heater temperature over a predetermined distribution
of puffs, wherein the
target operating temperature associated with the applied puff is a temperature
of the
predetermined thermal profile for the puff in the predetermined distribution
of puffs
corresponding to the cumulative puff count of the applied puff. In this
manner, the temperatures
of the predetermined thermal profile are linked to puff count. This contrasts
with the known
devices discussed above, in which the thermal profile temperatures are linked
solely to the
elapsed time in a usage session.
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The predetermined thermal profile may be stored in a controller used to
control the
power supply. Alternatively, the predetermined thermal profile may be stored
in a memory
module accessible to such a controller.
Advantageously, the predetermined thermal profile may comprise a predetermined
relationship between a puff parameter and the predetermined distribution of
puffs. The method
may further comprise: determining if a value of the puff parameter for either
or both the applied
puff and an earlier puff applied in the usage session differs from a value of
the puff parameter
for corresponding puffs of the predetermined distribution of puffs; modifying
the temperature of
the predetermined thermal profile for the puff in the predetermined
distribution of puffs
corresponding to the cumulative puff count of the applied puff by using the
determined
difference in the value of the puff parameter; and using the modified
temperature of the
predetermined thermal profile as the target operating temperature associated
with the applied
puff. In this manner, the predetermined thermal profile may be dynamically
adapted during a
usage session in response to characteristics of the puffs applied by an
individual user during the
usage session.
As described in more detail below, the puff parameter used in modifying the
thermal
profile may comprise one or more of: i) a time interval between successive
puffs; ii) an intensity
of a puff; and iii) a volume of aerosol generated from the aerosol-forming
substrate in response
to a puff.
The time interval between successive applied puffs is preferably determined by
a
controller based upon detection of each puff. The controller may contain
control electronics
configured to measure the time interval. Puff detection may be performed
directly by use of an
airflow sensor or the like. Preferably however, puff detection is performed
indirectly based upon
detecting a temperature change in the heater which would be expected to
accompany any
applied puff. Determination of a temperature of the heater may be performed
directly by use of
a temperature sensor. Preferably however, the temperature of the heater is
determined
indirectly based upon a change in one or more operating parameters of the
aerosol-generating
device. For example, the temperature of the heater may be determined based
upon an
electrical resistance of the heater; this is particularly relevant to where
the heater is a resistive
heater. In another example, if the heater takes the form of a susceptor which
in use is heated
by an inductor, the temperature of the susceptor may be determined based upon
changes in the
current supplied to the inductor from the power supply.
The volume of aerosol generated in response to an applied puff may be
determined
directly or indirectly. The volume may be determined directly by use of an
airflow sensor or the
like. Preferably however, the volume is determined indirectly by use of a
parameter indicative of
aerosol generation during a usage session. The parameter indicative of aerosol
generation
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may itself by representative of power supplied by the power supply during the
usage session.
For example, current, voltage, or both current and voltage supplied to the
heater may be
parameters representative of power. For example, the power supply may supply
power to
maintain the heater at a predetermined temperature during the usage session.
If a user puffs
5 on the aerosol-generating device to generate an aerosol, the heater cools
and a greater amount
of power is required to maintain the heater at the predetermined temperature.
So, by
monitoring a parameter representative of power supplied by the power supply, a
value indicative
of real time aerosol generation may be recorded.
Advantageously, there may be a predetermined threshold limit for the thermal
profile,
above which the temperatures of the thermal profile cannot be modified. By way
of example,
modification of the temperatures in the thermal profile may be limited to a
change in
temperature of no more than a predetermined threshold limit of +/- 10%, or +/-
7.5%, or +/- 5%,
or +/- 3% of the unmodified temperature. The provision of a threshold limit
for modifying the
temperatures of the thermal profile helps to avoid excessive temperature
fluctuations in the
heater (and substrate) between successive applied puffs. Additionally or
alternatively, the
predetermined threshold limit may comprise an absolute temperature limit. The
value of this
absolute temperature limit may be set so as to avoid ignition and combustion
of the aerosol-
forming substrate and the evolution of harmful compounds from the substrate.
By way of
example, the absolute temperature limit may be set to a value of 400 degrees
Celsius, or
375 degrees Celsius, or 350 degrees Celsius.
The associating of the applied puff with a corresponding target operating
temperature for
the heater may additionally be based on a time interval between the applied
puff and an earlier
puff applied in the usage session. In this manner, the target operating
temperature for the
heater may be a function of both i) the cumulative puff count of the applied
puff and ii) the time
interval between the applied puff and an earlier puff. This functionality
provides an ability to
adjust the target operating temperature for the heater during a usage session
to take account of
the rate at which puffs are applied by an individual user during the session.
This thereby
enables efficient extraction of aerosol from the substrate to be maintained
over the usage
session regardless of (or with less dependence on) the time interval between
successive
applied puffs. Preferably, the earlier puff is the immediate predecessor to
the applied puff in the
usage session.
Each puff applied by a user will itself have a finite duration. Preferably,
the time interval
between the applied puff and an earlier puff in the usage session is the time
interval between
initiation of the applied puff and initiation of the earlier puff.
Alternatively however, the time
interval between the applied puff and an earlier puff in the usage session may
be the time
interval between termination of the applied puff and termination of the
earlier puff.
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As described above, the aerosol-generating device may store a predetermined
thermal
profile defining a variation in heater temperature over a predetermined
distribution of puffs.
Preferably, the predetermined thermal profile comprises a predetermined time
spacing between
successive puffs of the predetermined distribution of puffs. The method may
further comprise:
determining if the time interval between the applied puff and the earlier puff
differs from the
predetermined time spacing between corresponding puffs of the predetermined
distribution of
puffs; modifying the temperature of the predetermined thermal profile for the
puff in the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
by using this time difference; and using the modified temperature of the
predetermined thermal
profile as the target operating temperature associated with the applied puff.
In this manner, the
temperatures of the predetermined thermal profile can be modified based upon
the actual, real-
time puff behaviour of a user so as to maintain efficient aerosol extraction
from the substrate.
As described above, the predetermined thermal profile may be stored in a
controller used to
control the power supply. Alternatively, the predetermined thermal profile may
be stored in a
memory module accessible to such a controller. The predetermined time spacing
may be
uniform across the predetermined distribution of puffs.
A non-limiting example of the use and modification of a predetermined thermal
profile
employing such a "predetermined time spacing" between successive puffs of a
predetermined
distribution of puffs is now described: The predetermined distribution of
puffs of the thermal
profile may have successive puffs spaced apart from each other by a time
interval of Atpredet.
So, a puff 'n would be separated from its successor puff 'n+1' in time by At --
predet in the thermal
profile. Conveniently, the time interval Atpredet is 30 seconds. However,
other values for the time
interval t A ---predet may be chosen according to the rate at which an
idealised or hypothetical user is
assumed to apply puffs over the course of a usage session. In this example,
the thermal profile
defines the heater temperature for puffs 'n' and 'n+1' as Tõ and TH+1
respectively. In the thermal
profile, Tõ and Tõ+, are different to each other and spaced apart from each
other by the time
interval of t A ---predet =
Two scenarios are now considered in which an actual user applies puffs to the
device
over the course of a usage session: In a first scenario, the user applies
puffs in accordance
with the predetermined time spacing of the thermal profile, meaning that each
puff is spaced
apart from its predecessor by Atpredef. In this first scenario, the target
operating temperature for
the heater for applied puff 'n+1' would simply correspond to temperature Tõ41,
with no
modification required to the thermal profile. In a second scenario, the same
user applies puffs
at a faster or slower rate than assumed in the thermal profile. In this second
scenario, the
temperature of the thermal profile for puff 'n+1' is modified according to
whether the user has
applied puff 'n+1' sooner or later than assumed in the thermal profile, i.e.
according to whether
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the applied puffs 'n', 'n+1' are separated in time by less than or more than
time interval Atpredet.
Preferably, the temperature of the thermal profile corresponding to puff 'n+1'
is modified
according to how much sooner or later puff 'n+1' is applied after puff 'n
relative to time interval
Atp,edet. Advantageously, the temperature of the thermal profile corresponding
to puff 'n+1' is
modified in proportion to how much sooner or later puff 'n+1' is applied after
puff 'n' relative to
Atprprieal.
The associating of the applied puff with a corresponding target operating
temperature for
the heater may additionally be based on an intensity of an earlier puff
applied in the usage
session. In this manner, the target operating temperature for the heater may
consequently be a
function of both i) the cumulative puff count of the applied puff and ii) the
intensity of an earlier
puff. Optionally, the target operating temperature may additionally be a
function of a time
interval between the applied puff and an earlier puff, as described in the
preceding paragraphs.
Puff intensity can affect both depletion of the aerosol-forming substrate and
the temperature of
the substrate. The greater the intensity of a puff applied by a user, the more
aerosol is
generated in response to that puff and the more the substrate becomes depleted
of those
compounds necessary for aerosol formation. Further, a puff of higher than
expected intensity
may cause cooling of the substrate below a level needed to ensure efficient
extraction of
aerosol from the substrate. As the substrate becomes more depleted, more
energy - and
consequently a higher heater temperature - is required to extract the
remaining compounds
necessary for aerosol formation. So, having the associating of the applied
puff with a
corresponding target operating temperature for the heater being additionally
based on an
intensity of an earlier puff provides a benefit of enabling the target
operating temperature to be
adjusted to counter substrate depletion caused by the intensity
characteristics of the puffs
applied by an individual user. This thereby enables efficient extraction of
aerosol from the
substrate to be maintained regardless of (or with less dependence) on the
intensity of puffs
applied by the user. Preferably, the earlier puff immediately precedes the
applied puff in the
usage session.
The intensity of a given puff can be characterised in various ways. By way of
example,
the intensity of a puff may be characterised by the volume of aerosol
generated from the
substrate in response to that puff. Accordingly, the method may further
comprise: determining a
volume of aerosol generated from the aerosol-forming substrate in response to
the earlier puff,
and using the determined volume to determine the intensity of the earlier
puff.
As described above, the aerosol-generating device may store a predetermined
thermal
profile defining a variation in heater temperature over a predetermined
distribution of puffs.
Preferably, the predetermined thermal profile comprises a predetermined
intensity for each puff
of the predetermined distribution of puffs. The method may further comprise:
determining if the
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intensity of the earlier puff differs from the predetermined intensity for the
corresponding puff of
the predetermined distribution of puffs; modifying the temperature of the
predetermined thermal
profile for the puff in the predetermined distribution of puffs corresponding
to the cumulative puff
count of the applied puff by using this intensity difference; and using the
modified temperature
of the predetermined thermal profile as the target operating temperature
associated with the
applied puff. In this manner, the predetermined thermal profile can be adapted
in real-time
according to the puff intensity characteristics of an individual user so as to
maintain efficient
extraction of aerosol from the substrate. As described above, the
predetermined thermal profile
may be stored in a controller used to control the power supply. Alternatively,
the predetermined
thermal profile may be stored in a memory module accessible to such a
controller. The
predetermined intensity may be uniform across the predetermined distribution
of puffs.
A non-limiting example of the use and modification of a predetermined thermal
profile
which employs such a "predetermined intensity" for each puff of the
predetermined distribution
of puffs is now described. In this example, the volume of aerosol generated in
response to a
puff is used as a measure of the puff intensity: For the predetermined thermal
profile, the
predetermined distribution of puffs consists of a predetermined number, N, of
puffs applied over
the course of a hypothetical usage session. The thermal profile also defines a
predetermined
total volume, V, of aerosol produced from an aerosol-forming substrate over
the course of the
hypothetical usage session. For the purposes of this example, the
predetermined total aerosol
volume, V, is assumed to be generated evenly over each of the N puffs. So, in
the
predetermined thermal profile, each puff of the 'N' puffs is assumed to result
in generation of the
same volume, v, of aerosol, where v = V/N. In this example, volume, v,
corresponds to the
"predetermined intensity".
Two scenarios are now considered of an actual user applying puffs to the
device over
the course of a usage session: In a first scenario, the user applies puffs in
accordance with the
predetermined distribution of puffs of the thermal profile. This means that
each puff applied by
the user during the usage session has an intensity which conforms to the
thermal profile,
i.e. each applied puff results in generation of volume, v, of aerosol. In this
first scenario, no
modification to the thermal profile would occur, with the target operating
temperature for the
heater for each applied puff simply tracking the corresponding temperature in
the thermal profile
for the puff in the predetermined distribution of puffs corresponding in
number to the cumulative
puff count of the applied puff. However, in a second scenario, the user may
apply puffs which
differ in intensity (and therefore in volume of aerosol generated) from the
assumptions made in
the thermal profile. In this second scenario, two successive puffs applied by
a user are
monitored: puffs 'n' and 'n+1'. If applied puff 'n has an intensity stronger
than assumed in the
thermal profile, then the aerosol volume, vn, resulting from puff 'n' would be
greater than the
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idealised volume, v, of the thermal profile. The greater than expected
intensity (aerosol volume
vn) for puff 'n' would result in greater than expected depletion of the
substrate in response to
puff 'n'. To compensate for the greater than expected depletion, the target
operating
temperature for the next puff 'n+1' may need to be higher than is defined in
the predetermined
thermal profile. Alternatively, if applied puff 'n' has an intensity weaker
than assumed in the
thermal profile, then the aerosol volume, 'in, for puff 'n' would be less than
the idealised volume,
v, of the thermal profile. The less than expected intensity (aerosol volume
vn) for puff 'n' would
result in less than expected depletion of the substrate in response to puff
'n'. To compensate
for the lower than expected depletion, the target operating temperature for
the next puff 'n+1'
may need to be lower than is defined in the predetermined thermal profile. The
modification of
the temperature for puff 'n+1' in the predetermined thermal profile can be
expressed as follows:
Eation 1: TnrViried T
= qu n 1 1- C
for which:
Tn+i is the temperature initially defined in the thermal profile for puff
'n+1'
TnnZdified is the modified temperature of the thermal profile for puff 'n+1';
and
a is a correction factor applied to Tn+ito address the actual "intensity" of
puff 'n'. The correction
factor a may vary dependent on the amount by which the volume of aerosol, vn,
produced in
response to applied puff 'n' is greater than or less than idealised volume, v.
In one example, the correction factor, a, may be expressed as follows:
Equation 2: oc= [(1. + o. (!z))]
for which:
6 is a scale factor, whose value may be chosen so as to increase or reduce the
effect of 'in
being different to v when modifying the initially defined temperature T121.
The associating of the applied puff with a corresponding target operating
temperature for
the heater may additionally be based on a volume of aerosol generated from the
aerosol-
forming substrate in response to an earlier puff applied in the usage session.
In this manner,
the target operating temperature for the heater may consequently be a function
of both i) the
cumulative puff count of the applied puff and ii) the volume of aerosol
generated in response to
an earlier puff. Optionally, the target operating temperature may additionally
be a function of
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one or more of i) a time interval between the applied puff and the earlier
puff (as described in
the preceding paragraphs), and ii) an intensity of the earlier puff (as
described in the preceding
paragraphs). This can be understood to be closely related to the situation
described above of
the target operating temperature being a function of puff intensity, with the
volume of aerosol
5 generated in response to a puff being one suitable means of
characterising an intensity of that
puff. The greater the volume of aerosol generated in response to a puff, the
more the substrate
becomes depleted. As the substrate becomes more depleted, more energy - and
consequently
a higher heater temperature - is required to extract the remaining compounds
necessary for
aerosol formation. So, having the associating of the applied puff with a
corresponding target
10 operating temperature for the heater being additionally based on a
volume of aerosol generated
in response to an earlier puff provides a benefit of enabling the target
operating temperature to
be adjusted to counter substrate depletion caused by the characteristics of
the puffs applied by
an individual user. Preferably. the earlier puff immediately precedes the
applied puff in the
usage session.
As described above, the aerosol-generating device may store a predetermined
thermal
profile defining a variation in heater temperature over a predetermined
distribution of puffs.
Preferably, the predetermined thermal profile comprises a predetermined volume
of aerosol
generated from the aerosol-forming substrate for each puff of the
predetermined distribution of
puffs. The method may further comprise determining if the volume of aerosol
generated for the
earlier puff differs from the predetermined volume for the corresponding puff
of the
predetermined distribution of puffs; modifying the temperature of the
predetermined temperature
profile for the puff in the predetermined distribution of puffs corresponding
to the cumulative puff
count of the applied puff by using this volume difference; and using the
modified temperature of
the predetermined thermal profile as the target operating temperature
associated with the
applied puff. In this manner, the predetermined thermal profile can be adapted
according to the
puff characteristics of an individual user, thereby facilitating maintaining
efficient extraction of
aerosol from the substrate over a usage session. As described above, the
predetermined
thermal profile may be stored in a controller used to control the power
supply. Alternatively, the
predetermined thermal profile may be stored in a memory module accessible to
such a
controller. The predetermined volume may be uniform across the predetermined
distribution of
puffs. The non-limiting example outlined in the preceding paragraphs with
reference to
Equations 1 and 2 describing the use and modification of a predetermined
thermal profile which
employs a "predetermined intensity" for each puff of the predetermined
distribution of puffs is
also applicable to the variant described in this paragraph of the
predetermined thermal profile
employing a "predetermined volume" of aerosol generated.
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Conveniently, the target operating temperature varies over the usage session
within a
range of 320 degrees Celsius to 350 degrees Celsius. Such an operating
temperature has
been found especially suitable when generating aerosol from aerosol-forming
substrates which
are solid and comprise tobacco. However, the present disclosure is not limited
to the use of
solid aerosol-forming substrates, and may also be applied to use with liquid
aerosol-forming
substrates. It is also desirable to limit a maximum value for the target
operating temperature
over the usage session so as to avoid ignition and combustion of the substrate
and the
evolution of harmful compounds from the substrate; by way of example, this
limit may be set at
400 degrees Celsius, or 375 degrees Celsius, or 350 degrees Celsius. The
specific range and
limit for target operating temperature over a usage session may be set
according to the heating
characteristics of the specific aerosol-forming substrate which is used, as
well as the energy
capacity of the power source which is used.
The method may comprise detecting the applied puff by monitoring a change in
heater
temperature in response to the applied puff. By way of example, the heater
temperature may
be detected as described in the preceding paragraphs.
The method may further comprise terminating the usage session upon the first
to occur
of: i) a cumulative number of puffs applied in the usage session reaching a
predetermined puff
limit, or ii) the usage session reaching a predetermined maximum time
duration. By way of
example, the predetermined puff limit may be 12 puffs and the predetermined
maximum time
duration be 6 minutes. However, other values for the puff limit and maximum
time duration may
be set, with their selection affected by a number of factors. These factors
may include the
amount and composition of aerosol-forming substrate which is used and the
amount of power
available from the power supply in a given usage session. It is preferable for
the aerosol-
generating device to be portable and to have a size and a mass suitable for
the device to be
held by the hand of a user. These preferences will, in turn, affect the size
and energy capacity
of the power source of the aerosol-generating device, which will thereby
affect the values set for
the puff limit and maximum time duration.
According to a second aspect of the present invention, there is provided a
computer-
readable medium for use in an aerosol-generating device, the computer-readable
medium
containing instructions for performing 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 discrete component
separate to but
accessible to such a controller. Preferably, the computer-readable medium is
both readable
and writable in use, which thereby provides a benefit of enabling a thermal
profile stored in the
computer-readable medium to be modified during the course of a usage session.
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According to a third aspect of the present invention, there is provided an
aerosol-
generating device for generating aerosol from an aerosol-forming substrate
during a usage
session. The aerosol-generating device comprises:
a power supply arranged to supply power to a heater during the usage session;
the aerosol-generating device configured to:
associate a puff applied in the usage session with a corresponding target
operating
temperature for the heater based on a cumulative puff count of the applied
puff in the usage
session; and
for the applied puff, control the supply of power from the power supply in
order to adjust a
temperature of the heater to the target operating temperature associated with
the applied puff.
This third aspect provides an aerosol-generating device which, in general
terms, is able to
perform the method of the first aspect and its variants described above. For
completeness,
different variants of the aerosol-generating device are briefly outlined
below.
As described above in relation to the first aspect, the aerosol-generating
device may store
a predetermined thermal profile defining a variation in heater temperature
over a predetermined
distribution of puffs, the aerosol-generating device configured such that the
target operating
temperature associated with the applied puff is a temperature of the
predetermined thermal
profile for the puff in the predetermined distribution of puffs corresponding
to the cumulative puff
count of the applied puff.
As described above in relation to the first aspect, the predetermined thermal
profile may
be stored in a controller used to control the power supply. Alternatively, the
predetermined
thermal profile may be stored in a memory module accessible to such a
controller.
As described above in relation to the first aspect, the predetermined thermal
profile may
comprise a predetermined relationship between a puff parameter and the
predetermined
distribution of puffs. Further, the aerosol-generating device is preferably
configured to:
determine if a value of the puff parameter for either or both the applied puff
and an earlier puff
differs from a value of the puff parameter for corresponding puffs of the
predetermined
distribution of puffs; modify the temperature of the predetermined thermal
profile for the puff in
the predetermined distribution of puffs corresponding to the cumulative puff
count of the applied
puff by using this difference in the value of the puff parameter; and use the
modified heater
temperature of the predetermined thermal profile as the target operating
temperature
associated with the applied puff.
As described for the first aspect, the puff parameter may comprise one or more
of: a time
interval between successive puffs; an intensity of a puff; and a volume of
aerosol generated
from the aerosol-forming substrate in response to a puff.
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13
The provision of a predetermined threshold limit for the thermal profile as
described for the
first aspect is equally applicable to the aerosol-generating device of this
third aspect of the
invention.
The aerosol-generating device may also be configured: to determine a time
interval
between the applied puff and an earlier puff; and such that the associating of
the applied puff
with a corresponding target operating temperature for the heater is
additionally based on the
determined time interval.
As previously described, the aerosol-generating device may store a
predetermined
thermal profile defining a variation in heater temperature over a
predetermined distribution of
puffs. Preferably, the predetermined thermal profile comprises a predetermined
time spacing
between successive puffs of the predetermined distribution of puffs, with the
aerosol-generating
device configured to: determine if the determined time interval between the
applied puff and the
earlier puff differs from the predetermined time spacing between corresponding
puffs of the
predetermined distribution of puffs; modify the temperature of the
predetermined thermal profile
for the puff in the predetermined distribution of puffs corresponding to the
cumulative puff count
of the applied puff by using this time difference; and use the modified
temperature of the
predetermined thermal profile as the target operating temperature associated
with the applied
puff. The example described in the preceding paragraphs (for the method of the
first aspect) of
the use and modification of a predetermined thermal profile employing a
"predetermined time
spacing" between successive puffs of a predetermined distribution of puffs is
equally applicable
to providing an understanding of the configuration of the device outlined in
this paragraph.
The aerosol-generating device may also be configured to: determine an
intensity of an
earlier puff applied in the usage session; and such that the associating of
the applied puff with a
corresponding target operating temperature for the heater is additionally
based on the
determined intensity of the earlier puff. As discussed in the preceding
paragraphs for the first
aspect, the intensity of a given puff can be characterised in various ways. By
way of example,
the intensity of a puff may be characterised by the volume of aerosol
generated from the
substrate in response to that puff. Accordingly, the aerosol-generating device
may be
configured to: determine a volume of aerosol generated from the aerosol-
forming substrate in
response to the earlier puff; and use the determined volume in determining the
intensity of the
earlier puff.
As described above, the aerosol-generating device may store a predetermined
thermal
profile defining a variation in heater temperature over a predetermined
distribution of puffs.
Preferably, the predetermined thermal profile comprises a predetermined
intensity for each puff
of the predetermined distribution of puffs, with the aerosol-generating device
configured to:
determine if the determined intensity of the earlier puff differs from the
predetermined intensity
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for the corresponding puff of the predetermined distribution of puffs; modify
the temperature of
the predetermined thermal profile for the puff in the predetermined
distribution of puffs
corresponding to the cumulative puff count of the applied puff by using this
intensity difference:
and use the modified temperature of the predetermined thermal profile as the
target operating
temperature associated with the applied puff. The example described in the
preceding
paragraphs (for the method of the first aspect) of the use and modification of
a predetermined
thermal profile employing a 'predetermined intensity" for each puff of a
predetermined
distribution of puffs is equally applicable to providing an understanding of
the configuration of
the device outlined in this paragraph.
The aerosol-generating device may also be configured: to determine a volume of
aerosol
generated from the aerosol-forming substrate in response to an earlier puff
applied in the usage
session; and such that the associating of the applied puff with a
corresponding target operating
temperature for the heater is additionally based on the determined volume for
the earlier puff.
As noted in previous paragraphs, this is closely related to the situation
described above of the
target operating temperature being a function of puff intensity, with the
volume of aerosol
generated in response to a puff being one suitable means of characterising the
intensity of that
puff.
As described above, the aerosol-generating device may store a predetermined
thermal
profile defining a variation in heater temperature over a predetermined
distribution of puffs.
Preferably, the predetermined thermal profile comprises a predetermined volume
of aerosol
generated from the aerosol-forming substrate for each puff of the
predetermined distribution of
puffs, with the aerosol-generating device configured to: determine if the
determined volume of
aerosol generated for the earlier puff differs from the predetermined volume
for the
corresponding puff of the predetermined distribution of puffs: modify the
temperature of the
predetermined temperature profile for the puff in the predetermined
distribution of puffs
corresponding to the cumulative puff count of the applied puff by using this
volume difference;
and use the modified temperature of the predetermined thermal profile as the
target operating
temperature associated with the applied puff.
In a similar manner and for the same reasoning as discussed in preceding
paragraphs
for the method of the first aspect, the aerosol-generating device may be
configured such that
the target operating temperature is restricted to vary within a range of 320
degrees Celsius to
350 degrees Celsius.
The aerosol-generating device may be configured to detect the applied puff by
monitoring a change in heater temperature in response to the applied puff.
In a similar manner and for the same reasoning as discussed in preceding
paragraphs
for the method of the first aspect, the aerosol-generating device may also be
configured to
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terminate the usage session upon the first to occur of: i) a cumulative number
of puffs applied in
the usage session reaching a predetermined puff limit, or ii) the usage
session reaching a
predetermined maximum time limit duration.
The aerosol-generating device may comprise the heater. By way of example, the
heater
5 may be a resistive heating element which is intended to fit around or
within an aerosol-forming
substrate. Alternatively, the heater may be distinct and separate to the
device. For example,
the heater may be a susceptor forming part of an article distinct from the
device, in which the
article houses the aerosol-forming substrate. In such an example, the aerosol-
generating
device may comprise an inductor, with the power supply configured to provide
power to the
10 inductor such that, in use of the device with the article, the inductor
would induce eddy currents
into the susceptor, thereby resulting in heating of the susceptor.
In a fourth aspect, there is provided an aerosol-generating system, the system
comprising
the aerosol-generating device according to the third aspect and any of its
variants described
above and an aerosol-generating article, the aerosol-generating article
comprising the heater and
15 aerosol-forming substrate, wherein the aerosol-generating device is
configured to receive the
aerosol-generating article.
By way of example, the heater may be in the form of a susceptor. with the
aerosol-
generating device comprising an inductor coupled to the power supply. The
aerosol-generating
article and device are preferably configured such that when the article is
received by the device,
the inductor and susceptor are positioned relative to each other so that the
provision of power
from the power supply to the inductor induces eddy currents into the
susceptor, thereby causing
heating of the aerosol-forming substrate.
The invention is defined in the claims. However, below there 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 another example, embodiment, or
aspect described
herein.
Example Ex1: A method of operating an aerosol-generating device for generating
aerosol
from an aerosol-forming substrate during a usage session, the aerosol-
generating device
corn prisi ng:
a power supply arranged to supply power to a heater during the usage session;
the method comprising:
associating a puff applied in the usage session with a corresponding target
operating
temperature for the heater based on a cumulative puff count of the applied
puff in the usage
session; and
for the applied puff, controlling the supply of power from the power supply in
order to adjust
a temperature of the heater to the target operating temperature associated
with the applied puff.
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Example Ex2: A method according to Ex1, in which the aerosol-generating device
stores a
predetermined thermal profile defining a variation in heater temperature over
a predetermined
distribution of puffs, wherein the target operating temperature associated
with the applied puff is
a temperature of the predetermined thermal profile for the puff in the
predetermined distribution
of puffs corresponding to the cumulative puff count of the applied puff.
Example Ex3: A method according to Ex2, the predetermined thermal profile
comprising a
predetermined relationship between a puff parameter and the predetermined
distribution of puffs;
the method further comprising:
determining if a value of the puff parameter for either or both the applied
puff and an earlier
puff applied in the usage session differs from a value of the puff parameter
for corresponding
puffs of the predetermined distribution of puffs;
modifying the temperature of the predetermined thermal profile for the puff in
the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
by using the determined difference in the value of the puff parameter; and
using the modified temperature of the predetermined thermal profile as the
target operating
temperature associated with the applied puff.
Example Ex4: A method according to Ex3, in which the puff parameter comprises
one or
more of:
a time interval between successive puffs:
an intensity of a puff; and
a volume of aerosol generated from the aerosol-forming substrate in response
to a puff.
Example Ex5: A method according to any one of Ex1 to Ex4, wherein the
associating of
the applied puff with a corresponding target operating temperature for the
heater is additionally
based on a time interval between the applied puff and an earlier puff applied
in the usage session
Example Ex6: A method according to Ex5, in which the earlier puff immediately
precedes
the applied puff in the usage session.
Example Ex7: A method according to either one of Ex5 or Ex6, in which the
aerosol-
generating device stores a predetermined thermal profile defining a variation
in heater
temperature over a predetermined distribution of puffs, the predetermined
thermal profile
comprising a predetermined time spacing between successive puffs of the
predetermined
distribution of puffs;
the method further comprising:
determining if the time interval between the applied puff and the earlier puff
differs from the
predetermined time spacing between corresponding puffs of the predetermined
distribution of
puffs;
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modifying the temperature of the predetermined thermal profile for the puff in
the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
by using this time difference; and
using the modified temperature of the predetermined thermal profile as the
target operating
temperature associated with the applied puff.
Ex8: A method according to Ex7, in which the predetermined time spacing is non-
uniform
across the predetermined distribution of puffs.
Ex9: A method according to any one of Ex1 to Ex8, wherein the associating of
the applied
puff with a corresponding target operating temperature for the heater is
additionally based on an
intensity of an earlier puff applied in the usage session.
Ex10: A method according to Ex9, in which the earlier puff is the immediate
predecessor to
the applied puff.
Ex11: A method according to either one of Ex9 or Ex10, in which the aerosol-
generating
device stores a predetermined thermal profile defining a variation in heater
temperature over a
predetermined distribution of puffs, the predetermined thermal profile
comprising a predetermined
intensity for each puff of the predetermined distribution of puffs;
the method further comprising:
determining if the intensity of the earlier puff differs from the
predetermined intensity for the
corresponding puff of the predetermined distribution of puffs;
modifying the temperature of the predetermined thermal profile for the puff in
the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
by using this intensity difference; and
using the modified temperature of the predetermined thermal profile as the
target operating
temperature associated with the applied puff.
Ex12: A method according to Exl 1, in which the predetermined intensity is non-
uniform
across the predetermined distribution of puffs.
Ex13: A method according to any one of Ex9 to Ex12, the method further
comprising:
determining a volume of aerosol generated from the aerosol-forming substrate
in response
to the earlier puff, and using the determined volume to determine the
intensity of the earlier puff.
Ex14: A method according to any one of Ex1 to 13, wherein the associating of
the applied
puff with a corresponding target operating temperature for the heater is
additionally based on a
volume of aerosol generated from the aerosol-forming substrate in response to
an earlier puff
applied in the usage session.
Ex15: A method according to Ex14, in which the earlier puff is the immediate
predecessor
to the applied puff.
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Ex16: A method according to either one of Ex14 or Ex15, in which the aerosol-
generating
device stores a predetermined thermal profile defining a variation in heater
temperature over a
predetermined distribution of puffs, the predetermined thermal profile
comprising a predetermined
volume of aerosol generated from the aerosol-forming substrate for each puff
of the
predetermined distribution of puffs;
the method further comprising:
determining if the volume of aerosol generated for the earlier puff differs
from the
predetermined volume for the corresponding puff of the predetermined
distribution of puffs;
modifying the temperature of the predetermined temperature profile for the
puff in the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
by using this volume difference: and
using the modified temperature of the predetermined thermal profile as the
target operating
temperature associated with the applied puff.
Ex17: A method according to Ex16, in which the predetermined volume is non-
uniform
across the predetermined distribution of puffs.
Ex18: A method according to any one of Ex1 to Ex17, in which the target
operating
temperature varies over the usage session within a range of 320 degrees
Celsius to 350 degrees
Celsius.
Ex19: A method according to any one of Ex1 to Ex18, the method comprising
detecting the
applied puff by monitoring a change in heater temperature in response to the
applied puff.
Ex20: A method according to any one of Exl to Ex19, the method further
comprising
terminating the usage session upon the first to occur of:
i) a cumulative number of puffs applied in the usage session reaching a
predetermined puff
limit, or ii) the usage session reaching a predetermined maximum time duration
Ex21: A computer-readable medium for use in an aerosol-generating device, the
computer-
readable medium containing instructions for performing the method according to
any one of Ex1
to Ex20.
Ex22: An aerosol-generating device for generating aerosol from an aerosol-
forming
substrate during a usage session, the aerosol-generating device comprising:
a power supply arranged to supply power to a heater during the usage session;
the aerosol-generating device configured to:
associate a puff applied in the usage session with a corresponding target
operating
temperature for the heater based on a cumulative puff count of the applied
puff in the usage
session; and
for the applied puff, control the supply of power from the power supply in
order to adjust a
temperature of the heater to the target operating temperature associated with
the applied puff.
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Ex23: An aerosol-generating device according to Ex22, in which the aerosol-
generating
device stores a predetermined thermal profile defining a variation in heater
temperature over a
predetermined distribution of puffs, the aerosol-generating device configured
such that the target
operating temperature associated with the applied puff is a temperature of the
predetermined
thermal profile for the puff in the predetermined distribution of puffs
corresponding to the
cumulative puff count of the applied puff.
Ex24: An aerosol-generating device according to Ex23, in which the
predetermined thermal
profile stored by the aerosol-generating device comprises a predetermined
relationship between
a puff parameter and the predetermined distribution of puffs; wherein the
aerosol-generating
device is configured to:
determine if a value of the puff parameter for either or both the applied puff
and an earlier
puff differs from a value of the puff parameter for corresponding puffs of the
predetermined
distribution of puffs;
modify the temperature of the predetermined thermal profile for the puff in
the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
by using this difference in the value of the puff parameter; and
use the modified heater temperature of the predetermined thermal profile as
the target
operating temperature associated with the applied puff.
Ex25: An aerosol-generating device according to Ex24, in which the puff
parameter
comprises one or more of:
a time interval between successive puffs;
an intensity of a puff; and
a volume of aerosol generated from the aerosol-forming substrate in response
to a puff.
Ex26: An aerosol-generating device according to any one of Ex22 to Ex25,
wherein the
aerosol-generating device is configured:
to determine a time interval between the applied puff and an earlier puff; and
such that the associating of the applied puff with a corresponding target
operating
temperature for the heater is additionally based on the determined time
interval.
Ex27: An aerosol-generating device according to Ex26, wherein the aerosol-
generating
device stores a predetermined thermal profile defining a variation in heater
temperature over a
predetermined distribution of puffs, the predetermined thermal profile
comprising a predetermined
time spacing between successive puffs of the predetermined distribution of
puffs;
wherein the aerosol-generating device is configured to:
determine if the determined time interval between the applied puff and the
earlier puff differs
from the predetermined time spacing between corresponding puffs of the
predetermined
distribution of puffs;
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modify the temperature of the predetermined thermal profile for the puff in
the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
by using this time difference; and
use the modified temperature of the predetermined thermal profile as the
target operating
5 temperature associated with the applied puff.
Ex28: An aerosol-generating device according to any one of Ex22 to Ex27, the
aerosol-
generating device further configured:
to determine an intensity of an earlier puff applied in the usage session; and
such that the associating of the applied puff with a corresponding target
operating
10 temperature for the heater is additionally based on the determined
intensity of the earlier puff.
Ex29: An aerosol-generating device according to Ex28, in which the aerosol-
generating
device stores a predetermined thermal profile defining a variation in heater
temperature over a
predetermined distribution of puffs, the predetermined thermal profile
comprising a predetermined
intensity for each puff of the predetermined distribution of puffs;
15 wherein the aerosol-generating device is configured to:
determine if the determined intensity of the earlier puff differs from the
predetermined
intensity for the corresponding puff of the predetermined distribution of
puffs;
modify the temperature of the predetermined thermal profile for the puff in
the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
20 by using this intensity difference; and
use the modified temperature of the predetermined thermal profile as the
target operating
temperature associated with the applied puff.
Ex30: An aerosol-generating device according to either one of Ex28 or Ex29, in
which the
aerosol-generating device is configured to:
determine a volume of aerosol generated from the aerosol-forming substrate in
response
to the earlier puff; and
use the determined volume in determining the intensity of the earlier puff.
Ex31: An aerosol-generating device according to any one of Ex22 to Ex30, the
aerosol-
generating device further configured:
to determine a volume of aerosol generated from the aerosol-forming substrate
in response
to an earlier puff applied in the usage session; and
such that the associating of the applied puff with a corresponding target
operating
temperature for the heater is additionally based on the determined volume for
the earlier puff.
Ex32: An aerosol-generating device according to Ex31, in which the aerosol-
generating
device stores a predetermined thermal profile defining a variation in heater
temperature over a
predetermined distribution of puffs, the predetermined thermal profile
comprising a predetermined
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volume of aerosol generated from the aerosol-forming substrate for each puff
of the
predetermined distribution of puffs;
wherein the aerosol-generating device is configured to:
determine if the determined volume of aerosol generated for the earlier puff
differs from the
predetermined volume for the corresponding puff of the predetermined
distribution of puffs;
modify the temperature of the predetermined temperature profile for the puff
in the
predetermined distribution of puffs corresponding to the cumulative puff count
of the applied puff
by using this volume difference; and
use the modified temperature of the predetermined thermal profile as the
target operating
temperature associated with the applied puff.
Ex33: An aerosol-generating device according to any one of Ex22 to Ex32, in
which the
aerosol-generating device is configured such that the target operating
temperature is restricted
to vary within a range of 320 degrees Celsius to 350 degrees Celsius.
Ex34: An aerosol-generating device according to any one of Ex22 to Ex33, in
which the
aerosol-generating device is configured to detect the applied puff by
monitoring a change in
heater temperature in response to the applied puff.
Ex35: An aerosol-generating device according to any one of Ex22 to Ex34, in
which the
aerosol-generating device is configured to terminate the usage session upon
the first to occur of:
i) a cumulative number of puffs applied in the usage session reaching a
predetermined puff
limit, or ii) the usage session reaching a predetermined maximum time limit
duration.
Ex36: An aerosol-generating device according to any of Ex22 to Ex35, in which
the aerosol-
generating device comprises the heater.
Ex37: An aerosol-generating system, the system comprising the aerosol-
generating device
according to any one of claims 22 to 35 and an aerosol-generating article, the
aerosol-generating
article comprising the heater and aerosol-forming substrate, wherein the
aerosol-generating
device is configured to receive the aerosol-generating article.
Examples will now be further described with reference to the figures, in
which:
Figure 1 illustrates a schematic side view of an aerosol-generating device;
Figure 2 illustrates a schematic upper end view of the aerosol-generating
device of figure 1;
Figure 3 illustrates a schematic cross-sectional side view of the aerosol-
generating device
of figure 1 and an aerosol-generating article for use with the device;
Figure 4 illustrates a prior art thermal profile used in the operation of
known aerosol-
generating devices;
Figure 5 illustrates a variation in target operating temperature of a heater
of an aerosol-
generating device resulting from use of the prior art thermal profile of
figure 4, in a scenario in
which a user applies successive puffs each spaced apart by 15 seconds;
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Figure 6 illustrates a variation in target operating temperature of a heater
of an aerosol-
generating device resulting from use of the prior art thermal profile of
figure 4, in a scenario in
which a user applies successive puffs each spaced apart by 11 seconds;
Figure 7 illustrates a method in accordance with the present disclosure, in
which the target
operating temperature for the heater is adjusted as a function of puff count;
Figure 8 illustrates a thermal profile according to the present disclosure, in
which the target
operating temperature for the heater is defined as a function of puff count;
Figure 9 illustrates how the target operating temperature of the heater is
varied when using
the thermal profile of figure 8, in a scenario in which a user applies puffs
at uniform intervals;
Figure 10 illustrates how the target operating temperature of the heater is
varied when using
the thermal profile of figure 8, in a scenario in which a user applies puffs
at varying (i.e. non-
uniform) intervals.
An exemplary aerosol-generating device 10 is a hand-held aerosol generating
device, and
has an elongate shape defined by a housing 20 that is substantially circularly
cylindrical in form
(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 in use. An electrically-operated heater 40 is
arranged within the
device 10 to heat at least an aerosol-forming substrate portion 31 of an
aerosol-generating
article 30 when the aerosol-generating article is received in 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 a target operating temperature
for the heater 40
varies in a usage session.
The aerosol-generating device is configured to receive a consumable aerosol-
generating
article 30. The aerosol-generating article 30 is in the form of a cylindrical
rod and comprises an
aerosol-forming substrate 31 (see figure 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 arranged 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 longer than a
depth of the cavity 25,
such that when the article 30 is received in the cavity 25 of the device 10,
the mouthpiece 32
extends out of the cavity 25 and may be drawn on by a user, similarly to a
conventional cigarette.
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 figure 1) to
activate the heater 40
to start a usage session. The heater 40 heats the aerosol-forming substrate 31
of the article 30
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such that volatile compounds of the aerosol-forming substrate are released and
atomised to form
an aerosol. The user draws on the mouthpiece of the article 30 and inhales the
aerosol generated
from the heated aerosol-forming substrate 31. After activation, the
temperature of the heater 40
increases from an ambient temperature to a predetermined temperature for
heating the aerosol-
forming substrate. The predetermined temperature is defined in the thermal
profile stored in
memory 28. After activation and over the course of the usage session, the
control electronics 27
of the device 10 access the thermal profile stored in the memory module 28 so
as to control the
supply of power from the battery 26 to the heater 40 to adjust the heater
temperature in
accordance with the thermal profile. The heater 40 continues to heat the
aerosol-generating
article 30 until an end of the usage session, when the heater is deactivated
and cools. In some
specific examples the heater 40 may be a resistance heating element. In some
specific examples
the heater 40 may be a susceptor arranged within a fluctuating magnetic field
such that it is heated
by induction.
At the end of the 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 of
the battery 26 of
the device 10.
The aerosol-generating article 30 for use with the device 10 has a finite
quantity of aerosol-
forming substrate 31 and, thus, a usage session needs to have a finite
duration to prevent a user
trying to produce aerosol when the aerosol-forming substrate has been
depleted. A usage
session is configured to have a maximum duration determined by a maximum time
period from
the start of the usage session. A usage session is also configured to have a
duration of less than
the maximum time period if a user interaction parameter recorded during the
usage session
reaches a threshold before elapse of the maximum time period. In a specific
example the user
interaction parameter is representative of a cumulative number of puffs
applied to the device by
a user over a usage session, with a threshold of 14 puffs defined for the
cumulative number of
puffs. So, for this specific example, the aerosol-generating device 10 is
configured such that each
usage session has a maximum duration defined by the first to occur of: i) 6
minutes from activation
of the usage session. or ii) a total of 14 puffs being applied in the usage
session.
In prior art devices, the thermal profile used to adjust the temperature of
the heater 40 is a
predetermined temperature profile which varies the target operating
temperature for the heater
solely as a function of the elapsed time of a usage session. Figure 4 shows
such a prior art
thermal profile. The prior art thermal profile is based on the behaviour of an
idealised or
hypothetical user, and defines a temperature profile for the heater 40 which
varies a target
operating temperature for the heater 40 solely as a function of elapsed time.
The prior art thermal
profile of figure 4 is constructed on the assumption that a user applies each
successive puff to
the device 10 at intervals of 30 seconds, resulting in a usage session having
a duration of 6
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minutes (360 seconds). These hypothetical or idealised puffs are represented
by dashed lines in
figure 4.
The operation of the device 10 using the prior art thermal profile of figure 4
is now described
for three different scenarios:
In a first scenario, a user activates the device 10 by pressing user button 50
to start a usage
session with an unused article 30 and then applies a series of 12 successive
puffs spaced apart
from each other at intervals of 30 seconds. As the user is applying puffs at a
rate which conforms
to the assumptions made for the thermal profile of figure 4, the battery 26
(under the control of
the control electronics 27) would provide power to the heater 40 for a usage
session of 6 minutes,
corresponding to 12 puffs spaced 30 seconds apart. In essence. the heater 40
would be adjusted
in accordance with the thermal profile shown in figure 4. As a result, the
aerosol-forming
substrate 31 would be substantially depleted of aerosol.
In a second scenario, the user activates the device 10 by pressing user button
50 to start a
usage session with an unused article 30. However, in contrast to the first
scenario, after taking
the first puff at 30 seconds from the start of the usage session, the user
applies all subsequent
puffs spaced apart from each other at intervals of only 15 seconds. This
higher puff rate results
in the usage session being terminated early by the device 10 for the reason
that the threshold
limit of 14 puffs is reached before the elapse of 6 minutes (360 seconds) in
the usage session.
The effect of the increased puffing rate on heater temperature over the course
of this reduced
length usage session can be seen in figure 5, with each applied puff
represented by a dashed
line. In this second scenario, as the thermal profile assumes successive puffs
are applied at a
time interval of 30 seconds, the effect of a real-life user applying puffs at
a faster rate of one puff
every 15 seconds is that the heater 40 never attains the temperatures needed
in the second half
of the usage session to extract all aerosol from the aerosol-forming substrate
31.
In a third scenario, the user activates the device 10 by pressing user button
50 to start a
usage session with an unused article. However, in contrast to the second
scenario, after taking
the first puff at 30 seconds from the start of the usage session, the user
then applies all
subsequent puffs spaced apart from each other at intervals of only 11 seconds.
As shown in
figure 6, this higher puff rate results in the usage session being terminated
by the device 10 even
earlier than for the second scenario. Again, early termination of the usage
session occurs for the
reason that the threshold limit of 14 puffs is reached before the elapse of 6
minutes (360 seconds)
in the usage session. The effect of the further increased puffing rate on
heater temperature over
the course of this reduced length usage session can be seen in figure 6, with
each applied puff
represented by a dashed line. As can be understood from figure 6, the
consequences of
inadequate heating of the aerosol-forming substrate 31 by the heater 40 are
even more severe
for this third scenario than they were for the second scenario of figure 5.
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Figures 5 and 6 can therefore be seen to illustrate the problems of use of a
known thermal
profile for a heater which varies target operating temperature for the heater
40 solely as a function
of elapsed time.
Figure 7 illustrates a method 100 in accordance with the present disclosure.
The
5 method 100 is performed by the aerosol-generating device 10 of the
present disclosure when a
user applies a series of puffs to the aerosol-generating device 10 during a
usage session. In
step 101, an applied puff is associated with a corresponding target operating
temperature for the
heater 40 based on the cumulative puff count of the applied puff in the usage
session. In step 102,
for the applied puff, the supply of power from the battery 26 is controlled by
the control
10 electronics 27 so as to adjust the temperature of the heater 40 to the
target operating temperature
associated with the applied puff.
Steps 101, 102 of method 100 are performed for each of puffs applied by the
user in the
usage session, until termination of the usage session. The method 100 thereby
enables the
temperature of the heater 40 to be adjusted as a function of the cumulative
puff count in a usage
15 session.
The method 100 would be performed by a combination of the control electronics
27 and a
thermal profile stored in the memory module 28. In the course of a usage
session, the control
electronics 27 would access the memory module 28 to read the thermal profile,
and then control
the supply of power from the power supply 26 in order to adjust the
temperature of the heater 40
20 according to instructions provided in the thermal profile. However, the
thermal profile employed
by method 100 is different to the prior art thermal profile described above in
relation to figures 4
to 6.
Figure 8 illustrates an example of a thermal profile for use in performing the
method 100
with aerosol-generating device 10 However, in contrast to the prior art
thermal profile described
25 previously, the thermal profile of figure 8 defines a target operating
temperature for the heater 40
as a function of puff count. So, for the thermal profile of figure 8, each
puff of a usage session is
associated with a given target operating temperature for the heater 40. The
thermal profile of
figure 8 defines a target operating temperature for each puff of a
predetermined distribution of 12
puffs. As stated above, the thermal profile is stored inside the memory module
28 of the aerosol-
generating device 10. When a user applies each puff of a series of puffs to
the device 10, the
control electronics 27 access the memory 28 to read the thermal profile. The
control
electronics 27 then control the supply of power from the battery 26 to the
heater 40 to adjust the
target operating temperature for the heater in accordance with the thermal
profile of figure 8 and
the cumulative puff count of each applied puff.
Figures 9 and 10 show two examples of how the target operating temperature for
the
heater 40 is varied with time when using the thermal profile of figure 8 for a
usage session in
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which a succession of puffs are applied by a user to the aerosol-generating
device 10. Figure 9
illustrates the temperature variation where the user applies puffs each spaced
apart by a uniform
interval, in this case of 15 seconds. Figure 10 illustrates the temperature
variation where the user
applies puffs each spaced apart by a non-uniform time interval. When examining
figures 9 and
10, it can be seen that use of the thermal profile of figure 8 results in the
target operating
temperature being adjusted on the basis of the cumulative puff count of the
applied puff in the
usage session, rather than being adjusted solely as a function of the elapsed
time in a usage
session. In essence, the target operating temperature for the heater 40 is
adjusted by tracking
the puff count of the applied puffs with reference to the thermal profile of
figure 8 stored in the
memory module 28. So, in contrast to the use of the prior art thermal profile
of figure 4, the
thermal profile of figure 8 enables the target operating temperature to be
increased over the
second half of a usage session regardless of the rate and timing of the puffs
applied by a user.
In another example, the associating of an applied puff with a corresponding
target operating
temperature may additionally be a function of a time interval between the
applied puff and an
earlier puff in the usage session. In this example, a second thermal profile
corresponding to the
profile shown in figure 8 is used. However, this second thermal profile also
contains a
"predetermined time spacing", Atpitdet. For this example, Atpredet has a value
of 30 seconds. The
predetermined time spacing Atpredet represents a hypothetical or idealised
time interval between
successive puffs in the thermal profile. In this example, the temperature in
the thermal profile
corresponding to an applied puff is itself modified dependent upon whether the
actual time
interval, At, between an applied puff and its predecessor is different to the
predetermined time
spacing Atpredet. In the thermal profile, heater temperatures Tn. Tn+1 are
defined for successive
applied puffs 'n' and 'n+1'. Where a user applies puffs to the device in a
usage session, if the
time interval At between applied puff 'n+1' and earlier puff 'n' is less than
or greater than the
predetermined time spacing Atpredet, then the temperature in the thermal
profile for puff 'n+1' is
modified in proportion to the difference between At and Atpredet. Expressed
mathematically, the
temperature of the thermal profile for puff 'n+1' is modified to a temperature
77:idif1ed as follows:
Tri+1 t-Arpred,o
Equation 3
r nn. Tn)
Atpredet )
However, the modification of the temperatures of the thermal profile is
subject to a
predetermined threshold limit of +1- 3% of the unmodified temperature.
Additionally, the
modification of the temperatures of the thermal profile is also subject to an
absolute temperature
limit of 350 degrees Celsius. In other embodiments, different values may be
set for the
percentage threshold limit and absolute temperature limit.
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For this second thermal profile, when a user applies a succession of puffs to
the aerosol-
generating device 10 over a usage session, the time interval between an
applied puff and an
earlier puff is first determined. Then the temperature in the thermal profile
corresponding to the
puff count of the applied puff (for example, for puff 'n+1 ') is modified in
accordance with the
methodology discussed above (see equation 3). The modified temperature in the
thermal profile
is then used as the target operating temperature for the applied puff, with
the control electronics
27 controlling the supply of power to the heater 40 so as to achieve this
target operating
temperature for the applied puff. If the user should happen to apply puffs at
intervals equating to
the "predetermined time spacing" Atpredet, then no modification of the
temperature(s) of the thermal
profile would occur for those puffs.
In yet another example, the associating of an applied puff with a
corresponding target
operating temperature may additionally be a function of an intensity of an
earlier puff in the usage
session. For this example, the intensity of a puff is characterised by the
volume of aerosol
generated in response to the puff. In this example, a third thermal profile
corresponding to the
profile shown in figure 8 is used.
However, this third thermal profile also contains a
"predetermined intensity", which in this example is in the form of a
predetermined volume. The
predetermined intensity (or volume) can be thought of as representing an
idealised or assumed
volume of aerosol generated by each puff in the thermal profile. For this
example, the thermal
profile has a predetermined number, N, of puffs which are assumed applied over
a usage session.
The thermal profile also has a predetermined total volume, V, of aerosol
produced over the course
of the usage session. In this example, the predetermined total aerosol volume,
V, is assumed to
be generated uniformly over each of the N puffs. So, for this thermal profile
each puff of the 'N'
puffs is assumed to result in generation of the same volume, v, of aerosol,
where v = V/N. This
volume, v, is the predetermined intensity (or volume)
In the thermal profile, heater temperatures Tõ, Tõ,, are defined for
successive applied puffs
'n' and 'n+1'. If applied puff 'n has an intensity stronger than assumed in
the thermal profile, then
the aerosol volume, vn, for puff 'n' would be greater than the predetermined
volume, v. The
greater than expected intensity (aerosol volume vn) for puff 'n' would result
in greater than
expected depletion of the substrate in response to puff 'n'. To compensate for
the greater than
expected depletion, the target operating temperature for the next puff 'n+1'
may need to be higher
than is defined in the predetermined thermal profile. Alternatively, if
applied puff 'n' has an
intensity weaker than assumed in the thermal profile, then the aerosol volume,
võ, for puff
would be less than the idealised volume, v, of the thermal profile. The less
than expected intensity
(aerosol volume vn) for puff 'n' would result in less than expected depletion
of the substrate in
response to puff 'n'. To compensate for the lower than expected depletion, the
target operating
temperature for the next puff 'n-f-1 may need to be lower than is defined in
the predetermined
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28
thermal profile. The modification of the temperature for puff 'n+1' in the
predetermined thermal
profile can be expressed shown in equations 1 and 2 recited above, which are
repeated below
for completeness:
Tril od f led = Tn+ 1. cc
for which:
Tn + 1 is the temperature initially defined in the thermal profile for puff
'n+1'
Tninifid ified is the modified temperature of the thermal profile for puff
'n+1'; and
a is a correction factor applied to T+1 to address the actual "intensity" of
puff en'. The correction
factor a will vary dependent on the amount by which the volume of aerosol, vn,
produced in
response to applied puff 'n' is greater than or less than idealised volume v.
The correction factor, a, may be expressed as follows:
cx = + ( ))I
for which:
6 is a scale factor, whose value may be chosen so as to increase or reduce the
effect of võ
being different to v when modifying the initially defined temperature Tn+1 for
puff 'n+1' of the
thermal profile.
For this third thermal profile, when a user applies a succession of puffs to
the aerosol-
generating device 10 over a usage session, the volume of aerosol generated by
each puff is
determined. Then the temperature in the thermal profile corresponding to the
puff count of the
applied puff (for example, for puff 'n+1') is modified in accordance with the
methodology discussed
above. The modified temperature in the thermal profile is then used as the
target operating
temperature for the applied puff, with the control electronics 27 controlling
the supply of power to
the heater 40 so as to achieve this target operating temperature for the
applied puff. If the user
applies puffs over a usage session each generating a volume of aerosol
equating to volume v,
then no modification of the temperatures of the thermal profile would occur.
However, it is more
probable that there will be variations in the volume of aerosol generated by
each successive puff,
with some or all of the applied puffs generating a volume of aerosol different
to volume v.
For the purpose of the present description and of the appended claims, except
where
otherwise indicated, all numbers expressing amounts, quantities, percentages,
and so forth, are
to be understood as being modified in all instances 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 enumerated herein. In this context, therefore,
a number "A" is
understood as "A" 10% of "A". Within this context, a number "A" may be
considered to include
numerical values that are within general standard error for the measurement of
the property that
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29
the number "A" modifies. The number "A", in some instances as used in the
appended claims,
may deviate by the percentages enumerated above provided that the amount by
which "A"
deviates does not materially affect the basic and novel characteristic(s) 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 enumerated herein.
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