INDUCTIVELY HEATED AEROSOL-GENERATING SYSTEM WITH AMBIENT TEMPERATURE SENSOR

Abstract

An aerosol-generating system is provided, including: a cartridge containing a volatile substrate and having a susceptor; and an aerosol-generating device configured to receive the cartridge, the aerosol-generating device including: a housing having a chamber sized to receive at least a portion of the cartridge, an inductor coil disposed around at least a portion of the chamber, a power supply, an ambient temperature sensor, and control circuitry configured to control a supply of power from the power supply to the inductor coil based on one or more ambient temperature readings from the ambient temperature sensor. An aerosol-generating device and a method of controlling inductive heating in an aerosol-generating system are also provided.

Claims

1.-15. (canceled)

16. An aerosol-generating system, comprising: a cartridge containing a volatile substrate and having a susceptor; and an aerosol-generating device configured to receive the cartridge, the aerosol-generating device comprising: a housing having a chamber sized to receive at least a portion of the cartridge, an inductor coil disposed around at least a portion of the chamber, a power supply, an ambient temperature sensor, and control circuitry configured to control a supply of power from the power supply to the inductor coil based on one or more ambient temperature readings from the ambient temperature sensor, the control circuitry being configured to control the supply of power by: adjusting a target value based on the one or more ambient temperature readings from the ambient temperature sensor, and controlling the supply of power to the inductor coil based on the adjusted target value.

17. The aerosol-generating system according to claim 16, wherein a magnitude of the adjustment of the target value varies as a function of the one or more ambient temperature readings from the ambient temperature sensor.

18. The aerosol-generating system according to claim 16, wherein a magnitude of the adjustment of the target value is determined based on a comparison of the one or more ambient temperature sensor readings with a plurality of reference ambient temperature values, each reference ambient temperature value being associated with a particular target value adjustment.

19. The aerosol-generating system according to claim 16, wherein: the power supply is a DC power supply and the control circuitry is further configured to monitor an apparent resistance of the susceptor by measuring DC current supplied from the DC power supply, the target value is a target apparent resistance of the susceptor, and the control circuitry is further configured to control the supply of DC power to the inductor coil to maintain the apparent resistance of the susceptor at the adjusted target apparent resistance value.

20. The aerosol-generating system according to claim 16, wherein the control circuitry is further configured to adjust the target value based on the one or more ambient temperature readings to raise a temperature of the cartridge from ambient temperature to a desired operating temperature in a predetermined preheating time.

21. The aerosol-generating system according to claim 16, wherein the ambient temperature sensor is spaced from the chamber configured to receive the cartridge.

22. The aerosol-generating system according to claim 21, wherein the control circuitry and the ambient temperature sensor are provided on a printed circuit board spaced from the chamber configured to receive the cartridge.

23. The aerosol-generating system according to claim 16, wherein the cartridge further comprises: a first compartment having a first air inlet and a first air outlet, the first compartment containing a nicotine source, and a second compartment having a second air inlet and a second air outlet, the second compartment containing an acid source.

24. The aerosol-generating system according to claim 23, wherein the cartridge further comprises a third compartment, separate from the first and the second compartments, and the second susceptor material is arranged in the third compartment.

25. An aerosol-generating device configured to receive a cartridge containing a volatile substrate and having a susceptor, the aerosol generating device comprising: a housing having a chamber sized to receive at least a portion of a cartridge; an inductor coil disposed around at least a portion of the chamber; a power supply; an ambient temperature sensor; and control circuitry configured to control a supply of power from the power supply to the inductor coil based on one or more ambient temperature readings from the ambient temperature sensor.

26. A method of controlling inductive heating in an aerosol-generating system comprising a cartridge containing a volatile substrate and having a susceptor and an aerosol-generating device configured to receive the cartridge, the aerosol-generating device having an inductor coil disposed around at least a portion of a chamber configured to receive the cartridge, a power supply, an ambient temperature sensor, and control circuitry configured to control a supply of power from the power supply to the inductor coil, the method comprising: sensing ambient temperature using the ambient temperature sensor; and controlling the supply of power from the power supply to the inductor coil based on one or more ambient temperature readings from the ambient temperature sensor by: adjusting a target value based on the one or more ambient temperature readings from the ambient temperature sensor, and controlling the supply of power to the inductor coil based on the adjusted target value.

27. The method according to claim 26, wherein a magnitude of the adjustment of the target resistance varies as a function of the one or more ambient temperature readings from the ambient temperature sensor.

28. The method according to claim 26, wherein a magnitude of the adjustment in the target value is determined based on a comparison of the one or more ambient temperature readings from the ambient temperature sensor with a plurality of reference ambient temperature values, each reference ambient temperature value being associated with a particular target value adjustment.

29. The method according to claim 26, wherein: the power supply of the aerosol-generating device is a DC power supply, the method further comprises the step of monitoring an apparent resistance of the susceptor, the target value is a target apparent resistance of the susceptor, and the supply of power to the inductor coil is controlled to maintain the apparent resistance of the susceptor at the adjusted target apparent resistance.

30. The method according to claim 26, wherein the target value is adjusted based on the one or more ambient temperature readings to raise a temperature of the cartridge from the ambient temperature to a desired operating temperature in a predetermined preheating time.

Description

[0132] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0133] FIG. 1 shows a perspective view of a cartridge according to an embodiment of the present invention;

[0134] FIG. 2 shows a cross-sectional view of the cartridge of FIG. 1 along the line A-A;

[0135] FIG. 3 shows a perspective view of the distal end cap of the cartridge of FIG. 1;

[0136] FIG. 4 shows cross-sectional plan view of the cartridge portion of the cartridge of FIG. 1, along the line B-B;

[0137] FIG. 5 shows a partially exploded perspective view of the cartridge of FIG. 1, including the nicotine source and susceptor arrangement and the lactic acid source and susceptor arrangement;

[0138] FIG. 6 shows an embodiment of an aerosol-generating system according to the present invention having the cartridge of FIG. 1 and an aerosol-generating device;

[0139] FIG. 7 shows an embodiment of control circuitry for the device of FIG. 6;

[0140] FIG. 8 shows a first example of a target apparent resistance profile over time set by the control circuitry of the device of FIG. 6; and

[0141] FIG. 9 shows a second example of a target apparent resistance profile over time set by the control circuitry of the device of FIG. 6.

[0142] FIGS. 1 to 5 show schematic illustrations of a cartridge according to an embodiment of the invention for use in an aerosol-generating system for generating an aerosol comprising nicotine lactate salt particles.

[0143] The cartridge 102 comprises an elongate body 104 and a distal end cap 106. The cartridge 102 has a length of about 28 millimetres and a diameter of about 6.9 millimetres.

[0144] The cartridge 102 comprises a cartridge portion 105 at a distal end of the cartridge, which extends between the distal end of the body 104 and a proximal end wall 108. The cartridge portion 105 has a length of about 15 millimetres and a diameter of about 6.9 millimetres.

[0145] The cartridge portion 105 of the cartridge 102 comprises an elongate first compartment 110 that extends from the distal end of the body 104 to the proximal end wall 108. The first compartment 110 contains a nicotine source and susceptor arrangement 112 in accordance with the present invention. The nicotine source comprises a first carrier material impregnated with about 10 milligrams of nicotine and about 4 milligrams of menthol. The susceptor comprises a ferromagnetic stainless steel mesh covering one side of the first carrier material.

[0146] The cartridge portion 105 of the cartridge 102 also comprises an elongate second compartment 114 that extends from the distal end of the body 104 to the proximal end wall 108. The second compartment 114 contains a lactic acid source and susceptor arrangement 116 in accordance with the present invention. The lactic acid source comprises a second carrier material impregnated with about 20 milligrams of lactic acid. The susceptor comprises a ferromagnetic stainless steel mesh covering one side of the second carrier material.

[0147] The first compartment 110 and the second compartment 114 are arranged in parallel. The first compartment 110 and the second compartment 114 are arranged adjacent to each other, separated by a partition wall 118.

[0148] The first compartment 110 and the second compartment 114 are substantially the same shape and size. The first compartment 110 and the second compartment 114 have a length of about 12 millimetres, a width of about 5 millimetres and a height of about 1.7 millimetres.

[0149] The first carrier material and the second carrier material comprise a non-woven sheet of PET/PBT and are substantially the same shape and size. The shape and size of the first carrier material and the second carrier material is similar to the shape and size of the first compartment 110 and the second compartment 114 of the cartridge 102, respectively.

[0150] As shown in FIG. 3, the distal end cap 106 comprises a first elongate raised portion 119 and a second elongate raised portion 121. The first and second elongate raised portions 119, 121 are arranged in parallel and extend out of the plane of the cap 106 in substantially the same direction. The first elongate raised portion 119 is sized and arranged to be received in the open distal end of the first compartment 110 and the second elongate raised portion 121 is sized and arranged to be received in the open distal end of the second compartment 114. The distal end cap 106 further comprises a first air inlet 120 comprising a row of two spaced apart apertures and a second air inlet 122 comprising a row of four spaced apart apertures. The row of apertures of the first air inlet 120 and the row of apertures of the second air inlet 122 are arranged in parallel.

[0151] The row of apertures of the first air inlet 120 are arranged along the first raised portion 119 and extend through the first raised portion 119. The row of apertures of the second air inlet 122 are arranged along the second raised portion 121 and extend through the second raised portion 121. Each of the apertures forming the first air inlet 120 and the second air inlet 122 is of substantially circular transverse cross-section and has a diameter of about 0.5 millimetres.

[0152] As shown in FIG. 4, the proximal end wall 108 of the cartridge portion 105 comprises a first air outlet 126 comprising a row of two spaced apart apertures and a second air outlet 128 comprising a row of four spaced apart apertures. The first air outlet 126 is aligned with the first compartment 110 and the second air outlet 128 is aligned with the second compartment 114. Each of the apertures forming the first air outlet 126 and the second air outlet 128 is of substantially circular transverse cross-section and has a diameter of about 0.5 millimetres.

[0153] Also as shown in FIG. 4, the first compartment 110 comprises two protrusions or ribs 127 protruding from the partition wall 118 towards the opposite side of the chamber 110. The protrusions 127 of the first chamber 110 extend substantially the length of the first compartment 110 and are spaced apart such that an air channel forms between the protrusions. The second compartment 114 comprises three protrusions or ribs 129 protruding from the partition wall 118 towards the opposite side of the chamber 114. The protrusions 129 of the second chamber 114 are substantially similar to the protrusions of the first chamber 110, having the same width and extending substantially the length of the second chamber 114. The protrusions 129 of the second chamber 124 are spaced apart such that two air channels are formed between them, one air channel between each of the adjacent protrusions. The protrusions 127 of the first chamber 110 and the protrusions 129 of the second chamber 114 are provided to space the first and second carrier material and susceptor arrangements 112, 116 from the partition wall 118, to ensure sufficient airflow over the outer surface of the carrier material and susceptor arrangements at least on one side.

[0154] As shown in FIG. 5, to form the cartridge 102, the first carrier material is impregnated with nicotine and menthol and the first carrier material and susceptor arrangement 112 is inserted into the first compartment 110 and the second carrier material is impregnated with lactic acid and the second carrier material and susceptor arrangement 116 is inserted into the second compartment 114. The distal end cap 106 is then inserted onto the distal end of the body 104 such that the first air inlet 120 is aligned with the first compartment 110 and the second air inlet 122 is aligned with the second compartment 114.

[0155] The first air inlet 120 is in fluid communication with the first air outlet 126 so that a first air stream may pass into the cartridge 102 through the first air inlet 120, through the first compartment 110 and out of the cartridge 102 though the first air outlet 126. The second air inlet 122 is in fluid communication with the second air outlet 128 so that a second air stream may pass into the cartridge 102 through the second air inlet 122, through the second compartment 114 and out of the cartridge 102 though the second air outlet 128.

[0156] Prior to first use of the cartridge 102, the first air inlet 120 and the second air inlet 122 may be sealed by a removable peel-off foil seal or a pierceable foil seal (not shown) applied to the external face of the distal end cap 106. Similarly, prior to first use of the cartridge 102, the first air outlet 126 and the second air outlet 128 may be sealed by a removable peel-off foil seal or a pierceable foil seal (not shown) applied to the external face of the proximal end wall of the body 104.

[0157] The cartridge 102 further comprises a third compartment 130 downstream of the first compartment 110 and the second compartment 114 and in fluid communication with the first air outlet 120 of the first compartment 110 and the second air outlet 122 of the second compartment 114. During use, the nicotine vapour in the first air stream react with the acid vapour in the second air stream in the third compartment 130 to form an aerosol of nicotine salt particles.

[0158] The third compartment 130 comprises a single opening 132 at the proximal end of the compartment, with a diameter of about 1.3 millimetres. The third compartment 130 also comprises a ventilation inlet 132 to allow external air to enter the third compartment and dilute the nicotine, acid and nicotine lactate salt vapours. The ventilation inlet has a diameter of about 0.5 millimetres.

[0159] The cartridge 102 also comprises a mouthpiece portion 140 downstream of the third compartment 130 and in fluid communication with the opening 132 at the proximal end of the third compartment 130. The mouthpiece portion 140 has a length of about 13 millimetres and an opening at the proximal end of the cartridge 102 with a diameter of about 5 millimetres.

[0160] In use, a user draws on the mouthpiece portion 140 of the cartridge 102 to draw air through the first and second compartments 110, 112 into the third compartment 130, through the third compartment 130 into the mouthpiece portion 140 and out of the mouthpiece portion 140 through the opening at the proximal end.

[0161] FIG. 6 shows a schematic illustration of an aerosol-generating system 200 according to an embodiment of the invention for generating an aerosol comprising nicotine lactate salt particles.

[0162] The aerosol-generating system comprises an aerosol-generating device 202 and a cartridge 102 according the embodiment of the invention shown in FIGS. 1 to 5. The aerosol-generating device 202 comprises a housing 204 defining a cavity 206 at a proximal end of the housing 204 for receiving the distal portion of the cartridge 102 between the distal end cap 106 and the proximal end wall 108.

[0163] An inductor coil 208 is provided along the length of the cavity 206, and is coaxially aligned with the cavity 206 such that the coil 208 substantially circumscribes the cavity. When the cartridge 102 is received in the cavity 206, the inductor coil 208 extends along the length of the first and second compartments 110, 114.

[0164] The aerosol-generating device 202 further comprises a power supply 210 and control circuitry 212 housed within the housing 204. The power supply 210 is connected to the inductor coil 208 via the control circuitry 212 and the control circuitry is configured to control the supply of power supplied to the inductor coil 208 from the power supply 210.

[0165] The power supply 210 is configured to provide a high frequency oscillating current to the inductor coil 208, with a frequency of between about 5 and about 7 MHz. In operation, the high frequency oscillating current is passed through the inductor coil 208 to generate an alternating magnetic field that induces a voltage in the susceptor elements. The induced voltage causes a current to flow in the susceptor elements and this current causes Joule heating of the susceptor elements that in turn heats the nicotine in the first chamber 110 and the acid in the second chambers 114. During use, the control circuitry 212 of the aerosol-generating device 202 controls the supply of power from the power supply 210 aerosol-generating device 202 to the inductor coil 208 to heat the susceptor in the first compartment 110 and the susceptor in the second compartment 114 of the cartridge 102 to substantially the same temperature of about 100° C.

[0166] The control circuitry 212 comprises a microcontroller having a temperature sensor 214, in accordance with the present invention.

[0167] In this embodiment, the control circuitry 212 is arranged at a distal end of the device 202, opposite a proximal end of the device 202 comprising the cavity 206 for receiving the cartridge 102. Since the control circuitry 212 is arranged at the opposite end of the device 202 to the cavity 206, the control circuitry 212 is substantially thermally isolated from the cavity 206. In other words, the control circuitry 212 is spaced from the cavity 206 such that raising the temperature of the cartridge does not raise the temperature of the control circuitry 212. Since the control circuitry 212 is thermally isolated from the cavity 206, the temperature sensor 214 of the control circuitry 212 may be used as an ambient temperature sensor. Advantageously, this arrangement of the control circuitry and the ambient temperature sensor in the device may simplify construction of the device and may the reduce cost, as an additional temperature sensor, separate from the control circuitry 212, is not required.

[0168] When the cartridge 102 has been inserted into the cavity 206 of the aerosol-generating device 202, the mouthpiece 140 extends out of the cavity 206 such that a user may access the mouthpiece 140 to draw on the proximal end and receive an aerosol of nicotine lactate salt particles.

[0169] The device 202 comprises a switch (not shown). In use, a user presses the switch to turn on the device 202. When the device is turned on, the control circuitry 212 supplies an oscillating current from the power supply 210 to the inductor coil 208 to heat the susceptor elements in the first and second compartments of the cartridge 102. The system 200 requires the temperature of the first and second compartments to be increased to an operating temperature of around 100 degrees Celsius before a user may take a first puff on the device. This is to ensure consistent aerosol of nicotine lactate salt particles is generated. In this embodiment, the preheating time is around 5 seconds, if the system 200 is heated from an ambient room temperature of 20 degrees Celsius. After the preheating time, when the first and second compartments are at an operating temperature of around 100 degrees Celsius, a user may take a first puff on the mouthpiece 140 of the cartridge 102. When taking a puff, the user draws on the proximal end of the mouthpiece 140 to draw a first air stream through the first compartment 110 of the cartridge 102 and a second air stream through the second compartment 114 of the cartridge 102. As the first air stream is drawn through the first compartment 110 of the cartridge 102, nicotine vapour is released from the first carrier material into the first air stream. As the second air stream is drawn through the second compartment 114 of the cartridge 102, lactic acid vapour is released from the second carrier material into the second air stream. The nicotine vapour in the first air stream and the lactic acid vapour in the second air stream are drawn from the first and second compartments into the third compartment 130. Ambient air is also drawn into the third compartment 130 via the ventilation inlet 134. In the third compartment 130 the nicotine vapour from the first air stream and the lactic acid vapour in the second air stream react with one another in the gas phase to form an aerosol of nicotine salt particles. The aerosol of nicotine salt particles is drawn out of the third compartment 130 through the proximal opening 132 into the mouthpiece 140 and is delivered to the user through the proximal end of the mouthpiece 140.

[0170] FIG. 7 illustrates an example of part of a control circuit 212 that may be used to provide a high frequency oscillating current to the inductor coil, using a Class-E power amplifier. As can be seen from FIG. 7, the circuit includes a Class-E power amplifier including a transistor switch 1100 comprising a Field Effect Transistor (FET) 1110, for example a Metal-Oxide-Semiconductor Field Effect Transistor (MOSFET), a transistor switch supply circuit indicated by the arrow 1120 for supplying the switching signal (gate-source voltage) to the FET 1110, and an LC load network 1130 comprising a shunt capacitor C1 and a series connection of a capacitor C2 and inductor coil L2. The DC power source, which comprises the battery 210, includes a choke L1, and supplies a DC supply voltage. Also shown in FIG. 7 is the ohmic resistance R representing the total ohmic load 1140, which is the sum of the ohmic resistance R.sub.Coil of the flat spiral inductor coil, marked as L2, and the ohmic resistance R.sub.Load of the susceptor element.

[0171] The DC supply voltage V.sub.DC and the DC current I.sub.DC drawn from the DC power source (the battery 210) are shown in FIG. 7. The DC supply voltage V.sub.DC and the DC current I.sub.DC drawn from the DC power source are provided by feed-back channels (not shown) to the microcontroller of the control circuitry 212. Measurements of both the DC supply voltage V.sub.DC and the DC current I.sub.DC drawn from the DC power source are used to determine the apparent resistance R.sub.A of the susceptor. More specifically, the quotient of the DC supply voltage V.sub.DC and the DC supply current I.sub.DC are used to determine the apparent resistance R.sub.A of the susceptor. The apparent resistance R.sub.A of susceptor is used to control the further supply of AC power to the LC load network, and in particular to inductor L2, as described in more detail below.

[0172] In this embodiment, both the DC supply voltage V.sub.DC and the DC current I.sub.DC drawn from the DC power source are measured, which may be achieved with a suitable DC voltage sensor and a suitable DC current sensor integrated in the circuit. However, in some embodiments the DC power source may be a constant voltage DC power source, and as such, the DC supply voltage V.sub.DC may be known. In these embodiments, only the DC current I.sub.DC drawn from the DC power source needs to be measured, and so the DC voltage sensor may be dispensed with.

[0173] Due to the very low number of components the volume of the power supply electronics can be kept extremely small. This extremely small volume of the power supply electronics is possible due to the inductor L2 of the LC load network 1130 being directly used as the inductor for the inductive coupling to the susceptor element, and this small volume allows the overall dimensions of the entire inductive heating device to be kept small.

[0174] The general operating principle of the Class-E power amplifier is known and is described in detail in “Class-E RF Power Amplifiers”, Nathan O. Sokal, published in the bimonthly magazine QEX, edition January/February 2001, pages 9-20, of the American Radio Relay League (ARRL), Newington, Conn., U.S.A., and in WO 2015/177043 A1, in the name of Philip Morris Products S.A.

[0175] Although a Class-E power amplifier is preferred for most systems in accordance with the disclosure, it is also possible to use other circuit architectures, such as circuit architectures including a Class-D power amplifier, as also described in WO 2015/177043 A1, in the name of Philip Morris Products S.A.

[0176] As mentioned above, the control circuitry 212 is configured to measure the apparent resistance R.sub.A of the susceptor

[0177] In accordance with the present invention, the microcontroller of the control circuitry 212 is programmed to measure the apparent resistance R.sub.A of the susceptor and control the power supplied from the DC power supply 210 to the inductor coil 208 to maintain the apparent resistance R.sub.A of the susceptor at a target apparent resistance value over time. The control circuitry 212 is configured to control the supply of power from the DC power supply 210 to the inductor coil 208 by controlling the switch duty cycle of the class-E power amplifier.

[0178] A “normal” or “standard” target apparent resistance value, R.sub.0, corresponds to the desired target apparent resistance of the susceptor when the system is being used in a normal ambient temperature range. In this embodiment, a normal ambient temperature range is between 13 degrees Celsius and 27 degrees Celsius (i.e. 7 degrees Celsius above and below a normal room temperature of 20 degrees Celsius).

[0179] The control circuitry 212 is programmed to measure the ambient temperature in the vicinity of the system by taking ambient temperature readings from the ambient temperature sensor 214.

[0180] The control circuitry 212 is programmed to measure the ambient temperature before supplying power to from the power supply 210 to the inductor coil 208.

[0181] When the ambient temperature readings from ambient temperature sensor 214 indicate that the ambient temperature is within the normal ambient temperature range, the control circuitry 212 is programmed to supply power from the power supply 210 to the inductor coil 208, measure the apparent resistance of the susceptor 210, compare the measured apparent resistance to the normal target apparent resistance R.sub.0 and control the supply of power from the power supply 210 to the inductor coil 208 to maintain the measured apparent resistance at the normal target apparent resistance R.sub.0.

[0182] In this example, when the ambient temperature readings from ambient temperature sensor 214 indicate that the ambient temperature is outside of the normal ambient temperature range, the control circuitry 212 is configured to adjust the normal target apparent resistance value, R.sub.0, by a predetermine amount. In this way, the control circuitry 212 is programmed to compensate for the ambient temperature in which the system is being used. It has been found that this temperature control may improve the consistency of the aerosol generated by such an aerosol-generating system.

[0183] FIGS. 8 and 9 illustrate two exemplary target apparent resistance profiles for the system and two target apparent resistance profile adjustments in accordance with the present invention.

[0184] FIG. 8 illustrates a first exemplary target apparent resistance profile during an aerosol-generating experience. In this example, target apparent resistance value is constant during the aerosol-generating experience. In other words, the target apparent resistance value for the system does not vary with time during the aerosol-generating experience.

[0185] In this example, a normal target apparent resistance value, R.sub.0, is stored on a memory of the control circuitry. The normal target apparent resistance value R.sub.0 is set during a calibration procedure before first use of the device, such as in the factory before the device is shipped. Calibration may comprise providing a cartridge in the device as shown in FIG. 6 above, arranging the cartridge and device in an environment having a known ambient temperature, supplying power from the DC power supply to the inductor coil to heat susceptor in the cartridge, measuring the temperature of the susceptor using a separate temperature sensor and measuring the apparent resistance of the susceptor when the temperature of the susceptor reaches a desired temperature. The normal target resistance value, R.sub.0, is taken to be the measured apparent resistance and is stored on a memory of the control circuitry.

[0186] When the ambient temperature readings indicate that the ambient temperature is within the normal ambient temperature range (i.e. in this example, between 13 degrees Celsius and 27 degrees Celsius) the control circuitry is programmed to adjust the duty cycle of the power supply such that the apparent resistance of the susceptor is maintained at the normal target apparent resistance value R.sub.0.

[0187] Predetermined adjustment values for the target apparent resistance value are also stored on the memory of the control circuitry. The predetermined adjustment values are also set during a calibration procedure, similar to the calibration procedure for the normal target apparent resistance value. Each adjustment value may be based on a measured apparent resistance of the susceptor when the susceptor is at a known temperature.

[0188] When the ambient temperature readings indicate that the ambient temperature is below the normal ambient temperature range (i.e. in this example, below 13 degrees Celsius) the control circuitry is programmed to add a first predetermined adjustment value, R.sub.1, to the normal target apparent resistance value. The control circuitry is further programmed to adjust the duty cycle of the power supply such that the apparent resistance of the susceptor is maintained at the adjusted target apparent resistance value, R.sub.0+R.sub.1.

[0189] When the ambient temperature readings indicate that the ambient temperature is above the normal ambient temperature range (i.e. in this example, above 27 degrees Celsius) the control circuitry is programmed to subtract a second predetermined adjustment value, R.sub.2, from the normal target apparent resistance value. The control circuitry is further programmed to adjust the duty cycle of the power supply such that the apparent resistance of the susceptor is maintained at the adjusted target apparent resistance, R.sub.0−R.sub.2.

[0190] FIG. 9 illustrates a second exemplary target apparent resistance profile during an aerosol-generating experience. In this example, the target apparent resistance value is a first value R.sub.0′ during a preheating time period T.sub.0 and is a second value R.sub.0 after the preheating time period T.sub.0.

[0191] In this example, a normal preheating target apparent resistance value, R.sub.0′, is stored on a memory of the control circuitry, associated with a predetermined preheating time period T.sub.0, and a normal target apparent resistance value, R.sub.0, is also stored on a memory of the control circuitry.

[0192] When the ambient temperature readings indicate that the ambient temperature is within the normal ambient temperature range (i.e. in this example, between 13 degrees Celsius and 27 degrees Celsius) the control circuitry is programmed to adjust the duty cycle of the power supply such that the apparent resistance of the susceptor is maintained at the normal preheating target apparent resistance value R.sub.0′ during a preheating time period T.sub.0, and to adjust the duty cycle of the power supply such that the apparent resistance of the susceptor is maintained at the normal target apparent resistance value R.sub.0 after a preheating time period T.sub.0.

[0193] When the ambient temperature readings indicate that the ambient temperature is below the normal ambient temperature range (i.e. in this example, below 13 degrees Celsius) the control circuitry is programmed to add a first predetermined adjustment value, R.sub.1, to the normal preheating target apparent resistance value R.sub.0′ and to the normal target apparent resistance value R.sub.0. The control circuitry is further programmed to adjust the duty cycle of the power supply such that the apparent resistance of the susceptor is maintained at the adjusted preheating target apparent resistance, R.sub.0′+R.sub.1, for the preheating time period T.sub.0, and at the adjusted target apparent resistance, R.sub.0+R.sub.1, after the preheating time period T.sub.0.

[0194] When the ambient temperature readings indicate that the ambient temperature is above the normal ambient temperature range (i.e. in this example, above 27 degrees Celsius) the control circuitry is programmed to subtract a second predetermined adjustment value, R.sub.2, from the normal preheating target apparent resistance value R.sub.0′, and from the normal target apparent resistance value R.sub.0. The control circuitry is further programmed to adjust the duty cycle of the power supply such that the apparent resistance of the susceptor is maintained at the adjusted preheating target apparent resistance, R.sub.0′−R.sub.2, for the preheating time period T.sub.0, and at the adjusted target apparent resistance, R.sub.0−R.sub.2, after the preheating time period T.sub.0.

[0195] In this example, the normal preheating target resistance is constant over the preheating time period; however, it will be appreciated that in other embodiments the normal preheating target resistance may be increased over time from an initial preheating target resistance to a final preheating target resistance. The rate of increase may be constant, such that the increase is linear with time, or may increase or decrease such that the increase forms a convex or concave curve with time. The rate of increase may be determined by the materials and geometry of the susceptor.

[0196] In this example, the magnitude of the adjustment of the target apparent resistance value is the same for each target apparent resistance value in the target apparent resistance profile. In other words, the same amount is added to or subtracted from the target preheating apparent resistance and the target apparent resistance.

[0197] In both of these examples, the magnitude of the first adjustment value R.sub.1 and the second adjustment value R.sub.2 are the same. However, it will be appreciated that in other examples each adjustment value may have a different magnitude.

[0198] In some embodiments, the control circuitry may be programmed to adjust the normal target apparent resistance, R.sub.0, by further predetermined amounts when the ambient temperature readings indicate that the ambient temperature is outside of one or more further ambient temperature ranges. For example, an extreme ambient temperature range may be defined by ambient temperature indications below 15 degrees Celsius and above 35 degrees Celsius. When the ambient temperature is determined to be below the extreme ambient temperature threshold (i.e. below 5 degrees Celsius), the control circuitry may be programmed to increase the normal target apparent resistance R.sub.0 by a third predetermined amount, R.sub.3, greater than the first predetermined amount, R.sub.1, such that the target apparent resistance value is R.sub.0 +R.sub.3. When the ambient temperature is determined to be above the extreme ambient temperature threshold (i.e. above 35 degrees Celsius), the control circuitry may be programmed to decrease the normal target apparent resistance R.sub.0 by a fourth predetermined amount, R.sub.4, greater than the second predetermined amount, R.sub.2, such that the target apparent resistance value is R.sub.0−R.sub.4.

[0199] In some embodiments, the control circuitry may be programmed to substantially prevent or inhibit power from being supplied from the power supply to the inductor coil when the ambient temperature readings indicate that the ambient temperature is outside of a particular operating temperature range.

[0200] In some embodiments, the target apparent resistance value may be adjusted by amounts that vary over time. In some embodiments, the control circuitry may be configured to take ambient temperature readings during an aerosol-generating experience and to adjust the target apparent resistance value based on the ambient temperature readings throughout the aerosol generating experience. In some embodiments, the target apparent resistance value is adjusted as a function of the ambient temperature readings, based on a known relationship between susceptor temperature and the apparent resistance.

[0201] Other cartridge designs incorporating susceptor elements in accordance with this disclosure can now be conceived by one of ordinary skill in the art. For example, the cartridge may not comprise susceptor elements in one or more of the first and second compartments, but rather may comprise may comprise one or more susceptor elements arranged in one or more additional compartments, isolated from the first and second compartments such that the one or more susceptor elements do not contact the nicotine or the acid. In some embodiments, the cartridge may comprise one or more susceptor elements within one or more of the first and second compartments and one or more susceptor elements in one or more additional compartments, isolated from the nicotine and acid. For example, the cartridge may not include a mouthpiece portion, but rather the device may include a mouthpiece portion. The mouthpiece portion may have any desired shape. Furthermore, a coil and susceptor arrangement in accordance with the disclosure may be used in systems of other types to those already described, such as humidifiers, air fresheners, and other aerosol-generating systems comprising cartridges.

[0202] It will also be appreciated that other types of cartridges containing other types of volatile substrate may be used with such a device comprising an ambient temperature sensor according to the invention. For example, a cartridge comprising a susceptor and a single compartment containing a liquid aerosol-forming substrate may be used with such a device having an ambient temperature sensor. In these embodiments, the device may be configured to supply sufficient power to the inductor coil to heat the susceptor to vaporise an aliquot of the aerosol-forming substrate. In these embodiments, the device may comprise a puff sensor, and the control circuitry may be configured to supply power to the inductor coil when a puff from a user is detected by the puff sensor. In another example, cartridges in the form of a rod comprising a solid aerosol-forming substrate, such as a plug of homogenised, crimped tobacco, a susceptor and a filter, wrapped together in the form of a rod, for example with cigarette paper, may be used with such a device having an ambient temperature sensor.

[0203] The exemplary embodiments described above are illustrative but are not limiting. In view of the above discussed exemplary embodiments, other embodiments consistent with the above exemplary embodiments will now be apparent to one of ordinary skill in the art.