Aerosol generating device, method and control circuit therefor

Abstract

1. A method for controlling an aerosol generating device, the method comprising: receiving, via a user input element, an instruction to initiate an aerosol generation session; receiving a heater temperature measured by a temperature sensor; retrieving a session counter value from a memory; controlling the heater to perform an aerosol generation session according to the heater temperature and the session counter value; and resetting the session counter value if the heater temperature falls below a first predetermined temperature. A control circuit is configured to perform the method. The aerosol generating device includes a control circuit.

Description

[Technical field]

[0001] The present disclosure relates to an aerosol generating device in which an aerosol-generating substrate is heated to form an aerosol. The disclosure is particularly applicable to portable aerosol generating devices that may be self-contained and low-temperature. Such devices may heat tobacco or other suitable aerosol substrate material by conduction, convection, and / or radiation, rather than by combustion, to generate an aerosol for inhalation. [Background technology]

[0002] The popularity and use of risk reduction or risk modification devices (also known as vaporizers) has grown rapidly in recent years as an aid to assist habitual smokers wishing to quit smoking traditional tobacco products such as cigarettes, cigars, cigarillos, and rolling tobacco. A variety of devices and systems are available that heat or warm an aerosolizable substance, as opposed to burning tobacco in traditional tobacco products.

[0003] A commonly available risk reduction or risk modification device is the substrate heated aerosol generating device or heat-not-burn device. This type of device generates an aerosol or vapor by heating an aerosol substrate, which typically includes moist tobacco or other suitable aerosolizable material, to a temperature typically ranging from 150°C to 350°C. By heating rather than burning or combusting the aerosol substrate, an aerosol is released that includes the ingredients desired by the user but does not include the toxic and carcinogenic by-products of combustion and burning. Furthermore, aerosols generated by heating tobacco or other aerosolizable material typically do not include the burnt or bitter taste that can result from combustion and burning, which can be unpleasant to the user. Thus, the substrate does not require sugars and other additives that are typically added to such materials to make the smoke and / or vapor more palatable to the user. Summary of the Invention [Problem to be solved by the invention]

[0004] Aerosol generating devices are often handheld. However, the operating temperatures for aerosol generation are too high for direct contact by the user of the device. It is therefore desirable to provide a safe device that does not reach temperatures that would affect the comfort or safety of the user. [Means for solving the problem]

[0005] According to a first aspect, the present disclosure provides a method for controlling an aerosol generating device, comprising receiving an instruction via a user input element to start an aerosol generating session, receiving a heater temperature measured by a temperature sensor, retrieving a session counter value from a memory, controlling the heater to perform an aerosol generating session according to the heater temperature and the session counter value, and resetting the session counter value if the heater temperature falls below a first predetermined temperature.

[0006] The session counter value is a counter indicating the number of aerosol generation sessions that were performed while the device was in a relatively hot state, i.e., without the device reaching thermal equilibrium after the session.

[0007] It is inevitable that some heat will leak from the heater to the rest of the aerosol generating device. By controlling the heater according to its temperature and the session counter, the heat accumulation in the rest of the aerosol generating device can be estimated, and as a result, the temperature of the rest of the aerosol generating device can also be estimated.

[0008] Setting a session limit also limits the temperature of the rest of the aerosol generating device. The session limit may be set, for example, by empirically determining the number of times that consecutive sessions can be performed.

[0009] Optionally, the session counter value is incremented at the start of an aerosol generation session.

[0010] Incrementing the session counter value at the beginning of an aerosol generation session improves the safety of the device compared to counting completed aerosol generation sessions. For example, an aerosol generation session may not be completed if the user presses a button to shut off the device or removes consumables from the device. However, this may occur after a significant amount of heat has been delivered in the aerosol generation session. By counting sessions at the beginning, the session counter value is biased to overestimate and indicate the temperature of the aerosol generation device, which further reduces the possibility that the aerosol generation device will become too hot for the user.

[0011] Resetting the session counter value based on the heater temperature provides an additional safety feature because the rate at which the device cools down depends on external factors such as the ambient temperature, and therefore verifying cooling directly is the most predictable way to ensure that the device is safe for continued use.

[0012] Optionally, the method includes resetting the session counter value when the temperature of the heater falls below a second predetermined temperature that is higher than the first predetermined temperature and the session counter value is lower than the first predetermined session limit.

[0013] By providing a first absolute threshold and a higher second conditional temperature threshold for resetting the session counter value, a user can strike a compromise between safety and user convenience by being able to perform more consecutive aerosol generation sessions, as long as some time is allowed for cooling between sessions.

[0014] Optionally, the aerosol generation session includes a temperature increase phase, increasing the temperature of the heater to at least a third predetermined temperature, a temperature maintenance phase, maintaining the temperature of the heater, and a temperature decrease phase, decreasing the temperature of the heater below the third predetermined temperature.

[0015] By maintaining the heater temperature for a stage of the aerosol generation session, aerosols can be generated effectively and efficiently.

[0016] Optionally, the method further comprises controlling the heater to not perform the aerosol generating session if the session counter value is greater than or equal to a second predetermined session limit.

[0017] Prohibiting an aerosol generating session when the session limit is reached has the effect of reducing the risk of the aerosol generating device becoming excessively hot.

[0018] Optionally, the method further includes controlling the heater to not perform the aerosol generation session if the temperature of the heater is greater than a fourth predetermined temperature when an instruction to start an aerosol generation session is received, regardless of the session counter value.

[0019] By setting a heater temperature above which an aerosol generating session will not begin, a minimum level of cooling is enforced between sessions, thereby increasing the number of nearly consecutive sessions that can be performed while maintaining user safety and comfort.

[0020] Optionally, if the temperature of the heater is below a fifth predetermined temperature when an instruction to start an aerosol generation session is received, the session counter value is not incremented.

[0021] By setting a heater temperature that must not be exceeded before a session is considered consecutive, the device avoids unnecessarily limiting aerosol generation sessions when adequate cooling between sessions is possible.

[0022] Optionally, the method includes, after receiving an instruction to start an aerosol generation session, controlling a heater not to perform an aerosol generation session, and controlling a user output element to indicate a status that the instruction has been received but the aerosol generation session is not being performed.

[0023] Providing a status indication when an aerosol generating session is prohibited allows the user to understand that the device is functioning properly and ensures that the above safety features do not make the device difficult to use.

[0024] Optionally, the method includes, after receiving an instruction to start an aerosol generation session, controlling the heater not to perform the aerosol generation session, waiting until the temperature of the heater drops below a sixth predetermined temperature, and then performing the aerosol generation session.

[0025] Delaying the aerosol generation session until the heater temperature has decreased allows for safe and frequent aerosol generation sessions while ensuring safety and comfort.

[0026] Optionally, the heater comprises a heating element and the temperature sensor is positioned to measure the temperature of the heating element.

[0027] Optionally, the heating element comprises a flexible sheet having resistive tracks and a temperature sensor mounted thereon.

[0028] Optionally, the heater comprises a heating chamber for receiving the consumable and insulation surrounding the heating chamber, the temperature sensor being disposed between the heating chamber and the consumable.

[0029] Optionally, the heater comprises a pot-shaped heating chamber having an open end for receiving the consumable, and comprises a heating element arranged to supply heat to the heating chamber through a sidewall of the heating chamber.

[0030] According to a second aspect, the present disclosure provides a control circuit configured to carry out the method as above.

[0031] Optionally, the control circuit is a control circuit for an aerosol generating device additionally comprising a second temperature sensor for measuring a temperature of the control circuit, and the method further includes controlling the heater to not perform the aerosol generation session, regardless of the session counter value, if the temperature of the control circuit is higher than a seventh predetermined temperature when an instruction to start an aerosol generation session is received.

[0032] By specifically measuring the temperature of the control circuit prior to performing an aerosol generation session and setting a threshold that, if exceeded, will not cause the aerosol generation session to be performed, safety can be improved by reducing the likelihood of the control circuit falling outside of its normal operating temperature range.

[0033] According to a third aspect, the present disclosure provides an aerosol generating device comprising the above control circuit, a heater for heating a consumable aerosol-generating substrate to generate an aerosol, a temperature sensor for measuring the temperature of the heater, a user input element for initiating an aerosol generation session, and a memory for storing a session counter value. [Brief description of the drawings]

[0034] [Figure 1] FIG. 1 is a schematic diagram of an aerosol generating device. [Diagram 2] FIG. 2 is a schematic diagram of a heater for an aerosol generating device. [Diagram 3] 1 is a flow chart that generally illustrates a method for controlling an aerosol generating device. [Figure 4] 1 is a graph showing a schematic representation of an aerosol generation session in an aerosol generating device, with heater temperature shown on the y-axis and time shown on the x-axis. [Diagram 5] 10 is a flow chart that generally illustrates additional details of a method for controlling an aerosol generating device. [Figure 6] 10 is a flow chart that generally illustrates additional details of a method for controlling an aerosol generating device. [Figure 7] 1 is a graph showing a schematic representation of successive aerosol generation sessions in an aerosol generating device, with heater temperature shown on the y-axis and time shown on the x-axis. [Figure 8] 1 is a graph showing a schematic representation of successive aerosol generation sessions in an aerosol generating device, with heater temperature shown on the y-axis and time shown on the x-axis. [Figure 9] 10 is a flow chart that generally illustrates additional details of a method for controlling an aerosol generating device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] FIG. 1 is a schematic diagram of an aerosol generating device 1 comprising a heating chamber 11, a heating element 12, a control circuit 14, a power supply 15, a temperature sensor 13, a user input element 16 and a lid 17.

[0036] In use, an aerosol-generating substrate is received in the heating chamber 11 and the heating element 12 supplies heat within the heating chamber 11 to heat the substrate and generate an aerosol. Additionally, a temperature sensor 13 is disposed in or near the heating chamber 11. The heating chamber 11, heating element 12, and temperature sensor 13 together may be referred to as a heater.

[0037] The heating chamber 11 is a structure having an internal hollow and adapted to receive an aerosol-generating substrate. The heating chamber 11 may be formed, for example, from ceramic or metal. For example, the heating chamber 11 may be formed by bending or pressing a sheet of metal. In one example, the heating chamber 11 may be a tubular structure with a sidewall extending between a first end and a second end. The first end is open or openable during use to allow the substrate to be added or removed. The second end may be open to provide an air inlet for air to flow through the consumable. Alternatively, the second end may be closed to reduce heat leakage.

[0038] The heater 12 may be any heater suitable for delivering heat to the heating chamber 11. For example, the heater 12 may be a planar heater attached to a flexible support and wrapped around the sidewall of the heating chamber 11. Such a planar heater may be in the form of an electrically powered resistive track, and the support may be one or more plastic or polymer sheets, for example, polyimide, a fluoropolymer such as PTFE, or polyetheretherketone (PEEK). Alternatively, other types of heaters may be used, such as heaters in which heat is provided by a chemical reaction, such as fuel combustion. Alternatively, the heating element 12 may be located inside or on the surface of the heating chamber 11. The heating element 12 may also be formed integrally with the heating chamber 11.

[0039] The heating element 12 is typically surrounded by insulation so as to more efficiently deliver heat to the heating chamber 11 rather than heating the rest of the device 1. However, generally at least some heat will be dissipated to the remainder of the aerosol generating device.

[0040] The heating element 12 and temperature sensor 13 are operated by a control circuit 14 comprising a logic circuit 141 (e.g. a general purpose processor or ASIC) and a memory 142 that stores at least a session counter value 143. The logic circuit 141 may be configured, for example using a general purpose processor, to execute a series of instructions stored in the memory 142 and / or may be "hard coded" with logic to control the heating element 12 based on input from the session counter value 143 and the temperature sensor 13.

[0041] Optionally, the control circuit 14 may include a second temperature sensor 144 for measuring its own temperature.

[0042] Power supply 15 may be an electrical power supply, such as a battery. The power supply may be rechargeable, for example, via an external power connector on the exterior of device 1. Control circuitry 14 is configured to control the supply of power from power supply 15 to heating element 12. In addition, control circuitry 14 may be configured to regulate the charging of power supply 15.

[0043] Alternatively, the heating element 12 may be powered by a non-electrical power supply, such as a fuel that is combusted in the heating element 12. In such an embodiment, the control circuit 14 may be configured to control the supply of fuel as a manner of controlling the supply of power to the heating element 12.

[0044] The control circuitry 14 is also configured to receive input from a user input element 16. The user input element 16 may be any type of input element, such as, for example, a button, a slider or a capacitive sensor, or a slider. The user input element 16 is operated by a user of the device 1 to indicate that the aerosol-generating substrate is ready in the heating chamber 11 and that the user wishes to begin an aerosol-generating session.

[0045] The user input element 16 may alternatively be integrated into the heater. More specifically, the user input element 16 may be a detection means for detecting the presence of an aerosol-generating substrate in the heating chamber 11, such as a light gate for detecting a consumable comprising an aerosol-generating substrate. In this way, an aerosol-generating session may be automatically initiated upon providing the aerosol-generating substrate.

[0046] The device 1 may also be provided with additional user input elements for other purposes, such as setting the intensity of the aerosol generated, and may be provided with input elements that are not directly operated by the user, such as a sensor for detecting the open / closed state of the lid 17.

[0047] The lid 17 is a preferred but optional feature. In this embodiment, the lid 17 is arranged to keep the heating chamber 11 closed and protected when not in use. The lid 17 may be, for example, a sliding lid constrained by rails to move between a closed position and an open position.

[0048] The components of the aerosol generating device 1 are housed in a housing 10. The housing 10 may comprise, for example, a polymer, such as polyetheretherketone (PEEK) or polyamide (PA), and / or a metal frame, including, for example, aluminum. When an aerosol generating session is performed, some heat leaks from the heater into the housing. How much the housing 10 heats up over successive aerosol generating sessions depends on the balance between the heat leak from the heater and the dissipation of heat from the outside of the device 1.

[0049] FIG. 2 is a schematic diagram showing additional details of a heater in one embodiment of an aerosol-generating device 1 and its use for heating a consumable 2 comprising an aerosol-generating substrate 21.

[0050] More specifically, the consumable 2 in this embodiment is a tubular structure with a section 21 at one end along its length in which the aerosol-generating substrate is housed, and which is inserted into the heating chamber 11 of the heater to generate the aerosol, while a mouth end 22, which may include a filter, extends from the heating chamber 11 to form a mouthpiece.

[0051] In this example, the heating chamber 11 is a tubular structure with ribs 111 along the sidewalls to maintain space between the consumable 2 and the sidewall, and with a platform 112 to maintain space between the consumable 2 and the end wall of the heating chamber 11. In use, a user inhales aerosol from the consumable 2 through the mouth end 22. Air flows into the heating chamber 11 between the consumable 2 and the sidewall of the chamber 11 via arrow F1, into the consumable 2 at arrow F2, and out at arrow F3.

[0052] This is just one example of a configuration of the heating chamber 11 and the aerosol-generating substrate 21. In other alternative examples, air may be forced through the free aerosol-generating substrate in the heating chamber 11. The mouthpiece may form part of the aerosol-generating device 1 rather than being part of the consumable 2. The heating chamber 11 may be provided with an air inlet separate from the air outlet.

[0053] The specific configuration of the heater and the aerosol-generating substrate is not constrained herein, rather the invention relates to a means for improving the safety of the device 1 using a particular method for controlling the heater.

[0054] Aerosol generation is typically done in sessions. In case a consumable 2 is used, a "session" may be the period during which the consumable is fully used. Alternatively, a "session" may be the period during which a predefined amount of aerosol (which may be exact or approximate) is generated by the aerosol generating device 1.

[0055] FIG. 3 is a graph showing a schematic representation of an exemplary aerosol generation session in an aerosol generating device, with heater temperature shown on the y-axis and time shown on the x-axis.

[0056] In this example, the aerosol-generating session includes a temperature ramp-up phase t1, which ramps up the temperature of the heater to at least an aerosol-generating temperature T3. The duration of the temperature ramp-up phase t1 may be predetermined. In another example, the temperature ramp-up phase t1 may continue until feedback from the temperature sensor 13 indicates that the aerosol-generating temperature T3 has been reached. The aerosol-generating temperature T3 is selected based on the type of aerosol-generating substrate, and is the temperature at which an aerosol is generated by heating the aerosol-generating substrate. As shown in FIG. 3, the temperature of the heater is ramped up somewhat above the aerosol-generating temperature T3, which is the lower limit for aerosol generation. In an example where the aerosol-generating substrate includes tobacco and an aerosol former such as glycerin, it has been found that 170° C. is a suitable value for T3, and that continuing to heat the aerosol-generating substrate to 230° C. improves aerosol generation.

[0057] This is followed by a temperature maintenance phase t2 during which the temperature of the heater is maintained. Although the temperature is shown as plateauing, it may vary around the desired temperature. For example, the temperature may be maintained using pulse width modulation (PWM) control of the heater. During this time, aerosol may be extracted from the aerosol-generating substrate with one or more puffs. In an example where the aerosol-generating substrate includes tobacco and an aerosol former, 4 minutes and 10 seconds has been found to be an exemplary suitable length for t2.

[0058] Finally, there is a temperature reduction phase t3, which reduces the temperature of the heater below the aerosol generation temperature T3. Generally, no power is supplied to the heater during the temperature reduction phase, although controlling the cooling rate may be advantageous, for example for cleaning the heating chamber after use. The duration of the temperature reduction phase t3 is generally not constrained, and the temperature reduction phase may optionally be interrupted by the start of the next aerosol generation session. However, in some embodiments, a minimum duration t3 may be set, e.g., 20 seconds.

[0059] 3 also illustrates a "cold" temperature T1 at which the aerosol generating device 1 is considered cool enough that there is no need to track the cumulative heating of the device over multiple sessions, as will be explained further below. In a specific example, 65°C has been found to be a suitable temperature T1.

[0060] FIG. 4 is a flow chart that generally illustrates a method for controlling an aerosol generating device.

[0061] In step S410, control circuitry 14 receives an instruction via user input element 16 to begin an aerosol generation session.

[0062] In step S420, the control circuit 14 receives the temperature of the heater measured by the temperature sensor. This measurement may be an indirect measurement. For example, if the temperature sensor 13 is a thermistor, the control circuit 14 measures the resistance using the electrical connection across the temperature sensor 13 and determines the temperature using a known relationship between resistance and temperature (e.g., a look-up table or a continuous function).

[0063] In step S430, the control circuit 14 retrieves a session counter value 143 from the memory 142. The session counter value is a counter indicating the number of aerosol generation sessions performed while the device was in a relatively hot state, i.e., without the device reaching a thermal equilibrium state after the session. The relatively hot state may be defined differently in different embodiments. For example, a "relatively hot state" may be any temperature higher than the cold temperature T1. In addition, the meaning of a "relatively hot state" may depend on the session counter value, which will be described further below. The session counter value 143 is stored to persist between aerosol generation sessions. When the control circuit 14 is first started, the session counter value 143 may be initialized with a default value, practically zero. As will be described further below, the session counter value may be incremented depending on the aerosol generation session, and may be reset to a default value under certain conditions.

[0064] In step S440, the control circuit 14 controls the heater to perform an aerosol generation session according to the heater temperature and the session counter value obtained in steps S420 and S430. More specifically, the control circuit 14 determines whether to perform an aerosol generation session according to the user request in step S410, and controls the heating element 12 in the aerosol generation session if an aerosol generation session is to be performed. For example, the aerosol generation session may be a session as described above in relation to FIG. 3.

[0065] FIG. 5 is a flow chart that generally illustrates additional details of an exemplary method for controlling an aerosol generating device.

[0066] In the embodiment of FIG. 5, step S440 is more specifically defined as steps S510 to S540.

[0067] In steps S510 and S520, the control circuit 14 determines the maximum continuous session limit S maxThe session counter value 143 acquired in step S430 is compared with the session limit S max In one embodiment, it is determined to perform an aerosol generation session if S max It has been found that an R of 3 is suitable, but this depends on the specific configuration of device 1, and in particular on how much heat leaks from the heater to the rest of the device during an aerosol generation session.

[0068] In step S530, the control circuit 14 increments the session counter value 143. Typically, this means increasing the value by one, but any counting unit may be used. In a preferred embodiment, a minimum start temperature T2 is defined for counting sessions, below which sessions are not considered consecutive and are not counted. In a specific example, the minimum start temperature T2 may be a temperature preferably in the range of 100°C to 120°C, and is most preferably 100°C.

[0069] In step S540, the control circuit 14 controls the heater to perform an aerosol generation session according to the temperature of the heater, which may be the aerosol generation session described with reference to FIG.

[0070] In the example of Figure 5, the session counter value 143 is incremented in step S530 before the aerosol generation session is performed in step S540. However, the session counter value 143 may be incremented at other times to record the aerosol generation session. For example, with reference to the example session of Figure 3, the session counter value 143 may instead be incremented after the temperature increase phase t1, or after the temperature maintenance phase t2, or after a predetermined time has elapsed since the start of the aerosol generation session.

[0071] On the other hand, in step S520, the session counter value 143 is equal to or greater than the session limit S maxIf so, control circuit 14 controls the heater so as not to perform an aerosol generation session (ie, control circuit 14 does not activate the heater).

[0072] Optionally, if the control circuitry 14 determines not to perform an aerosol generation session, the device 1 indicates a status that it received user input in step S410 but confirmed not to perform an aerosol generation session. By way of example, this status indication may take the form of a static light indicator, a flashing light indicator, an animation of several light indicators combined together, a vibration output, or an audio output.

[0073] Alternatively, if the control circuitry 14 decides not to perform an aerosol generation session, the control circuitry 14 may wait for appropriate conditions to perform an aerosol generation session after a delay. For example, instead of proceeding from step S520 to the end of the method of FIG. 5, the control circuitry 14 may alternatively wait until the temperature of the heater drops below the sustained temperature threshold and then perform an aerosol generation session. The sustained temperature threshold is preferably equal to the "cold" temperature T1 described with respect to FIG. 3, although the sustained temperature threshold may be set separately. This alternative has the advantage that the device 1 can automatically perform an aerosol generation session as soon as it is ready, but the disadvantage that a user may not expect this. If the device 1 is going to provide a delayed aerosol generation session, this is preferably indicated as part of the status indication described above.

[0074] FIG. 6 is a flow chart that generally illustrates additional details of a method for controlling an aerosol generating device.

[0075] Specifically, FIG. 6 shows a control flow for resetting the session counter value 143.

[0076] In step S610, the control circuit 14 receives the heater temperature measured by the temperature sensor.

[0077] In step S620, the control circuit 14 determines whether the received temperature indicates that the heater temperature has dropped below the absolute reset temperature, and if so, skips to step S670 where the session counter value 143 is reset to an initial value, typically 0.

[0078] The absolute reset temperature may be the "cold" temperature T1 mentioned above, for example 65°C. For example, the control circuit 14 may store a previous temperature measurement in the memory 142, and if the previous temperature measurement is higher than the absolute reset temperature T1 and the temperature received in step S610 is lower than the absolute reset temperature T1, the temperature becomes (transitions) below the absolute reset temperature. By detecting a temperature transition rather than a single temperature measurement, resetting is not repeated while the device 1 is not heated. Alternatively, the steps of FIG. 6 may be disabled when the session counter value 143 is at an initial value, in which case the single temperature measurement received in step S610 may be used.

[0079] If the heater temperature has not fallen below the absolute reset temperature, flow proceeds to step S630, in which the control circuit 14 determines whether the received temperature indicates that the heater temperature has fallen below the early reset temperature T2, and if not, ends the process.

[0080] The early reset temperature is a temperature that is higher than the absolute reset temperature but indicates that significant cooling has occurred since the last aerosol generation session. The early reset temperature is preferably equal to the minimum start temperature T2 described above in step S530 of Figure 5. More specifically, in the particular exemplary embodiment described above, a temperature in the range of 100°C to 120°C, most preferably 100°C, has been found to be an exemplary suitable value for the early reset temperature.

[0081] Otherwise, flow proceeds to step S640. In step S640, the session counter value 143 is obtained from the memory 142, similar to step S430.

[0082] In steps S650 and S660, the session counter value 143 is compared to an early reset session limit, for example the maximum consecutive session limit S in step S510 of FIG. max Thus, if the session counter value 143 is lower than the early reset session limit, this indicates that the device 1 has not yet reached the maximum safe temperature due to heat leakage from the heater during continued use. In a specific example, the early reset session limit may be 3 sessions.

[0083] If the session counter value 143 is less than the early reset session limit, then in step S670 the session counter value 143 is reset, otherwise the process of Figure 6 ends.

[0084] Control circuitry 14 may execute the steps of Figure 6 in parallel with the methods of Figure 4 or Figure 5. For example, the flow of Figure 6 may be triggered by an interrupt input of logic circuitry 141 connected to a hardwired temperature comparison unit.

[0085] Alternatively, the steps of Figure 4 or Figure 5 and the steps of Figure 6 may be performed alternately in one continuous control loop that controls both the response to a user instruction to start an aerosol generation session and the resetting of the session counter value.

[0086] In some embodiments, the early reset temperature and its associated logic in steps S630-S660 may be omitted, in which case the process ends following a negative result in step S620.

[0087] Furthermore, in some embodiments, the process for resetting the session counter value 143 may be omitted entirely, for example, the user may be required to turn off the device in order to reset the session counter value 143. This may be accomplished by storing the session counter value 143 in volatile memory.

[0088] FIG. 7 is a graph showing a schematic representation of successive aerosol generation sessions in an aerosol generating device, with heater temperature shown on the y-axis and time shown on the x-axis.

[0089] FIG. 7 shows four aerosol generation sessions S1 to S4.

[0090] At the start of session S1, the session counter value 143 is an initial value (zero). Since device 1 starts below the minimum starting temperature T2 mentioned above, in step S530 of session S1, the session counter value 143 is not incremented. In step S540 of Fig. 5, stages t1, t2, and t3 of Fig. 3 are performed.

[0091] However, before the device 1 can cool completely at stage t3 of session S1, the control circuitry 14 receives a further instruction to start an aerosol generation session (step S410), starting session S2. This time, the heater temperature at the start of the session is higher than the minimum start temperature T2, and the session counter value 143 is incremented (from 0 to 1) in step S530. Then, in step S540, stages t1, t2, and t3 of Figure 3 are executed.

[0092] At this time, at stage t3 of session S2, the heater temperature becomes lower than the early reset temperature T2 of step S630 of Figure 6. Control circuit 14 evaluates the condition of step S660, determines that session counter value 143(1) is lower than early reset session limit (3), and resets the session counter value in step S670.

[0093] The user then gives further instructions (step S410) to perform further sessions S3 and S4, as shown in Figure 7. However, the session counter value 143 has been reset and only records a value of 1 at the end of step S4, since session S3 was started below the minimum starting temperature T2. Thus, it can be seen how the control flow extends the number of consecutive sessions allowed if the user allows the device to partially cool down.

[0094] FIG. 8 is a flow chart that generally illustrates additional details of a method for controlling an aerosol generating device.

[0095] The method of FIG. 8 is generally similar to that of FIG. 5, but introduces an additional condition for the aerosol-generating session in step S810.

[0096] That is, a maximum start temperature T4 is defined. If the temperature received in step S420 is equal to or greater than this maximum start temperature, the user input in step S410 is discarded and the aerosol generation session is not performed.

[0097] Alternatively, similar to the alternative implementation of step S520 described above, if the control circuit 14 decides not to perform an aerosol generation session, the control circuit 14 may wait for suitable conditions to perform an aerosol generation session after a delay. For example, instead of proceeding from step S810 to the end of the method of FIG. 5, the control circuit 14 may alternatively wait until the temperature of the heater drops below the continued temperature threshold and then perform an aerosol generation session. In the case of step S810, the continued temperature threshold may be equal to the aerosol generation temperature T3 described with respect to FIG. 3, but the continued temperature threshold may be set separately. This alternative has the advantage that the device 1 can automatically perform an aerosol generation session as soon as it is ready, but the disadvantage that the user may not expect this. If the device 1 is going to provide a delayed aerosol generation session, this is preferably indicated as part of the status indication described above.

[0098] Additionally or alternatively to the heater maximum start temperature T4, the maximum start temperature of the control circuit 14 may be compared to the temperature measurement received from the temperature sensor 144, and if the control circuit 14 exceeds its maximum start temperature, the aerosol generation session is not performed. This has the advantage that the control circuit 14 is prevented from continuing to heat itself, which would risk overheating and becoming unreliable or unpredictable. In a specific example, the maximum start temperature of the control circuit 14 is preferably 65° C.

[0099] FIG. 9 is a graph showing a schematic representation of successive aerosol generation sessions in an aerosol generating device, with heater temperature shown on the y-axis and time shown on the x-axis.

[0100] FIG. 9 can be used to understand the maximum onset temperature T4 described above with respect to FIG.

[0101] More specifically, after each of sessions S1 and S2, regardless of the session counter value, the next session cannot begin until the heater temperature drops below the maximum start temperature T4. For ease of explanation, the maximum start temperature T4 is shown as being higher than the aerosol generation temperature T3. However, it is preferred that the maximum start temperature T4 is equal to the aerosol generation temperature T3.

[0102] In the above described embodiment, an aerosol generating device 1 is provided having a control circuit 14 configured to carry out a method for safely operating the heater. The control circuit 14 may also be provided as a self-contained component separate from the remainder of the aerosol generating device while still being the control circuit for the aerosol generating device 1. Additionally, an aerosol generating device 1 may be similar to the devices described above but does not include the control circuit 14 as a component of the device and is externally controlled according to the methods described above.

[0103] The heating element 12 may be any device for outputting sufficient thermal energy to form an aerosol from the aerosol substrate. The transfer of thermal energy from the heating element 12 to the aerosol substrate may be conductive, convective, radiative, or any combination of these means. As a non-limiting example, a conductive heater may directly contact the aerosol substrate, forcing the aerosol substrate against it, or may contact a separate component, such as a heating chamber, that itself causes heating of the aerosol substrate by conduction, convection, and / or radiation.

[0104] The heating element may be electrically powered, combustion powered, or powered by any other suitable means. Electrically powered heating elements may include resistive track elements (optionally including insulating packaging), inductive heating systems (including, for example, electromagnets and high frequency oscillators), and the like. The heating element 12 may be disposed around the outside of the aerosol substrate, may penetrate partway or completely into the aerosol substrate, or any combination thereof. For example, instead of the heater of the embodiment described above, the aerosol generating device may have a blade-type heater that extends into the aerosol substrate in the heating chamber 11.

[0105] The term "temperature sensor" is used to describe an element capable of determining the absolute or relative temperature of a portion of the aerosol generating device 1. This may include a thermocouple, a thermopile, a thermistor, etc. The temperature sensor 13 may be provided as part of another component or may be a separate component. In some examples, multiple temperature sensors may be provided, for example to monitor the heating of various parts of the aerosol generating device 1, for example to determine a thermal profile. Additionally, in some examples, the temperature sensor may be combined with another feature. For example, the thermistor characteristic of a resistive heating element may be used to measure the temperature.

[0106] The aerosol-generating substrate comprises tobacco, e.g., in dried or cured form, and optionally with additional ingredients for flavor or to provide a smoother or otherwise more satisfying effect. In some examples, the substrate, such as tobacco, may be treated with a vaporizer. The vaporizer may improve the generation of vapor from the substrate. The vaporizer may include, for example, a polyol, such as glycerol, or a glycol, such as propylene glycol. In some cases, the substrate may not include tobacco or even nicotine, but may instead include natural or artificial ingredients for flavoring, volatility, improved smoothness, and / or other satisfying effects. The substrate may be provided as a solid or paste-type material in shredded, pelleted, powdered, granular, strip or sheet form, optionally a combination thereof. Alternatively, the aerosol substrate may be a liquid or gel.

[0107] The aerosol generating device 1 may, in some embodiments, be referred to as a "heated tobacco device," a "heated non-combustion tobacco device," a "device for vaporizing tobacco products," or the like, and is to be construed as a device suitable for achieving these effects. The features disclosed herein are equally applicable to devices designed to vaporize any aerosol substrate.

[0108] The aerosol generating device 1 may be configured to receive the aerosol substrate in a prepackaged substrate carrier. The substrate carrier may be generally similar to a cigarette with a tubular region with the aerosol substrate arranged in a suitable configuration. Some designs may also include filters, vapor collection regions, cooling regions, and other structures. An outer layer of paper or other flexible planar material such as foil may also be provided, for example, to hold the aerosol substrate in place to further enhance the similarity to a cigarette or the like. The substrate carrier may fit within the heating chamber 11 or may be longer than the heating chamber 11, such that the lid 17 remains open while the aerosol generating device 1 is equipped with the substrate carrier. In such an embodiment, the aerosol may be provided directly from the substrate carrier, which serves as a mouthpiece for the aerosol generating device.

[0109] As used herein, the term "fluid" shall be taken to collectively describe a type of non-solid material that is capable of flowing, including, but not limited to, liquids, pastes, gels, powders, etc. Accordingly, a "fluidized material" shall be taken as a material that is inherently fluid or that has been modified to behave as a fluid. Fluidization may include, but is not limited to, powdering, dissolving in a solvent, gelling, thickening, thinning, etc.

[0110] As used herein, the term "volatile" refers to a material that can be easily changed from a solid or liquid state to a gaseous state. As a non-limiting example, a volatile material may have a boiling or sublimation temperature near room temperature at ambient pressure. Thus, "volatilize" or "volatilise" shall be interpreted to mean to cause (a material) to volatilize and / or to evaporate or disperse into a vapor.

[0111] As used herein, the term "vapour" (or "vapor") means: (i) the form into which a liquid is transformed spontaneously by the action of a sufficient degree of heat; or (ii) liquid / moisture particles suspended in the atmosphere and visible as a cloud of steam / smoke; or (iii) a fluid that fills space like a gas, but can be liquefied by pressure alone when below a critical temperature.

[0112] Consistent with this definition, the term "vaporize" (or "vaporize") means: (i) to change or cause to change into a vapor, and (ii) when a particle changes physical state (i.e., from a liquid or solid to a gaseous state).

[0113] As used herein, the term "atomise" (or "atomize") shall mean: (i) to change (a substance, especially a liquid) into very small particles or droplets, and (ii) where the particles remain in the same physical state (liquid or solid) as they were before atomization.

[0114] As used herein, the term "aerosol" shall mean a system of particles dispersed in air or gas, such as mist, fog, or smoke. Thus, the term "aerosolize" (or "aerosolize") means to make into an aerosol and / or to disperse as an aerosol. It is noted that the meaning of aerosol / aerosolize is consistent with each of volatilization, atomization, and vaporization defined above. For the avoidance of doubt, aerosol is used consistently to describe mist or droplets containing atomized, volatilized, or vaporized particles. Aerosol also includes mist or droplets containing any combination of atomized, volatilized, or vaporized particles.

Claims

1. receiving an instruction via a user input element to initiate an aerosol generation session; receiving a temperature of the heater measured by a temperature sensor; Retrieving a session counter value from memory; controlling the heater to perform an aerosol generation session according to the temperature of the heater and the session counter value; resetting the session counter value when the temperature of the heater falls below a first predetermined temperature; A method for controlling an aerosol generating device, comprising:

2. The method of claim 1 , wherein the session counter value is incremented at the start of the aerosol generation session.

3. 2. The method of claim 1, further comprising resetting the session counter value when the temperature of the heater falls below a second predetermined temperature that is higher than the first predetermined temperature and the session counter value is below a first predetermined session limit.

4. The aerosol-generating session comprises: a temperature increasing step of increasing the temperature of the heater to at least a third predetermined temperature; a temperature maintaining step of maintaining the temperature of the heater; a temperature reducing step of reducing the temperature of the heater below the third predetermined temperature; The method according to any one of claims 1 to 3, comprising:

5. controlling the heater to not perform an aerosol generating session if the session counter value is greater than or equal to a second predetermined session limit. The method of any one of claims 1 to 4, further comprising:

6. controlling the heater to not perform an aerosol generation session if the temperature of the heater is greater than a fourth predetermined temperature when the instruction to start an aerosol generation session is received, regardless of the session counter value. The method of any one of claims 1 to 5, further comprising:

7. A method according to any one of claims 1 to 6, wherein the session counter value is not incremented if the temperature of the heater is lower than a fifth predetermined temperature when the instruction to start an aerosol generation session is received.

8. controlling the heater not to perform an aerosol generation session after receiving an instruction to start an aerosol generation session; controlling a user output element to indicate a status that the instruction has been received but the aerosol generation session has not been performed; The method according to any one of claims 1 to 7, comprising:

9. controlling the heater not to perform an aerosol generation session after receiving an instruction to start an aerosol generation session; waiting until the temperature of the heater drops below a sixth predetermined temperature, and then performing an aerosol generation session. The method according to any one of claims 1 to 8, comprising:

10. A control circuit configured to carry out the method according to any one of claims 1 to 9.

11. The control circuit for an aerosol generating device further comprising a second temperature sensor for measuring a temperature of the control circuit, the method comprising: controlling the heater to not perform an aerosol generation session if the temperature of the control circuit is greater than a seventh predetermined temperature when an instruction to start an aerosol generation session is received, regardless of a session counter value. The control circuit of claim 10 further comprising:

12. A control circuit according to claim 10 or 11; a heater for heating a consumable aerosol-generating substrate to generate an aerosol; a temperature sensor for measuring a temperature of the heater; a user input element for initiating an aerosol generating session; A memory for storing a session counter value; An aerosol generating device comprising:

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