Steam supply system and method

Abstract

To provide a vapor provision device comprising a vaporizer for generating vapor from a vapor precursor material and a reservoir for storing the vapor precursor material.SOLUTION: The vapor provision device further comprises control circuitry configured to: supply a first, non-zero level of power to the vaporizer to generate vapor from at least a portion of the vapor precursor material; determine a depletion condition of the vapor precursor material based on monitoring a parameter (such as resistance) indicative of a quantity of at least a portion of the vapor precursor material and comparing the monitored parameter to a first threshold; and, when the control circuitry determines that there is depletion based on the comparison between the monitored parameter and the first threshold, supply a second, non-zero level of power to the vaporizer, the second level of power being lower than the first level of power.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to vapor delivery systems, such as nicotine delivery devices (e.g., electronic cigarettes, etc.). [Background technology]

[0002] Electronic vapor delivery systems, such as electronic cigarettes (e-cigarettes), include a vapor precursor material, such as a reservoir, such as a liquid source containing a drug, typically nicotine, or a solid material, such as a tobacco-based product, from which vapor is emitted for inhalation by the user, for example via thermal vaporization. Thus, a vapor delivery system typically includes a vapor generation chamber, which includes a vaporizer, e.g., a heating element, arranged to vaporize a portion of the precursor material to generate vapor in the vapor generation chamber. When a user inhales through the device and electricity is supplied to the vaporizer, air is drawn into the device through an inlet hole and into the vapor generation chamber, where it mixes with the vaporized precursor material to form a condensation aerosol. There is a flow path between the vapor generation chamber and the mouthpiece opening, such that the incoming air drawn through the vapor generation chamber continues along the flow path to the mouthpiece opening, carrying with it a portion of the vapor / condensation aerosol, and then exits the mouthpiece opening for inhalation by the user. Some e-cigarettes may include a flavoring member in the flow path through the device to impart additional flavor. Such devices are sometimes referred to as hybrid devices, and the flavour member may comprise, for example, a portion of tobacco disposed in the air passage between the vapour generating chamber and the mouthpiece such that vapour / condensation aerosol drawn into the device passes through that portion of tobacco before exiting the mouthpiece for inhalation by the user.

[0003] Such vapor delivery systems can experience problems (also known as vapor delivery system starvation) if there is not enough vapor precursor material adjacent to the heating element. This can occur, for example, due to a halt in the supply of vapor precursor material to the heating element. Rapid overheating can then occur in or around the heating element. Under typical operating conditions, the overheated section is expected to rapidly reach temperatures of up to 500-900°C. This rapid heating can not only damage components within the vapor delivery system, but can also adversely affect the vaporization process of any remaining precursor material. For example, excessive heat can decompose the remaining precursor material, for example via pyrolysis, releasing unpleasant tasting substances into the air stream inhaled by the user. Such unpleasant tasting substances can also be released from overheating of other components of the aerosol delivery device, such as the wick in some liquid vapor precursor systems.

[0004] Various attempts have been made to help address some of these issues. Summary of the Invention

[0005] In a first aspect of certain embodiments, a vapor delivery system is provided that includes a vaporizer for generating vapor from a vapor precursor material; a storage section for storing the vapor precursor material; and control circuitry configured to supply a first non-zero level of power to the vaporizer to generate vapor from at least a portion of the vapor precursor material, determine a depletion state of the vapor precursor material based on monitoring a parameter indicative of an amount of at least the portion of the vapor precursor material and comparing the monitored parameter to a first threshold value, and supply a second non-zero level of power to the vaporizer, the second non-zero level being lower than the first level of power, if the control circuitry determines that depletion has occurred based on comparing the monitored parameter to the first threshold value.

[0006] In a second aspect of a particular embodiment, there is provided a control circuit for use in a vapor delivery system for generating vapor from a vapor precursor material, the vapor delivery system including a vaporizer for generating vapor from the vapor precursor material, the control circuit being configured to supply a first non-zero level of power to the vaporizer to generate vapor from at least a portion of the vapor precursor material, monitor a parameter indicative of an amount of the at least a portion of the vapor precursor material, determine a depletion state of the vapor precursor material based on a comparison of the monitored parameter to a first threshold value, and supply a second non-zero level of power to the vaporizer, the second non-zero level being lower than the first level of power, if the control circuit determines that depletion has occurred based on a comparison of the monitored parameter to the first threshold value.

[0007] In a third aspect of a particular embodiment there is provided a vapour delivery device comprising a control circuit according to the second aspect.

[0008] In a fourth aspect of certain embodiments, there is provided a method of operating a control circuit for a vapor delivery system including a vaporizer for generating vapor from a vapor precursor material and a reservoir for storing the vapor precursor material, the method including: supplying a first non-zero level of power via the control circuit to the vaporizer to generate vapor from at least a portion of the vapor precursor material; determining a depletion state of the vapor precursor material via the control circuit based on monitoring a parameter indicative of an amount of at least the portion of the vapor precursor material and comparing the monitored parameter to a first threshold value; and supplying a second non-zero level of power via the control circuit to the vaporizer, the second non-zero level of power being lower than the first level of power, when the circuit determines that depletion exists based on comparing the monitored parameter to the first threshold value.

[0009] In a fifth aspect of a particular embodiment, there is provided a vapor delivery system including a vaporization means for generating vapor from a vapor precursor material, a storage means for storing the vapor precursor material, and a control means configured to supply a first non-zero level of power to the vaporization means to generate vapor from at least a portion of the vapor precursor material, monitor a parameter indicative of an amount of at least a portion of the vapor precursor material, determine a depletion state of the vapor precursor material based on comparing the monitored parameter to a first threshold, and supply a second non-zero level of power lower than the first level of power to the vaporization means when the control means determines that depletion exists based on comparing the monitored parameter to the first threshold.

[0010] It will be appreciated that the features and aspects of the invention discussed above in relation to the first and other aspects of the invention are applicable to and may be combined with embodiments of the invention according to other aspects of the invention as appropriate and are not limited to only the particular combinations discussed above.

[0011] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0012] [Figure 1] 1 is a highly abbreviated cross-sectional view of a steam supply system according to certain embodiments of the present disclosure. [Diagram 2] 2 is a flow diagram illustrating an operating process for the vapor delivery system of FIG. 1 in accordance with some implementations of the present disclosure, where power levels are measured on a puff-by-puff basis. [Diagram 3] FIG. 2 is a flow diagram illustrating an operating process for the steam supply system of FIG. 1 according to a further implementation of the present disclosure. [Figure 4] FIG. 2 is a flow diagram illustrating an operating process for the vapor delivery system of FIG. 1 according to a further implementation of the present disclosure, where multiple power levels are measured per puff. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Aspects and features of particular examples and embodiments are described and illustrated herein. Aspects and features of particular examples and embodiments may be conventionally implemented and will not be detailed or illustrated for the sake of brevity. It is understood that aspects and features of the apparatus and methods described herein that are not detailed may be implemented in accordance with any conventional technique for implementing such aspects and features.

[0014] The present disclosure relates to vapor delivery systems, also referred to as aerosol delivery systems, such as e-cigarettes, including hybrid devices. Throughout the following description, the terms "e-cigarette" or "electronic cigarette" are sometimes used, but it should be understood that these terms are used interchangeably with vapor delivery systems / devices and electronic vapor delivery systems / devices. Additionally, the terms "vapor" and "aerosol" and the related terms "vaporize," "volatilize," and "aerosolize" are commonly used interchangeably in the art.

[0015] Vapor delivery systems (e-cigarettes) sometimes, but not always, include a modular system that includes both reusable and replaceable (disposable) cartridge parts. Sometimes the replaceable cartridge part includes the vapor precursor material and the vaporizer, while the reusable part includes the power source (e.g., a rechargeable battery), the triggering mechanism (e.g., a button or puff sensor), and the control circuitry. However, it is understood that these different parts also include further elements depending on the functionality. For example, in the case of a hybrid device, the cartridge part may further include a flavor member, e.g., a small amount of tobacco provided as an insert ("pod"). In such cases, the flavor member insert is itself removable from the disposable cartridge part, so that the insert can be replaced separately from the cartridge, e.g., to change the flavor or because the available time of the flavor member insert is shorter than the available time of the vapor generating part of the cartridge. The reusable device part sometimes includes additional parts, e.g., a user interface for receiving user input and displaying operational status characteristics.

[0016] In modular systems, the cartridge and reusable device portion are electrically and mechanically linked in use, for example using threads, latches, friction fits or bayonet caps with suitable electrical contact engagement. When the vapor precursor material in the cartridge is used up or when the user wishes to change to a different cartridge having a different vapor precursor material, the cartridge is removed from the device portion and a replacement cartridge is installed in its place. Systems corresponding to this type of two-part modular construction are commonly referred to as two-part or multi-part devices.

[0017] Electronic cigarettes including multi-part devices generally have a generally elongated shape, and the specific embodiments of the present disclosure described herein for the purpose of providing a concrete example are intended to include a generally elongated multi-part system employing a disposable cartridge containing a liquid vapor precursor material. However, it will be understood that the basic principles described herein apply equally to different electronic cigarette structures, such as single-part devices or modular devices including three or more parts, refillable devices and single-use disposable devices, as well as hybrid devices with additional flavor members such as tobacco pod inserts placed upstream of the vaporizer along the airflow path, and devices corresponding to other overall shapes, such as those based on so-called box mod high-performance devices, typically having a box-like shape. More generally, it will be understood that the specific embodiments of the present disclosure are based on electronic cigarettes configured to provide the operating functions according to the principles described herein, and the specific structural aspects of the electronic cigarettes configured to provide the described operating functions are not of primary importance.

[0018] 1 is a cross-sectional view of an example of an e-cigarette 1 according to certain embodiments of the present disclosure. The e-cigarette 1 includes two main components: a reusable component 2 and a replaceable / disposable cartridge portion 4.

[0019] In normal use, the reusable part 2 and the cartridge part 4 are removably connected at a joint 6. When the cartridge part is used up or the user simply wants to change to a different cartridge part, the cartridge part is detached from the reusable part and replaced. The cartridge part is instead attached to the reusable part. The connection 6 provides structural, electrical and air path connections between the two parts and may be established according to conventional techniques, e.g., based on threads, latching mechanisms or bayonet caps, with appropriately positioned electrical contacts and openings for establishing electrical and air paths between the two parts as required. The specific manner in which the cartridge part 4 is mechanically attached to the reusable part 2 is not important to the principles described herein, but to provide an illustrative example, it is assumed herein that, for example, a portion of the cartridge includes a latching mechanism received by a latch-engaging member (not shown in FIG. 1 ) that cooperates with a corresponding receptacle in the reusable part 2. It should also be appreciated that the connection 6 in some implementations does not support an electrical connection between the corresponding parts. For example, in some implementations, the vaporizer may be located in the reusable part rather than the cartridge part, or the transfer of power from the reusable part to the cartridge part may be wireless (e.g., based on electromagnetic induction) such that no electrical connection between the reusable part and the cartridge part is required.

[0020] The cartridge part 4 according to certain embodiments of the present disclosure may be broadly conventional. In FIG. 1, the cartridge 4 includes a cartridge housing 42 formed of a plastic material. The cartridge housing 42 supports the other parts of the cartridge part and provides a mechanical interface 6 with the reusable part 2. The cartridge housing is approximately circularly symmetric about the longitudinal axis along which the cartridge part is connected to the reusable part 2. In this example, the cartridge part has a length of about 4 cm and a diameter of about 1.5 cm. However, it will be appreciated that the specific shape and more generally the overall shape and materials used may vary in different implementations.

[0021] Within cartridge housing 42 is a reservoir 44 that contains a liquid vapor precursor material. The liquid vapor precursor material may be conventional and is also referred to as e-liquid. The liquid reservoir 44 in this example has an annular shape with an outer wall defined by cartridge housing 42 and an inner wall that defines an air passage 52 through cartridge portion 4. The reservoir 44 is closed at each end by end walls for containing the e-liquid. The reservoir 44 may be formed according to conventional techniques, for example the reservoir may comprise a plastic material and may be integrally molded into cartridge housing 42.

[0022] The cartridge portion further includes a wick (vapor precursor transport member) 46 and a heating element (vaporizer) 48 located towards the end of the reservoir 44 opposite the mouthpiece outlet 50. The wick 46 in this example extends laterally across the cartridge air passage 52 with both ends extending into the e-liquid reservoir 44 through openings in the interior walls of the reservoir 44. The openings in the interior walls of the reservoir are roughly sized to fit the dimensions of the wick 46 and provide an adequate seal against leakage from the liquid reservoir into the cartridge air passage without undue compression of the wick that could be detrimental to fluid transport performance.

[0023] The wick 46 and heating element 48 are disposed within the cartridge air passage 52 such that the area of ​​the cartridge air passage 52 around the wick 46 and heating element 48 in effect defines a vaporization area for the cartridge portion. E-liquid within the reservoir 44 permeates the wick 46 through the end of the wick that extends into the reservoir 44 and is drawn along the wick by surface tension / capillary action (i.e., wicking). In this example, the heating element 48 comprises an electrically resistive wire wound around the wick 46. The heating element 48 may be formed from any suitable metallic or conductive material that exhibits a change in resistance with temperature. In this example, the heating element 48 comprises a nickel-iron alloy (e.g., NF60) wire and the wick 46 comprises a cotton fiber bundle.

[0024] In one example, the heating element 48 has a thickness (of the wire) of 0.17 mm to 0.20 mm (e.g., 0.188 mm ± 0.02 mm) and a length of 55 mm to 65 mm (e.g., 60.0 The wire has an axial length of 4.0 to 6.0 mm (e.g., 5.00 mm ± 0.5 mm) and an outer diameter of 2.2 mm to 2.7 mm (e.g., 5.00 mm ± 0.5 mm). The core 46 is formed into a helical coil having a length of 15 mm to 25 mm (e.g., 2.50 mm ± 0.2 mm). The coil in this example is formed into 9 turns with a turn pitch of 0.67 ± 0.2 per mm. The resistance of the coil measured unpowered and at room temperature (e.g., 25°) is 1.1 to 1.6 ohms, more specifically 1.4 ohms ± 0.1 ohms. As described in more detail below, the power supplied to the heating element 48 is set to be 6.0 to 6.5 watts. The core 46 in this example is formed of organic cotton (although alternative implementations may use fiberglass fibers). The core is formed into a generally cylindrical structure having a length of 15 mm to 25 mm (e.g., 20.00 ± 2.0 mm) and a diameter of 2 to 5 mm (e.g., 3.5 mm + 1.0 mm / - 0.5 mm). The organic cotton fibers are twisted with 40 ± 5 turns per meter. Such a configuration provides an e-liquid absorption rate of 0.2 g to 0.5 g (e.g., 0.3 g ± 0.05 g) and an absorption time of 65 seconds ± 10 seconds. Of note, upon formation, the wick 46 is partially disposed within the interior volume defined by the helical coil.

[0025] In another example, the heating element 48 comprises a nickel-iron alloy wire having a thickness (of the wire) of 0.14 mm to 0.18 mm (e.g., 0.16 mm ± 0.02 mm) and a length of 37 mm to 47 mm (e.g., 43.0 mm ± 2.5 mm). The wire is formed into a helical coil having an axial length of 3.0 to 5.0 mm (e.g., 4.00 mm ± 0.5 mm) and an outer diameter of 2.2 mm to 2.7 mm (e.g., 2.50 mm ± 0.2 mm). The coil in this example is formed into 7 turns with a turn pitch of 0.67 ± 0.2 per mm. The resistance of the coil measured at room temperature (e.g., 25°) in an unpowered state is 1.1 to 1.6 ohms, more specifically 1.4 ohms ± 0.1 ohms. The power supplied to the heating element 48 as described above is set to be 6.0 to 6.5 watts. The wick 46 in this example is also formed of organic cotton (although alternative implementations may use fiberglass fibers). The wick is formed into a generally cylindrical structure having a length of 12 mm to 18 mm (e.g., 15.00±2.0 mm) and a diameter of 2 to 5 mm (e.g., 3.5 mm+1.0 mm / -0.5 mm). The organic cotton fibers are twisted with 40±5 twists per meter. Such a configuration results in an e-liquid absorption rate of 0.2 g to 0.5 g (e.g., 0.3 g±0.05 g) and an absorption time of 65 seconds±10 seconds. As described above, the wick 46 is partially disposed within an interior volume defined by the helical coil.

[0026] However, it will be understood that the particular vaporizer construction is not critical to the principles described herein, and the above limitations are presented as examples.

[0027] In use, power is supplied to the heating element 48 to vaporize a quantity of e-liquid (vapor precursor material) that is drawn into the vicinity of the heating element 48 by the wick 46. The vaporized e-liquid is then drawn along the cartridge air path and entrained in air that passes from the vaporization region through the cartridge air path 52 and out the mouthpiece outlet 50 for inhalation by the user.

[0028] Broadly speaking, the rate at which e-liquid is vaporized by the vaporizer (heating element) 48 depends on the amount (level) of power supplied to the heating element 48 during normal use. Thus, power can be supplied to the heating element 48 to selectively generate vapor from the e-liquid in the cartridge portion 4, and the rate of vapor generation can be altered by varying the amount of power supplied to the heating element 48, for example, by pulse width and / or frequency modulation techniques. However, one factor that affects the rate and / or amount of vaporization, as discussed in more detail below, is the amount of vapor precursor material proximate the heating element 48.

[0029] The reusable component 2 includes an outer housing 12 having an opening defining an air inlet 28 for the e-cigarette, a battery 26 for providing operating power to the e-cigarette, a control circuit 20 for controlling and monitoring the operation of the e-cigarette, a user input button 14, and an inhalation sensor (puff detector) including a pressure sensor located in a pressure sensor chamber 18 in this example. ) 16 and a visual display 24. Although the reusable part 2 of Figure 1 includes a display 25, the display 25 is optional and may not be included in other implementations.

[0030] The outer housing 12 may be formed, for example, from a plastic or metal material, and in this example has a circular cross-section that generally matches the shape and size of the cartridge portion 4, with a smooth transition between the two portions at connection portion 6. In this example, the reusable portion is approximately 8 cm in length, such that the overall length of the e-cigarette when the cartridge portion and the reusable portion are combined is approximately 12 cm. However, as previously described, it will be appreciated that the overall shape and scale of an electronic cigarette embodying an embodiment of the present disclosure is not critical to the principles described herein.

[0031] The air inlet 28 connects to an air path 30 through the reusable part 2. The reusable part air path 30 connects to the cartridge air path 52 across the connection 6 when the reusable part 2 and the cartridge part 4 are connected to each other. The pressure sensing chamber 18 containing the pressure sensor 16 is in fluid communication with the reusable part 2 air path 30 (i.e., the pressure sensing chamber 18 branches off from the reusable part 2 air path 30). Thus, when a user inhales at the mouthpiece opening 50, there is a pressure drop in the pressure sensing chamber 18 that is detected by the pressure sensor 16, and air is drawn from the air inlet 28 along the reusable part air path 30, across the connection 6, through the vapor generation area near the atomizer 48 (vaporized e-liquid is entrained in the airflow when the vaporizer is in operation), along the cartridge air path 52 and into the mouthpiece opening 50 for user inhalation.

[0032] The battery 26 in this example is rechargeable and may be of any conventional type, such as the type commonly used in e-cigarettes and other applications requiring the supply of relatively high current for a relatively short period of time. The battery 26 may be recharged through a charging connector, such as a USB connector, within the reusable component housing 12.

[0033] The user input button 14 in this example is a conventional mechanical button that includes, for example, a spring-mounted component that is pressed by a user to establish electrical contact. In this regard, the input button may be considered to provide a manual input mechanism for the terminal device, although the particular manner in which the button is implemented is not important. For example, different forms of mechanical buttons or tactile buttons (e.g., based on capacitive or optical sensing technology) may be used in other implementations. The particular manner in which the button is implemented is selected based, for example, on a desired aesthetic appearance.

[0034] The display 24 visually displays to the user various characteristics associated with the e-cigarette, such as current power setting information, remaining battery power, etc. The display may be implemented in a variety of ways. In this example, the display 24 includes a conventional pixelated screen that is driven to display the desired information according to conventional techniques. In other implementations, the display may include one or more separate indicators, such as LEDs, arranged to display the desired information, such as by using a particular color and / or blinking. More generally, the manner in which the display is provided and the information displayed to the user using the display is not critical to the principles described herein. Some embodiments may not include a visual display, may include other means of providing the user with information related to the operating characteristics of the e-cigarette, such as using audio signals or tactile feedback, or may not include any means of providing the user with information related to the operating characteristics of the e-cigarette.

[0035] The control circuitry 20 is suitably configured / programmed to control the operation of the electronic cigarette to provide functionality according to the embodiments of the present disclosure described further herein, and to provide conventional operational functions of an electronic cigarette according to established techniques for controlling such devices. The control circuitry (processing circuitry) 20 can be considered to logically include various sub-circuits / circuit elements associated with different aspects of the operation of the electronic cigarette according to the principles described herein, as well as other conventional operational aspects of an electronic cigarette, such as display driver circuitry and user input sensing. It will be appreciated that the functionality of the control circuitry 20 can be provided in a variety of different ways, for example using one or more suitably programmed programmable computers and / or one or more suitably configured application specific integrated circuits / circuits / chips / chipsets to provide the desired functionality.

[0036] The vapor delivery system 1 of FIG. 1 is shown including a user input button 14 and a puff sensor 16. In the illustrated implementation of FIG. 1, the control circuit 20 is configured to receive a signal from the puff sensor 16 and use the signal to determine whether the user is taking a puff on the e-cigarette, and also to receive a signal from the input button 14 and use the signal to determine whether the user is pressing (i.e., activating) the input button. These aspects of the operation of the e-cigarette (i.e., puff detection and button press detection) may be performed according to established techniques in themselves (e.g., using conventional puff sensor and puff sensor signal processing techniques and using conventional input button and input button signal processing techniques). The control circuit 20 is configured to provide power to the heating element 48 when the control circuit 20 determines that the user is taking a puff on the e-cigarette and / or that the user is pressing the input button 14. However, it will be appreciated that in other implementations, only one of the puff sensor 16 or the user input button 14 is provided for the purpose of volatilizing e-liquid.

[0037] The indicator 25, as mentioned above, is configured to output a signal to the user indicative of a particular state of the vapor delivery system 1. In particular, the indicator is configured to output a signal to the user indicative of a depletion state of the vapor delivery system 1. The depletion state is defined herein as a state of the system indicative of depletion of the vapor precursor material in the vapor delivery system 1. For example, the depletion state may be defined with respect to the wick 46. The vapor delivery system is said to be depleted when the amount of e-liquid in the wick falls below a normal operating amount. The wick 46 may be depleted for a number of reasons, some of which are described in more detail below. Of course, the depletion state may also be defined with respect to other components, such as the reservoir 44 of the cartridge portion 4.

[0038] Referring again to the display 25, the display 25 may output any suitable signal to the user to indicate the depletion status of the system 1. For example, the signal may be an optical signal (e.g., an LED or similar light output element), a tactile signal (e.g., output by a vibrator or the like), or an audio signal (e.g., output by a speaker). The display may therefore be any suitable component capable of outputting one or more of these signals. For example, the display 25 in the illustrative implementation illustrated in FIG. 1 is an LED configured to output an optical signal when depletion is detected. It will be appreciated that in some implementations a separate display 25 may not be provided, and instead other components of the aerosol delivery system 1 may provide the functionality of the display 25. For example, in some implementations the display device 24 may be configured to output a signal indicative of depletion. It will be appreciated that the display 25 may be separate from the electronic cigarette 1 itself, or may form part of an element separate from the electronic cigarette 1. For example, the display 25 may be part of a smartphone or similar remote device configured to be communicatively connected (wirelessly or by wire) to the electronic cigarette 1.

[0039] As alluded to above, the present disclosure provides a system 1 in which a depletion condition of the vapor delivery system 1 is detected and / or indicated to a user. Figure 2 illustrates a method of operation of such a vapor delivery system 1 according to some embodiments of the present disclosure.

[0040] FIG. 2 begins with step S102 where a user powers on the steam delivery system 1. The steam delivery system 1 is powered on in response to a user input. In the implementation of FIG. 1, this is done by a user actuating a user input button 14. In the example steam delivery system 1 of FIG. 1, the user input button 14 is actuated by the user according to a predefined sequence, such as pressing the button three times in quick succession (e.g., within two seconds) to power on the system 1. Having a predefined predefined power-on sequence is advantageous when the user input button 14 performs multiple functions, as in the case of the steam delivery system shown in FIG. 1. The same sequence (or a different sequence) may be used to turn off the steam delivery system 1. Of course, other implementations may employ a dedicated on / off button mechanism (or other user input mechanism) instead.

[0041] Of course, prior to step S102, the vapor delivery system 1 is in a low power state such that a low (minimal) level of power is provided to the control circuit 20 (or certain components thereof) to monitor certain functions, such as when a user turns on the system 1 using the input button 14. In other implementations, the user may power on the system 1 by physically moving a button (not shown), such as a slide button, to complete an electrical circuit within the control circuit 20 or between the control circuit 20 and the battery 26, thereby allowing power to flow to the control circuit.

[0042] Once the system 1 is powered on in step S102, the control circuitry 20 is configured to monitor for user input (to generate or deliver aerosol to a user) in step S104. As discussed above, in the implementation described in FIG. 1, the control circuitry 20 is configured to receive a signal from the puff sensor 16 and use the signal to determine if the user is taking a puff on the e-cigarette, and / or receive a signal from the input button 14 and use the signal to determine if the user is pressing (i.e., activating) the input button. In the implementation described herein, the control circuitry 20 is configured to repeatedly determine if a user input has been received. For example, the control circuitry 20 may be configured to periodically check, e.g., every 5 seconds, to determine if either the input button 14 or the puff sensor 16 (or both) are outputting a signal indicative of user activation. In another implementation, the signal output from the input button and / or the puff sensor 16 may cause an operation in the control circuitry 20, e.g., as an input to a charging capacitor or a comparator. That is, the control circuitry 20 may instead be responsive to the signal, or may perform an operation in response to receiving the signal. Of course, either approach (i.e., active monitoring or passive reception of a signal) may be implemented in accordance with the principles of the present disclosure.

[0043] 2, if the control circuit 20 determines that either the inhalation sensor 16 or the input button 14 has output a signal indicating actuation, the control circuit 20 determines that a user input indicating the user's intent to receive aerosol has been received, which is "Yes" at step S106. Conversely, if the control circuit 20 determines that a user input indicating the user's intent to receive aerosol has not been received, the method of the present invention returns to step S104, and the control circuit 20 continues to monitor for a user input indicating the user's intent to receive aerosol.

[0044] In response to determining that user input has been received at step S106, control circuit 20 is configured to provide a first level of power to heating element 48 at step S108.

[0045] A first level of power is provided to the heating element 48, which gradually raises the temperature of the heating element 48 to an operating temperature at which at least a portion of the e-liquid held within the wick 46 is vaporized. In general, the amount of power provided as the first level of power will vary from implementation to implementation and may vary depending on a number of different factors, including, but not limited to, the amount of liquid held within the wick, the relative surface area between the heating element and the e-liquid, and the voltage and current characteristics of the heating element. In the above example of FIG. 1, the first level of power is set to provide a balance between the power dissipated by the heating element 48 in normal use and used to vaporize the e-liquid and the mass of e-liquid being heated. As the liquid undergoes a phase transition from liquid to vapor in this case, the energy dissipated into the liquid will volatilize the liquid and, broadly speaking, will not further increase the temperature of the liquid. However, there are other factors to consider such that only a certain percentage of the mass of the e-liquid will be susceptible to vaporization, while the remaining e-liquid held within the wick 46 will be heated but not vaporized. This remaining mass acts as a heat sink, absorbing a portion of the dissipated energy from the heating element 48. In this example vapor delivery system 1, the power supplied to the heating element 48 is balanced with the mass of e-liquid held in the wick 46 to generate sufficient aerosol without substantially increasing the temperature of the heating element 48. That is, once the wick 46 is sufficiently replenished with e-liquid, the temperature of the heating element will be approximately constant during normal use (and after an initial warm-up period) within a certain tolerance.

[0046] In an example of system 1, such as the system described above, where the heating element is nickel alloy wire with a resistance of 1.3-1.5 ohms measured at room temperature (e.g., 25° C.), a winding pitch of 0.67±0.2 per mm, and a core of organic cotton with a liquid absorption rate of 0.3 g±0.05 g and an absorption time of 65 seconds±10 seconds (as described in the example above), a suitable power level for such a system is 6-7 watts, and in some implementations, 6.0-6.5 watts. The control circuitry 20 may be configured to deliver power to the heating element 48 according to any suitable technique. In some embodiments, the control circuitry 20 is configured, upon determining that there is user input in step S106, to provide continuous (constant) direct current power from the power source 26 to the heating element 48, possibly via some component such as a DC / DC boost converter, and adjust an electrical characteristic (e.g., voltage) of the provided power as needed. In other implementations, modulation techniques such as pulse width modulation, PWM, etc. may be used. In these implementations, pulses of power are provided to the heating element 48. PWM delivers pulses according to a particular duty cycle, which is roughly the ratio of the pulse width to the length of the signal waveform. In these implementations, the first level of power delivered in step S108 may be considered to be the average (RMS) power delivered over one duty cycle (i.e., the power provided by a pulse multiplied by the percentage of the duration of the pulse over the duration of the duty cycle). A typical duty cycle may be on the order of 40 milliseconds or less (note that having too large a duty cycle will cause fluctuations in the temperature of the heating element).

[0047] As shown in Figure 2, when the control circuit 20 provides the first level of power in step S108, the control circuit 20 is also configured to monitor a parameter associated with a depletion state of the vapor delivery system 1. In the example of Figure 2, the control circuit 20 is configured to monitor the electrical resistance of the heating element 48. The electrical resistance of the heating element 48 is a parameter indicative of a depletion state of the wick 46. This is because, as the wick 46 depletes, the temperature of the heating element 48, and therefore its electrical resistance, increases due to the fact that less e-liquid is available for vaporization or absorbs dissipated energy from the heating element 48.

[0048] With respect to the system used by the control circuit 20 to monitor the resistance of the heating element 48, the process of measuring the resistance of the heating element 48 is performed according to conventional resistance measurement techniques. That is, the control circuit 20 may include a resistance measurement component based on established techniques for measuring resistance (or a corresponding electrical parameter). In one implementation, the control circuit 20 includes a reference resistor (not shown) of known resistance value coupled in series with the heating element 48 (the reference resistor may be provided in the device portion 2 rather than the cartridge portion 4). The control circuit 20 includes a switching device including one or more FETs that act to selectively couple the reference resistor to the control circuit 20 (and in particular to ground). A signal line is coupled between the reference resistor and the heating element 48 and fed into a voltage measurement component of the control circuit 20. When the reference resistor is coupled to the heating element 48, a voltage along the signal line is indicative of the voltage of the heating element 48. In this manner, a voltage divider balance can be used to infer the resistance of the heating element 48 based on the known resistance of the reference resistor and the input voltage to the heating element 48. However, it will be appreciated that this is not an exact method of measuring resistance. By way of example only, any other suitable technique for measuring the resistance of a heating element may be used in accordance with the principles of the present disclosure.

[0049] The control circuit 20 may be configured to sample the resistance periodically (e.g., every 50 milliseconds) as it provides the first level of power to the heating element 48. In another implementation, the control circuit 20 may continuously monitor, for example, using a comparator that is fed with the voltage signal (or a derived resistance signal). In either case, the control circuit 20 is configured to repeatedly determine / derive or measure the resistance value of the heating element 48.

[0050] In step S112, the control circuit 20 is configured to compare the resistance of the heating element against a first threshold. Specifically, the control circuit 20 is configured to determine whether the resistance of the heating element 48 is greater than the first threshold. It should be noted that depending on the value of the first threshold and the specific manner in which the control circuit 20 is set up, another implementation of the control circuit may simply determine whether the resistance is greater than the first threshold.

[0051] In the vapor delivery system 1 described above where the heating element 48 is resistively heated by passing an electric current through the conductive heating element 48, the resistance of the heating element 48 generally increases with temperature. In some cases, the relationship between resistance and temperature may be approximately linear. Thus, the resistance of the heating element 48 is proportional to the temperature of the heating element 48.

[0052] The heating element 48 typically has a room temperature resistance and an operating resistance (i.e., the value at which the heating element reaches its operating temperature). For example, in the system described above, the operating resistance is approximately 2.1 ohms. The first threshold is set to a value, e.g., at least 5% higher than the operating resistance. In the above example, this equates to a value of approximately 2.21 ohms. The first threshold is set to a value that is large enough that minor variations in the temperature of the heating element 48 caused by oscillations around the operating temperature are ignored, but not too large that the temperature of the heating element 48 increases significantly. For example, a resistance value of 2.21 ohms in the above example corresponds to a temperature increase of approximately 10-20°C (for a total temperature of approximately 210-220°C) compared to the operating temperature (which is approximately 200°C). The first threshold may be defined as a fixed resistance value, e.g. 2.21 ohms, pre-stored in the memory of the control circuit 20, or the first threshold may be calculated based on a previous measurement of the resistance of the heating element (e.g. the previous measurement plus a fixed resistance value or the previous measurement plus a certain percentage of this previous measurement, e.g. 14%). The previous measurement may be taken, for example, at the start of a puff and thus approximates the operating resistance value of the heating element.

[0053] If, at step S112, the control circuit 20 determines that the resistance of the heating element 48 is less than the first threshold value (ie, "NO" at step S112), the method of the present invention proceeds to step S114.

[0054] At step S114, the control circuit 20 determines whether there is any further user input indicating the user's intent to generate aerosol. In normal use, the user will inhale into the system 1 or press the input button 14 for as long as the user wishes to receive aerosol, usually about 3 seconds. In other words, in this implementation, the user controls the start and stop of aerosol generation. The control circuit 20 determines whether a signal is received from the input button 14 or from the inhalation sensor 16 indicating activation of either or both of the input button 14 or the inhalation sensor 16. If so, i.e., "yes" at step S114, the method returns to step S108, and the control circuit 20 continues to supply the first level of power to the heating element 48. The method then proceeds to steps S110 and S112 as described above. Thus, the control circuit 20 repeatedly (or periodically) determines whether the resistance of the heating element 48 is greater than or equal to the first threshold value when the first level of power is being supplied.

[0055] On the other hand, if no further user input is received, i.e., "No" at step S114, the method proceeds to step S120 where power to heating element 48 is stopped. When no further user input is received, this indicates that the user has stopped inhaling on system 1 or has stopped pressing input button 14 and does not wish to receive any more aerosol. That is, the user has ended their puff / inhale. As a result, control circuit 20 Upon detecting this, power to heating element 48 is terminated so that no further aerosol is generated by system 1. The method of the present invention returns to step S104 and control circuitry 20 then monitors for the next user input indicating the user's desire to receive aerosol (i.e., the start of the next puff).

[0056] In some embodiments of the present disclosure, if the resistance of the heating element 48 at step S112 is greater than or equal to the first threshold (i.e., "Yes" at step S112), the method proceeds to step S116, where the control circuit 20 delivers a second level of power (instead of the first level of power) to the heating element 48. In other words, the temperature of the heating element 48 increases as the resistance increases. When the threshold value of one is exceeded, a reduced power is supplied to the heating element 48. The second level of power is less than the first level of power, but is a non-zero level of power. In other words, the control circuit supplies a non-zero level of power to the heating element 48 as the second level of power. As described above, the power supplied to the heating element 48 is controlled via the control circuit 20, for example PWM control. The control circuit 20 is therefore configured to vary the level of power supplied to the heating element 48 using any suitable technique, such as PWM control (by varying the duty cycle) or by reducing the magnitude of the voltage supplied to the heating element.

[0057] As mentioned above, it is understood that during normal use, a certain amount of e-liquid held within the wick 46 will be vaporized and inhaled by the user. Under normal conditions, and particularly when there is sufficient e-liquid within the reservoir 44, the wick 46 will be sufficiently refilled with e-liquid such that the wick 46 holds a substantially constant amount of e-liquid. Assuming there is sufficient e-liquid to be vaporized, the power dissipated by the heating element will be absorbed within the e-liquid and vaporized. The temperature of the e-liquid will then be substantially constant. If there is still more e-liquid to be vaporized, the remaining e-liquid will act as a heat sink, absorbing a portion of the dissipated power that will increase the temperature of the remaining e-liquid but not vaporize it.

[0058] However, if the amount of liquid in the wick 46 falls below a certain amount, for example because the reservoir 44 runs out of e-liquid and is therefore unable to refill the wick 46, not as much dissipated power is absorbed by the e-liquid. In some instances, power is provided to the cartridge portion 4, which does not have the same phase change properties as the material of the wick 46 or the e-liquid. As a result, the temperature of the wick and heating element 48 continues to rise, leading to scorching of the wick 46, which can have undesirable effects, among other things, that affect the taste of the generated aerosol and / or cause damage to the vapor delivery system 1. That is, when the e-liquid in the wick 46 is depleted, the e-liquid is transferred to the e-liquid. As a result, a greater proportion of the energy is dissipated by the heating element 48 (and instead transferred to the core material of the core 46, for example).

[0059] However, in reality, this does not mean that the wick 46 will be completely drained of e-liquid. In some systems that detect dry wicks earlier than normal, this remaining e-liquid in the wick is less likely to be vaporized, even if there is a significant amount of e-liquid available to vaporize. Thus, consumers unnecessarily discard the cartridge portion that contains the vaporizable, inhalable e-liquid. This is inefficient in terms of material utilization, leading to significant costs for consumers and increased waste disposal.

[0060] In accordance with the present disclosure, at step S112, if the resistance (and therefore temperature) of the heating element 48 is equal to or greater than the first threshold value, the control circuit 20 determines that the system 1 is depleted, and in particular that the e-liquid in the wick 46 is depleted. Notably, upon comparing the resistance value to the first threshold value at step S112, the control circuit 20 may be said to determine a depletion condition associated with the vapor delivery system 1 (i.e., whether the system 1 is depleted or not).

[0061] As a result, the control circuit 20 provides a second, reduced level of power to the heating element 48, as shown in step S116. Compared to providing the first level of power, the second level of power reduces the temperature that the heating element reaches for a given mass of e-liquid in the wick 46 (based on a balance between the energy dissipated and the mass of e-liquid available to receive this dissipated energy) in the given amount of e-liquid. In practice, this does not necessarily mean that the temperature of the heating element will fall below the operating temperature, and in some implementations the second level of power is selected such that the temperature will not fall below the operating temperature. Rather, less power is dissipated because there is less mass of e-liquid available for vaporization. This in turn means that the heating element 48 will be substantially less likely to exceed the operating temperature and burn the wick. In this regard, although the control circuit 20 determines that the e-liquid stored in the wick 46 is depleted, the vapor delivery system 1 can still generate vapor from the remaining e-liquid that can be inhaled by the user and that would otherwise be lost, but may reduce the likelihood of overheating the e-liquid or the wick.

[0062] The second level of power may be set to 70% or less than the first level of power, 50% or less than the first level of power, or 30% or less than the first level of power, the exact value depending on several factors including the difference between the first threshold and the actuation resistance of the heating element 48.

[0063] 2, at step S118, the control circuit 20 is configured to determine whether there is any more user input indicating the user's intent to generate an aerosol. As discussed above in connection with step S114, the control circuit 20 determines whether a signal is received from the input button 14 or from the inhalation sensor 16 indicating activation of either or both of the input button 14 or the inhalation sensor 16. If so, i.e., "yes" at step S118, the method of the present invention returns to step S116, where the control circuit 20 continues to supply the second level of power to the heating element 48. Thus, the control circuit 20 continues to monitor whether there is any more user input received while supplying the second level of power to the heating element 48.

[0064] On the other hand, if no further user input is received, i.e., "no" at step S118, the method proceeds to step S120, as described above, where power is stopped from being supplied to heating element 48. The method returns to step S104, where control circuit 20 monitors for the next user input indicating the user's desire to receive aerosol.

[0065] As described above, the present disclosure provides a vapor delivery system 1 in which the resistance of the heating element 48 is compared against a first threshold value to determine whether the e-liquid in at least a portion of the system, particularly in the wick, is depleted. When depletion is detected (corresponding to an increase in temperature or resistance of the heating element 48 in the above implementation), a reduced level of power is provided to the heating element. The reduced level of power is provided in a manner that still allows aerosol to be generated from the e-liquid remaining in the wick 46, but with less chance of damage to the cartridge portion 4 (particularly the wick and / or the heating element). This increases the efficiency of use of the e-liquid in the cartridge portion 4, thereby allowing the user to use more of the e-liquid provided in the cartridge portion 4. This reduces the number of times the user needs to replace the cartridge portion 4 compared to other modular systems.

[0066] Of course, when the control circuitry provides a second, reduced level of power to the heating element 48, the amount of aerosol generated (or liquid volatilized) may be reduced as compared to when the control circuitry 20 provides the first level of power. The difference in volume may be noticeable to a user, for example, when the user exhales the aerosol that he or she has inhaled. In some cases, this may be sufficient to realize that the reservoir 44 is depleted and that the cartridge portion 4 will soon require replacement. The change in volume of aerosol may act as a cue for the user to take necessary action.

[0067] In the case where the change in the amount of aerosol generated is not noticeable or where the control circuitry 20 determines that there is depletion in step S112 in an example where the change is to be highlighted to the user, the control circuitry 20 in some implementations, such as that described in FIG. 1, is configured to activate the indicator 25. As already mentioned, the indicator 25 can be used to output a signal, such as an optical signal via an LED, to indicate to the user that depletion has been detected. In much the same manner as above, the indicator 25 can act as a cue for the user to take the necessary action in terms of replacing the cartridge part 4. More specifically, in an implementation where the indicator 25 is used, the control circuitry is configured to activate the indicator simultaneously with step S116 of FIG. 2. The control circuitry 20 may turn off the indicator in step S120 or the indicator may remain activated until the user takes an action that is detected by the control circuitry 20, such as changing the cartridge part 4 to another cartridge part 4. The indicator 25 may output a continuous signal, such as a continuous light signal, or an intermittent signal, such as a series of light pulses. In either case, The display unit 25 detects the depletion of liquid in the wick (or, more broadly, the depletion of liquid in the vapor supply system 1). Provide a signal to the user that a message has been sent.

[0068] It will also be appreciated that allowing the user to vaporize the remaining e-liquid using a second level of power not only increases the amount of e-liquid available for use, but also provides the user with the option to continue inhaling aerosol even when the user is unable to change the cartridge portion 4, such as while driving. Even if the amount of aerosol generated is slightly less, the user will still be able to consume some aerosol. Thus, the combination of depletion warning (either via a noticeable change in aerosol volume or via display 25) and the ability to generate vapor even when depletion is detected in system 1 allows the user to take necessary action or plan their vaping activity.

[0069] Although control circuitry 20 has been described as determining whether a user input signal is still being received (at steps S114 and S118), these steps may be omitted. For example, in some implementations, if control circuitry 20 determines that a user input has been received at step S106, power is provided to the heating element for a predetermined time from detection of the user input. For example, power may be provided for a time approximately equal to a typical puff duration, e.g., 3 seconds. After the predetermined time has elapsed, power may no longer be provided to heating element 48. Of course, in these implementations, control circuitry 20 may be configured to provide different levels of power depending on whether the resistance of heating element 48 is above or below a first threshold, but instead of determining whether user input is being received, control circuitry 20 may be configured to determine whether the predetermined time has elapsed.

[0070] In the implementation described above in FIG. 2, the control circuitry 20 is configured to provide a second level of power in response to detecting that depletion has occurred. The second level of power is provided for the duration of the given puff as long as user input is still being provided (step S118). Once power is no longer provided to the heating element 48 (at step S120), i.e., at the end of the given puff, the method returns to step S104, where the control circuitry monitors user input. For subsequent puffs, the control circuitry 20 provides the first level of power according to step S108 before providing the second level of power at step S116. This method is useful for some applications, particularly when the wick 46 is deemed depleted of e-liquid (based on the resistance of the heating element 48), but the reservoir 44 is not completely depleted. For example, some users may use the vapor delivery system 1 at an angle that is greater than the angle at which it would normally be used (e.g., the user is lying down). In these instances, the end of the wick 46 disposed within the reservoir 44 may not come into contact with the e-liquid within the reservoir 44, thus meaning that vaping in this orientation would result in the wick 46 being considered depleted, but the reservoir 44 not being considered depleted. In response to the user receiving an indication from the indicator 25 and / or a decrease in the amount of aerosol, the user tilts the system 1 so that the end of the wick 46 once again comes into contact with the e-liquid within the reservoir 44. Thus, the determination of whether depletion occurs during a given puff is effectively reset between puffs.

[0071] 2, once the user finishes the puff, assuming that depletion has occurred and the control circuitry provides the second level of power, the control circuitry 20 will provide the first level of power to the heating element 48 for the initiation of the next puff. This is advantageous when the heating element 48 is cold, i.e., the temperature of the heating element can be quickly brought up to operating temperature even if a small amount of e-liquid is retained in the wick 46.

[0072] 2, the determination of whether there is depletion during a given puff is effectively reset between puffs. Once a determination that there has been depletion is made in step S112, control circuit 20 therefore does not have to continue monitoring the resistance of heating element 48 at the time it determines that the resistance of heating element 48 exceeds or equals the first threshold. This saves power that would otherwise be used to monitor and compare resistance during a puff.

[0073] However, in some embodiments it may be beneficial to adjust the power multiple times during a puff to accommodate more rapid changes in the depletion state of the vapor delivery system 1. Figure 3 illustrates another example method of operating the vapor delivery system 1 of Figure 1 according to a further embodiment of the present disclosure, whereby the power level may be adjusted multiple times during a given puff. The method of Figure 3 is broadly similar to the method of Figure 2, and various steps etc. common to Figure 3 (as indicated by common numerals) will not be repeated; only the differences will be described in detail.

[0074] In FIG. 2, if user input is still received at step S118, the control circuit 20 is configured to provide a second level of power to the heating element 48. However, in FIG. 3, if user input is still received at step S118, i.e., "yes" at step S118, the method of the present invention returns to step S112. That is, the control circuit 20 is configured to monitor the resistance of the heating element 48 while user input is being received. In this regard, it should be appreciated that FIG. 3 illustrates a system 1 in which the resistance of the heating element 48 is repeatedly compared to a first threshold value during a given inhalation, regardless of whether the control circuit 20 is providing the first or second level of power to the heating element 48. In some embodiments, a predetermined delay (e.g., 10-20 milliseconds) between steps S118 and S110 may force the resistance of the heating element 48 to be adjusted in response to the second power level being applied.

[0075] Providing a control circuit 20 configured in this manner means that faster changes in the depletion state of the wicks 46 can be accounted for and the appropriate power level can be supplied accordingly.

[0076] In another example based on Fig. 2, not shown, to reduce the possibility of burning the wick when the control circuit 20 determines that there is depletion in step S112, the control circuit 20 is configured to store or record, such as in a memory, an indication that depletion was detected. Thereafter, before supplying any power in the next puff, the control circuit 20 determines whether depletion was detected during the last puff, and if so, begins to supply a second level of power. This configuration may be advantageous when the depletion is a depletion of the reservoir in addition to the wick 46, i.e., not just depletion of the wick 46.

[0077] Figure 4 illustrates another example method of operating the vapor delivery system 1 of Figure 1 according to a further embodiment of the present disclosure, where the power level can be adjusted during a given puff. The method of Figure 4 is broadly similar to the method of Figure 2, and various steps etc. common to Figure 4 (as indicated by common numerals) will not be repeated; only the differences will be described in detail.

[0078] In broad overview, Figure 4 illustrates a system 1 in which the control circuit 20 is configured to select one of a plurality of (three) power levels to supply to the heating element 48, namely a first power level, a second power level lower than the first power level, and a third power level lower than the second power level. Such a system offers the possibility to further vaporize the e-liquid remaining in the wick 46, but at a reduced power level supplied to the heating element 48. The principle of operation is generally the same as described for Figure 2, except for the additional power level.

[0079] If the monitored resistance of the heating element 48 at step S116 was previously determined to be greater than or equal to the first threshold at step S112, the method of the present invention proceeds to step S130. At step S130, the monitored resistance of the heating element 48 is compared to a second threshold. In some embodiments, the second threshold is the same as the first threshold, assuming that the resistance of the heating element 48 is proportional to the temperature of the heating element 48, in which case the system 1 is configured to operate such that the heating element 48 reaches the same or similar temperature during use. That is, taking the values ​​used in connection with FIG. 2, the first and second thresholds are set at 2.21 ohms. In other implementations, the second threshold may be set slightly lower than the first threshold, for example 10% lower than the first threshold. In this manner, the maximum temperature of the heating element 48 is further limited when the second level of power is applied, which can be advantageous when the system 1 experiences a sudden and significant change in the mass of e-liquid remaining in the wick. However, in other implementations, the second threshold may be set differently from the first threshold, particularly in implementations where the heating characteristics of the heating element 48 differ based on the amount of e-liquid held in the wick 46.

[0080] At step S130, the control circuit 20 is configured to determine whether the resistance is greater than or equal to a second threshold. It should be noted that alternative implementations of the control circuit may determine whether the measured or determined resistance is greater than the second threshold depending on the second threshold. If at step S130 the control circuit 20 determines that the resistance of the heating element 48 is less than the second threshold (i.e., "NO" at step S130), the method of the present invention proceeds to step S132.

[0081] In step S132, control circuitry 20 determines whether there is any further user input indicating the user's intent to generate aerosol. In normal use, the user will inhale into system 1 or press input button 14 for as long as the user wishes to receive aerosol, usually about three seconds. In other words, in this implementation, the user will initiate and control the generation of aerosol. The control circuit 20 then controls the start and stop of the second threshold value. The control circuit 20 determines whether a signal is received from the input button 14 or from the inhalation sensor 16 indicative of activation of either or both of the input button 14 or the inhalation sensor 16. If so, i.e., "yes" at step S132, the method returns to step S116 and the control circuit 20 continues to supply the second level of power to the heating element 48. The method proceeds to step S130 as described above. Thus, the control circuit 20 repeatedly (or periodically) determines whether the resistance of the heating element 48 is greater than or equal to the second threshold value when the second level of power is being supplied.

[0082] On the other hand, if no further user input is received, i.e., "no" at step S132, the method proceeds to step S120 where power is stopped from being supplied to heating element 48. When no further user input is received, this indicates that the user has stopped inhaling on system 1 or has stopped pressing input button 14 and no longer wishes to receive aerosol. As a result, when control circuitry 20 detects this condition, power is stopped from being supplied to heating element 48 such that no further aerosol is emitted. The method returns to step S104 where control circuitry 20 monitors for the next user input indicating the user's desire to receive aerosol.

[0083] In some embodiments of the present disclosure, if the resistance of the heating element 48 is greater than or equal to the second threshold value at step S130 (i.e., "yes" at step S112), the method proceeds to step S134 where the control circuit 20 is configured to send a third level of power (instead of the second level of power) to the heating element 48. In other words, when the temperature of the heating element 48 reaches a temperature such that the resistance exceeds the second threshold value, a further reduced power is supplied to the heating element 48. The third level of power is less than the second level of power, but is a non-zero level of power. In other words, the control circuit supplies a non-zero level of power to the heating element 48 as the third level of power.

[0084] The third level of power may be set to be 70% or less of the second level of power, or 50% or less of the second level of power, or 30% or less of the second level of power, the exact value depending on several factors such as the difference between the second threshold and the actuation resistance value of the heating element 48.

[0085] In substantially the same manner as above, the control circuit 20 performs the same operation as in step S114 or S132. A determination is then made at step S136 as to whether user input is still being received. If so, the method returns to step S134 where a third level of power is applied to heating element 48 by control circuit 20. Conversely, if user input is not being received at step S136, the method proceeds to step S120 where power is removed from heating element 48.

[0086] 4, the control circuit 20 is configured to compare the resistance of the heating element 48 to a number of thresholds, each of which corresponds to a particular power level delivered to the heating element 48. Providing multiple power levels allows for fine control of the power delivered to the heating element 48. In one example, the power can be varied throughout the puff such that a suitable level of power is delivered to the heating element 48 to accommodate changes in the amount of e-liquid in the wick.

[0087] The principles of Figure 4 may be incorporated into those of Figure 3. Similarly, the principles of Figure 4 may be applied to a system in which the power level of a previous puff is recorded and a subsequent puff begins at the previously recorded power level. Further, it will be appreciated that although only three power levels have been described in connection with Figure 4, four or more power levels may also be applied in accordance with the principles of the present disclosure. Each of these multiple power levels is set to have successively decreasing values, and each of the power levels is a non-zero power level.

[0088] Although the above relates to a system 1 aimed at measuring the resistance of the heating element 48 to determine a depletion condition, it will be appreciated that any other suitable technique may be used to determine depletion. For example, an infrared camera may be used to measure the temperature of the heating element 48. A similar process of comparing the temperature to a threshold value may be performed in such situations. Additionally, depletion may be determined by monitoring a parameter related to the reservoir 44, for example using a time of flight sensor to monitor the liquid level in the receptacle 44. In principle, any suitable technique for determining depletion of e-liquid in a part of a vapor delivery system (wick 46 or reservoir 44) may be employed in accordance with the principles of the present disclosure.

[0089] Although the vapor delivery system 1 has been described as including a sealed cartridge portion 4, it will be appreciated that the cartridge portion 4 may be refillable in some implementations. The principles of the present disclosure apply equally to such implementations. In yet further implementations, the cartridge portion 4 may be an integral part of the reusable device portion 2, for example formed as a part of the housing or with minimal common features. The integrated cartridge portion 4 may be repeatedly refillable with e-liquid. Such a configuration of the vapor delivery system is known as an open system. The principles of the present disclosure apply equally to such implementations.

[0090] While the above embodiments have focused in some respects on some specific example steam supply systems, it will be appreciated that the same principles are applicable to steam supply systems using other technologies, i.e., the particular manner in which various aspects of the steam supply system function is not directly related to the principles in the examples described herein.

[0091] For example, while the above embodiments have focused primarily on devices having electronic heater-based vaporizers for heating liquid vapor precursor materials, the same principles may be applied to vaporizers based on other technologies. The vaporizers may be adapted accordingly based on other vapor precursor materials, such as vaporizers, e.g. piezoelectric vibrator based vaporizers or optically heated vaporizers, and also other vapor precursor materials, e.g. solid materials, e.g. plant-derived materials, e.g. tobacco-derived materials, or vapor precursor materials in other forms, such as gels, pastes or foam-based vapor precursor materials.

[0092] Additionally, and as already mentioned, it should be understood that the above-described approaches relating to electronic cigarettes may be implemented in cigarettes having a different overall structure than that shown in FIG. 1. For example, the same principles may be adapted to electronic cigarettes that do not have a two-part modular structure, but instead include a single-part device, such as a disposable (i.e., non-rechargeable, non-refillable) device. Furthermore, some implementations of modular devices may have different arrangements of parts. For example, in some implementations, the control unit may also include a vaporizer having a replaceable cartridge that provides a source of vapor precursor material for the vaporizer used to generate vapor. Furthermore, whereas in the above-described examples, the electronic cigarette 1 does not include a flavor insert, other exemplary implementations may include such additional flavor members.

[0093] Similarly, while the above system has been described with respect to liquid vapor precursor materials, similar principles can be applied to vapor precursor materials in different states of matter. For example, some solids, such as reconstituted tobacco, may exhibit characteristics that change their thermal properties when vaporized. Where such materials exhibit such characteristics, the techniques of the present disclosure may be equally applied to these materials.

[0094] Thus, a vapor delivery system is described that includes a vaporizer for generating vapor from a vapor precursor material, a reservoir for storing the vapor precursor material, and a control circuit configured to supply a first non-zero level of power to the vaporizer to generate vapor from at least a portion of the vapor precursor material, observe a parameter indicative of an amount of at least the portion of the vapor precursor material, determine a depletion state of the vapor precursor material based on comparing the monitored parameter to a first threshold, and supply a second non-zero level of power to the vaporizer if the control circuit determines that a depletion has occurred based on comparing the monitored parameter to the first threshold, the second level of power being lower than the first level of power.

[0095] To address various problems and advance the art, the entire disclosure illustratively illustrates various embodiments in which the claimed invention is practiced. The advantages and features of the disclosure are merely representative examples of embodiments, and are not exhaustive or exclusive. They are provided merely to aid in the understanding and teaching of the claimed features. It is to be understood that the advantages, embodiments, examples, functions, features, structures, and / or other aspects of the disclosure should not be construed as limiting the disclosure to the exact scope of the claims or to the equivalents of the claims, but that other embodiments may be utilized or modified without departing from the scope and / or spirit of the disclosure. Various embodiments may suitably comprise, consist of, or consist essentially of the disclosed elements, components, features, parts, steps, means, or other combinations, and it is to be understood that the features of the dependent claims may be combined with the features of the independent claims in combinations other than those expressly recited in the claims. The disclosure also includes other inventions not currently claimed but which may be claimed in the future.

Claims

1. a vaporizer for generating vapor from a vapor precursor material; a reservoir for storing a vapor precursor material; providing a first non-zero level of power to the vaporizer to generate vapor from at least a portion of the vapor precursor material; determining a depletion state of the vapor precursor material based on monitoring a parameter indicative of the amount of at least a portion of the vapor precursor material and comparing the monitored parameter to a first threshold; providing a second non-zero level of power to the vaporizer that is less than the first level of power when the control circuit determines that depletion has occurred based on a comparison of the monitored parameter to a first threshold; When user input is complete, power is cut off, and control circuitry configured to, in response to a subsequent user input, cycle between delivering the first level of power, determining the depletion condition, and delivering the second level of power if the control circuitry determines that depletion has occurred.

2. The steam supply system of claim 1 , wherein the second level of power is at least one of less than 70%, less than 50%, or less than 30% of the first level of power.

3. 3. The vapor delivery system of claim 1, wherein the second level of power is set to enable the vapor delivery system to continue generating vapor even after the control circuitry determines that there is depletion of the at least a portion of the vapor precursor material.

4. 4. The vapor supply system of claim 1, wherein the control circuit is configured to power the vaporizer using pulse width modulation, and the first and second power levels are average powers over one duty cycle of the pulse width modulation.

5. 5. The steam supply system of claim 1, further comprising a display, and wherein the control circuit is configured to activate the display when the control circuit determines that there is depletion based on a comparison of the monitored parameter to a first threshold.

6. 6. The vapor delivery system of claim 1, further comprising a vapor precursor material transport member configured to transport the vapor precursor material from the reservoir to the vaporizer.

7. 7. The vapor delivery system of claim 6, wherein the vapor precursor material depletion state is indicative of an amount of vapor precursor material in the vapor precursor material transport member.

8. 8. The vapor delivery system of claim 1, wherein the vaporizer includes an electrically heated heating element, the parameter indicative of the quantity of at least a portion of the vapor precursor material is an electrical resistance of the heating element, and the control circuit is further configured to measure the electrical resistance of the heating element.

9. 9. The steam supply system of claim 1, wherein the control circuit is configured to repeatedly compare the monitored parameter to a first threshold value.

10. 10. The vapor supply system of claim 1, wherein after the control circuit begins to supply the second level of power to the vaporizer, the control circuit is configured to supply the first level of power if the control circuit determines that there is no longer any depletion based on a comparison of the monitored parameter to a first threshold.

11. 11. The vapor delivery system of claim 1, wherein the control circuitry is configured to compare the monitored parameter to a plurality of thresholds, each threshold being indicative of a degree of depletion of at least a portion of the vapor precursor material, each threshold corresponding to one of a plurality of different non-zero levels of power configured to be output by the control circuitry.

12. 12. The vapor supply system of claim 1, wherein when the control circuit determines that depletion occurs based on the first threshold, the control circuit is configured to compare the monitored parameter to a second threshold and to supply a third non-zero level of power to the vaporizer that is lower than the second level of power when the control circuit determines that depletion occurs based on a comparison of the monitored parameter to the second threshold.

13. 1. A control circuit for use in a vapor delivery system for generating vapor from a vapor precursor material, the vapor delivery system including a vaporizer for generating vapor from a vapor precursor material, the control circuit comprising: providing a first non-zero level of power to the vaporizer to generate vapor from at least a portion of the vapor precursor material; determining a depletion state of the vapor precursor material based on monitoring a parameter indicative of an amount of at least a portion of the vapor precursor material; Comparing the monitored parameter to a first threshold; providing a second non-zero level of power to the vaporizer that is less than the first level of power when the circuit determines that depletion exists based on a comparison of the monitored parameter to a first threshold; When user input is complete, power is cut off, and control circuitry configured to, in response to a subsequent user input, cycle through providing the first level of power, determining the depletion condition, and providing the second level of power if the control circuitry determines that depletion has occurred.

14. A vapor delivery device comprising the control circuit of claim 13.

15. 1. A method of operating a control circuit for a vapor delivery system including a vaporizer for generating vapor from a vapor precursor material and a reservoir for storing the vapor precursor material, the method comprising: providing a first non-zero level of power via a control circuit to a vaporizer to generate vapor from at least a portion of the vapor precursor material; determining a depletion state of the vapor precursor material based on monitoring a parameter indicative of the amount of at least a portion of the vapor precursor material via control circuitry and comparing the monitored parameter to a first threshold value; providing a second non-zero level of power to the vaporizer via a control circuit when the circuit determines that depletion exists based on a comparison of the monitored parameter to a first threshold, the second non-zero level of power being lower than the first level of power; When the user input is completed, the power supply is stopped. and in response to a subsequent user input, repeating the process of providing the first level of power, determining the depletion condition, and providing the second level of power if the control circuitry determines that depletion has occurred.

16. a vaporizing means for generating a vapor from the vapor precursor material; a storage means for storing the vapor precursor material; providing a first non-zero level of power to a vaporizing means to generate vapor from at least a portion of the vapor precursor material; determining a depletion state of the vapor precursor material based on monitoring a parameter indicative of the amount of at least a portion of the vapor precursor material and comparing the monitored parameter to a first threshold; providing a second non-zero level of power to the vaporization means, the second non-zero level being less than the first level of power when the control means determines that depletion exists based on a comparison of the monitored parameter to a first threshold; When user input is complete, power is cut off, and control means configured to, in response to subsequent user input, cycle through the supplying of said first level of power, determining said depletion condition, and supplying said second level of power if the control means determines that depletion has occurred.

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