Aerosol Generator

Abstract

The aerosol generating device (1) includes sensing means for detecting when an aerosol product article (10) is inserted into or withdrawn from a heating chamber (12) of the device (1). A roller (26) is mounted for rotation about a roller axis (28) such that an article (10) moving along a predetermined insertion path engages a surface of the roller (26) causing the roller (26) to rotate. The sensing means determines the direction of rotation of the roller (26). The sensing means may be responsive to a property, such as a radius or a magnetic field, of the roller (26). The property may vary with angle about the roller axis (28) to define one or more indicia (54) detectable by one or more sensors (34) disposed adjacent the roller (26).

Description

[Technical field]

[0001] The present disclosure generally relates to an aerosol generating device for heating an aerosol-generating substrate to generate an aerosol that is inhaled by a user of the aerosol generating device. The disclosure is particularly applicable to portable (hand-held) aerosol generating devices. Such devices heat an aerosol-generating substrate, such as tobacco or other suitable material, by conduction, convection, and / or radiation, rather than by combustion, to generate an aerosol that is inhaled by a user. [Background technology]

[0002] Risk reduction or risk modification devices (also known as aerosol generating devices or vapour generating devices) have grown rapidly in popularity and use in recent years as an alternative to the use of traditional tobacco products. A variety of devices and systems are available that heat or warm an aerosol generating material to produce an aerosol that is inhaled by the user.

[0003] Commonly available risk reduction or risk modification devices are substrate heated aerosol generators or so-called heated non-combustion devices. This type of device generates an aerosol or vapour by heating an aerosol-forming substrate to a temperature typically in the range 150° C. to 300° C. Heating the aerosol-forming substrate to a temperature within the range, without burning the aerosol-forming substrate, generates vapour which is typically cooled and condensed to form an aerosol which is inhaled by the user of the device.

[0004] Generally speaking, a vapor is a substance that is in the gas phase below its critical temperature, meaning that the vapor can be condensed into a liquid by increasing the pressure without decreasing the temperature. An aerosol, on the other hand, is a suspension of fine solid particles or liquid droplets in air or another gas. However, it should be noted that the terms "aerosol" and "vapor" may be used interchangeably herein, particularly with respect to the form of inhalable medium that is produced for inhalation by the user. Summary of the Invention [Problem to be solved by the invention]

[0005] Currently available aerosol generating devices can use one of many different approaches to provide heat to the aerosol-generating substrate. One such approach employs an induction heating system. In such devices, an induction coil is provided within the device and an inductively heatable susceptor is provided to heat the aerosol-generating substrate. When a user activates the device, electrical energy is provided to the induction coil, which in turn generates an alternating electromagnetic field. The susceptor couples with the electromagnetic field to generate heat, which is transferred, for example, by conduction, to the aerosol-generating substrate, which heats up and generates an aerosol. Another approach employs a resistive heating system that supplies electrical current directly to a heating element. The heating element generates heat, which is transferred, for example, by conduction, to the aerosol-generating substrate. The susceptor or heating element can surround the aerosol-generating substrate to transfer heat to the outer surface of the aerosol-generating substrate. Alternatively, the susceptor or heating element can be in the form of a blade that is embedded in the aerosol-generating substrate when the aerosol-generating substrate is inserted into the aerosol-generating device.

[0006] The aerosol-generating substrate forms part of a consumable that is removably received in an aerosol generating device. Typically, a distal end of the consumable that includes the aerosol-generating substrate is received in a heating chamber of the aerosol generating device, while a proximal end of the consumable protrudes from the aerosol generating device so that it can be held in a user's mouth. It is beneficial for the aerosol generating device to be able to detect when a consumable is inserted or withdrawn from the device, so that certain functions of the device can be enabled or disabled in an appropriate manner. [Means for solving the problem]

[0007] The present invention relates to a heating chamber for receiving an elongated aerosol product article that can be inserted into the heating chamber along a predetermined insertion path or withdrawn from the heating chamber along the same insertion path; a roller mounted for rotation about a roller axis generally perpendicular to the insertion path such that an aerosol product article moving along the insertion path engages a surface of the roller, thereby rotating the roller; sensing means for determining the direction of rotation of the roller; The present invention provides an aerosol generating device comprising:

[0008] The use of rollers provides a convenient and mechanically simple way to convert the linear motion of the consumable when it is inserted or removed into a rotational motion that can be detected using many alternative methods. The rotational motion of the rollers occurs in a compact space, allowing the sensing means to be placed within the limited volume of the portable aerosol generating device. By detecting the direction of rotation of the rollers, the device can determine whether the consumable is being inserted or removed, which is important for controlling the device in an appropriate manner. When detecting movement without determining the direction of movement, insertion and removal can only be distinguished if the previous state of the consumable is known. In other words, if the consumable was previously known to be present, the movement must indicate that the consumable is now being removed, and if the consumable was previously known not to be present, the movement must indicate that the consumable is now being inserted. The present invention does not require the state of the consumable to be stored or, alternatively, the use of a separate sensor to detect the presence or absence of the consumable.

[0009] Preferably, the roller has a property which varies with angle about the roller axis and the sensing means comprises at least one sensor capable of measuring the change in the property as the roller rotates past the sensor to determine the direction of rotation of the roller. The property may be any physical characteristic which can be measured by a sensor. The measurement need not be a continuous value and may include sensing the presence or absence of the property to provide a two-state (ON / OFF) output signal from the sensor. The property may be an internal property of the roller, for example a magnetic property, a surface property such as brightness or colour, or an external property such as radius, etc.

[0010] Preferably, the change in the property of the roller as a function of angle about the roller axis defines an indicia at an indicia angular position on the roller, and the sensing means includes a first sensor capable of detecting movement of the indicia past a first sensor angular position about the roller axis, and a second sensor capable of detecting movement of the indicia past a second sensor angular position about the roller axis, the angle between the first and second sensor angular positions being less than 180°. The indicia is any feature of the property that can be measured by the sensor and used to identify an angular position on the roller as it rotates past the sensor. The indicia can only be well defined in relation to other aspects of the sensor or sensing means. The indicia need not necessarily identify an angular position that is unique around the circumference of the roller. The indicia may still be useful in determining the direction of rotation of the roller if it forms part of an identifiable pattern (including a repeating pattern) around the circumference. By positioning the first and second sensors at an angular interval of less than 180°, the order in which the two sensors detect the passage of the indicia varies depending on the direction of rotation of the roller, thereby enabling a determination of direction.

[0011] In some embodiments of the invention, the sensing means further includes a timer and a comparator. As the roller rotates, the timer measures a first time interval from when the first sensor detects movement of the index past the first sensor angular position to when the second sensor detects movement of the index past the second sensor angular position, and a second time interval from when the second sensor detects movement of the index past the second sensor angular position to when the first sensor detects movement of the index past the first sensor angular position. The comparator then compares the first interval with the second interval to determine the direction of rotation of the roller.

[0012] In another embodiment of the invention, the sensing means further includes a timer, a comparator, and a third sensor capable of detecting movement of the index through a third sensor angular position about the roller axis. As the roller rotates, the timer measures a first time point when the first sensor detects movement of the index through the first sensor angular position, a second time point when the second sensor detects movement of the index through the second sensor angular position, and a third time point when the third sensor detects movement of the index through the third sensor angular position. The comparator can determine the direction of rotation of the roller from the order in which the first, second, and third times occur. In this embodiment, the determination does not rely on measuring and comparing time intervals, and the trade-off for the additional sensor is that it is less susceptible to possible changes in the rotational speed of the roller.

[0013] In some embodiments of the invention, the measured property of the roller preferably varies in a mirror asymmetric pattern as a function of the angle about the roller axis, which has the advantage that only a single sensor, or a simpler arrangement of sensors, can be used to determine the direction of rotation of the roller.

[0014] In some embodiments of the invention, the asymmetric change in a property of the roller as a function of angle about the roller axis defines first and second indicia on the roller that are identifiable by the sensor, the angular positions of the first and second indicia being less than 180° apart. Thus, the order in which the sensor detects the movement of each indicia past it varies depending on the direction of rotation of the roller, thereby allowing a direction to be determined.

[0015] In another embodiment of the invention, the asymmetric variation of the roller properties as a function of angle about the roller axis defines first, second and third indicia at first, second and third indicia angular positions on the roller respectively, the angles between the first, second and third indicia angular positions all being different. When the roller rotates at a substantially constant speed, the angular spacing of each indicia is different, resulting in a pattern of different time intervals that the sensor detects as the indicia move past. The sensing means can therefore determine the direction of rotation of the roller from the order in which the different time intervals occur. This embodiment has the advantage that the sensor does not need to distinguish between different types of indicia, e.g. it only needs to determine the presence or absence of an indicia.

[0016] In some embodiments of the invention, the property that varies with the angle of the roller axis is a magnetic property, and the or each sensor is capable of detecting a change in a magnetic field as the roller rotates past the sensor. Magnetic field sensors do not require moving mechanical parts and can be easily integrated into microelectronic circuits, simplifying the design and manufacture of the aerosol generating device. The magnetic field sensor can be, for example, a Hall effect sensor. The roller can include one or more permanent magnets arranged to generate a magnetic property that varies with the angle about the roller axis.

[0017] In another embodiment of the invention, the property that varies with angle about the roller axis is the radius of the roller and the or each sensor is capable of detecting the change in radius of the roller as it rotates past the sensor. A roller with a varying radius is simple to manufacture and avoids problems that can arise from the use of permanent magnets in a manufacturing environment, for example as permanent magnets tend to attract or repel each other and attract metal particles.

[0018] The changing radius of the roller can be measured in a variety of ways, with or without contacting the surface of the roller. For example, the or each sensor may include a sensor element that engages the surface of the roller and moves toward and away from the roller axis in response to the change in radius of the roller as it rotates. Such a sensor may measure the change in radius as a continuous variable, or may further include an electrical switch that is switched between ON and OFF states as the sensor element moves toward and away from the roller axis. The measurement signal output by the sensor is therefore necessarily analogue or digital.

[0019] The aerosol generating device may further include a heater for heating the aerosol product article received in the heating chamber, a counter for counting the number of revolutions of the roller, and a controller for activating the heater when the counter has counted a predetermined number of revolutions. By counting the number of revolutions of the roller as the aerosol product article is inserted along the predetermined insertion path, the device can measure the distance traveled by the article to determine when the article is fully inserted into the heating chamber. This eliminates the need for an additional sensor at the distal end of the heating chamber that may be exposed to high temperatures.

[0020] The present invention further provides a method for determining when an aerosol product article is inserted into or withdrawn from a heating chamber of an aerosol generating device, the method comprising: moving the aerosol product article into or out of the heating chamber along a predetermined insertion path; rotating the roller by engaging the aerosol product article with a surface of the roller mounted for rotation about a roller axis generally perpendicular to the insertion path; using sensing means to determine the direction of rotation of the roller; Includes. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a schematic elevational view of an aerosol generating device according to the present invention. [Diagram 2] FIG. 2 is a schematic plan view taken along line AA in FIG. [Diagram 3-6] 1 illustrates diagrammatically different types of roller properties and sensors that may be used to measure them according to the present invention; [Figure 7-12] Figure 1 shows some examples of possible arrangements of indicia and sensors according to the present invention and how they can be used to derive the direction of rotation of a roller. Each numbered figure includes figure A which shows a schematic of the arrangement of indicia and sensors relative to a roller, and figure B which shows a plot of the signal output by the sensor against time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] FIG. 1 shows a portable aerosol generating device 1 assembled in a housing 2. The housing 2 includes a battery 4 and a control circuit 6, not shown in detail. The battery 4 may be of conventional type and serves as a power source for the device 1. The control circuit 6 receives power from the battery 4 and controls the operation of the device 1, including powering a heater 8 from the battery 4 to heat a consumable 10. The control circuit 6 may vary the operation of the device 1 in response to signals received from one or more sensors, examples of which are given below. The device 1 may also include a user interface (not shown), which may be used to communicate information to a user, for example via light, sound or a display screen, or to receive instructions from a user, for example via buttons or a touch screen. The device may further include a transmitter / receiver (not shown) for transmitting information to and / or receiving information from a remote device. The transmitter / receiver may use any suitable communication technology, preferably wireless technology such as Bluetooth or WiFi. The remote device may be the user's smartphone and may be used to provide information to the user, receive instructions from the user, or perform data processing for the control circuit 6. The remote device may alternatively be a central computer operated, for example, by the manufacturer of device 1, which may be used to collect and store data regarding the usage of device 1, perform data processing for the control circuitry 6 of device 1, or provide data to device 1, for example for software upgrades.

[0023] The housing 2 contains a heating chamber 12 that is closed at one end. The other end of the heating chamber 12 opens to the exterior of the device through an opening 14 in the housing 2. A sliding cover 16 may be provided that can be moved across the opening 14 to close it when the device 1 is not in use. The heating chamber 12 is sized and shaped to receive a distal end 18 of the consumable 10 such that a proximal end 19 of the consumable 10 projects from the device 1 through the opening 14 and can be received in the mouth of a user during a smoking session. For example, the heating chamber 12 may have a substantially circular cross-section to receive a typical cylindrical consumable 10. Other shapes of consumables 10 are also known, for example in the shape of a flat card, the heating chamber 12 may be in the form of a slot with a substantially rectangular cross-section. The internal dimensions of the heating chamber 12 may be slightly larger than the external dimensions of the consumable 10 such that when a user draws on the proximal end 19 of the consumable 10, there is space around the outside for air to flow from the opening 14 and be drawn into the distal end 18.

[0024] The consumable 10 is inserted into the heating chamber 12 through the opening 14 and reaches a desired position when fully inserted into the heating chamber 12 along a predetermined insertion path 20, as indicated by arrow 21. The cross section of the opening 14 may be slightly larger than the cross section of the heating chamber 12 to facilitate insertion of the consumable 10 into the opening 14 by a user. A throat 22 may be provided between the opening 14 and the heating chamber 12, the cross section of the throat 22 tapering inwardly from the opening 14 to guide the consumable 10 along the insertion path 20 towards the desired position. The throat 22 may be integrally formed with the wall of the heating chamber 12 (as shown) or may be a separate element formed of a material that does not need to withstand the high temperatures within the heating chamber 12. The throat 22 provides a rotational mounting location for a roller 26. A projection 23 may be provided inside the heating chamber 12 to support the consumable 10 in the desired position. It will be appreciated that the consumable 10 may then be withdrawn from the heating chamber 12 in the opposite direction along the same insertion path 20.

[0025] The consumable 10 includes an aerosol-generating substrate 24 at or near its distal end 18. As the temperature of the aerosol-generating substrate 24 increases, the aerosol-generating substrate generates a vapor or aerosol that may be inhaled through the proximal end 19 of the consumable into the user's mouth and lungs. The aerosol may include an active ingredient, such as nicotine, and additional ingredients, such as flavorings. The gap between the aerosol-generating substrate 24 and the proximal end 19 allows the aerosol an opportunity to cool to an appropriate temperature before being inhaled. This gap may also include a filter (not shown).

[0026] The heater 8 is configured to heat the interior of the heating chamber 12 to increase the temperature of the aerosol-generating substrate 24 of the consumable 10 received within the heating chamber 12. For example, the heater 8 may include an induction coil around the heating chamber 12 that can be activated to induce heat into a susceptor (not shown) within the heating chamber 12. In other embodiments, the heater 8 may use resistive heating. The heater 8 may include a blade or other element (not shown) that directly contacts the consumable 10 to conduct heat therein. Additionally or alternatively, the heater 8 may be designed to preheat air before it flows into the distal end 18 of the consumable 10. To conserve energy and prevent the temperature of the aerosol-generating material from increasing excessively, the device 1 may include a pressure or flow sensor (not shown) that can sense the movement of air through the heating chamber 12, such that the control circuit 6 activates the heater 8 only if it determines that the user is inhaling the consumable 10.

[0027] In accordance with the present invention, a roller 26 is mounted on the aerosol generating device 1 for rotation about an axis 28 that is approximately perpendicular to the line of the insertion path 20 (as seen in FIG. 2). A peripheral surface 30 of the roller 26 extends slightly into the heating chamber 12 or throat 22 for contacting the surface of the consumable 10 placed in the insertion path 20. As the consumable 10 is inserted into the heating chamber along the insertion path 20 (indicated by arrow 21), friction between the surface of the consumable 10 and the roller 26 causes the roller 26 to rotate in one direction (counterclockwise, as indicated by arrow 32 in FIG. 1). If the consumable 10 is withdrawn from the heating chamber in the opposite direction along the insertion path 20, friction between the surface of the consumable 10 and the roller 26 causes the roller 26 to rotate in the opposite direction (clockwise, as shown in FIG. 1). The frictional contact between the surface 30 of the roller 26 and the surface of the consumable 10 can be enhanced by texturing the roller surface 30 or forming it from a resilient or high friction material such as rubber. The rollers 26 are preferably located relatively close to the opening 14 so that the insertion of the consumable 10 is detected immediately after the consumable 10 enters the opening 14. The diameter and position of the rollers 26 should preferably be such that the rollers 26 are driven to rotate at least one full revolution as the consumable 10 moves from initial contact with the rollers 26 until fully inserted into the heating chamber 12.

[0028] Not all properties of the roller 26 are perfectly circularly symmetric about the roller axis 28, there being at least one property (described below) that varies with the angle around the axis 28. One or more sensors 34 are positioned adjacent the roller 26 to measure changes in properties as the roller 26 rotates. The one or more sensors 34 form a sensing means for detecting the direction of rotation of the roller 26, either alone or in combination with logic provided by the control circuitry 6. From the direction of rotation, the control circuitry 6 can recognize when the consumable 10 is inserted or withdrawn and respond by operating the aerosol generation device 1 in an appropriate manner. For example, the device 1 may be activated when the consumable 10 is inserted, or prior to activation, steps may be taken to authenticate the consumable 10 as suitable for use with the device 1 and / or to authenticate the user as an authorized user of the device 1. When the consumable 10 is withdrawn, the control circuitry 6 may shut down the device 1 and take other steps, such as recording or transmitting details of the smoking session just concluded.

[0029] The sensor 34 is able to measure a property of the roller 26 that varies with the angle around the roller axis 28, so that the measurement is repeated periodically with each revolution of the roller 26. It is therefore easy for the sensing means to count the revolutions and determine, from the known circumference of the roller 26, how far the consumable 10 has been inserted into (or withdrawn from) the device. This in particular enables the control circuit 6 to prevent start-up of the aerosol generating device 1 if the consumable 10 is not fully inserted into the heating chamber 12 such that the aerosol generating substrate 24 is not in an optimal position for heating by the heater 8. In this situation, the control circuit 6 preferably issues a warning to the user that the consumable 10 is not correctly inserted.

[0030] FIG. 2 is a schematic plan view taken along line AA in FIG. 1. It shows roller 26 mounted for rotation about roller axis 28, which is generally perpendicular to the axis of cylindrical consumable 10. Preferably, roller 26 is mounted on bearings (not shown) at both ends, but could also rotate about an axis passing through the bore of the roller. FIG. 2 shows how sensor 34 can be offset in the axial direction of the roller from surface 30 that contacts consumable 10. This allows for the index portion 36 of roller 26 sensed by sensor 34 to be separated from contact surface 30. In particular, if the varying property of roller 26 measured by sensor 34 is the radius of roller 26, the radius of index portion 36 can be freely varied while the radius of contact surface 30 remains uniform to maintain good contact with consumable 10. Alternatively, sensor 34 can be designed for sliding contact with index portion 36, while contact surface 30 is designed for high friction engagement with consumable 10.

[0031] 2 shows the contact surface 30 of the roller 26 having a slightly larger radius than the rest of the consumable. The extra radius may be occupied by shallow teeth (not shown) that can indent the wrapper of the consumable 10, or a sleeve of a resilient material such as rubber that can deform to grip the surface as the consumable 10 moves past the roller 26. In other embodiments, the contact surface 30 and the indicator portion 36 of the roller 26 may be axially aligned with one another, and the one or more sensors 34 are similarly aligned at an angular location on the roller axis 28 that does not impede the passage of the consumable 10. In yet other embodiments, the measurable property of the roller 26 may be present along the entire axial length of the roller 26 such that there is no distinct indicator portion 36.

[0032] The term "indicator" is used herein in relation to a property of the roller 26 that varies with angle about the roller axis 28 to mean any characteristic of the property that can be measured by the sensor 34 and used to identify the angular position of the roller 26 as it rotates past the sensor 34. The indicator can only be well defined in relation to the sensing means used, and can be, for example, the angular position at which a measured value of a continuously varying property exceeds a predefined threshold. With this in mind, whether or not the sensing means detects the indicator may also depend on the direction of rotation of the roller 26; in a given embodiment of the invention, if an indicator is detected if the measured value of the property rises above a threshold, then it is likely that at the same angular position of the roller 26, if the roller 26 is rotating in the opposite direction, the value will conversely be below the threshold. Furthermore, the indicator need not necessarily identify a unique angular position around the entire circumference of the roller 26; the indicator may still be useful if it forms part of a pattern (including a repeating pattern) that is identifiable around the circumference.

[0033] 3-6 show schematic diagrams of different types of properties of the index portion 36 of the roller 26 and possible uses of the sensor 34 to measure them.

[0034] In FIG. 3, the property that changes is the magnetic field. A permanent magnet 38 is mounted at the center of the roller 26, with the north-south axis of the magnet 38 approximately perpendicular to the roller axis 28, so that the north pole of the magnet 38 is in one half-cylinder of the roller 26 and the south pole of the magnet 38 is in the other half-cylinder. The sensor 34 is a magnetic field sensor 40, such as a Hall effect sensor, positioned near the surface of the index portion 36 of the roller 26 and capable of sensing the change in the magnetic field due to the permanent magnet 38 as the roller 26 rotates. The index can be defined, for example, as the angular position of the roller 26 where the measured magnetic field changes from negative to positive (or south to north). It is not necessary that the permanent magnet 38 be mounted at the center of the roller 26. A single magnet could be mounted off-center using a suitable counterweight to prevent the roller 26 from losing balance, or multiple magnets could be positioned around the circumference of the roller 26, each defining an index as it rotates past the sensor 34.

[0035] Other methods of using magnets to sense the direction of rotation are readily contemplated. For example, a rotating magnetic field produced by a permanent magnet, such as that shown in Figure 3, can act as a dynamo to induce a current in a coil. Such a current can be detected and its direction may indicate the direction of rotation of roller 26.

[0036] In FIG. 4, the property that changes is again a magnetic field, and the sensor 34 is again a magnetic field sensor 40, such as a Hall effect sensor. However, in this case the magnetic field is provided by a fixed magnet 41 external to the roller 26, which may be a permanent magnet or an electromagnet that is only active when the aerosol generating device 1 is in use. In this case the property of the roller 26 that changes with the angle around the roller axis 28 is magnetic susceptibility or magnetizability. FIG. 4 shows one half 42 of the cylindrical roller 26 made of a material with relatively high magnetic susceptibility, such as iron, while the other half of the roller 26 is made of a material with relatively low magnetic susceptibility. As the roller 26 rotates, the magnetic field lines from the fixed magnet 41 are deflected to different degrees through the material of the roller 26, and the magnetic field sensor 40 measures different magnetic field strengths at its fixed position, from which one or more indices can be determined to identify the angular position of the roller 26.

[0037] It is not necessary that roller 26 be divided exactly in half between relatively high and low magnetic susceptibility material, for example, one or more intercalations of high magnetic susceptibility material may be embedded into an otherwise uniform roller material to form one or more indicia at locations disposed around the circumference of roller 26.

[0038] FIG. 5 shows a roller 26 in which the property that varies with angle about the roller axis 28 is the radius of the roller. In this example, the index portion 36 of the roller has a substantially uniform radius over most of its circumference. However, over a small range of angles, the radius increases to form a radial protrusion 44. A sensor 34 capable of measuring the radius of the roller 26 is shown diagrammatically as a pin 45 that slides over the surface of the roller 26 as the roller 26 rotates. The pin 45 is maintained in contact with the roller surface by the force of a spring 46 which urges the pin 45 radially inward. The pin 45 is rounded at its tip so that, at least in a plane perpendicular to the roller axis 28, the pin 45 straddles the radial protrusion 44 as it moves past the sensor 34, displacing the pin 45 radially outward against the force of the spring 46. Means (not shown) are responsive to the radial movement of the pin 45 for generating a signal representative of the changing radius of the roller 26. It will be appreciated that radial movement of pin 45 may simply operate a switch (not shown) to generate either an ON or OFF signal, thereby allowing a digital code to be generated in the signal using a number of such protrusions 44 arranged around the circumference of roller 26.

[0039] The index position about the roller axle 28 can also be defined by a radial recess 48, as shown in dashed lines in Figure 5, rather than a radial protrusion 44. As such a recess 48 rotates past the angular position of the sensor 34, the pin 45 moves radially inward rather than outward. The recess 48 is shown extending over a greater angle than the protrusion 44, since it must be wide enough to accommodate at least the width of the pin 45. The use of a combination of protrusion 44 and recess 48 is not precluded, so that the sensor produces a signal having three possible states, e.g., zero, positive or negative.

[0040] The protrusions 44 and recesses 48 shown in FIG. 5 are essentially "square", i.e., formed by a nearly uniform increase or decrease in radius of each over their angular length. This leads to a relatively rapid movement of the pin 45 as it rotates past the sensor at the beginning or end of the feature 44, 48. (The signal generated by the sensor 34 will not have the exact same square profile as the protrusion 44 or recess 48, because the tip of the pin 45 is rounded to ensure smooth rotation of the roller 26.) Such a shape of the protrusion 44 or recess 48 is suitable when a two-state (ON / OFF) output signal is desired. FIG. 6 shows an alternative possibility for a radial protrusion 50, where the radius changes more gradually with angle. This creates less resistance to the rotation of the roller 26, and is more suitable when the sensor 34 measures the position of the pin 45 as a continuous variable rather than an ON or OFF signal. Although the radial projections 50 in FIG. 6 are still shown as discrete projections from an essentially uniform radius, it will be understood that since the radius varies smoothly around the entire circumference of the roller 26, it is not possible to specify a "default" radius at all.

[0041] Other types of sensors than those shown may be employed in the device according to the invention. For example, a radial projection 44 as shown in FIG. 5 may be detected by intercepting a light beam that is irradiated parallel to the roller axis 28. In that case, the radial projection 44 may be formed as a part of a thin disk that does not have a large axial extent, which may be an advantage in the limited space of the portable aerosol generating device 1. Other examples of properties that may vary as a function of the angle around the roller axis 28, and other examples of sensors that measure them, will be apparent to the reader.

[0042] It should be noted that in some of the above examples it is in principle possible to swap the positions of the indicia and the sensors, so that one or more sensors rotate with the rollers and the sensors sense indicia located at fixed angular positions around the rollers as they move past the rollers. In practice it is more difficult to make electrical connections to sensors mounted on a rotating roller to form part of an electrical circuit capable of powering the sensors and receiving measurement signals from the sensors.

[0043] Figures 7-12 show some examples of possible arrangements of indicators and sensors according to the invention, and how they can be used to derive the direction of rotation of roller 26. In each case there is a pair of figures, of which figure A shows the arrangement of indicators and sensors diagrammatically, and figure B shows the signal output by the sensor plotted against time. It can be seen that figure B is mirror asymmetric with respect to time, which means that the pattern of signals shown can be used to determine the direction of rotation of roller 26.

[0044] FIG. 7A shows a roller 26 similar to FIG. 3 in which a permanent magnet (not shown in FIG. 7A) is mounted on the roller 26 with its two halves acting as north and south poles of the magnetic field. Two magnetic field sensors 34, labeled s1 and s2, are positioned at fixed angular positions adjacent to the roller 26. The sensors 34 are spaced apart by an angle of less than 180°. In this example, they are spaced apart by approximately 90°. Although the roller 26 is shown as being split into two separate poles, in reality the magnetic field measured by each sensor 34 will vary smoothly as the roller 26 rotates past. As the roller 26 rotates, each sensor 34 can measure a magnetic field that varies approximately as a sinusoid, as shown by their respective output signals 61, 62 in FIG. 7B. Because the sensors s1, s2 are at different angular positions, the two waves 61, 62 are out of phase, and in this example, the signal 61 from sensor s1 leads the signal 62 from sensor s2 by approximately 90°.

[0045] The index of roller 26 can be identified by a consistently identifiable index point 65 on the periodic curve of each signal 61, 62, for example the point 65 where the signal transitions from a negative to a positive value. In practice this may correspond to the angular position on the circumference of roller 26 where roller 26 transitions from a south pole to a north pole, but the physical interpretation of the index is not important so long as it can be consistently identified by the two sensors 34. The sensing means may be implemented as part of the control circuit 6 or in its own dedicated circuit (not shown) and the timing of the index 65 in each signal is compared to determine the direction of rotation of roller 26.

[0046] The sensing means detects a first time interval Δt from when the first sensor s1 detects the movement of the index passing through its angular position to when the second sensor s2 detects the movement of the index passing through its angular position. 12 The sensing means also determines a second time interval Δt from when the second sensor s2 detects the movement of the index past its angular position to when the first sensor s1 detects the movement of the index past its angular position again. 21 Since the initial position of the roller 26 is unknown, the two time intervals may be generated in either order. 12 does not necessarily have to be detected first. 12 is the second time interval Δt 21 , indicating that roller 26 is rotating clockwise. If the phase of signal 61 from sensor s1 lags rather than leads signal 62 from sensor s2, the first time interval Δt 12 is the second time interval Δt 21 , indicating that roller 26 is moving counterclockwise. From this it can be seen why the angle between the positions of the first and second sensors s1, s2 cannot be 180°. In that case the two waves would be 180° out of phase and the pattern would be mirror symmetric in time. In other words it would look the same if roller 26 were rotating in the opposite direction and this arrangement could not be used to determine the direction of rotation of roller 26.

[0047] The embodiment shown in FIG. 7A and FIG. 7B shows two time intervals Δt 12 and Δt 21 , and therefore depends on the comparison of the second time interval Δt 21 is the first time interval Δt 12 The time lag between the first and second detected rotations of the rollers 26 is three times longer than the time lag between the first and second detected rotations of the rollers 26. This would require the user to make drastic changes in the speed of movement of the consumable 10 during one revolution of the rollers 26 in order to make the two time intervals equal in length, which could result in a false detection of the direction of rotation. Since changes in speed of insertion or extraction are most likely to occur near the beginning or end of movement, if this is a concern the sensing means may be configured to allow for speed changes, for example by ignoring the first detected revolutions of the rollers 26 before determining the direction of rotation.

[0048] 8A illustrates a roller 26 in which a measured property of the roller 26, represented diagrammatically by a blown up triangle 52, varies with angle about the roller axis in a mirror asymmetric pattern. For example, if the measured property is the radius of the roller 26, then, over at least a range of angles, the radius may gradually increase to form a smooth ramp that terminates in a steep step back to the initial value. Because the property varies in an asymmetric pattern, the direction of rotation of the roller 26 can be determined by measuring the change in the property as the roller rotates and moves past a single sensor 34, labeled s1.

[0049] FIG. 8B shows an example of a signal 61 from a sensor 34 measuring the radius of roller 26 which varies in the pattern just described. The ramp-like pattern of the radius varying over the circumference of roller 26 is reflected in the ramp-like triangular pattern of signal 61. (In this example, sensor 34 needs to be able to measure a range of property values, not just two states, ON or OFF.) An indication can be identified by a point 65 on the curve at the end of the "ramp" where the signal drops sharply from a high value back to its original value. If roller 26 were rotating in the opposite direction, there would be no such drop, and instead there would be a spike in value at the same angular position of roller 26. Thus, signal 61 can be used by the sensing means to determine the direction of rotation of roller 26.

[0050] It will be appreciated that any pattern of variation in a property that is mirror asymmetric with respect to the roller axis 28 can be used as described above to determine the direction of rotation. The pattern need not be ramp-like. The pattern can extend around the entire circumference of the roller 26, as seen in FIG. 8A, or it can extend around only a portion of the circumference. The pattern can be repeated around the circumference so that the direction of rotation can be determined before the roller 26 completes one revolution.

[0051] 9A-12A triangles are used to diagrammatically show the indicia positions on roller 26, but the principles described do not depend on how these indicia are physically implemented, e.g. properties of roller 26 that vary with angle around axis of rotation 28. In these figures, only the placement of indicia and sensor 34 is important.

[0052] 9B-12B, signals 61, 62, 63 measured by sensor 34 are shown diagrammatically illustrating the detection of indices as points 65, 66 on a time axis. The principles described above do not depend on the particular appearance of the indices in the signals output by the sensors, but examples include rising edges, falling edges, crossings of zero or another threshold (in either direction), peaks or valleys, etc. In these figures, only the relative timing of the indices 65, 66 detected in signals 61, 62, 63 is important.

[0053] Figure 9A shows a similar arrangement to Figure 7A, except that the indicia 54 are shown as distinct angular positions on the roller 26, which may correspond, for example, to the transitions between the north and south poles of a magnet as shown in Figure 7A, or any other identifiable feature in the angularly varying property of the roller 26. Again, two sensors 34, labeled s1 and s2, are positioned at fixed angular positions adjacent the roller 26. (It will be appreciated that for measurements of some angularly varying properties, such as the radius of the roller 26, the sensors 34 may contact the surface of the roller 26.) The sensors 34 are spaced apart by less than 180°, for example about 90°.

[0054] Figure 9B shows two signals 61, 62, respectively representing the timing of the indices detected in measurements from the first sensor s1 and the second sensor s2 as the roller 26 rotates. When the roller 26 rotates at a constant speed, the position of the indices along each time axis 61, 62 corresponds to the angular position of the two sensors 34 (relative to an arbitrary zero position) about the roller axis 28. As in Figure 7B, the sensing means measures a first time interval Δt from the time when the first sensor s1 detects the movement of the indices past its angular position to the time when the second sensor s2 detects the movement of the indices past its angular position. 12 The sensing means also determines a second time interval Δt from when the second sensor s2 detects the movement of the index past its angular position to when the first sensor s1 detects the movement of the index past its angular position again. 21 In FIG. 9B, a first time interval Δt 12 is the second time interval Δt 21 t , which indicates that the roller 26 is rotating clockwise. 12 is the second time interval Δt 21 indicates that roller 26 is moving counterclockwise.

[0055] 10A illustrates a schematic of an embodiment of the invention having three sensors 34, labeled s1, s2, and s3, positioned adjacent roller 26 at different angular positions about roller axis 28. These are shown approximately equally spaced apart by 120°, although this is not required.

[0056] FIG. 10B shows three signals 61, 62, 63, each representing the timing of the indicators 65 detected in measurements from the first, second, and third sensors s1, s2, and s3, respectively, as the roller 26 rotates. In this case, it is not the timing of the indicators 65 that is important, but rather the order in which the indicators 65 occur. In the example shown, the indicators 65 are detected periodically in the order s1, s2, s3 (whichever is first), indicating that the roller 26 is rotating clockwise. If the indicators 65 were detected periodically in the reverse order s3, s2, s1, it would indicate that the roller 26 is moving counterclockwise. The order in which the indicators 65 are detected by the three sensors 34 remains the same even if the rotational speed of the rollers changes dramatically (as long as the direction is not reversed during the measurement), so an arrangement with three sensors 34 is more robust when uneven insertion or withdrawal of the consumable 10 is expected.

[0057] FIG. 11A shows a schematic of one embodiment of the invention with a single sensor 34, labeled s1, positioned at an angular position adjacent to a roller 26. The roller 26 includes two indicators 54, 55 that the sensor 34 can distinguish. For example, the indicators 54, 55 may represent the radial projection 44 and recess 48 of FIG. 5, or the beginning and end of a ramp-like projection as described in connection with FIG. 8A, or signals at the time when the magnetic field exceeds a threshold in the rising and falling directions. The indicators 54, 55 are positioned on the roller 26 at angular positions less than 180° around the roller axis 28. It should be noted that a sensor 34 that has only two measurement states (e.g., a switch with ON and OFF positions) is unlikely to be able to distinguish between the two types of indicators 54, 55.

[0058] 11B shows a signal 61 representing the timing of detection 65 of the first index 54 and detection 66 of the second index 55 in the measurement signal from the sensor s1 as the roller 26 rotates. The sensing means detects a first time interval Δt from the time when the sensor s1 detects the movement of the first index 54 past its angular position to the time when the sensor s1 detects the movement of the second index 55 past its angular position. 12 The sensing means also determines a second time interval Δt from when the sensor s1 detects the movement of the second index 55 past its angular position to when the sensor s1 detects the movement of the first index 54 again past its angular position. 21 In FIG. 11B, a first time interval Δt 12 is the second time interval Δt 21 The first time interval Δt 12 is the second time interval Δt 21 If it is longer than 1, it would indicate that the roller 26 is moving counterclockwise.

[0059] 12A illustrates a schematic of another embodiment of the invention in which a single sensor 34, labeled s1, is positioned at adjacent angular positions on roller 26. In this embodiment, roller 26 includes three indicia 54, which may be identical in the sense that the sensor 34 is indistinguishable (thus, simple ON / OFF sensors may be used). The indicia 54 are positioned on roller 26 at angular positions distributed about roller axis 28 such that all three angles between adjacent pairs of indicia are different. In the illustrated embodiment, the ratio of the angles between each pair of adjacent indicia is approximately 1:2:4, although this is not required.

[0060] FIG. 12B shows a signal 61 representing the timing of detections 65 of the index in the measurement signal from sensor s1 as the rotation of roller 26 carries index 54 past the angular position of sensor 34. Each individual detection 65 can represent any one of indexes 54, but it is known that they must be detected periodically (assuming that the direction of rotation of roller 26 does not reverse during the measurement). The sensing means determines three time intervals Δt1, Δt2, Δt3 between four successive detections 65 of the index by sensor s1. The sensing means then compares the duration of the successive time intervals to determine the direction of rotation of roller 26. In FIG. 12B, the time intervals Δt1, Δt2, Δt3 occur periodically in ascending order of duration (although any of them may be generated first during a period), indicating that roller 26 is rotating clockwise. If the time intervals Δt1, Δt2, Δt3 occur periodically in descending order of duration, it would indicate that roller 26 is moving counterclockwise.

[0061] It should be noted that in embodiments that rely on comparing the time intervals between detection of an index in the sensor signal as the roller rotates, different choices for the time intervals to compare are possible. For example, with reference to FIG. 7B, the time interval Δt 12 and Δt 21 9B, 11B, 12B are possible and are intended to be within the scope of the present invention.

[0062] The illustrated embodiment of the invention discloses the use of a single index 54 on the roller 26 in combination with multiple sensors 34 distributed around the roller axis 28, or multiple indexes 54, 55 distributed around the roller 26 in combination with a single sensor 34 located at a fixed angular position adjacent to the roller 26. Multiple sensors 34 and multiple indexes 54, 55 can also be combined, but care must be taken to avoid ambiguity in the signal generated. For example, with reference to FIG. 9A, it is easy to imagine that a second index on the roller 26 at an angular position of 180° from the illustrated index 54 would have the advantage of being able to determine the direction of rotation of the roller 26 when it has completed only half a rotation instead of a full rotation. This is only true if the angular separation between sensors s1 and s2 is reduced to less than 90°. If the sensors were spaced 90° apart and the indices 180° apart, each sensor s1, s2 would alternately detect the moving indices each time the roller 26 rotated 90° in either direction, so the pattern would be symmetrical and the direction of rotation would not be able to be determined.

Claims

1. a heating chamber (12) for receiving an aerosol product (10) that can be inserted into the heating chamber (12) along a predetermined insertion path (20) or withdrawn from the heating chamber (12) along the same insertion path (20); a roller (26) mounted for rotation about a roller axis (28) substantially perpendicular to said insertion path (20) such that an aerosol product article (10) moving along said insertion path (20) engages a surface of the roller (26), thereby rotating said roller (26); sensing means (34) for determining the direction of rotation of said roller (26); An aerosol generating device (1) comprising:

2. the roller (26) includes a property that varies with the angle around the roller axis (28); the sensing means includes at least one sensor (34) capable of measuring the change in the property as the roller (26) rotates past the sensor (34) to determine the direction of rotation of the roller (26); 2. An aerosol generating device (1) according to claim 1.

3. the variation of the property of the roller (26) as a function of angle about the roller axis (28) defines an index (54) at an index angular position on the roller (26); the sensing means includes a first sensor (34) capable of detecting movement of the index (54) through a first sensor angular position about the roller axis (28), and a second sensor (34) capable of detecting movement of the index (54) through a second sensor angular position about the roller axis (28); the angle between the first sensor angular position and the second sensor angular position is less than 180°; 3. An aerosol generating device (1) according to claim 2.

4. The sensing means further comprises: When the roller (26) rotates, a first time interval from a time when the first sensor (34) detects movement of the index (54) past the first sensor angular position to a time when the second sensor (34) detects movement of the index (54) past the second sensor angular position; a timer that measures a second time interval from the time when the second sensor (34) detects the movement of the index (54) passing through the second sensor angular position to the time when the first sensor (34) detects the movement of the index (54) passing through the first sensor angular position; a comparator that compares the first time interval with the second time interval to determine the direction of rotation of the roller (26); 4. The aerosol generating device (1) according to claim 3, comprising:

5. The sensing means further comprises: a third sensor (34) capable of detecting movement of the index (54) through a third sensor angular position about the roller axis (28); When the roller (26) rotates, a first time point at which the first sensor (34) detects movement of the index (54) past the first sensor angular position; a second time point at which the second sensor (34) detects movement of the index (54) through the second sensor angular position; a timer that measures a third point in time at which the third sensor (34) detects movement of the index (54) past the third sensor angular position; a comparator that determines the direction of rotation of the roller (26) based on the order in which the first, second, and third time points occur; 4. The aerosol generating device (1) according to claim 3, comprising:

6. the properties of the roller (26) vary in a mirror asymmetric pattern as a function of the angle around the roller axis (28); 3. An aerosol generating device (1) according to claim 2.

7. the variation of the property of the roller (26) as a function of angle about the roller axis (28) defines a first index (54) at a first index angular position on the roller (26) and a second index (55) at a second index angular position on the roller (26); the sensor (34) is capable of distinguishing between the first indicator and the second indicator (54, 55); the angle between the first index angular position and the second index angular position is less than 180°; 7. An aerosol generating device (1) according to claim 6.

8. the variation of the property of the roller (26) as a function of angle about the roller axis (28) defines first, second, and third indicia (54) at first, second, and third indicia angular positions on the roller (26), respectively; the angles between the first, second, and third index angular positions are all different; 7. An aerosol generating device (1) according to claim 6.

9. the property that varies with angle around the roller axis (28) is a magnetic property; the or each sensor (34) is capable of detecting changes in the magnetic field as the roller (26) rotates past the sensor (34); An aerosol generating device (1) according to any one of claims 2 to 8.

10. 10. The aerosol generating device (1) of claim 9, wherein the roller (26) includes one or more permanent magnets (38) arranged to generate the magnetic properties that vary depending on the angle around the roller axis (28).

11. the property that varies with angle around the roller axis (28) is the radius of the roller (26); An aerosol generating device (1) as claimed in any one of claims 2 to 8, wherein the or each sensor (34) is capable of detecting a change in the radius of the roller (26) as the roller (26) rotates and passes the sensor (34).

12. 12. The aerosol generating device (1) of claim 11, wherein the or each sensor (34) includes a sensor element (45) that engages the surface of the roller (26) and moves toward and away from the roller axis (28) in response to changes in the radius of the roller (26) as the roller rotates.

13. 13. The aerosol generating device (1) of claim 12, wherein the or each sensor (34) further comprises an electrical switch that is switched between an ON state and an OFF state when the sensor element (45) moves toward and away from the roller axis (28).

14. a heater (8) for heating the aerosol product (10) received in the heating chamber (12); a counter for counting the number of rotations of the roller (26); a controller (6) for activating the heater (8) when the counter has counted a predetermined number of revolutions; 2. The aerosol generating device (1) according to claim 1, further comprising:

15. 1. A method for determining when an aerosol product (10) is inserted into or withdrawn from a heating chamber (12) of an aerosol generating device (1), comprising: moving the aerosol product article (10) into or out of the heating chamber (12) along a predetermined insertion path (20); rotating the aerosol product article (10) by engaging the roller (26) with a surface of the roller (26) mounted for rotation about a roller axis (28) substantially perpendicular to the insertion path (20); using sensing means to determine the direction of rotation of said roller (26); A method comprising:

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