Patent Description:
Recently, the demand for alternative methods to overcome the shortcomings of traditional cigarettes has increased. For example, there is growing demand for a method of generating aerosol by heating an aerosol generating material in cigarettes, rather than by combusting cigarettes. Accordingly, studies on a heating-type cigarette and a heating-type aerosol generating device have been actively conducted.

A heater within an aerosol generating device heats a cigarette inserted into the aerosol generating device. The aerosol generating device may control electric power supplied to the heater, based on a preset temperature profile.

The heater may operate in a preheating mode and a heating mode, based on the preset temperature profile. When the heater operates in the preheating mode, the aerosol generating device may consume a large amount of current for the heater to reach a preheating target temperature within a short period of time. Accordingly, an output voltage of a battery may suddenly drop rapidly. When the output voltage of the battery drops rapidly, it is difficult to monitor a temperature change of the heater in real time. Therefore, it may be difficult to regulate a preheating time to be constant for each cigarette being heated. As a result, the taste of a cigarette may not be consistent. <CIT> relates to a heating method of an electronic smoking set. The heating method comprises the following steps of a first heating device preheating stage before smoking, a second heating device preheating stage before smoking, a heat preservation stage during smoking, heat preservation stage pausing during smoking and smoking stage completion. <CIT> relates to a controller in an electrical smoking system and method, wherein the method includes the steps of: establishing a preferred thermal pathway to be executed with each heater activation responsively to a puff on an electrically heated cigarette; configuring a power cycle in accordance with the desired thermal pathway; dividing the power cycle into at least first and second phases each having a respective, predetermined time period and total energy input for each phase; and adjusting a respective duty cycle in each phase of the power cycle responsively to a voltage reading of the power source such that the established, respective total energy input of each phase is achieved during the time period of each power cycle. <CIT> relates to an aerosol generation system comprising: a holder for generating aerosols by heating a cigarette; and a cradle including an interior space into which the holder is inserted, wherein the holder is inserted into the interior space of the cradle, is tilted, and then generates the aerosols.

One or more embodiments of the present disclosure provide an aerosol generating device including a voltage converter. One or more embodiments of the present disclosure provide a solution to a problem that the preheating time is not the same for each cigarette due to a rapid drop in the output voltage of a battery in the preheating mode.

Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by the practice of the presented embodiments.

According to an aspect of the present disclosure, an aerosol generating device includes: a battery; a heater configured to heat an aerosol generating material; a voltage converter configured to output a preset fixed voltage by converting a voltage applied from the battery to a constant voltage; and a controller configured to determine whether the heater is operating in a preheating mode, and control electric power supplied from the voltage converter to the heater such that the preset fixed voltage is applied to the heater in the preheating mode.

When the voltage applied from the battery is lower than the preset fixed voltage, the voltage converter may raise the applied voltage, and when the voltage applied from the battery is higher than the preset fixed voltage, the voltage converter may lower the applied voltage.

The heater operates in the preheating mode and a heating mode, and the controller
controls the electric power supplied to the heater such that a temperature of the heater reaches a preset preheating target temperature in the preheating mode, and controls the electric power supplied to the heater such that the temperature of the heater is maintained below the preset preheating target temperature in the heating mode.

In addition, the controller determines a period of time for preheating the heater in the preheating mode, based on an amount of power required for the temperature of the heater to reach the preset preheating target temperature and the preset fixed voltage applied to the heater, and the period of time may be relatively constant while the preset fixed voltage is applied to the heater.

The voltage converter may include any one of a buck boost converter, an operating amplifier (OP Amp), and a low dropout (LDO) voltage regulator.

The aerosol generating device may further include a first switch located between the voltage converter and the heater, and configured to switch between an open state and a closed state according to an input control signal; and a second switch located between the heater and ground, and configured to switch between an open state and a closed state according to an input control signal.

Moreover, the controller may output a control signal that closes the first switch during a heating period of the heater, and may also output the control signal that repeatedly opens and closes the second switch according to a power duty cycle of the heater during the heating period of the heater.

The first switch and the second switch may include a field-effect transistor.

As a voltage converter output a preset fixed voltage by converting a voltage applied from a battery to a constant voltage, such that the preset fixed voltage may be applied to a heater. Therefore, since the preset fixed voltage may be constantly supplied to the heater, the same preheating time may be maintained for each cigarette being heated. In addition, since a degree to which an output voltage of the battery drops rapidly in a preheating mode may be reduced, power efficiency of the battery may be increased.

Advantageous embodiments are provided by the dependent claims.

The examples with regard to <FIG> do not fall under the scope of independent claim <NUM>. However, they are helpful for understanding the invention.

Referring to <FIG>, the aerosol generating device <NUM> may include a battery <NUM>, a controller <NUM>, and a heater <NUM>. Referring to <FIG> and <FIG>, the aerosol generating device <NUM> may further include a vaporizer <NUM>. Also, the cigarette <NUM> may be inserted into an inner space of the aerosol generating device <NUM>.

When the cigarette <NUM> is inserted into the aerosol generating device <NUM>, the aerosol generating device <NUM> may operate the heater <NUM> and/or the vaporizer <NUM> to generate an aerosol. The aerosol generated by the heater <NUM> and/or the vaporizer <NUM> is delivered to a user by passing through the cigarette <NUM>.

As necessary, even when the cigarette <NUM> is not inserted into the aerosol generating device <NUM>, the aerosol generating device <NUM> may heat the heater <NUM>.

The controller <NUM> may control overall operations of the aerosol generating device <NUM>.

The vaporizer <NUM> may generate an aerosol by heating a liquid composition and the generated aerosol may pass through the cigarette <NUM> to be delivered to a user. In other words, the aerosol generated via the vaporizer <NUM> may move along an air flow passage of the aerosol generating device <NUM> and the air flow passage may be configured such that the aerosol generated via the vaporizer <NUM> passes through the cigarette <NUM> to be delivered to the user.

The liquid storage may be formed to be detachable from the vaporizer <NUM>, or may be formed integrally with the vaporizer <NUM>.

The aerosol generating device <NUM> may further include general-purpose components in addition to the battery <NUM>, the controller <NUM>, the heater <NUM>, and the vaporizer <NUM>. For example, the aerosol generating device <NUM> may include a display capable of outputting visual information and/or a motor for outputting haptic information. Also, the aerosol generating device <NUM> may include at least one sensor. Also, the aerosol generating device <NUM> may be formed as a structure where, even when the cigarette <NUM> is inserted into the aerosol generating device <NUM>, external air may be introduced or internal air may be discharged.

The cigarette <NUM> may be similar as a general combustive cigarette. For example, the cigarette <NUM> may be divided into a first portion including an aerosol generating material and a second portion including a filter, etc. The second portion of the cigarette <NUM> may also include an aerosol generating material. For example, an aerosol generating material made in the form of granules or capsules may be inserted into the second portion.

For example, the external air may flow into at least one air passage formed in the aerosol generating device <NUM>. For example, opening and closing of the air passage and/or a size of the air passage may be adjusted by the user. Accordingly, the amount and quality of the aerosol may be adjusted by the user. As another example, the external air may flow into the cigarette <NUM> through at least one hole formed in a surface of the cigarette <NUM>.

<FIG> is a schematic diagram showing temperature control characteristics of a general aerosol generating device.

<FIG> illustrates a temperature profile <NUM> of a heater that heats an aerosol generating material within the aerosol generating device <NUM>. Here, the temperature profile of a heater refers to a preset temperature profile to heat the heater. According to an embodiment of the present disclosure, the temperature profile <NUM> may be applied to the heater <NUM> that heats the cigarette <NUM> illustrated in <FIG>. However, the type of the heater <NUM> and the object that the heater <NUM> heats are not limited thereto.

The temperature profile <NUM> of the heater <NUM> may include a preheating mode <NUM> and a heating mode <NUM>.

The preheating mode <NUM> may correspond to a time period during which electric power is supplied to the heater <NUM> for a temperature of the heater <NUM> to reach a preset preheating target temperature. The preset preheating target temperature may range from <NUM> to <NUM>. A length of the time period corresponding to the preheating mode <NUM> may range from <NUM> seconds to <NUM> seconds.

The aerosol generating device <NUM> may receive a user input for operating the heater <NUM> in the preheating mode <NUM>. For example, when the user presses a button provided within the aerosol generating device <NUM> to use the aerosol generating device <NUM>, the heater <NUM> may enter the preheating mode <NUM> that rapidly raises the temperature of the heater <NUM> to the preheating target temperature.

When the heater <NUM> has entered the preheating mode <NUM>, the controller <NUM> may control electric power supplied to the heater <NUM>, based on a temperature profile of the preheating mode <NUM>. For example, the controller <NUM> may supply electric power to the heater <NUM> for the temperature of the heater <NUM> to reach the preset preheating target temperature in the preheating mode <NUM>. In order for the temperature of the heater <NUM> to reach the preset preheating target temperature within a short period of time, the controller <NUM> may set a frequency and a duty cycle of the pulse of current that the battery <NUM> supplies to the heater <NUM> through pulse width modulation to their maximum values, respectively.

The pulse width modulation is a modulation technique that controls an analogue circuit with a digital output of a processor. When a duration (i.e., pulse width) refers to a period of time during which a signal is on in a period T , and a duty refers to a ratio of on and off times, a duty value is determined by duration (pulse width)*<NUM>/T (period). As the duty value increases, the ratio of the on-time in the entire period T increases, and the average power delivered to the load also increases. Therefore, the controller <NUM> may regulate electric power supplied to the heater <NUM> in the preheating mode <NUM> by adjusting the duty value of a pulse width modulator.

However, the method of the controller <NUM> for regulating electric power supplied to the heater <NUM> is not limited thereto, and the temperature of the heater <NUM> may be controlled in various ways such as ON/OFF control, proportional control, integral control, differential control, PID control, and the like.

When the temperature of the heater <NUM> reaches the preheating target temperature, the aerosol generating device <NUM> may end the preheating mode <NUM>. However, the criteria for starting and ending a preheating mode <NUM> are not limited thereto. When the preheating mode <NUM> is terminated, the aerosol generating device <NUM> may notify the user that the preheating has ended, through a display or lamp that outputs visual information, a motor that outputs tactile information, a speaker that outputs sound information, or the like.

When the preheating mode <NUM> is terminated, the aerosol generating device <NUM> may cause the heater <NUM> to enter the heating mode <NUM>. The heating mode <NUM> may refer to a time period that starts after the preheating mode <NUM> is terminated due to the heater <NUM> being heated to the preheating target temperature or higher.

The controller <NUM> may control electric power supplied to the heater <NUM>, based on a temperature profile of the heating mode <NUM>. For example, the controller <NUM> may control electric power supplied to the heater <NUM> for the temperature of the heater <NUM> to be maintained lower than the preheating target temperature.

A length of the time period corresponding to the heating mode <NUM> may be in the range of <NUM> minutes to <NUM> minutes. When a preset period of time elapses after the heating mode <NUM> has started, the aerosol generating device <NUM> may cut off electric power supplied to the heater <NUM>. On the other hand, even before the preset period of time elapses after the heating mode <NUM> has started, if a frequency of puffs of the user counted by the aerosol generating device <NUM> reaches a preset number, the aerosol generating device <NUM> may cut off electric power supplied to the heater <NUM>.

Depending on the length of the time period corresponding to the preheating mode <NUM>, in other words, depending on the preheating time, the temperature of each cigarette being heated may be different. This may be problematic because the taste of the cigarette is not constant during smoking. Therefore, the controller <NUM> may monitor an output voltage of the battery <NUM> and a change in the temperature of the heater <NUM> to control the preheating time of the cigarette being heated to be constant.

Still, the aerosol generating device <NUM> may consume a large amount of current for the temperature of the heater <NUM> to reach the preset preheating target temperature within a short period of time in the preheating mode <NUM> as described above. Accordingly, the output voltage of the battery <NUM> may drop rapidly.

When the output voltage of the battery <NUM> drops rapidly, it is difficult for the controller <NUM> to monitor a change in the temperature of the heater <NUM> in real time, and accordingly, the controller <NUM> may not be able to regulate the preheating time of each cigarette being heated to be constant. In addition, when the output voltage of the battery <NUM> drops to a cut-off voltage or lower, the user may not complete smoking.

Hereinafter, a configuration of the aerosol generating device <NUM> for resolving such voltage drop phenomenon of the battery <NUM> will be described.

<FIG> is a diagram illustrating an example of a configuration of an aerosol generating device.

Referring to <FIG>, an aerosol generating device <NUM> includes a battery <NUM>, a voltage converter <NUM>, a heater <NUM>, a controller <NUM>, and may include a first switch <NUM>, and a second switch <NUM>. <FIG> only shows certain components the aerosol generating device <NUM> which are particularly related to the present embodiment. However, those skilled in the art will understand that the aerosol generating device <NUM> may further include other general-purpose components in addition to the components illustrated in <FIG>.

The battery <NUM> supplies electric power used for the aerosol generating device <NUM> to operate. The battery <NUM> supplies electric power for the heater <NUM> to be heated. The battery <NUM> may also supply electric power needed for other hardware, the controller <NUM>, a sensor, and an interface installed in the aerosol generating device <NUM> to operate.

The battery <NUM> may include a lithium iron phosphate (LiFePO4) battery. However, embodiments of the present disclosure are not limited thereto. The battery <NUM> may be made of a lithium cobalt oxide (LiCoO2) battery, a lithium titanate battery, or the like. The battery <NUM> may include a rechargeable battery or a disposable battery.

The battery <NUM> may be discharged by supplying electric power used for each component of the aerosol generating device <NUM> including the heater <NUM> to operate. As the battery <NUM> is discharged, a voltage output from the battery may drop. If the battery <NUM> is over-discharged, the battery <NUM> may not be used any longer. Therefore, a cut-off voltage may be set within the aerosol generating device <NUM>. The cut-off voltage indicates a voltage value for determining that a battery is completely discharged, and is designed to prevent over-discharge. When the cut-off voltage is set high, the battery <NUM> may be considered completely discharged at an early time, and thus available capacity of the battery <NUM> may be reduced. On the other hand, when the cut-off voltage is set low, there may be a risk of the battery <NUM> being over-discharged. Therefore, it is necessary to set an appropriate cut-off voltage.

For example, when the battery <NUM> is a lithium-ion battery, the battery <NUM> may be discharged rapidly from a point where the voltage of the battery <NUM> is discharged to about <NUM> V to about <NUM> V. As a result, the battery <NUM> may be in an over-discharge state. Therefore, the cut-off voltage of about <NUM> V may be set within the aerosol generating device <NUM> to prevent over-discharge.

The voltage converter <NUM> may be electrically connected to the battery <NUM> in series. For example, the voltage converter <NUM> may be arranged between the battery <NUM> and the first switch <NUM> to be electrically connected to the battery <NUM> in series.

The voltage converter <NUM> converts the voltage applied from the battery <NUM> to a constant voltage to output a preset fixed voltage. The voltage applied from the battery <NUM> is identical with an output voltage of the battery <NUM>. The preset fixed voltage may be decided in consideration of temperature rise efficiency of the heater <NUM>, uniformity of generated atomization, quality of tobacco taste, and the like.

When the heater <NUM> operates in a preheating mode, the preset fixed voltage may be set to rectify a voltage drop phenomenon in which the output voltage of the battery <NUM> drops rapidly. For example, when the output voltage of the battery <NUM> is a low voltage, a large amount of current consumed for a temperature of the heater <NUM> to reach a preset preheating target temperature may cause the output voltage of the battery <NUM> to drop rapidly. In order to prevent such rapid voltage drop, the output voltage of the battery <NUM> may be raised to a preset fixed voltage through the voltage converter <NUM> and be applied to the heater <NUM>. In this case, a relatively smaller amount of current may be consumed than when the output voltage of the battery <NUM> is applied to the heater <NUM> without converting the output voltage of the battery <NUM> into the preset fixed voltage. Therefore, a degree to which the output voltage of the battery <NUM> drops rapidly in the preheating mode may be reduced.

For example, the preset fixed voltage may range from <NUM> V to <NUM> V, and it is desirable that the preset fixed voltage be <NUM> V.

The voltage converter <NUM> may include any one of a buck boost converter, an operating amplifier (OP Amp), and a low dropout (LDO) voltage regulator.

When the voltage applied from the battery <NUM> is lower than the preset fixed voltage, the voltage converter <NUM> may raise the applied voltage. Also, when the voltage applied from the battery <NUM> is higher than the preset fixed voltage, the voltage converter <NUM> may lower the applied voltage.

As described above, by arranging the voltage converter <NUM> between the battery <NUM> and the heater <NUM>, the output voltage of the battery <NUM> is not applied to the heater <NUM> directly. Instead, the preset fixed voltage output from the voltage converter <NUM> is be applied to the heater <NUM>.

Therefore, since the preset fixed voltage is able to be applied to the heater <NUM> constantly, the preheating time may be maintained the same for each cigarette being heated. In addition, when the output voltage of the battery <NUM> is a low voltage, as the output voltage of the battery <NUM> is raised to the preset fixed voltage through the voltage converter <NUM> before being applied to the heater <NUM>, a relatively smaller amount of current may be consumed than when the output voltage of the battery <NUM> is applied to the heater <NUM> without converting the output voltage of the battery <NUM> into the preset fixed voltage. Therefore, since a degree to which the output voltage of the battery <NUM> drops rapidly in the preheating mode may be reduced, power efficiency of the battery <NUM> may be enhanced.

The heater <NUM> is electrically heated by electric power supplied by the battery <NUM> under the control of the controller <NUM>. The heater <NUM> is located inside an accommodation passage of the aerosol generating device <NUM> that accommodates a cigarette. As the cigarette is inserted into the aerosol generating device <NUM> from outside through an insertion hole and then is moved through the accommodation passage, one end portion of the cigarette may be inserted into the heater <NUM>. Thus, the heated heater <NUM> may raise a temperature of an aerosol generating material inside the cigarette. The heater <NUM> may include any type of heater as long as it may be inserted into the cigarette.

The heater <NUM> may include a heat source and a heat transfer object. For example, the heat source of the heater <NUM> may be manufactured in the form of a film including an electrical resistivity pattern, and the film-shaped heater <NUM> may be arranged to surround at least a portion of an outer surface of the heat transfer object (e.g., a heat transfer tube).

The heat transfer tube may include a metal material capable of transferring heat such as aluminum or stainless steel, an alloy material, carbon, a ceramic material, or the like. When electric power is supplied to the electrical resistivity pattern of the heater <NUM>, heat is generated, and the generated heat may heat the aerosol generating material through the heat transfer tube.

The aerosol generating device <NUM> may be provided with a separate temperature detection sensor. Without a separate temperature detection sensor, the heater <NUM> may play a role of a temperature detection sensor. Alternatively, the heater <NUM> plays a role of a temperature detection sensor, and at the same time, the aerosol generating device <NUM> may be further provided with a separate temperature detection sensor. The temperature detection sensor may be arranged on the heater <NUM> in the form of a conductive track or a device.

If voltage applied to the temperature detection sensor and current flowing through the temperature detection sensor are measured, resistance R may be determined. In that case, the temperature detection sensor may measure temperature T through Equation <NUM> below.

In Equation <NUM>, R refers to a current resistance value of the temperature detection sensor, R0 refers to a resistance value at temperature T0 (for example, <NUM>), and α refers to a resistance temperature coefficient of the temperature detection sensor. Since a conductive material (for example, metal) has a unique resistance temperature coefficient, α may be predetermined according to the conductive material constituting the temperature detection sensor. Therefore, if the resistance R of the temperature detection sensor is determined, the temperature T of the temperature detection sensor may be calculated through Equation <NUM> above.

The controller <NUM> may control operation of the components included in the aerosol generating device <NUM>. The controller <NUM> is an integrated circuit implemented with a processing unit such as a microprocessor, microcontroller, and the like.

The controller <NUM> may control an amount of electric power supplied to the heater <NUM> and a period of time for which electric power is supplied to the heater <NUM> so that a result sensed by the temperature detection sensor is analyzed, and accordingly, the heater <NUM> is heated to a certain temperature or maintains an appropriate temperature.

As the voltage converter <NUM> is arranged between the battery <NUM> and the heater <NUM>, the controller <NUM> controls electric power supplied to the heater <NUM> by the voltage converter <NUM>. When the heater <NUM> operates in the preheating mode, the controller <NUM> controls electric power supplied to the heater <NUM> for the temperature of the heater <NUM> to reach the preset preheating target temperature. Also, when the heater <NUM> operates in a heating mode, the controller <NUM> may control electric power supplied to the heater <NUM> for the temperature of the heater <NUM> to be maintained within a range of temperature lower than the preset preheating target temperature.

For example, the controller <NUM> determines whether the heater <NUM> operates in the preheating mode, and when the heater <NUM> operates in the preheating mode, the controller <NUM> controls electric power supplied to the heater <NUM> such that a preset fixed voltage output from the voltage converter <NUM> may be applied to the heater <NUM>.

The controller <NUM> determines the period of time for which the heater <NUM> is preheated in the preheating mode, based on the amount of electric power required for the temperature of the heater <NUM> to reach the preset preheating target temperature and the preset fixed voltage that is output from the voltage converter <NUM> to the heater <NUM>.

In order to maintain a uniform tobacco taste, an amount of heat supplied to the aerosol generating material of each cigarette being heated needs to be constant. To this end, the amount of electric power supplied to the heater <NUM> may be constant in the preheating mode. The amount of electric power supplied to the heater <NUM> may be determined by the voltage applied to the heater <NUM> and a period of time for which the voltage is applied to the heater <NUM>. Here, since the voltage applied to the heater <NUM> is constant as the preset fixed voltage, regardless of the output voltage of the battery <NUM>, the period of time for which the heater <NUM> is preheated to supply electric power required to the heater <NUM> in the preheating mode may be relatively constant.

The first switch <NUM> may be arranged between the voltage converter <NUM> and the heater <NUM>. The first switch <NUM> may switch between an open state and a closed state depending on a signal input from outside. As the first switch <NUM> switches to the open state, the heater <NUM> may be cut off from electric power by the battery <NUM>. On the other hand, as the first switch <NUM> switches to the closed state, the heater <NUM> may be supplied with electric power by the battery <NUM>.

The controller <NUM> may output a control signal that controls the open and closed states of the first switch <NUM>. The controller <NUM> may output the control signal that controls the first switch <NUM> to be closed for a period of time for which the heater <NUM> needs to be heated, and controls the first switch <NUM> to be opened for the remaining periods of time. Therefore, since the first switch <NUM> is closed for the period of time for which the heater <NUM> needs to be heated, the preset fixed voltage output from the voltage converter <NUM> may be applied to the heater <NUM>.

The first switch <NUM> may include a field-effect transistor (FET). Alternatively, the first switch <NUM> may include a different electric device other than the FET, which is capable of switching between the open state and the closed state depending on the signal input from outside. For example, the first switch <NUM> may include a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), or a thyristor. However, embodiments of the present disclosure are not limited thereto.

The second switch <NUM> may be arranged between the heater <NUM> and ground. The second switch <NUM> may switch between the open state and the closed state depending on the signal input from outside. The second switch <NUM> may repeatedly switch between the open state and the closed state for a short period of time. The second switch <NUM> may repeatedly switch between the open state and the closed state based on the duty cycle of power required by the heater <NUM>.

For example, the controller <NUM> may output a control signal that controls the open and closed states of the second switch <NUM>. The controller <NUM> may output the control signal that causes the second switch <NUM> to repeatedly switch between the open state and the closed state such that the heater <NUM> may generate heat according to a temperature profile. Therefore, the controller <NUM> may regulate a time at which the preset fixed voltage output from the voltage converter <NUM> is applied to the heater <NUM>, through the control signal that controls the open and closed states of the second switch <NUM>.

The second switch <NUM> may include a FET like the first switch <NUM>. Alternatively, the second switch <NUM> may include a different electric device other than the FET, which is capable of switching between the open state and the closed state depending on the signal input from outside. For example, the second switch <NUM> may include a BJT, an IGBT, or a thyristor. However, embodiments of the present disclosure are not limited thereto.

<FIG> is a diagram illustrating an example of a preheating time when a voltage converter is located between a battery and a heater.

<FIG> is a diagram illustrating preheating time when the voltage converter <NUM> is not located between the battery <NUM> and the heater <NUM> and when the voltage converter <NUM> is located between the battery <NUM> and the heater <NUM>, respectively. The preheating time may indicate an amount of time that is taken for a temperature of the heater <NUM> to reach a preset preheating target temperature when the heater <NUM> operates in a preheating mode.

Table of <FIG> illustrates the preheating time according to an output voltage of the battery <NUM> at the moment when a user presses a button provided on the aerosol generating device <NUM> to use the aerosol generating device <NUM>. The table shows part of the results of measuring the preheating time according to the output voltage of the battery <NUM>. The preheating time has been measured with and without the voltage converter <NUM>, under the condition that other configurations of the aerosol generating device <NUM> and a cigarette inserted into the aerosol generating device <NUM> are exactly the same.

Referring to the table of <FIG>, it may be seen that when the voltage converter <NUM> is not located between the battery <NUM> and the heater <NUM>, the preheating time varies according to the output voltage of the battery <NUM>. For example, when the output voltage of the battery <NUM> is <NUM> V, it takes <NUM> seconds for the temperature of the heater <NUM> to reach the preset preheating target temperature. On the other hand, when the output voltage of the battery <NUM> is <NUM> V, it takes <NUM> seconds for the temperature of the heater <NUM> to reach the preset preheating target temperature. Therefore, depending on the output voltage of the battery <NUM>, the preheating time may vary by up to <NUM> seconds. If the preheating time varies, a degree to which the cigarette inserted into the aerosol generating device <NUM> is preheated may vary. As a result, the taste of a cigarette may not be consistent.

On the other hand, when the voltage converter <NUM> is located between the battery <NUM> and the heater <NUM>, even if the output voltage of the battery <NUM> changes in the range of <NUM> V to <NUM> V, the preheating time is constant within a range of <NUM> seconds to <NUM> seconds. That is because even when the output voltage of the battery <NUM> varies, the voltage converter <NUM> located between the battery <NUM> and the heater <NUM> converts the output voltage of the battery <NUM> into a preset fixed voltage, and thus, a constant voltage is supplied to the heater <NUM>. As the preheating time is constant, the degree to which the cigarette inserted into the aerosol generating device <NUM> is preheated is constant. Therefore, the taste of a cigarette may be consistent.

<FIG> is a diagram illustrating a change of an output voltage of a battery over time when a voltage converter is located between the battery and a heater.

<FIG> is a graph illustrating an output voltage of the battery <NUM> from the moment when a user presses a button provided on the aerosol generating device <NUM> to use the aerosol generating device <NUM> to the moment when a preheating mode ends. The output voltage of the battery <NUM> that varies over time has been measured with and without the voltage converter <NUM>, under the condition that other configurations of the aerosol generating device <NUM>, a cigarette inserted into the aerosol generating device <NUM>, and the output voltage of the battery <NUM> at the moment when the user presses a button provided on the aerosol generating device <NUM> to use the aerosol generating device <NUM> are exactly the same. For example, the output voltage of the battery <NUM> at the moment when the user presses a button provided on the aerosol generating device <NUM> to use the aerosol generating device <NUM> may be <NUM> V as illustrated in <FIG>. However, embodiments are not limited thereto, and the output voltage may have a different value.

The aerosol generating device <NUM> may consume a large amount of current for a temperature of the heater <NUM> to reach a preset preheating target temperature within a short period of time in the preheating mode. Accordingly, the output voltage of the battery <NUM> may drop rapidly.

Referring to the graph of <FIG>, it may be seen that the output voltage of the battery <NUM> drops more rapidly when the voltage converter <NUM> is not located between the battery <NUM> and the heater <NUM> than when the voltage converter <NUM> is located between the battery <NUM> and the heater <NUM>. That is because, since the output voltage of the battery <NUM> is raised to a preset fixed voltage through the voltage converter <NUM> to be applied to the heater <NUM>, a relatively smaller amount of current may be consumed when the voltage converter <NUM> is located between the battery <NUM> and the heater <NUM> than when the voltage converter <NUM> is not located between the battery <NUM> and the heater <NUM>.

In addition, when the voltage converter <NUM> is not located between the battery <NUM> and the heater <NUM>, the output voltage of the battery <NUM> drops to a preset cut-off voltage or lower. In this case, a user may not be able to complete smoking. The cut-off voltage may be <NUM> V as illustrated in <FIG>. However, embodiments are not limited thereto, and the cut-off voltage may be set differently.

Claim 1:
An aerosol generating device (<NUM>, <NUM>) comprising:
a battery (<NUM>, <NUM>);
a heater (<NUM>, <NUM>) configured to heat an aerosol generating material;
a voltage converter (<NUM>) configured to output a preset fixed voltage by converting a voltage applied from the battery (<NUM>, <NUM>) to a constant voltage; and
a controller (<NUM>, <NUM>) configured to determine whether the heater (<NUM>, <NUM>) is operating in a preheating mode (<NUM>), and control electric power supplied from the voltage converter (<NUM>) to the heater (<NUM>, <NUM>) such that the preset fixed voltage is applied to the heater (<NUM>, <NUM>) in the preheating mode (<NUM>),
wherein the heater (<NUM>, <NUM>) is further configured to operate in the preheating mode (<NUM>) or a heating mode (<NUM>), and the controller (<NUM>, <NUM>) is further configured to:
control the electric power supplied to the heater (<NUM>, <NUM>) such that a temperature of the heater (<NUM>, <NUM>) reaches a preset preheating target temperature in the preheating mode (<NUM>), and
control the electric power supplied to the heater (<NUM>, <NUM>) such that the temperature of the heater (<NUM>, <NUM>) is maintained below the preset preheating target temperature in the heating mode (<NUM>), and
characterized in that
the controller (<NUM>, <NUM>) is configured to determine a period of time for preheating the heater (<NUM>, <NUM>) in the preheating mode (<NUM>), based on an amount of power required for the temperature of the heater (<NUM>, <NUM>) to reach the preset preheating target temperature and the preset fixed voltage applied to the heater (<NUM>, <NUM>), and the period of time is relatively constant while the preset fixed voltage is applied to the heater (<NUM>, <NUM>).