Patent Publication Number: US-2021161212-A1

Title: Heater assembly, method of manufacturing heater assembly, and aerosol generating device including heater assembly

Description:
TECHNICAL FIELD 
     The present disclosure relates to a heater assembly, a method of manufacturing a heater assembly, and an aerosol generating device including a heater assembly. More particularly, the present disclosure relates to a heater assembly including a susceptor material which generates heat by an external magnetic field, a method of manufacturing the same, and an aerosol generating device including a heater assembly. 
     BACKGROUND ART 
     Recently, the demand for alternative methods to overcome the shortcomings of general cigarettes has increased. For example, there is an increasing demand for a method of generating aerosol by heating a cigarette medium in cigarettes, rather than by burning cigarettes. Accordingly, studies on a heating-type cigarette and a heating-type aerosol generating device have been actively conducted. 
     An alternative heating method has been proposed to replace a method of arranging a heater including an electrical resistor in an aerosol generating device and supplying power to the heater to heat a cigarette accommodated in the aerosol generating device. For example, research is being conducted into an induction heating method of heating cigarettes by using a magnetic body, which generates heat by a magnetic field applied from the outside. 
     When a cigarette is heated by a magnetic body, which generates heat by a magnetic field, because a coil or the like configured to apply the magnetic field to the magnetic body must be included in an aerosol generating device in addition to the cigarette and the magnetic body, additionally arranging a separate temperature sensor in the aerosol generating device may be difficult in terms of space. Accordingly, because maintaining constant a temperature at which the cigarette is heated by directly measuring the temperature of the magnetic body may be difficult, aerosol is unevenly generated from the cigarette and smoking quality may decrease. 
     Therefore, to improve smoking quality by more precisely controlling the temperature at which a cigarette is heated, a structure of the magnetic body that allows the temperature of the cigarette heated by the magnetic body to be measured without a temperature sensor may be required. 
     DESCRIPTION OF EMBODIMENTS 
     Technical Problem 
     Provided are a heater assembly, a method of manufacturing a heater assembly, and an aerosol generating device including a heater assembly. The technical problems of the present disclosure are not limited to the above-described description, and other technical problems may be derived from the embodiments to be described hereinafter. 
     Solution to Problem 
     According to an aspect of the present disclosure, a heater assembly configured to heat a cigarette may include a heating layer having at least a portion including a susceptor material generating heat by an external magnetic field and having a cylindrical shape therein in which an accommodation space configured to accommodate the cigarette is formed, an insulating layer surrounding at least a portion of an outer side surface of the heating layer, and a sensor pattern embedded in the insulating layer and configured to measure a temperature of the heating layer. 
     According to another aspect of the present disclosure, a method of manufacturing a heater assembly configured to heat a cigarette may include forming a heating layer having at least a portion including a susceptor material generating heat by an external magnetic field and having a cylindrical shape therein in which an accommodation space configured to accommodate the cigarette is formed, coating, on an outer side surface of the heating layer, a first insulating layer surrounding at least a portion of the outer side surface of the heating layer, printing, on an outer side surface of the first insulating layer, a sensor pattern configured to measure a temperature of the heating layer, and coating a second insulating layer on the outer side surface of the first insulating layer to embed the sensor pattern. 
     According to another aspect of the present disclosure, an aerosol generating device including a heater assembly may further include a coil configured to apply an alternating magnetic field to the heater assembly, a power supply unit configured to supply power to the coil, and a controller configured to control power supplied to the coil. 
     Advantageous Effects of Disclosure 
     In a case of a heater assembly of the present disclosure, because a heating layer including a susceptor material and a sensor pattern configured to measure the temperature of the heating layer may be formed as a single body, the temperature at which a cigarette is heated may be measured without a separate temperature sensor, and accordingly, the structure of an aerosol generating device may be simplified. 
     In addition, in an aerosol generating device including a heater assembly, because the temperature at which a cigarette is heated may be relatively accurately measured by a sensor pattern formed as a single body with a heating layer, the temperature at which the cigarette is heated may be precisely controlled, and accordingly, the quality at which an aerosol is produced may be improved. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a diagram explaining components configuring an aerosol generating device including a heater assembly according to some embodiments; 
         FIG. 2  is a diagram explaining a cigarette heated by a heater assembly according to some embodiments; 
         FIG. 3  is a diagram explaining an operation in which a cigarette is accommodated in an aerosol generating device and heated by a heater assembly, according to some embodiments; 
         FIG. 4  is a diagram explaining a heater assembly configured to heat a cigarette, according to some embodiments; 
         FIG. 5  is a diagram explaining an operation in which a temperature of a cigarette is controlled in an aerosol generating device, according to some embodiments; and 
         FIG. 6  is a flow chart illustrating operations of a method of manufacturing a heater assembly configured to heat a cigarette, according to some embodiments. 
     
    
    
     BEST MODE 
     A heater assembly according to an aspect includes a heating layer having at least a portion including a susceptor material which generates heat by an external magnetic field and having a cylindrical shape therein in which an accommodation space configured to accommodate the cigarette is formed, an insulating layer surrounding at least a portion of an outer side surface of the heating layer, and a sensor pattern embedded in the insulating layer and configured to measure a temperature. 
     In addition, the sensor pattern is formed by printing a resistor having a temperature coefficient of resistance (TCR) deriving the temperature of the heating layer. 
     In addition, the sensor pattern includes at least one material of ceramic, a semiconductor, metal, carbon, and a thermistor. 
     In addition, the metal includes at least one of silver (Ag) and palladium (Pd), and the sensor pattern includes silver in a weight ratio of 45 to 70 and palladium in a weight ratio of 10 to 35. 
     In addition, the insulating layer includes a first insulating layer configured to support an inner side surface of the sensor pattern and a second insulating layer configured to surround the outer side surface of the sensor pattern. 
     In addition, the insulating layer includes at least one material of silicon (Si) oxide, boron (B) oxide, calcium (Ca) oxide, zirconium (Zr) oxide, and aluminum (Al) oxide. 
     In addition, the susceptor material includes at least a portion including a ferromagnetic body. 
     In addition, the heater assembly may further include an electrode connected to the sensor pattern and configured to read a characteristic value of the sensor pattern. 
     A method of manufacturing a heater assembly according to another aspect includes forming a heating layer having at least a portion including a susceptor material generating heat by an external magnetic field and having a cylindrical shape therein in which an accommodation space configured to accommodate the cigarette is formed, coating, on an outer side surface of the heating layer, a first insulating layer surrounding at least a portion of the outer side surface of the heating layer, printing, on an outer side surface of the first insulating layer, a sensor pattern configured to measure a temperature of the heating layer, and coating a second insulating layer on the outer side surface of the first insulating layer to embed the sensor pattern. 
     An aerosol generating device according to another aspect includes the heater assembly and further includes a coil configured to apply an alternating magnetic field to the heater assembly, a power supply unit configured to supply power to the coil, and a controller configured to control power supplied to the coil. 
     In addition, the coil is wound along an outer side surface of the heater assembly, extends in a longitudinal direction of the aerosol generating device, and is arranged in a position corresponding to the heater assembly. 
     In addition, the power supply unit includes a battery configured to supply a direct current to the aerosol generating device, and a conversion unit configured to convert the direct current supplied from the battery into an alternating current to be applied to the coil. 
     In addition, the controller is configured to receive, from the sensor pattern, a characteristic value of the sensor pattern associated with the temperature of the heating layer, and adjust the power supplied to the coil from the power supply unit based on the temperature of the heating layer. 
     MODE OF DISCLOSURE 
     Hereinafter, example embodiments will be described in detail with reference to the drawings. It is to be understood that the following description is only for the purpose of embodying the embodiments and does not limit the scope of the present disclosure. Contents which can be easily derived by one of ordinary skill in the art should be construed as being included in the scope of the present disclosure. 
     In the present disclosure, it is to be understood that the term such as “configuring” or “including” is intended to indicate the existence of the various components or various operations disclosed in the present disclosure, some of the components or operations may be absent, and are not intended to preclude the possibility that additional components or operations may be added. 
     In the present disclosure, while such terms as “first,” “second,” etc., may be used to describe various components, such components must not be limited to the above terms. The above terms are used only to distinguish one component from another. 
     With respect to the terms in the present disclosure, the general terms which are currently and widely used are selected in consideration of functions of structural elements in the various embodiments of the present disclosure. However, meanings of the terms can be changed according to intention, a judicial precedence, the appearance of a new technology, and the like. In addition, in certain cases, a term which is not commonly used can be selected. In such a case, the meaning of the term will be described in detail at the corresponding portion in the description of the present disclosure. Therefore, the terms used in the various embodiments of the present disclosure should be defined based on the meanings of the terms and the descriptions provided herein. 
     The present embodiments relate to a heater assembly, a method of manufacturing a heater assembly, and an aerosol generating device including a heater assembly. Details that are well known to one of ordinary art to which the following embodiments pertain are omitted. 
       FIG. 1  is a diagram explaining components configuring an aerosol generating device including a heater assembly according to some embodiments. 
     Referring to  FIG. 1 , an aerosol generating device  100  may include a heater assembly  110 , a coil  120 , a power supply unit  130 , and a controller  140 . However, the present disclosure is not limited thereto. In addition to the components shown in  FIG. 1 , other general-purpose components may be further included in the aerosol generating device  100 . 
     The aerosol generating device  100  may generate aerosol by heating a cigarette accommodated in the aerosol generating device  100  by an induction heating method. The induction heating method may refer to a method of heating a magnetic body by applying an alternating magnetic field, which has a periodically changing direction, to the magnetic body generating heat by an external magnetic field. 
     When an alternating magnetic field is applied to a magnetic body, energy loss according to eddy current loss and hysteresis loss may occur in the magnetic body, and the lost energy may be released from the magnetic body as thermal energy. The greater the amplitude of frequency of the alternating magnetic field applied to the magnetic body, the more heat energy may be released from the magnetic body. The aerosol generating device  100  may release thermal energy from a magnetic body by applying an alternating magnetic field to the magnetic body, and may transfer the thermal energy emitted from the magnetic body to a cigarette. 
     The magnetic body generating heat by the external magnetic field may include a susceptor. The susceptor may be provided in the aerosol generating device  100  in the shape of a piece, thin plate, strip or the like instead of being included in a cigarette. For example, at least a portion of the heater assembly  110  arranged in the aerosol generating device  100  may include a susceptor material. 
     At least a portion of the susceptor material may include a ferromagnetic body. For example, the susceptor material may include metal or carbon. The susceptor material may include at least one of ferrite, ferromagnetic alloy, stainless steel, and aluminum (Al). In addition, the susceptor material may include at least one of graphite, molybdenum, silicon carbide, niobium, nickel alloy, metal film, ceramics such as zirconia or the like, a transition metal such as nickel (Ni), cobalt (Co), or the like, and a metalloid such as boron (B) or phosphorus (P). 
     The aerosol generating device  100  may accommodate a cigarette. A space accommodating a cigarette may be formed in the aerosol generating device  100 . The heater assembly  110  may be arranged in the space accommodating a cigarette. The heater assembly  110  may have a cylindrical shape therein in which an accommodation space accommodating a cigarette is formed. Accordingly, when a cigarette is accommodated in the aerosol generating device  100 , the cigarette may be accommodated in the accommodation space of the heater assembly  110 , and the heater assembly  110  may be arranged at a position surrounding at least a portion of an outer side surface of the cigarette. 
     The heater assembly  110  may surround at least a portion of the outer side surface of a cigarette accommodated in the aerosol generating device  100 . For example, the heater assembly  110  may surround at least a portion of the outer side surface of a cigarette at a position corresponding to a position of a cigarette medium included in the cigarette. Accordingly, heat may be more efficiently transferred from the heater assembly  110  to the cigarette medium included in the cigarette. 
     The heater assembly  110  may heat a cigarette accommodated in the aerosol generating device  100 . As described above, the heater assembly  110  may heat a cigarette in the induction heating method. The heater assembly  110  may include a susceptor material that generates heat by an external magnetic field, and the aerosol generating device  100  may apply an alternating magnetic field to the heater assembly  110 . 
     The coil  120  may be included in the aerosol generating device  100 . The coil  120  may apply an alternating magnetic field to the heater assembly  110 . When power is supplied to the coil  120  from the aerosol generating device  100 , a magnetic field may be formed inside the coil  120 . When an alternating current is applied to the coil  120 , a direction of the magnetic field formed inside the coil  120  may be continuously changed. When the heater assembly  110  is located inside the coil  120  and is exposed to an alternating magnetic field having a periodically changing direction, the heater assembly  110  may generate heat, and a cigarette accommodated in the heater assembly  110  may be heated. 
     The coil  120  may be wound along an outer side surface of the heater assembly  110 . The coil  120  may be wound along an inner surface of an external housing of the aerosol generating device  100 . The heater assembly  110  may be located in an inner space formed by winding the coil  120 , and when power is supplied to the coil  120 , an alternating magnetic field generated by the coil  120  may be applied to the heater assembly  110 . 
     The coil  120  may extend in a longitudinal direction of the aerosol generating device  100 . The coil  120  may extend to a proper length in the longitudinal direction. For example, the coil  120  may extend to a length corresponding to the length of the heater assembly  110 , or may extend to a length greater than the length of the heater assembly  110 . 
     The coil  120  may be arranged at a position suitable for applying an alternating magnetic field to the heater assembly  110 . For example, the coil  120  may be arranged at a position corresponding to the heater assembly  110 . The efficiency in which the alternating magnetic field of the coil  120  is applied to the heater assembly  110  may be improved by the size and arrangement of the coil  120 . 
     When the amplitude or frequency of the alternating magnetic field formed by the coil  120  is changed, the degree to which the heater assembly  110  heats a cigarette may also be changed. Because the amplitude or frequency of the magnetic field by the coil  120  may be changed by the power to be applied to the coil  120 , the aerosol generating device  100  may control the heating of a cigarette by adjusting the power to be applied to the coil  120 . For example, the aerosol generating device  100  may control the amplitude and frequency of an alternating current to be applied to the coil  120 . 
     As an example, the coil  120  may be implemented as a solenoid. The coil  120  may be a solenoid wound along the inner surface of the external housing of the aerosol generating device  100 , and the heater assembly  110  and a cigarette may be located in an inner space of the solenoid. A material of a leading wire configuring the solenoid may be copper (Cu). However, the present disclosure is not limited thereto, and at least one of silver (Ag), gold (Au), aluminum (Al), tungsten (W), zinc (Zn), and nickel (Ni), or an alloy including at least one of the above materials may be a material of the leading wire configuring the solenoid. 
     The power supply unit  130  may supply power to the aerosol generating device  100 . The power supply unit  130  may supply power to the coil  120 . The power supply unit  130  may include a battery supplying a direct current to the aerosol generating device  100  and a conversion unit converting a current supplied from the battery into an alternating current supplied to the coil  120 . 
     The battery may supply a direct current to the aerosol generating device  100 . The battery may include a lithium iron phosphate (LiFePO 4 ) battery, but is not limited thereto. For example, the battery may include a lithium cobalt oxide (LiCoO 2 ) battery, a lithium titanate battery, or the like. 
     The conversion unit may include a low-pass filter performing filtering on a direct current supplied from the battery and outputting a current supplied to the coil  120 . The conversion unit may further include an amplifier configured to amplify a direct current supplied from the battery. For example, the conversion unit may include a low-pass filter configuring a load network of a class-D amplifier. 
     The controller  140  may control power supplied to the coil  120 . The controller  140  may control the power supply unit  130  such that power supplied to the coil  120  is adjusted. For example, the controller  140  may perform a control to maintain a constant temperature at which the heater assembly  110  heats a cigarette based on a temperature of the heater assembly  110 . 
     The controller  140  may be implemented as an array of a plurality of logic gates or may be implemented as a combination of a general-purpose microprocessor and a memory in which a program executable in the microprocessor is stored. In addition, the controller  140  may be configured by a plurality of processing elements. 
     In the aerosol generating device  100 , the temperature of the heater assembly  110  may be measured to maintain constant a temperature at which the heater assembly  110  heats a cigarette or to change the temperature of heating a cigarette according to a specific heating profile. However, the aerosol generating device  100  may not be separately provided with a unit configured to measure the temperature of the heater assembly  110 . Instead, the temperature of the heater assembly  110  may be derived through a sensor pattern included as a single body in the heater assembly  110 . Detailed descriptions of the sensor pattern included in the heater assembly  110  may be described below with reference to  FIG. 4 . 
       FIG. 2  is a diagram explaining a cigarette heated by a heater assembly according to some embodiments. 
     Referring to  FIG. 2 , a cigarette  200  may include a tobacco rod  210  and a filter rod  220 .  FIG. 2  illustrates that the filter rod  220  is configured in a single area, but is not limited thereto, and the filter rod  220  may be configured as a plurality of segments. For example, the filter rod  220  may include a first segment configured to cool aerosol and a second segment configured to filter a certain component included in the aerosol. In addition, the filter rod  220  may further include at least one segment configured to perform other functions. 
     The cigarette may be packaged via at least one wrapper  240 . The wrapper  240  may have at least one hole through which external air may be introduced or internal air may be discharged. For example, the cigarette  200  may be packaged via one wrapper  240 . As another example, the cigarette  200  may be doubly packaged via at least two wrappers  240 . In detail, the tobacco rod  210  may be packaged via a first wrapper, and the filter rod  220  may be packaged via a second wrapper. The tobacco rod  210  and the filter rod  220 , which are respectively packaged via wrappers, may be coupled to each other, and the cigarette  200  may be entirely packaged via a third wrapper. 
     The tobacco rod  210  may include an aerosol generating material. For example, the aerosol generating material may include at least one of glycerin, propylene glycol, ethylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and oleyl alcohol, but it is not limited thereto. The tobacco rod  210  may include other additives, such as flavors, a wetting agent, and/or organic acid. The tobacco rod  210  may include a flavored liquid, such as menthol or a moisturizer, which is injected to the tobacco rod  210 . 
     The tobacco rod  210  may be manufactured in various methods. For example, the tobacco rod  210  may be formed as a sheet or a strand. In addition, the tobacco rod  210  may be formed as a pipe tobacco, which is formed of tiny bits cut from a tobacco sheet. 
     The tobacco rod  210  may be surrounded by a heat conductive material. For example, the heat conductive material may be, but is not limited to, a metal foil such as aluminum foil. The heat conductive material surrounding the tobacco rod  210  may uniformly distribute heat transmitted to the tobacco rod  210 , and thus, the heat conductivity applied to the tobacco rod  210  may be increased and flavor of the aerosol generated from the tobacco rod  210  may be improved. 
     The filter rod  220  may include a cellulose acetate filter. The filter rod  220  may be manufactured in various shapes. For example, the filter rod  220  may include a cylinder-type rod or a tube-type rod having a hollow therein. In addition, the filter rod  220  may include a recess-type rod having a cavity therein. When the filter rod  220  includes a plurality of segments, the plurality of segments may be manufactured in different shapes from each other. 
     The filter rod  220  may be formed to generate flavors in the filter rod  220 . For example, a flavoring liquid may be injected onto the filter rod  220 , or an additional fiber coated with a flavoring liquid may be inserted into the filter rod  220 . 
     The filter rod  220  may include at least one capsule  230 . The capsule  230  may generate a flavor or aerosol. For example, the capsule  230  may have a configuration in which a liquid containing a flavoring material is wrapped with a film. The capsule  230  may have a spherical or cylindrical shape, but is not limited thereto. 
     When the filter rod  220  includes a segment configured to cool the aerosol, the cooling segment may include a polymer material or a biodegradable polymer material. For example, the cooling segment may include pure polyactic acid alone. Alternatively, the cooling segment may include a cellulose acetate filter having a plurality of holes. However, the cooling segment is not limited thereto, and the cooling segment may include a structure and a material cooling the aerosol. 
     In addition, the cigarette  200  described with reference to  FIG. 2  is only an example, and articles accommodated in the aerosol generating device  100  and capable of generating aerosol may not be limited to the cigarette of  FIG. 2 . Accordingly, the article capable of generating aerosol may have various structures or components different from the cigarette  200 . 
       FIG. 3  is a diagram explaining an operation in which a cigarette is accommodated in an aerosol generating device and heated by a heater assembly, according to some embodiments. 
     Referring to  FIG. 3 , an embodiment in which the cigarette  200  is accommodated in the aerosol generating device  100  including the heater assembly  110  is illustrated. However, the arrangements of the aerosol generating device  100 , the heater assembly  110 , the coil  120 , and the cigarette  200  shown in  FIG. 3  are only examples, and other arrangements in which the cigarette  200  accommodated in the aerosol generating device  100  is heated by the heater assembly  110  and the coil  120  may also be possible. In particular, the coil  120  is illustrated as being embedded in the external housing of the heater assembly  110 , but the coil  120  may be located outside the heater assembly  110  to be arranged in a position suitable for applying a magnetic field to the heater assembly  110 . 
     When the cigarette  200  is accommodated in the aerosol generating device  100 , the tobacco rod  210  may be surrounded by the heater assembly  110 . To this end, the heater assembly  110  may be arranged in the aerosol generating device  100  to surround at least a portion of the cigarette  200 , the portion corresponding to the tobacco rod  210 . Through such an arrangement, heat may be more directly transferred from the heater assembly  110  to the tobacco rod  210 , and power efficiency of the aerosol generating device  100  may be increased. 
     The coil  120  may have a size and position corresponding to the heater assembly  110 . As the coil  120  is arranged to correspond to the heater assembly  110 , an alternating magnetic field formed by the coil  120  may be more directly applied to the heater assembly  110 , and thus, the efficiency in which the heater assembly  110  is heated may be improved. As described above, because an arrangement of the heater assembly  110  and the tobacco rod  210  is also corresponds to each other, optimum power efficiency may be achieved by an arrangement of the heater assembly  110 , the coil  120 , and the tobacco rod  210 . 
       FIG. 4  is a diagram explaining a heater assembly configured to heat a cigarette, according to some embodiments. 
     Referring to  FIG. 4 , the heater assembly  110  may include a heating layer  111 , an insulating layer  112 , and a sensor pattern  113 . However, the present disclosure is not limited thereto. In addition to the components shown in  FIG. 4 , other general-purpose components may be further included in the heater assembly  110 . 
     At least a portion of the heating layer  111  may include a susceptor material that generates heat by an external magnetic field. Accordingly, when an alternating magnetic field is applied from the coil  120  to the susceptor material of the heating layer  111 , the susceptor material of the heating layer  111  may generate heat, and thus, the cigarette  200  may be heated to generate aerosol. 
     The susceptor material of the heating layer  111  may include any material that generates heat when an external magnetic field is applied from the outside. For example, at least a portion of the susceptor material may include a ferromagnetic body. When at least a portion of the susceptor material includes a ferromagnetic body, a large amount of heat may be released from the heating layer  111  by an external magnetic field. 
     The heating layer  111  may have a cylindrical shape therein in which an accommodation space accommodating the cigarette  200  is formed. When the cigarette  200  is accommodated in the aerosol generating device  100 , the cigarette  200  may be accommodated in the accommodation space formed in the heating layer  111 . The cross-sectional diameter of the accommodation space may be substantially the same as the cross-sectional diameter of the cigarette  200 , or may be slightly greater than the cross-sectional diameter of the cigarette  200  to support the cigarette  200  accommodated in the accommodation space. The thickness of the heating layer  111  may be set to a proper value by considering the power required to heat the heating layer  111 , the rate at which the cigarette  200  is heated by the heating layer  111 , the cross-sectional diameter of the aerosol generating device  100 , the cross-sectional diameter of the cigarette  200 , or the like. 
     The insulating layer  112  may surround at least a portion of an outer side surface of the heating layer  111 . The insulating layer  112  may prevent the sensor pattern  113  and other components of the aerosol generating device  100  from being electrically connected, such as an electrical contact between the heating layer  111  and the sensor pattern  113 , and an electrical contact between the sensor pattern  113  and the coil  120 . To this end, the insulating layer  112  may include a material corresponding to an electrical insulator or a non-conductor. 
     The insulating layer  112  may include a first insulating layer  112   a  and a second insulating layer  112   b . The sensor pattern  113  may be embedded by the first insulating layer  112   a  and the second insulating layer  112   b . For example, the first insulating layer  112   a  may support an inner side surface of the sensor pattern  113 , and the second insulating layer  112   b  may surround an outer side surface of the sensor pattern  113 . The sensor pattern  113  may be prevented from contacting other components of the aerosol generating device  100  through being embedded by the first insulating layer  112   a  and the second insulating layer  112   b.    
     The first insulating layer  112   a  and the second insulating layer  112   b  may be formed by different operations from each other. For example, the first insulating layer  112   a  may be coated on the outer side surface of the heating layer  111  to surround at least a portion of the outer side surface of the heating layer  111 , and the second insulating layer  112   b  may be, after printing the sensor pattern  113  on the first insulating layer  112   a , coated on the first insulating layer  112   a  on which the sensor pattern  113  is printed. Detailed descriptions of a method of manufacturing the heater assembly  110  may be described below with reference to  FIG. 6 . 
     The insulating layer  112  may include a material such as glass frit or an inorganic oxide. The glass frit may refer to a glass material such as glass powder. The inorganic oxide may include at least one of silicon (Si) oxide, boron (B) oxide, calcium (Ca) oxide, zirconium (Zr) oxide, and aluminum (Al) oxide. As the insulating layer  112  includes glass frit or an inorganic oxide, the insulating layer  112  may have a property of an electrical insulator or a non-conductor. 
     The sensor pattern  113  may be embedded in the insulating layer  112  and may be configured to measure the temperature of the heating layer  111 . As the sensor pattern  113  is embedded in the insulating layer  112 , the temperature of the heating layer  111  may be accurately measured by the sensor pattern  113 . For example, when the sensor pattern  113  is electrically connected to other components of the aerosol generating device  100 , an electrical resistance or a voltage at both ends of the sensor pattern  113 , which is a characteristic value of the sensor pattern  113  configured to measure the temperature of the heating layer  111 , may be changed. Accordingly, the characteristic value of the sensor pattern  113  may be prevented from being inaccurate by being embedded by the insulating layer  112 . 
     The sensor pattern  113  may be configured to measure the temperature of the heating layer  111 . For example, the sensor pattern  113  may be formed by printing a resistor having a temperature coefficient of resistance (TCR) configured to derive the temperature of the heating layer  111 . However, the present disclosure is not limited thereto, and the sensor pattern  113  may be formed in a single body with the heating layer  111  and may be implemented as other units that may be used to measure the temperature of the heating layer  111 . 
     When the sensor pattern  113  includes a resistor, the temperature of the heating layer  111  may be calculated based on a TCR of the sensor pattern  113 . The sensor pattern  113  having a TCR is based on a proportional relationship between a temperature and a resistance value according to the TCR, and when the temperature of the sensor pattern  113  is changed, the resistance value of the sensor pattern  113  may be also proportionally changed. Accordingly, when the resistance value of the sensor pattern  113  is measured, the temperature of the sensor pattern  113  corresponding to the resistance value may be calculated. As a result, the temperature of the heating layer  111  and the temperature at which the cigarette  200  is heated by the heating layer  111  may be derived from the resistance value of the sensor pattern  113 . The temperature of the sensor pattern  113  may be also determined from a voltage value or a current value deriving the resistance value of the sensor pattern  113 , in addition to the resistance value of the sensor pattern  113 . 
     The temperature of the resistor forming the sensor pattern  113  may be calculated in real time by the controller  140  from the resistance value and the TCR of the resistor. Alternatively, the controller  140  may derive the temperature of the resistor of the sensor pattern  113  by referring to a table prepared in advance with respect to a relationship between the resistance value of the resistor and the temperature of the resistor. 
     The characteristic at which the temperature of the heating layer  111  is derived by the sensor pattern  113  may vary depending on a material configuring the sensor pattern  113 . The sensor pattern  113  may include various materials that may be used to measure the temperature of the heating layer  111 . For example, the sensor pattern  113  may include at least one of ceramic, a semiconductor, metal, carbon, and a thermistor. 
     The accuracy at which the temperature of the heating layer  111  is derived by the sensor pattern  113  may vary depending on a numerical value of the TCR of the sensor pattern  113 . Because the TCR may refer to a ratio of a change in resistance value to a temperature change, the larger the numerical value of the TCR, the greater the change in resistance value according to the temperature change. Accordingly, the temperature of the sensor pattern  113  or the heating layer  111  may be precisely derived. Therefore, the sensor pattern  113  may be required to include a material having a TCR of a high numerical value. 
     For example, the sensor pattern  113  may include metal, and the metal forming the sensor pattern  113  may include at least one of silver (Ag) and palladium (Pd). Silver has a high electrical conductivity and may also have a TCR of a high numerical value. Accordingly, when the sensor pattern  113  includes silver, the accuracy at with the temperature of the heating layer  111  is derived may be improved. Palladium is a metal used for alloying with various metals, and has lightness and high hardness, and thus may strengthen hardness through alloying with soft metals such as silver. 
     As an example numerical value, the metal forming the sensor pattern  113  may include silver in a weight ratio of 45 to 70 and palladium in a weight ratio of 10 to 35. Alternatively, the metal forming the sensor pattern  113  may include silver in a weight ratio of 50 to 55 and palladium in a weight ratio of 13 to 33. Alternatively. the metal forming the sensor pattern  113  may include silver in a weight ratio of 65 to 67 and palladium in a weight ratio of 10 to 15. It has been experimentally confirmed that the sensor pattern  113  formed according to the above-described numerical values has a relatively high TCR and may have a proper hardness to be formed as a single body with the heater assembly  110 . 
     The sensor pattern  113  may include various patterns. The sensor pattern  113  may be formed on the outer side surface of the first insulating layer  112   a  to be positioned on at least a portion in a longitudinal direction and at least a portion in a circumferential direction of the outer side surface of the first insulating layer  112   a . For example, the sensor pattern  113  may be formed, on the outer side surface of the first insulating layer  112   a , in a spiral form in the circumferential direction and may be formed along only a portion in the longitudinal direction. Alternatively, the sensor pattern  113  may be formed, on the outer side surface of the first insulating layer  112   a , over the entire longitudinal direction and may be formed only on a portion in the circumferential direction. However, the present disclosure is not limited to the above embodiments, and the sensor pattern  113  may be formed in another suitable shape that may reflect the temperature of the heating layer  111 . 
     The heater assembly  110  may further include an electrode (not shown) connected to the sensor pattern  113  and configured to read a characteristic value of the sensor pattern  113 . The electrode may be connected to a leading wire (not shown) configured to provide the characteristic value of the sensor pattern  113  to the controller  140 . Because the electrode may be formed in the heater assembly  110 , the characteristic value of the sensor pattern  113  may be provided to the controller  140  even when the sensor pattern  113  is embedded in the insulating layer  112 . 
     As the sensor pattern  113  is formed as a single body with the heater assembly  110 , the temperature of the heater assembly  110  may be measured without a separate temperature sensor in the heater assembly  110  or the aerosol generating device  100 . Therefore, because a space configured to separately provide a temperature sensor may not be required, the design of the aerosol generating device  100  may be simplified, and the arrangement relationships between the components of the aerosol generating device  100  may be more flexible. In addition, as the sensor pattern  113  is coupled to the heating layer  111  as a single body, the temperature of the heating layer  111  may be accurately reflected, and accordingly, the control with respect to the temperature of the heating layer  111  may have high accuracy. 
       FIG. 5  is a diagram explaining an operation in which a temperature of a cigarette is controlled in an aerosol generating device, according to some embodiments. 
     Referring to  FIG. 5 , an embodiment of an operation in which the aerosol generating device  100  controls the temperature of the heater assembly  110  is illustrated. 
     In operation  10 , the controller  140  may read a characteristic value of the sensor pattern  113 . For example, when the sensor pattern  113  includes a resistor having a TCR, the controller  140  may apply a current to the sensor pattern  113  to read a voltage formed in the sensor pattern  113  or apply a voltage to the sensor pattern  113  to read a voltage flowing in the sensor pattern  113 . Alternatively, the controller  140  may include a resistance value measuring unit to directly read a resistance value of the sensor pattern  113 . 
     In operation  20 , the controller  140  may derive the temperature of the heating layer  111  based on the characteristic value of the sensor pattern  113 , and adjust the power supplied to the coil  120  from the power supply unit  130  based on the temperature of the heating layer  111 . The controller  140  may adjust power in a method of proportional-integral-differential (PID) control or on-off control. For example, when the temperature of the heating layer  111  is greater than an intended temperature, the controller  140  may reduce power supplied to the coil  120  or cut off power supplied to the controller  140 . 
     In operation  30 , the controller  140  may control the power supply unit  130  such that the power supplied to the controller  140  is adjusted. For example, when the temperature of the heating layer  111  is greater than an intended temperature, the controller  140  may control the power supply unit  130  to reduce the amplitude or frequency of an alternating current supplied to the coil  120 . 
     In operation  40 , the power supply unit  130  may adjust the power supplied to the controller  140  by the controller  140 . For example, when the amplitude or frequency of the alternating current supplied to the coil  120  is reduced, the amplitude or frequency of the alternating current formed by the coil  120  may decrease. 
     In operation  50 , an alternating magnetic field applied to the heating layer  111  from the coil  120  may be adjusted by the power supply unit  130 . For example, when the amplitude or frequency of the alternating magnetic field formed by the coil  120  decreases, a degree of heat generated by a susceptor material forming at least a portion of the heating layer  111  may decrease, and accordingly, the temperature of the heating layer  111  and the cigarette may be reduced. 
     The above-described operations  10  to  50  have been described in a case where the temperature of the heating layer  111  is greater than the intended temperature, but operations  10  to  50  may be performed in a corresponding manner even when the temperature of the heating layer  111  is less than the intended temperature. The aerosol generating device  100  may heat the cigarette  200  according to a specific heating profile by periodically repeating operations  10  to  50 . 
       FIG. 6  is a flow chart illustrating operations of a method of manufacturing a heater assembly configured to heat a cigarette, according to some embodiments. 
     The method of  FIG. 6  may be performed by a device configured to manufacture the heater assembly  110 . One of ordinary skill in the art may understand that the device configured to manufacture the heater assembly  110  may be any device generally used to manufacture heaters in the art. 
     Referring to  FIG. 6 , the method of manufacturing the heater assembly  110  configured to heat the cigarette  200  may include operations  610  to  630 . However, the present disclosure is not limited thereto, and other general-purpose operations other than operations shown in  FIG. 6  may be further included in the method of manufacturing the heater assembly  110  configured to heat the cigarette  200 . 
     In operation  610 , the device configured to manufacture the heater assembly  110  may form at least a portion of the heating layer  111  including a susceptor material that generates heat by an external magnetic field in a cylindrical shape in which an accommodation space configured to accommodate the cigarette  200  therein is formed. An operation of forming the heater assembly  110  into a cylindrical shape may be performed in various methods. For example, as a general method of forming a metal, a method such as compression, injection, extrusion, lamination or rolling may be applied. 
     In operation  620 , the device configured to manufacture the heater assembly  110  may coat the first insulating layer  112   a , which surrounds at least a portion of the outer side surface of the heating layer  111 , on the outer side surface of the heating layer  111 . The operation of coating the first insulating layer  112   a  may refer to an operation of forming the first insulating layer  112   a  as a film, such as deposition, injection, lamination, coating, or the like. 
     In operation  630 , the device configured to manufacture the heater assembly  110  may print the sensor pattern  113  configured to measure the temperature of the heating layer  111  on an outer side surface of the first insulating layer  112   a . The sensor pattern  113  may be formed on the outer side surface of the first insulating layer  112   a  in a method of screen printing or silk-screen printing. 
     In operation  640 , the device configured to manufacture the heater assembly  110  may coat the second insulating layer  112   b  on the outer side surface of the first insulating layer  112   a  such that the sensor pattern  113  is embedded. As described above, as the sensor pattern  113  is embedded by the first insulating layer  112   a  and the second insulating layer  112   b , the accuracy in which the temperature of the heating layer  111  or the heating layer  111  is measured by the sensor pattern  113  may be increased, and the sensor pattern  113  may be formed as a single body with the heating layer  111  such that the temperature of the heating layer  111  may be accurately measured without a temperature sensor. 
     The device configured to manufacture the heater assembly  110  may further form, in the heater assembly  110 , an electrode connected to the sensor pattern  113  and configured to read characteristic values of the sensor pattern  113 . The device configured to manufacture the heater assembly  110  may perform the operation of forming the electrode between operations  620  and  630 , between operations  630  and  640 , or after operation  640 . 
     Although the embodiments have been described in detail above, the scope of the present disclosure is not limited thereto, and those of ordinary skill in the art may understand that various modifications and improvements using the basic concept of the present disclosure as defined in the following claims are included in the scope of the present disclosure.