Abstract:
An electronic cigarette and a control method thereof are provided. An electronic cigarette with a heating wire component used for producing heat, where the heating wire component comprises a heating wire having a resistance that varies with temperature; a power source used for providing the heating component with a voltage; and, a controller electrically coupled to the heating wire component and the power source and used for controlling the voltage outputted by the power source. The controller comprises a temperature detection module used for detecting the resistance of the heating wire and thus acquiring the actual temperature of the heating wire component. The temperature detection module presets an upper limit heating temperature and a lower limit heating temperature.

Description:
FIELD OF THE INVENTION 
       [0001]    The present disclosure relates to electronic devices, and more particularly relates to an electronic cigarette and a control method thereof. 
       BACKGROUND OF THE INVENTION 
       [0002]    An electronic cigarette is a battery powered electronic device that implements smoking effect by using inner detecting modules to detect airflow movements to determine whether it is at working status, and control a heating wire to vaporize tobacco liquid. 
         [0003]    A conventional electronic cigarette uses a lithium battery having an initial voltage of 4.15V to 4.25V as a power source, and controls the power source to output the voltage by a micro controller, so that the heating wire produces heat. Such electronic cigarette usually applies two control modes: the first control mode is to output a constant voltage in a certain range, the voltage value of which may be 3.6V±0.15V or 3.4V±0.15V, and when the voltage of the lithium battery drops below 3.3V or 2.75V, the micro controller will control the power source to stop outputting voltage; the second control mode is to output the same voltage with the lithium battery, i.e. the working voltage applied to both ends of the heating wire is the same with the voltage of the lithium battery, and the voltage outputted by the power source drops along with the voltage of the lithium battery, and when the voltage of the lithium battery drops below 3.3V or 2.75V, the micro controller will control the power source to stop outputting voltage. 
         [0004]    However, since the voltage applies to both ends of the heating wire is a constant voltage or varies only with the voltage of the lithium battery, the greater the smoking time is, the higher temperature the heating wire will be. When the temperature of the heating wire is higher than the vaporization temperature of the tobacco liquid, the tobacco liquid will be cracked and release burning smell. Moreover, since the lung capacity or smoking habit of individuals is different, if the output voltage is a constant voltage or varies with the voltage of the lithium battery, the variation of the temperature of the heating wire will be relatively large, causing an inconsistent flavor of the atomized tobacco liquid. 
       SUMMARY OF THE INVENTION 
       [0005]    Accordingly, in order to address the problem of the burning smell caused by the high temperature of the heating wire and the inconsistent flavor caused by the unstable temperature of the heating wire, it is necessary to provide an electronic cigarette and a method of controlling the electronic cigarette to avoid producing burning smell, ensure the consistent flavor of each taste of the cigarette, and save the power. 
         [0006]    An electronic cigarette includes: a heating wire component configured to produce heat, wherein the heating wire component includes a heating wire having a resistance that varies with temperature; a power source configured to provide a voltage to the heating wire component; and a controller electrically coupled to the heating wire component and configured to control the power source to output the voltage; wherein the controller includes a temperature detecting module configured to detect the resistance of the heating wire and obtain a real-time temperature of the heating wire component, the temperature detecting module presets an upper limit heating temperature and a lower limit heating temperature; when the real-time temperature is lower than or equals to the lower limit heating temperature, the controller controls the power source to output a first voltage; when the real-time temperature is higher than or equals to the upper limit heating temperature, the controller controls the power source to output a second voltage that is lower than the first voltage; and when the real-time temperature is higher than the lower limit heating temperature and lower than the upper limit heating temperature, the controller controls the power source to maintain a current output voltage. 
         [0007]    In one of embodiments, the controller presets data of a correspondence between the real-time temperatures of the heating wire component and the resistances of the heating wire. 
         [0008]    In one of embodiments, the variation of the resistance of the heating wire is obtained by detecting the voltage applied to both ends of the heating wire and the current runs through the heating wire. 
         [0009]    In one of embodiments, the heating wire has a positive temperature coefficient, and the resistance of the heating wire increases with the increase of temperature. 
         [0010]    In one of embodiments, the electronic cigarette further includes a tobacco liquid storing component configured to store tobacco liquid, wherein the upper limit heating temperature is lower than an upper limit vaporization temperature of the vaporized tobacco liquid, and the lower limit heating temperature is higher than a lower limit vaporization temperature of the vaporized tobacco liquid. 
         [0011]    In one of embodiments, the electronic cigarette further includes a mouthpiece, wherein the controller further includes a smoking detecting module connected to the mouthpiece and a time detecting module electrically coupled to the smoking detecting module, the smoking detecting module is configured to detect a smoking action, the time detecting module presets a reference period and is configured to detect a duration of a single inhalation in the smoking action and compare the duration with the reference period, when the duration is greater than the reference period, the controller controls the power source to be shut down. 
         [0012]    In one of embodiments, the controller further includes a residual tobacco liquid detecting module configured to detect a heating time required for heating the heating wire component from starting to reaching the upper limit heating temperature, the residual tobacco liquid detecting module presets a standard period, when the heating time is less than the standard period, the controller controls the power source to be shut down. 
         [0013]    In one of embodiments, the electronic cigarette further includes an indicator light connected to the controller, wherein the controller controls the indicator light to show a normal working status and a tobacco liquid exhausting status. 
         [0014]    A method of controlling an electronic cigarette includes: setting a lower limit heating temperature and an upper limit heating temperature; detecting a real-time temperature of a heating wire component and comparing the real-time temperature with the lower limit heating temperature and the upper limit heating temperature; applying a first voltage to both ends of the heating wire component when the real-time temperature is lower than or equals to the lower limit heating temperature; applying a second voltage to both ends of the heating wire component when the real-time temperature is higher than or equals to the upper limit heating temperature, wherein the second voltage is lower than the first voltage, and maintaining a current voltage applied to both ends of the heating wire component when the real-time temperature is higher than the lower limit heating temperature and lower than the upper limit heating temperature. 
         [0015]    In one of embodiments, the method further includes: setting a standard period; detecting a heating time required for heating the heating wire component from starting to reaching the upper limit heating temperature, and comparing the heating time with the standard period; controlling the electronic cigarette to work normally when the heating time is greater than or equals to the standard period; and shutting down the electronic cigarette when the heating time is less than the standard period. 
         [0016]    The electronic cigarette described above includes the temperature detecting module, and the controller controls the power source to output voltage according to the real-time temperature of the heating wire component, thus avoiding the burning smell caused by the high temperature of the heating wire. In addition, the temperature of the heating wire is controlled to fluctuate in a certain range, thus ensuring the consistent flavor of each taste of the cigarette, and saving the power of the power source. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a cross-sectional view of an electronic cigarette in accordance with an embodiment; 
           [0018]      FIG. 2  is a block diagram of the electronic cigarette in accordance with an embodiment; 
           [0019]      FIG. 3  is a diagram illustrating, for comparison, the temperature vs. time ratio characteristic curves of the heating wire component of the electronic cigarette according to the present disclosure and a conventional heating wire at normal working status; 
           [0020]      FIG. 4  is a diagram illustrating, for comparison, the resistance vs. temperature ratio characteristic curves of the heating wire component of the electronic cigarette according to the present disclosure and a conventional heating wire; and 
           [0021]      FIG. 5  is a flow chart of the control method of the electronic cigarette in accordance with an embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0022]      FIG. 1  is a cross-section view of an electronic cigarette in accordance with an embodiment. The electronic cigarette includes a heating wire component  11 , a tobacco liquid storing component  12 , a power source  13 , and a controller  14 . 
         [0023]    The heating wire component  11  is used to produce heat, and it includes a heating wire  110  having a resistance varies with temperature. In the illustrated embodiment, the material of the heating wire  110  includes metal cerium (Ce), and the resistance of the heating wire  110  increases with the increase of temperature. 
         [0024]    The tobacco liquid storing component  12  is connected to the heating wire component  11  and configured to store tobacco liquid. The tobacco liquid has a lower limit vaporization temperature t 1  and an upper limit vaporization temperature t 2 . In the illustrated embodiment, the lower limit vaporization temperature t 1  is 190° C., while the upper limit vaporization temperature t 2  is 220° C. When the temperature of the heating wire component  11  is between the lower limit vaporization temperature t 1  and the upper limit vaporization temperature t 2 , the vaporized tobacco liquid has better taste, and thus the electronic cigarette can achieve a better smoking effect. However, when the temperature of the heating wire component  11  exceeds the upper limit vaporization temperature t 2 , the taste of the tobacco liquid will go worse. If the temperature of the heating wire component  11  continues to rise and reach 290° C., the tobacco liquid will be cracked and release burning smell. In order to avoid producing burning smell and keep the good taste of the electronic cigarette, it is necessary to maintain or slightly fluctuate the temperature of the heating wire component  11  between the minimum vaporize temperature t 1  and the maximum vaporize temperature t 2 . 
         [0025]    The power source  13  is configured to provide voltage to the heating wire component  11  and electrically coupled to the controller  14 . The controller  14  controls the power source  13  to output a first voltage U 1  and a second voltage U 2 , and the second voltage U 2  is lower than the first voltage U 1 . When the first voltage U 1  is applied to both ends of the heating wire component  11 , the temperature of the heating wire component  11  will rise; when the second voltage U 2  is applied to both ends of the heating wire component  11 , since the second voltage U 2  is lower than the first voltage U 1 , and the second voltage U 2  is low enough, the heating wire component  11  can continue to provide heat to the tobacco liquid without increasing its temperature. Along with the increase of the times of smoking the cigarette, the temperature of the heating wire component  11  under the second voltage U 2  may drop, and in order to avoid the temperature of the heating wire component  11  decreases to below the lower limit vaporization temperature t 1 , it is necessary to control the power source  13  to output the first voltage U 1  again by the controller  14 , so as to heat the heating wire component  11  again. In this manner, the temperature of the heating wire component  11  can be controlled by controlling the power source  13  to respectively output the first voltage U 1  and the second voltage U 2 . 
         [0026]      FIG. 2  is a block diagram of the electronic cigarette in accordance with an embodiment. The controller  14  includes a control module  140  configured to control the power source  13  to output voltages. The controller  14  presets data of a correspondence between real-time temperatures of the heating wire component  11  and resistances of the heating wire  110 . The controller  14  further includes a temperature detecting module  141  electrically coupled to the heating wire component  11  and configured to detect the real-time temperature t 0  of the heating wire component  11 . The temperature detecting module  141  presets a lower limit heating temperature t 3  and an upper limit heating temperature t 4 . Since there is a delay of the variation of the temperature of the heating wire component  11  after changing the voltage, the real-time temperature t 0  will continue to increase or decrease, the lower limit heating temperature t 3  is higher than the lower limit vaporization temperature t 1 , and the upper limit heating temperature t 4  is lower than the upper limit vaporization temperature t 2 . When the real-time temperature t 0  is lower than or equals to the lower limit heating temperature t 3 , the controller  14  controls the power source  13  to output the first voltage U 1 ; when the real-time temperature t 0  is higher than or equals to the upper limit heating temperature t 4 , the controller  14  controls the power source  13  to output the second voltage U 2 ; and when the real-time temperature t 0  is higher than the lower limit heating temperature t 3  and lower than the upper limit heating temperature t 4 , the controller  14  controls the power source  13  to maintain a current output voltage. 
         [0027]    Since controller  14  presets data of a correspondence between real-time temperatures of the heating wire component  11  and resistances of the heating wire  110 , and the resistance of the heating wire  110  increases with the increase of temperature, the temperature detecting module  141  can determine the real-time temperature t 0  of the heating wire component  11  by detecting the resistance of the heating wire  110 . The variation of the resistance of the heating wire  110  is obtained by detecting the voltage applied to both ends of the heating wire  110  and the current runs through the heating wire  110 , therefore, it is very simple to sense the variation of temperature of the heating wire component  11  through the variation of the resistance of the heating wire  110 . Preferably, the resistance of the heating wire  110  increases linearly with the increase of temperature, and the temperature detecting module  141  can rapidly determine the real-time temperature t 0  of the heating wire component  11  by simply detecting the resistance of the heating wire  110 , so that the controller  14  can rapidly control the power source  13  to output the voltage. Moreover, since the resistance of the heating wire  110  increases with the increase of temperature, and the amplitude of increasing is relatively large, i.e. when the temperature of the heating wire component  11  reaches the vaporization temperature of the tobacco liquid, the resistance of the heating wire  110  is relatively large, while the current running through the heating wire  110  is relatively low. Such feature helps to avoid a rapid increase of the temperature of the heating wire component  11 , thus ensuring the temperature stabilization of the tobacco liquid. In an embodiment, for each 100° C. the temperature of the heating wire component  11  rises, the resistance value of the heating wire  110  will be increased by 0.1Ω to 0.8Ω. The amplitude of increasing can be adjusted by changing the formula of the heating wire  110 . 
         [0028]      FIG. 3  is a diagram illustrating, for comparison, the temperature vs. time ratio characteristic curves of the heating wire component of the electronic cigarette according to the present disclosure and a conventional heating wire at normal working status. In  FIG. 3 , the curve L 1  represents the variation curve of the temperature of the heating wire component  11  in the electronic cigarette of the present disclosure varies with time, while the curve L 2  represents the variation curve of the temperature of a conventional heating wire component varies with time.  FIG. 4  is a diagram illustrating, for comparison, the resistance vs. temperature ratio characteristic curves of the heating wire component of the electronic cigarette according to the present disclosure and a conventional heating wire. In  FIG. 4 , the curve L 3  represents the variation curve of the resistance of the heating wire  110  in the electronic cigarette of the present disclosure varies with time, while the curve L 4  represents the variation curve of the resistance of the heating wire component varies with time. The resistance of the conventional heating wire does not vary with the temperature, and if there is no temperature detecting module in the electronic cigarette, the temperature of the heating wire will continue to rise, and finally exceed the upper limit vaporization temperature of the tobacco liquid, thus causing a bad taste or even releasing burning smell. The resistance of the heating wire  110  in the electronic cigarette of the present disclosure increases linearly with the increase of temperature, and the temperature detecting module  141  is used to sense the temperature of the heating wire component  11 , maintaining or slightly fluctuating the temperature of the heating wire component  11  between the lower limit vaporization temperature t 1  and the upper limit vaporization temperature t 2 . 
         [0029]    In an embodiment, the electronic cigarette further includes a mouthpiece  15 , and the controller  14  further includes a smoking detecting module  142  connected to the mouthpiece  15  and a time detecting module  143  electrically coupled to the smoking detecting module  142 . The smoking detecting module  142  is configured to detect a smoking action. The time detecting module  143  presets a reference period T 0  and is configured to detect a duration T 1  of a single inhalation in the smoking action. When the duration T 1  is less than or equals to the reference period T 0 , the controller  14  determines that the user is smoking normally, and controls the power source  13  to output the voltage; when the duration T 1  is greater than the reference period T 0 , the controller  14  determines that it is not a normal smoking action, and the controller  14  controls the power source  13  to be shut down. In the illustrated embodiment, the duration T 1  of a single inhalation in the smoking action is used to determine whether the user is smoking or not, and the electronic cigarette is automatically shut down when the duration is too long, which is conducive to saving the power. 
         [0030]    In an embodiment, the controller  14  further includes a residual tobacco liquid detecting module  144  electrically coupled to the temperature detecting module  141  and the control module  140 , and is configured to detect a heating time T 2  required for the heating wire component  11  to be heated from starting to reach the upper limit heating temperature t 4 . The residual tobacco liquid detecting module  144  presets a standard period T 3 , when the heating time T 2  is less than the standard period T 3 , the controller  14  determines that the tobacco liquid is exhausted and controls the power source  13  to be shut down, and the power source  13  stops outputting voltage. Since the temperature of the heating wire component  11  will rapidly rise when little tobacco liquid left or the tobacco liquid is exhausted, it is conducive to protect the circuit by using the residual tobacco liquid detecting module  144  to detect the rising speed of the temperature of the heating wire component  11  and shutting down the power source  13  when the rising speed is too fast. 
         [0031]    In an embodiment, the electronic cigarette further includes an indicator light  16  connected to the controller  14 . The controller  14  controls the indicator light  16  to show a normal working status and a tobacco liquid exhausting status by the control module  140 . 
         [0032]    Since the electronic cigarette includes the temperature detecting module  141 , and the controller  14  controls the power source  13  to output voltage according to the real-time temperature of the heating wire component  11 , the burning smell caused by the high temperature of the heating wire component  11  is avoided. Simultaneously, the temperature of the heating wire is controlled to fluctuate in a certain range, thus ensuring the consistent flavor of each taste of the cigarette, and saving the power of the power source. 
         [0033]    A method of controlling an electronic cigarette is also provided in the present disclosure. 
         [0034]      FIG. 5  is a flow chart of the method of controlling the electronic cigarette. The method includes the following steps. 
         [0035]    In step S 110 , a lower limit heating temperature t 30  and an upper limit heating temperature t 40  are set. 
         [0036]    In step S 120 , a real-time temperature t 00  of a heating wire component is detected and compared with the lower limit heating temperature t 30  and the upper limit heating temperature t 40 . 
         [0037]    In step S 130 , when the real-time temperature t 00  is lower than or equals to the lower limit heating temperature t 30 , a first voltage is applied to both ends of the heating wire component. 
         [0038]    In step S 140 , when the real-time temperature t 00  is higher than or equals to the upper limit heating temperature t 40 , a second voltage is applied to both ends of the heating wire component. The second voltage is lower than the first voltage. 
         [0039]    In step S 150 , when the real-time temperature t 00  is higher than the lower limit heating temperature t 30  and lower than the upper limit heating temperature t 40 , the voltage applied to both ends of the heating wire component is maintained at a current voltage value. 
         [0040]    In an embodiment, prior to detecting the real-time temperature t 00  and comparing the real-time temperature t 00  with the lower limit heating temperature t 30  and the upper limit heating temperature t 40 , the method further includes the following steps. 
         [0041]    In step S 210 , a reference period T 00  is set. 
         [0042]    In step S 220 , a smoking action and a duration T 10  of a single inhalation in the smoking action is detected, and the duration T 10  is compared with the reference period T 00 . 
         [0043]    In step S 230 , the electronic cigarette is controlled to work normally when the duration T 10  is less than or equals to the reference period T 00 . 
         [0044]    In step S 240 , the electronic cigarette is shut down when the duration T 10  is greater than the reference period T 00 . 
         [0045]    In an embodiment, prior to setting the reference period T 00 , the method further includes the following steps. 
         [0046]    In step S 310 , a standard period T 30  is set. 
         [0047]    In step S 320 , a heating time T 20  required for heating the heating wire component from starting to reach the upper limit heating temperature t 40  is detected and compared with the standard period T 30 . 
         [0048]    In step S 330 , the electronic cigarette is controlled to work normally when the heating time T 20  is greater than or equals to the standard period T 30 . 
         [0049]    In step S 340 , the electronic cigarette is shut down when the heating time T 20  is less than the standard period T 30 . 
         [0050]    In the present control method, the output voltage of the power source is adjusted by detecting the temperature of the heating wire component, avoiding the burning smell caused by the high temperature of the heating wire, and ensuring the flavor of each taste of the cigarette by making the temperature of the heating wire fluctuate in a certain range; the rising speed of the temperature of the heating wire component is detect and the power source is shut down when the rising speed is too fast, protecting the circuit; and the smoking action and the duration of a single inhalation are detected, and the electronic cigarette automatically shuts down when the duration is too long, saving the power of the power source. 
         [0051]    The embodiments described above only show a few implement manners of the present invention, the description is specific and detailed, but it cannot be interpreted as a limitation of the range of the present invention. What should be pointed out is that it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention. Thus, the range of the present invention should be defined by the appended claims.