Abstract:
The present invention introduces a method for controlling the power of an electric vaporizer, i.e. an electronic cigarette. In the method, the resistance of the heating unit of the vaporizer is measured. The system includes a controller and a memory, and the latter comprises a table where values of resistances and their corresponding default voltage or power values are stored. Additionally, minimum and maximum limit values of the voltages or powers may be stored. Based on the measured resistance, a suitable power or voltage value is determined. The power source is set to feed the heating element according to the selection. The user may however set the voltage or power input smaller or larger through the input means, comprising button(s) and a screen; despite the resistance value, but set limit values are not allowed to be exceeded.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates generally to electronic vaporizers. Specifically the invention relates to controlling electric vaporizers. 
       BACKGROUND OF THE INVENTION 
       [0002]    The following description of background art may include insights, discoveries, understandings or disclosures, or associations together with disclosures not known to the relevant art prior to the present invention but provided by the invention. Some such contributions of the invention may be specifically pointed out below, whereas other such contributions of the invention will be apparent from their context. 
         [0003]    In recent year electronic vaporizers have been developed. One use for the vaporizers is to simulate smoking. The electronic vaporizers comprise a heating element configured to vaporize given material, typically liquid material, which is then inhaled by the user. The vaporizers comprise a power source for the heating element and some sort of controlling element for the vaporizing process. 
         [0004]    The usage experience of electronic vaporizers depends on the components and the control process of the components of the vaporizer. The choice of the material to be inhaled is naturally important for the usage experience. Liquids with different flavours lead to different results. In addition, different types of heating elements and different power fed to the heating element have a strong effect on the usage experience. It has been noticed that best results are achieved when the power fed to the heating element is as constant as possible. 
       BRIEF DESCRIPTION 
       [0005]    According to an aspect of the present invention, there is provided an apparatus as specified in claim  1 . 
         [0006]    According to another aspect of the present invention, there is provided a method as specified in claim  9 . 
     
    
     
       LIST OF DRAWINGS 
         [0007]    Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which 
           [0008]      FIG. 1  illustrates an example of an electric vaporizer; 
           [0009]      FIG. 2  illustrates another example of an electric vaporizer; 
           [0010]      FIGS. 3 and 4  are flow charts illustrating embodiments. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0011]    The following embodiments are exemplary. Although the specification may refer to “an”, “one”, or “some” embodiment(s) in several locations, this does not necessarily mean that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments. 
         [0012]    Electric vaporizers are used for consuming or inhaling materials. Generally materials are in liquid which is heated by a heating element comprising a resistor. Electric power is fed to the heating element which vaporizes desired material for inhaling. 
         [0013]      FIG. 1  illustrates an example of an electric vaporizer  100 . The vaporizer  100  of  FIG. 1  comprises a battery compartment  102  and a liquid compartment  104  comprising a heating element  106  and liquid  108  to be heated. Typically the liquid compartment  104  is detachable from the battery compartment  102 . An electrical connection  110  connects the liquid compartment  104  and the battery compartment  102 . The electric vaporizer  100  may comprise one or more buttons  112  and a display  114 . 
         [0014]    The user may change the liquid compartments  104  comprising a heating element  106 . In addition, the heating element  106  of a liquid compartment  104  may be changed. The electrical properties of the heating elements may vary. For example if the heating element comprises a resistor wire, the electrical resistance of the resistor may vary. A typical value for the electrical resistance of a heating element varies between 0.3 to 10 ohms. The electrical resistance has an effect on the usage experience of the electronic vaporizer  100 . There are devices on the market which let the user select a suitable power fed to the heating element when using the electronic vaporizer. However, these devices have some drawbacks. Typically the user is given a possibility to control the power over a given range. For example, the vaporizer may let the user to select a power between 5 to 15 watts. These solutions do not take the electrical properties of the heating element into account. Thus, it is possible for the user to select such a power which burns the heating element. 
         [0015]    Let us study an example of the operation of the electric vaporizer in view of  FIGS. 2 and 3 . The embodiment starts at step  300 . The electric vaporizer  100  comprises a controller  200  which controls the operation of the vaporizer. The vaporizer may comprise a memory  202  operationally connected to the controller  200 . In some embodiments, the memory and the controller may be combined. 
         [0016]    In step  302 , the memory is configured to store a table comprising resistance values and a default power value for each resistance value. The power values may be predetermined on the basis of an experimental formula or empirical experiments, for example. 
         [0017]    As illustrated in  FIG. 1 , the electric vaporizer  100  comprises a liquid compartment  104  comprising a heating element  106 . Typically the liquid compartment  104  is detachable. The heating element  106  comprises a resistor wire. In an embodiment, the electric vaporizer comprises a current sense amplifier  204  connected to the heating unit  104 . The electric vaporizer comprises a battery  206  which provides the electrical power required by the apparatus. The electric vaporizer may further comprise a power controller unit  208  which may be configured to control the power fed from the battery  206  to the heating unit  104  and the current sense amplifier  204 . The power controller unit  208  may operate under the control of the controller  200 . In an embodiment, the power controller unit  208  is realized as a buck-boost controller. A buck-boost controller is configured to control the power fed to a load to be either smaller or greater than the power given by a source battery. 
         [0018]    Regarding the reference numberings in  FIG. 1 , the heating unit  104  is in practice the same as the liquid compartment. The heating unit  104  thus comprises the heating element  106  and liquid  108  to be heated and vaporized for the user to inhale. 
         [0019]    The electric vaporizer  100  further comprises user interface  210  which may be realized with one or more buttons and a display, for example. In an embodiment, a button may be reserved for initializing vaporizing operation. In an embodiment, some other buttons may be used for controlling the vaporizing operation. The button may be realized with push buttons, touch pad or with any other technology available. 
         [0020]    In step  304 , the controller is configured to receive input from the user via the user interface  210 . The input may be a command to initialize vaporizing operation. 
         [0021]    In step  306 , the controller is configured to measure the resistance of the heating unit  104 . The measurement may be performed by giving a command to the power controller unit and the current sense amplifier. The controller  200  may configure the power controller  208  to output a given voltage to the heating unit. The current sense amplifier may measure the current (and also the voltage) and send measurements to the controller. The controller may calculate the resistance of the heating unit using formula R=U/I, where U is voltage and I current. 
         [0022]    In step  308 , the controller is configured to read from the memory  202  a default voltage value corresponding to the determined resistance. 
         [0023]    The use of a default value enables the protection of the heating unit. The heating unit cannot be damaged accidentally. In known solutions, when a heating unit requiring a large voltage is changed to a unit requiring small voltage, the changed unit may accidentally receive too large voltage and get damaged. In addition, the use of tested default values provides immediately a satisfactory user experience to the user. 
         [0024]    One advantage related to the structure of the present electronic vaporizer is that the use of a power controller enables the use of a large range of voltages or powers which can be fed to the heating unit. 
         [0025]    In step  310 , the controller is configured to give a command to the power controller unit  208  to feed the default voltage value to the heating unit. 
         [0026]    In an embodiment, the controller may be configured to measure the power fed to the heating unit  104 , compare the measured power to the determined power, and control the power source on the basis of the comparison. In step  312 , the measurement is performed by the current sense amplifier. The controller may compare the measurement to the required value in step  314  and correct the voltage in step  316  if needed. This procedure may be executed at given intervals or a few times after the initialization of the vaporizing procedure. 
         [0027]    In an embodiment, the user may manually adjust the power fed to the heating unit using the user interface  210 . For example, the user may be given the possibility of adjusting the voltage fed into the heating unit in steps of 0.1 volts.  FIG. 4  illustrates this example. In step  400 , the controller  200  detects that the user has indicated voltage up function. This may be realized with a power up button, for example. In step  402 , the controller instructs the power control unit to increase the voltage fed to the heating unit by 0.1 volts. There may be some minimum and maximum values which the user is not allowed to exceed. 
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Resistance 
                 Min limit 
                 Default 
                 Max limit 
               
               
                   
                   
               
             
             
               
                   
                 0.5 
                 1.9 
                 2.3 
                 2.7 
               
               
                   
                 0.6 
                 2.0 
                 2.6 
                 3.0 
               
               
                   
                 0.7 
                 2.4 
                 3.0 
                 3.5 
               
               
                   
                 . . . 
                 . . . 
                 . . . 
                 . . . 
               
               
                   
                 5.4 
                 5.9 
                 7.4 
                 8.7 
               
               
                   
                 5.5 
                 6.2 
                 7.8 
                 9.0 
               
               
                   
                   
               
             
          
         
       
     
         [0028]    Table 1 illustrates an example of data stored in the memory  202 . The memory may store resistance values and corresponding default voltage or power values. In addition, for each resistance value a minimum and maximum value for the voltage or power may be stored. 
         [0029]    The memory  202  may also store the current measured resistance value. If the same heating unit is used, the power or voltage values selected by the user may be used repeatedly. However, if the heating unit is changed such that the resistance changes, the controller  200  may detect the change and select the default power or voltage value for the determined resistance. 
         [0030]    In an embodiment, the user is given the possibility to freely select any voltage or power value from a predetermined range, such as 2 to 8.2 volts, for example. In this mode, the resistance value measured from the heating unit has no effect. 
         [0031]    The controller  200  may be implemented as an electronic digital computer, which may comprise a working memory (RAM), a central processing unit (CPU), and a system clock. The CPU may comprise a set of registers, an arithmetic logic unit, and a control unit. The control unit is controlled by a sequence of program instructions transferred to the CPU from the RAM. The control unit may contain a number of microinstructions for basic operations. The implementation of microinstructions may vary, depending on the CPU design. The program instructions may be coded by a programming language, which may be a high-level programming language, such as C, Java, etc., or a low-level programming language, such as a machine language, or an assembler. The electronic digital computer may also have an operating system, which may provide system services to a computer program written with the program instructions. 
         [0032]    It will be obvious to a person skilled in the art that, as technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.