EP3446579B1 - Inhaler and method for controlling an inhaler - Google Patents

Description

The present invention relates to an inhaler with an electronic control device and an evaporator unit with at least one heating element, the evaporator unit being set up for evaporating liquid supplied from a liquid reservoir and the evaporated liquid being taken up by an air stream flowing through the evaporator unit.

Most of the evaporator units currently on the market are implemented in an electronic cigarette product and are based on the so-called wick-coil principle. A wick, eg made of glass fiber, is partially wrapped with a heating coil and is connected to a liquid reservoir. When the heating coil is heated, the liquid in the wick evaporates in the area of the heating coil. The liquid is typically a mixture of different substances that have different boiling temperatures and different physiological effects. In order to control the effect, the droplet size is regulated, since droplets of different sizes are absorbed by the body at different rates. The use of a suitable electronic control device allows the droplet size of the droplets in the resulting aerosol to be set in a targeted manner by setting the heating temperature of the heating element designed as a heating coil. Such an electronic cigarette is exemplified in US 2016/0021930 A1 (RJ Reynolds Tobacco Company ) described.

As a result of the different boiling temperatures of the substances present in the liquid, for example, a substance with a low boiling point can be completely used up after a corresponding period of use without the liquid reservoir being empty. Thus, in the course of consumption, the physiological or taste effect of the resulting aerosol changes. For example, if nicotine has been used up, the smoking experience can be inhibited.

Furthermore, the uncontrollable temperature development can lead to unwanted partial heating and overheating of the liquid, or one of the substances contained therein, and thus to undesirable pollutant emissions.

US2013/0340750A1 and U.S. 2016/0021934 A1 each disclose an inhaler having the features of the preamble of claim 1. U.S. 2016/021934 A1 discloses an evaporator for an electronic cigarette.

The object of the invention is to provide an inhaler with a safe, high-quality and energy-efficient evaporator unit in which the active substance is administered reliably and a potential risk of overheating and the associated pollutant emissions can be avoided.

The invention solves this problem with the features of the independent claims. It is proposed that the electronic control device be set up so that the at least one heating element is heated with a variable control frequency.

It has been shown that the control frequency with which the at least one heating element is heated has a decisive influence on the size of the droplets in the aerosol, in addition to the geometry and the advantageously set up liquid supply. The amount of vapor produced when pulsing or otherwise heating at different frequencies is different and therefore specifically adjustable and the droplet size of the aerosol changes significantly with the amount of steam, depending on the geometry of the heating element used. A high driving frequency favors the creation of smaller droplets, while a low driving frequency favors the creation of larger droplets. According to the invention, the absorption and effect of the substances in the liquid are adjusted by the droplet size with the control frequency. Furthermore, the heating temperature can be adjusted according to the substances contained in the liquid and overheating can be avoided. Furthermore, it has been shown that the energy requirement of the evaporator is improved by adjusting the droplet size over the frequency compared to adjusting the temperature.

The heating with a variable control frequency according to the invention allows the formation of droplets with variable size and thus a variable effect. The term variable control frequency is to be understood as meaning the temporal and/or local variation of the control frequency. For example, the administration of physiological active substances can be controlled by a time-variable control and, for example, the nicotine supply during smoking can be adjusted in such a way that the smoking pleasure is improved.

In a preferred embodiment, the electronic control device is set up to heat the at least one heating element with a plurality of different control frequencies in order to achieve a multimodal droplet size distribution. The heating of the at least one heating element with the plurality of different control frequencies means that a plurality of control frequencies can be superimposed and thus the at least one heating element with a plurality of frequencies at the same time can be heated. Several control frequencies can be applied globally or at defined locations of the at least one heating element, so that the at least one heating element is divided into different areas with different control frequencies.

The evaporator unit preferably has a plurality of heating elements and the electronic control device is set up to heat different heating elements with different control frequencies. By driving different heating elements with different control frequencies, different droplet sizes can be realized simultaneously. Each heating element can produce, for example, one or more droplet sizes, which together are picked up by the air flow flowing through the evaporator unit and delivered to the user.

The electronic control device is advantageously set up to control the control frequency of the plurality of heating elements in such a way that a multimodal droplet size distribution of the vaporized liquid results. If several heating elements are controlled in parallel with different frequencies, a multimodal, adjustable droplet size distribution can be achieved. For example, if it is desired to produce droplets of large size, e.g. >5 µm, and droplets of small size, e.g. <1 µm, the heating elements can be controlled in such a way that at least one of the heating elements produces large droplets and at least one of the heating elements produces small droplets. For this purpose, the at least one heating element for the small droplets is preferably heated with a high control frequency and the at least one heating element for large droplets is heated with a low control frequency. Further heating elements can also be added be used to create droplets of specific sizes.

The resulting droplet size distribution is multimodal and has maxima at the desired droplet sizes. This is conducive to a positive smoking sensation, for example, since small droplets penetrate far into the respiratory tract, where nicotine, but also other substances, have an effective effect, while large droplets can be tasted well. The targeted setting of the multimodal distribution corresponds to a targeted setting of the physiological and taste effect. A 1:1 ratio of small and large droplets would be conceivable in order to make the effect quick (small droplets) but also long-lasting (large droplets).

According to the invention, the electronic control device is set up to change the control frequency of the at least one heating element over the emptying period of the liquid reservoir. The concentrations of the substances in the liquid can change over the duration of the emptying of the liquid reservoir due to their different boiling temperatures and/or volatility. The liquid contained in the liquid reservoir separates as a result of the differential distillation that takes place during evaporation. Ie higher-boiling components accumulate, which leads to an inhomogeneous release of active substance. For example, there is significantly less nicotine from about a half-used liquid reservoir. A desired physiological effect of the active ingredients of the individual substances can preferably be achieved by changing the control frequency over the duration of the emptying of the liquid reservoir.

According to the invention, the electronic control device is set up to increase the activation frequency of the at least one heating element as the liquid reservoir is progressively emptied. Nicotine, for example, vaporizes at a comparatively low temperature. Therefore, the dose of nicotine absorbed per puff decreases over the duration of the emptying of the liquid reservoir at the same temperature and droplet size. By adjusting the droplets, e.g. by large droplets at the beginning (delayed effect in the body) and small droplets at the end (rapid effect) of the emptying time of the liquid reservoir, the subjective perception of the effect can be homogenized and changes in concentration are compensated. In order to promote a positive smoking experience, it is suggested to increase the control frequency over the duration of the liquid reservoir depletion and to produce more smaller droplets to keep the smoking experience constant.

It is advantageous to change the control frequency of the at least one heating element over the duration of a puff. The physiological and taste effects can be positively influenced over the duration of a puff if the control frequency and thus the droplet size are adjusted.

The control frequency of the at least one heating element can preferably be adjusted in a targeted manner such that a desired droplet size of the evaporated liquid of, for example, ≦5 μm results. Droplets with a diameter or an aerodynamic diameter (mass median aerodynamic diameter - MMAD) of less than 5 µm do not remain in the upper airways but penetrate the bronchi a, which promotes the absorption of nicotine or other active ingredients, for example for drug treatment. The aerodynamic diameter is the diameter at which the total of those particles with a smaller or larger diameter each contribute half of the total mass of all particles. In particularly preferred embodiments, the droplet size is less than or equal to 0.2 μm. These very small droplets with an MMAD or diameter of less than 1 µm penetrate into the alveoli and cross the blood-brain barrier particularly quickly. An effect can thus occur early or late, depending on the droplet size. The action time can be influenced by adjusting the droplet size.

In a preferred embodiment, an activation frequency of at least one heating element of at least 10 Hz and preferably at most 20 kHz is set. In a preferred embodiment, the variable control frequencies according to the invention are in the range from 10 Hz to 20 kHz, particularly preferably between 500 Hz and 2 kHz. The frequencies can be set individually for each heating element per heater. A preferred distribution of the droplet sizes and energy-efficient heating can thus be promoted.

It is advantageous to measure the resistance of the at least one heating element. If the heating element is implemented as a thermistor, the temperature can be determined by measuring the resistance. A diagnosis of the operating state, the state of the heating element wetted with liquid (with the wrong liquid, no liquid, too little liquid, the correct amount of liquid and/or too much liquid) and/or possible malfunctions can preferably be carried out. In a preferred embodiment, the control and measuring device is a data processing unit or is connected to one.

The control and measuring device advantageously has a reference resistor connected in series with the heating element. Preferably, each heating element is connected in series with a separate reference resistor. This enables a precise resistance measurement of the heating element or heating elements.

The control and measuring device preferably has at least one operational amplifier. An operational amplifier can amplify the current flowing through the heating element and allow easy evaluation by the data processing unit.

In a preferred embodiment, the control and measuring device has a switching device. The switching device can turn on the control and measuring device when no heating voltage is present at the heating element (follow-up phase) and off when a heating voltage is present at the heating element (heating or evaporation phase). However, it can also be measured during a heating pulse in the evaporation phase. The measurement results of the switching device are preferably processed in the preferably shared data processing unit.

• Zustandskontrolle, Überwachung und/oder Fehlerdetektion der Verdampfereinheit;
• Steuerung oder Regelung der Verdampfereinheit mit entsprechender Zeitskala;
• Ermittlung der Temperatur des mindestens einen Heizelements.

One or more of the following measures is or are preferably carried out on the basis of the measured values:

• condition control, monitoring and/or error detection of the evaporator unit;
• Control or regulation of the evaporator unit with appropriate time scale;
• Determining the temperature of the at least one heating element.

The electronic control unit can be set up to carry out the aforementioned measures such as monitoring, regulation, control or further measurement on the basis of the measured values.

The at least one heating element is preferably designed as a microsystem-technical unit. A microsystem technology unit (MEMS) preferably has a very low thermal capacity and/or a high thermal conductivity. As a result, the heating element has a low thermal inertia and can change its temperature quickly and cause particularly rapid evaporation. A rapid temperature change is particularly preferred at high driving frequencies and enables the production of particularly small droplets.

Fig. 1

einen schematischen Aufbau eines Inhalators;

Fign. 2,3

einen Schaltplan für eine bevorzugte Ausführungsform eines Inhalators;

Fig. 4

ein Beispiel für den zeitlichen Verlauf der Heizspannung; und

Fig. 5

ein Beispiel für den zeitlichen Verlauf der Ansteuerfrequenz.

The invention is explained below on the basis of preferred embodiments with reference to the accompanying figures. while showing

1

a schematic structure of an inhaler;

Figs. 2.3

a circuit diagram for a preferred embodiment of an inhaler;

4

an example of the time profile of the heating voltage; and

figure 5

an example of the timing of the control frequency.

figure 1 shows the schematic structure of an inhaler 10, for example an electronic cigarette product. The inhaler comprises a substantially rod-shaped or cylindrical housing 11 with a mouth end 15 and one or more air inlet openings 16. The mouth end 15 denotes the end on which the user pulls for the purpose of inhalation. An air channel is provided between the mouth end 15 and the air inlet openings 16 , through which an air flow 17 can pass. If the user pulls on the end 15 of the mouth, the inhaler 10 is subjected to a negative pressure, as a result of which an air flow 17 is established in the air duct between the air inlet openings 16 and the end 15 of the mouth. The air inlet openings 16 can be arranged on the shell side of the housing 11 . Additionally or alternatively, at least one air inlet opening 16 can be provided at the end of the inhaler 10 which is opposite the mouth end 15 .

The air flow 17 passes through an evaporator unit 20 arranged in the housing 11. The evaporator unit 20 is supplied with liquid from a liquid reservoir 12 and has at least one heating element 36. The inhaler 10 comprises the liquid reservoir 12, which accommodates the liquid to be vaporized. An advantageous volume of the liquid reservoir 12 is in the range of 0.1-5 ml, preferably between 0.5-3 ml, more preferably between 0.7-2 ml or 1.5 ml. The liquid reservoir 12 preferably has a closed surface and is preferably a flexible bag. The supply of liquid results advantageously from the amount of liquid evaporated.

The evaporator unit 20 is supplied with liquid from the liquid reservoir 12 and is electrically controlled in order to vaporize the liquid and add it to the air flow 17 in the form of gas and/or aerosol. The evaporator unit 20 is arranged in an axial heating section in the housing 11 .

The amount of aerosol generated in the evaporator unit 20 can be changed both by changing the applied electrical voltage and by the number of heating elements 36 used in parallel. An electrical voltage can be applied to the heating elements 36, for example, in a pulsed, oscillating manner or by means of pulse width modulation. The characteristics of the voltage, such as amplitude and/or frequency spectrum, may be advantageously adjusted over time or by adjustment of the inhaler 10 user.

The inhaler 10 comprises an electronic unit 14 which is connected to a power source 27 and can carry out measurement, control, regulation, data processing and/or data transfer. For this purpose, the electronic unit 14 advantageously comprises an electronic control device 21, in particular a microprocessor or microcontroller. The electronic unit 14 can preferably include an interface which is set up to have data output to the user of the inhaler 10 and/or to have data input by the user of the inhaler 10 . For example, a smoker can select their preferred settings via their smartphone and Bluetooth connectivity and share them via social networks, make recommendations and statistically evaluate their data and user behavior. The data preferably includes data about the at least one heating element 36, the control frequencies, and the fill level of the liquid reservoir 12, the power source 27 and/or diagnostic and error data. It is also possible to control the control frequencies on a control element arranged on the housing 11, such as a switch or setting wheel.

The power source 27 may be a disposable electrochemical battery or a rechargeable electrochemical battery such as a lithium ion battery or a Li battery. Using a step-up converter, starting with a lithium battery with 2.7-4.1 V, for example, variable voltages adapted to the heating elements 36 up to, for example, 43 V, preferably 5-15 V, particularly preferably 2.7-15 V , more particularly preferably 3.6-6V. The power source 27 is used to supply all active electrical components in the inhaler 10 with electricity.

The inhaler 10 preferably has a modular structure and is divided into at least one consumable unit and at least one reusable unit. The evaporator unit 20 can be a replaceable cartridge or part of such a cartridge. The main body of the inhaler 10 can be reusable. The electronic unit 14 and/or the power source 27 are preferably connected to the evaporator unit 20 via an interface. The power source 27 and/or the liquid reservoir 12 can be arranged in a consumable unit and intended for disposable use or arranged in a reusable unit in the housing 11 for reusable consumption.

The evaporator unit 20 can be used in electronic cigarette products as well as medical inhalers. In addition to using in stick-shaped electronic cigarette products For example, the evaporator unit 20 can be used in electronic pipes, shishas or other products in which a liquid from a liquid reservoir 12 is to be evaporated.

figure 2 Figure 1 shows a circuit diagram for a preferred embodiment of the inhaler 10 with, for example, three heating elements 36. In other embodiments not shown, the number of heating elements 36 is more or less than three.

The inhaler 10 comprises a control and measuring device 22 which is advantageously supplied with electrical power by the electronic unit 14 through the power source 27 . The control and measuring device 22 is controlled by the electronic control device 21 . The control and measuring device 22 comprises an operational amplifier 23, a switching device 24, at least one reference resistor 25 and at least one transistor 26. Preferably, for each heating element 36 there is a reference resistor 25 (shunt) connected in series with it and a transistor 26 also connected in series with it intended. In a preferred embodiment, the electronic unit 14 comprises the operational amplifier 23, the switching device 24, the reference resistor or resistors 25 and/or the transistor or transistors 26.

The electronic control device 21 is set up to detect a puff by the consumer by means of a suitable sensor, for example by means of a pressure sensor, and consequently to activate the heating elements 36 in the evaporator unit 20 in order to heat the liquid to a suitable temperature.

The electronic control unit 21 is connected to the transistors 26 and can control them independently to control the heating elements 36 corresponding to the transistors 26 independently of each other. The electronic control device 21 is connected to the switching device 24 and the operational amplifier 23 as in FIG figure 2 shown connected to realize resistance measurements of the heating elements 36. Additional sensors for measuring temperatures, pressures and other variables for describing the operating state can be contained in the control and measurement device 22 and coupled to the electronic control device 21 .

The operational amplifier 23 (current shunt monitor) is connected to the control unit 21, a ground, a positive pole, the reference resistor 25 and the switching device 24 and is used, for example, to measure the voltage drop between one of the reference resistors 25 and the voltage source 27. An amplified measurement result the operational amplifier 23 passes this on to the control unit 21, where the data processing takes place in order to determine the measured resistance of the corresponding heating element 36.

The switching device 24 is controlled by the control unit 21 and preferably defines one of the reference resistors 25 as the reference resistor 25 to be measured. An electrical connection is preferably established with the switching device 24 between the heating element 36 and the associated reference resistor 25 . The switching device 24 preferably has a switch for each reference resistor 25 to be measured, in order to enable targeted measurement.

The reference resistors 25 (shunts) are preferably ohmic resistors. Each heating element 36 has a reference resistor 25 for current measurement.

The transistors 26 are preferably designed as field effect transistors (FET) and are used to control and regulate the heating elements 36. Each heating element 36 can be controlled via an associated transistor 26.

By using a suitable circuit, control mechanisms can also be integrated in addition to the individual activation of the heating elements 36 . In this way, the evaporator unit 20 can be monitored and controlled. Measurements can be taken when switching on, off and/or during a puff, but with the heating voltage switched off, for example every 10-1000 ms per channel, preferably 20-500 ms, particularly preferably 250 -400ms. The amount of data can be reduced by multiplexing and modulating the signals onto a carrier signal.

The current data obtained from the individual heating elements 36 correlate with their resistance. The resistance clearly correlates with the temperature of the respective heating element 36 via the known NTC or PTC behavior. In addition to monitoring the structures, resistance and temperature information can be used to control and regulate the heating elements 36 . A detailed error detection allows the detection of, for example, wrong, too little or too much liquid or a defective heating element 36; an exact state detection is possible, taking into account the thermodynamic state known during the heating process and the composition of the liquid.

Additionally, other sensors may be included in the inhaler 10, preferably thermometers, humidity and/or pressure sensors, to accurately characterize the operational status of the vaporizer 20 and/or the heating elements 36.

The heating elements 36 are preferably designed as ohmic resistors and as a microsystem-technical unit (e.g. MEMS). The design as a microsystem-technical unit is particularly advantageous because of its very fine structures in the µm range and the associated thermal properties. The microsystem-technical heating elements 36 preferably consist of a semiconductor material, for example doped silicon. This is inert and has no catalytic effect, and the heating element 36 can thus be produced in a particularly small, reproducible and stable manner. A temperature-variable resistance of, for example, 0.1-20 ohms, preferably 0.5-1.5 ohms, can be set via the doping. Depending on the doping, a temperature-dependent NTC or PTC behavior of the resistance of the heating elements 36 can be achieved, i.e. the resistance decreases or increases with increasing temperature.

The heating elements 36 are connected to the liquid reservoir 12 . For example, the liquid is conveyed capillary into a pore structure of the heating elements 36 . When the heating elements 36 are heated to a temperature above a boiling point of a component of the liquid, evaporation takes place on the surface of the heating elements 36 . The structure and surface of the heating elements 36 can, for example, also be based on bionic structures, for example tracheae. A cross-linked heater structure of the heating elements 36 can form a capillary barrier for air on one side and liquid on the other side. the Heater structures are arranged along the air/liquid interface and upon reaching a boiling temperature the vaporized liquid can pass through the heater structure and be introduced into the air flow 17 .

The heating elements 36 preferably each have a layer structure, with each heating element 36 having an area of preferably 0.25-6 mm ² , particularly preferably 0.5-3 mm ² . The area of all heating elements 36 is preferably 0.2-1 cm ² , particularly preferably 0.3-0.8 cm ² , and a preferred layer thickness is in the range of 3-400 μm in order to achieve an optimal ratio to the liquid volume to be evaporated depending on the heating area . The pores of the heater structure have, for example, a diameter of between 10-100 μm, preferably between 15-50 μm.

The design of the heating elements 36 as a microsystem-technical unit offers the possibility of influencing the amount of steam with the same average (evaporation) power applied by changing the control frequency. This enables a particularly efficient and energy-saving generation of steam by the heating elements 36. If the heating element 36 is actuated, ie heated, at a specific frequency, the proportion of the heat output brought into the evaporation increases with the same average heat output with increasing frequency up to an optimum. Thus, larger amounts of steam are to be expected at higher frequencies, since the resulting evaporation capacity increases. The optimization of the energy input also leads to reduced power consumption.

In addition to the frequency-dependent influencing of the vapor quantity, a change in the aerosol quality with the activation frequency of the heating elements 36 can also be observed. A finer droplet size distribution can be determined with increasing control frequency, i.e. the distribution of the droplet size shifts in favor of a smaller droplet size. This is due to an improved input of heat into the liquid to be vaporized with increasing frequency. A suitable pulse is used or a sufficient frequency is selected so that the heat from the heating element 36 can go into the liquid and without losses due to rapid energy input at too high a frequency (short pulse duration) or excessive cooling at too low a frequency (long pulse duration) occur. This influencing of the steam is particularly advantageous if the heating elements 36 are designed as a microsystem-technical unit and are able to follow the rapid changes in the energy input with their heating surface temperature, i.e. only have a low thermal inertia. In contrast to a helical or lattice structure, the heating elements 36 have a significantly higher limit frequency.

figure 3 shows a circuit diagram for a preferred embodiment of the inhaler 10 with, for example, a heating element 36.

The inhaler 10 includes a control and measuring device 22 which is advantageously included in the electronic unit 14 and is supplied with electrical power by the power source 27 . The control and measuring device 22 is controlled by the electronic control device 21 . The control and measuring device 22 comprises an operational amplifier 23, a switching device 24, a reference resistor 25 and a transistor 26. Preferably, for the heating element 36, there is one connected in series with it Reference resistor 25 and a transistor 26 also connected in series with it are provided. In an embodiment that is not shown, the switching device 24 can be omitted when only one heating element 36 is used, in order to enable a simpler and more cost-effective construction.

In this embodiment with only one heating element 36, the heating element 36 can be acted upon with different and changeable drive frequencies. Both a superposition of different control signals and a change and/or modulation over time are conceivable in order to achieve a desired droplet size distribution.

figure 4 shows an example of the time course of the heating voltage U _H applied to the heating element 36 . In this embodiment, the heating element 36 is heated with pulses 32 as a function of the time t. A period 33 is divided into an evaporation phase 30 and a subsequent phase 31. In the evaporation phases 30, a heating voltage U _H is applied to the heating element 36 and enables the liquid on and/or on the heating element 36 to evaporate. During the subsequent phase 31 there is preferably no heating voltage on the heating element 36 . During a period 33, an evaporation phase 30 takes place, the length of which is defined by the duty cycle. For example, different heating elements 36 can be measured sequentially during a period 33 and/or a shorter fraction of a period 33 . With a suitable period 33, several measurements, regulations, controls and/or checks can also be carried out on different heating elements 36. In a preferred embodiment, in order to control the Simplify regulation, control and/or data processing.

The heat output in the form of other alternating currents, periodic and aperiodic curves is conceivable. The superimposition of periodic signals with different frequencies or periods 33, which makes it possible to produce droplets of different sizes, is advantageous. In a preferred embodiment, the period 33 changes over the duration of operation and/or is preferably adjustable. Each heating element 36 can be heated in the same way or differently.

figure 5 FIG. 12 shows an example of the timing of the drive frequency f applied to the heating element 36. FIG. The control frequency f increases over the period of time t over the period 42. The period 42 can be given, for example, by the emptying period of the liquid reservoir 12. The broken timeline makes it clear that the emptying duration in this example should not be limited to the illustrated number of five puffs. In this example, the driving frequency f is constant over a train 40 . The heat output at the heating element 36 follows, for example, during a puff in figure 4 shown course. The individual trains 40 are interrupted by pauses 41, during which measurement, control, regulation and/or monitoring of the operating state can take place. From puff 40 to puff 40, the control frequency f increases over the course of time t and, over the course of time t, enables ever smaller droplets to be generated in order, for example, to homogenize the smoking experience and the nicotine administration. Depending on the application, other frequency profiles over time are conceivable.

Claims (13)

1. Inhaler (10), comprising an electronic control device (21) and a vaporizer unit (20) with at least one heating element (36), wherein the vaporizer unit (20) is adapted for vaporizing a liquid fed from a liquid reservoir (12) and the vaporized liquid is received by an air stream flowing through the vaporizer unit (20), wherein the electronic control device (21) is adapted for heating the at least one heating element (36) with a variable control frequency, wherein the electronic control device (21) is adapted for varying the control frequency of the at least one heating element (36) over the emptying duration of the liquid reservoir (12), characterized in that the electronic control device (21) is adapted for increasing the control frequency of the at least one heating element (36) while the liquid reservoir (12) is progressively emptied.
2. Inhaler (10)) according to claim 1, characterized in that the electronic control device (21) is adapted for heating the at least one heating element (36) with a plurality of different control frequencies.
3. Inhaler (10) according to any one of the preceding claims, characterized in that the vaporizer unit (20) has a plurality of heating elements (36), and the electronic control device (21) is adapted for heating various heating elements (36) with different control frequencies.
4. Inhaler (10) according to any one of the preceding claims, characterized in that the electronic control device (21) is adapted for varying the control frequency of the at least one heating element (36) over the course of one breath.
5. Inhaler (10) according to any one of the preceding claims, characterized in that the electronic control device (21) is adapted for setting the control frequency of the at least one heating element (36).
6. Inhaler (10) according to any one of the preceding claims, characterized in that the electronic control device (21) is adapted for setting the control frequency of the at least one heating element (36) at at least 10 Hz and preferably at most at 20 kHz.
7. Inhaler (10) according to any one of the preceding claims, characterized in that a control and measurement device (22) is provided, which is adapted for measuring the resistance of the at least one heating element (36).
8. Inhaler (10) according to claim 7, characterized in that the control and measurement device (22) is provided with at least one reference resistor (25), which is series-connected with the at least one heating element (36).
9. Inhaler (10) according to claim 7 or 8, characterized in that the control and measurement device (22) is provided with at least one operational amplifier (23).
10. Inhaler (10) according to any one of claims 7 to 9, characterized in that the control and measurement device (22) is provided with at least one switching device (24).
11. Inhaler (10) according to any one of the preceding claims, characterized in that the at least one heating element (36) is a microsystem technology unit.
12. A method for controlling an inhaler (10) having an electronic control device (21) and a vaporizer unit (20) with at least one heating element (36), wherein the vaporizer unit (20) is adapted for vaporizing a liquid fed from a liquid reservoir (12), and wherein the vaporized liquid is received by an air stream flowing through the vaporizer unit (20), wherein the electronic control device (21) heats the at least one heating element (36) with a variable control frequency, wherein the electronic control device (21) varies the control frequency of the at least one heating element (36) over the emptying duration of the liquid reservoir (12), characterized in that the electronic control device (21) increases the control frequency of the at least one heating element (36) while the liquid reservoir (12) is progressively emptied.
13. Method of claim 12, wherein a control and measurement device (22) is provided, which is adapted for measuring the resistance of the at least one heating element (36), characterized in that, based on the measured values of the control and measurement device (22), one or more of the following measures are implemented:

    - status check, monitoring and/or fault detection of the vaporizer unit (20);

    - control or regulation of the vaporizer unit (20);

    - determination of the temperature of the at least one heating element.

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