Aerosol-generating device

Abstract

The present application discloses an aerosol-generating device comprising: a heating element for heating an aerosol-forming substrate to generate an aerosol; the thermocouple comprises a first lead and a second lead; the thermocouple is in contact with the surface of the heating element; a differential signal processing circuit configured to process a differential signal between the first lead and the second lead to output a processed differential signal; the compensation circuit is electrically connected between the thermocouple and the differential signal processing circuit; the compensation circuit is configured to compensate the impedance of the first lead and / or the second lead so as to balance the impedance between the first lead and the second lead; and the control unit is configured to determine the temperature of the heating element according to the differential signal output by the differential signal processing circuit. Impedance between the two leads of the thermocouple is balanced through the compensation circuit, so that the problem of common-mode rejection ratio attenuation of the circuit is effectively avoided, and the accuracy and precision of temperature measurement data are improved.

Description

Technical Field

[0001] The present application relates to the technical field of aerosol generation, and in particular to an aerosol generating device. Background Art

[0002] As an example, there is an aerosol generating device that generates aerosol for users to inhale by heating rather than burning a solid aerosol-forming substrate, such as a cigarette stick. As another example, there is another aerosol generating device that generates aerosol for users to inhale by heating a liquid aerosol-forming substrate, such as a cigarette oil.

[0003] In the above-mentioned device, devices such as NTC, PTC and thermocouples are usually used to detect the temperature of the heating element. Compared with devices such as NTC and PTC, thermocouples are widely used due to their low price, high linearity and high consistency. Since the thermocouple is composed of two metal leads of different materials, even if the lead lengths are the same, their resistivity will be quite different. When the thermocouple is attached to the heating element for temperature measurement, it is easy to cause the common-mode voltage to reach the amplifier circuit through two leads with different resistance values, thereby causing the common-mode rejection ratio of the entire temperature measurement amplifier circuit to attenuate. In this way, when there is a common-mode voltage or the common-mode voltage changes, the common-mode voltage is easy to interfere with the output of the thermocouple differential signal, causing the output of the thermocouple amplifier circuit to include a common-mode voltage part, affecting the accuracy of the temperature measurement data, or even completely wrong temperature measurement data. This effect is particularly obvious when the resistance difference between the two leads is large and the common-mode voltage changes greatly (for example, the lead is long and the wire diameter is small). Utility Model Content

[0004] The present application provides an aerosol generating device to solve the problem that due to the difference in the resistance of thermocouple leads, the common mode rejection ratio of the temperature measurement amplifier circuit is attenuated, thereby affecting the accuracy of the temperature measurement data, or even causing the temperature measurement data to be completely wrong.

[0005] The present application provides an aerosol generating device, comprising:

[0006] a heating element for heating the aerosol-forming substrate to generate an aerosol;

[0007] a thermocouple comprising a first lead and a second lead; the thermocouple being in contact with a surface of the heating element;

[0008] A differential signal processing circuit is configured to process a differential signal between the first lead and the second lead to output a processed differential signal;

[0009] A compensation circuit electrically connected between the thermocouple and the differential signal processing circuit; the compensation circuit is configured to compensate for the impedance of the first lead and / or the second lead to balance the impedance between the first lead and the second lead;

[0010] The control unit is configured to determine the temperature of the heating element according to the differential signal output by the differential signal processing circuit.

[0011] The aerosol generating device provided above balances the impedance between the two leads of the thermocouple through a compensation circuit, thereby effectively avoiding the problem of common mode rejection ratio attenuation of the circuit and improving the accuracy and precision of the temperature measurement data. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The realization of the purpose, functional features and advantages of this application will be further described in conjunction with the embodiments and with reference to the accompanying drawings. One or more embodiments are exemplarily described by the pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the drawings in the drawings do not constitute a scale limitation.

[0013] Figure 1 is a schematic diagram of an aerosol generating device provided in an embodiment of the present application;

[0014] Figure 2 is a schematic diagram of another aerosol generating device provided in an embodiment of the present application;

[0015] Figure 3 is a schematic diagram of a heating element and a thermocouple provided in an embodiment of the present application;

[0016] Figure 4 is a circuit block diagram provided by an embodiment of the present application;

[0017] Figure 5 It is a specific circuit schematic diagram provided in an embodiment of the present application;

[0018] Figure 6 is a circuit block diagram without a compensation circuit provided in an embodiment of the present application;

[0019] Figure 7 is a schematic diagram of a differential signal processing circuit provided in an embodiment of the present application;

[0020] Figure 8 is another schematic diagram of a differential signal processing circuit provided in an embodiment of the present application;

[0021] Fig. 9 This is another schematic diagram of a differential signal processing circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0022] It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. In order to facilitate the understanding of the present application, the present application is described in more detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by technicians in the technical field of the present application. The terms used in this specification and in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. The term "and / or" used in this specification includes any and all combinations of one or more related listed items.

[0023] Figure 1 It is a schematic diagram of an aerosol generating device provided in an embodiment of the present application.

[0024] like Figure 1 As shown, the aerosol generating device includes a mouthpiece 11, a liquid storage unit 12, a liquid transfer unit 13, a heating element 14, a circuit 15, a battery cell 16, and a puff detector 17. Figure 1 In the example, the above components are formed in one piece, and the aerosol generating device is a common one-piece device. In another example, the aerosol generating device includes an atomizer, a power supply assembly detachably connected to the atomizer, the atomizer is usually also called a cigarette cartridge, and the power supply assembly is usually also called a cigarette rod; wherein the circuit 15, the battery cell 16 and the puff detector 17 are in the power supply assembly; the mouthpiece 11, the liquid storage unit 12, the liquid transfer unit 13, and the heating element 14 are in the atomizer.

[0025] The mouthpiece 11 is used for the user to inhale the aerosol generated by heating.

[0026] Liquid storage unit 12 is used to store the liquid aerosol that can generate aerosol and forms matrix.Liquid aerosol forms matrix and can be the liquid that comprises the tobacco-containing material that contains volatile tobacco flavor component, can also be the liquid that comprises non-tobacco material.For example, liquid aerosol forms matrix and can comprise water, solvent, ethanol, plant extract, spices, flavoring agent or vitamin mixture.Spice can comprise menthol, European mint, spearmint oil, various fruity fragrance components etc., but is not limited to this.Flavoring agent can comprise the composition that can provide multiple fragrance or local flavor to the user.Vitamin mixture can be for being mixed with at least a material in vitamin A, vitamin B, vitamin C and the vitamin E, but is not limited to this.In addition, liquid aerosol forms matrix and can comprise the aerosol forming agent as glycerine and propylene glycol.

[0027] The liquid transfer unit 13 can transfer the liquid aerosol-forming substrate stored in the liquid storage unit 12 to the heating element 14. For example, the liquid transfer unit 13 can be a porous material such as cotton fiber, ceramic fiber, glass fiber, or porous ceramic, porous glass, etc., but is not limited thereto. The liquid transfer unit 13 can be configured in a tubular shape, a plate shape, or other regular or irregular shapes.

[0028] The heating element 14 is a component for heating the liquid aerosol-forming substrate transferred through the liquid transfer unit 13. For example, the heating element 14 may be a metal wire, a metal plate, a ceramic heater, etc., but is not limited thereto. In addition, the heating element 14 may be composed of a conductive heating wire such as a nickel-chromium wire, and may be arranged in a structure wound around the liquid transfer unit 13. The heating element 14 may be heated by supplying an electric current, and transfers heat to the liquid aerosol-forming substrate in contact with the heating element 14 to heat the liquid aerosol-forming substrate, thereby generating an aerosol.

[0029] The circuit 15 can control the overall operation of the aerosol generating device. In detail, the circuit 15 controls not only the operation of the battery cell 16 and the heating element 14, but also the operation of other components in the aerosol generating device. In addition, the circuit 15 can determine whether the aerosol generating device can be operated by checking the status of the components of the aerosol generating device.

[0030] The circuit 15 includes at least one control unit. The control unit may include, but is not limited to, a combination of a microcontroller and a memory storing a program executable in the microcontroller, and the memory may be integrated in the microcontroller or independent of the microcontroller.

[0031] The battery cell 16 provides power for operating the aerosol generating device. For example, the battery cell 16 can provide power to heat the heating element 14, and can provide power required to operate the circuit 15. In addition, the battery cell 16 can provide power required to operate sensors, motors, etc. provided in the aerosol generating device.

[0032] The battery cell 16 may be, but is not limited to, a lithium iron phosphate (LiFePO4) battery cell. For example, the battery cell 16 may be a lithium cobalt oxide (LiCoO2) battery cell or a lithium titanate battery cell. The battery cell 16 may be a rechargeable battery cell.

[0033] The puff detector 17 is used to detect the user's puffing action and generate a corresponding electrical signal, that is, to detect whether the aerosol generating device is puffed, so that the circuit 15, such as the control unit, controls the operation of the battery 16, the heating element 14, etc. according to the electrical signal, for example, controls the battery 16 to provide power to the heating element 14, so that the heating element 14 heats the atomized liquid aerosol to form a matrix. The puff detector 17 can be a common pressure sensor, a pressure difference sensor, an airflow sensor, etc.

[0034] An air inlet is provided at a position of the aerosol generating device adjacent to the puff detector 17. When the aerosol generating device is puffed, air flows in through the air inlet, flows through the puff detector 17, the battery cell 16, the circuit 15, the heating element 14, etc., and then flows out through the nozzle 11. The dotted arrow in the figure roughly shows the airflow path.

[0035] It should be noted that Figure 1 Only the components related to this embodiment are shown. A person skilled in the art will appreciate that the aerosol generating device may also include Figure 1 Other common components other than those shown.

[0036] Figure 2 It is a schematic diagram of an aerosol generating device provided in an embodiment of the present application.

[0037] like Figure 2 As shown, the aerosol generating device comprises:

[0038] a chamber A in which an aerosol-generating article B is removably received;

[0039] The aerosol-generating product B preferably uses a solid aerosol-forming matrix, which may include one or more of powders, particles, fragments, strips or flakes of one or more of vanilla leaves, tobacco leaves, homogenized tobacco, and expanded tobacco; alternatively, the solid aerosol-forming matrix may contain additional tobacco or non-tobacco volatile flavor compounds to be released when the matrix is ​​heated.

[0040] The heating element 14 can be inserted into the aerosol generating product B to heat the aerosol generating product B when the aerosol generating product B is received in the chamber A to generate aerosol.

[0041] It should be noted that the heating method of the heating element 14 includes but is not limited to resistance heating, electromagnetic heating, infrared heating, and air heating. The shape of the heating element 14 includes but is not limited to needle-shaped, pin-shaped, or thin sheet-shaped.

[0042] It should also be noted that Figure 2 Different from the examples, in other examples, the heating element 14 is configured to heat around at least a portion of the aerosol generating article B, which is commonly known as circumferential heating or peripheral heating, etc., which is also feasible.

[0043] The battery cell 16 is used for supplying power; the battery cell 16 may be a rechargeable battery cell or a disposable battery cell.

[0044] The circuit 15 is used to control the aerosol generating device; for example, the circuit 15 controls the battery cell 16 to provide power to the heating element 14 .

[0045] The circuit 15 comprises a control unit. The control unit is a hardware component that controls the overall operation of the aerosol generating device. The control unit may be implemented as an array of multiple logic gates, or may be implemented as a combination of a microcontroller and a memory in which a program executable in the microcontroller is stored. It will be appreciated by those skilled in the art that the control unit may be implemented in other forms of hardware.

[0046] exist Figure 1-Figure 2 In the example, a temperature detection element is usually also provided to detect the temperature of components such as heating elements and battery cells. It can also be used to detect the ambient temperature of the aforementioned components or the aerosol generating device, so as to facilitate the control unit to control the aerosol generating device. In this example, the temperature detection element includes a thermocouple made of two metal leads of different materials (shown as the first lead 181 and the second lead 182 in the figure). For example, the first lead 181 of the thermocouple is a nickel-chromium material, and the second lead 182 of the thermocouple is a nickel-silicon material. It can be understood that the specific material is not limited to the above situation.

[0047] like Figure 3 A heating element is shown, the heating element comprises a heating tube, the outer surface of the heating tube is coated with an infrared electric heating coating and an electrode, and the aerosol generating product B can be inserted into the heating tube. A thermocouple 18 is arranged on the outer surface of the heating tube, so as to detect the temperature of the infrared heating element. The control unit controls the amount of electricity provided to the infrared heating element by the battery cell 16 according to the temperature information fed back by the thermocouple 18, so as to control the heating temperature of the infrared heating element. Among them, the surface of the thermocouple 18 is not insulated and / or the surface of the heating element in contact with the thermocouple 18 is not insulated, for example, the outer surface of the thermocouple 18 is not coated with an insulating layer, or is not electrically insulated from the heating element by other insulating components.

[0048] Based on the above aerosol generating device, such as Figure 4 As shown, in one example, the circuit 15 includes a control unit 151, a compensation circuit 152, and a differential signal processing circuit 153.

[0049] The differential signal processing circuit 153 is configured to process the differential signal between the first lead 181 and the second lead 182 to output the processed differential signal;

[0050] The compensation circuit 152 is electrically connected between the thermocouple 18 and the differential signal processing circuit 153; the compensation circuit 152 is configured to compensate for the impedance of the first lead 181 and / or the second lead 182 to balance the impedance between the first lead 181 and the second lead 182;

[0051] The control unit 151 is configured to determine the temperature of the heating element 14 according to the differential signal output by the differential signal processing circuit 153 .

[0052] like Figure 5 As shown, in one example, the differential signal processing circuit 153 includes a differential amplifier circuit, which is configured to amplify the differential signal between the first lead 181 and the second lead 182 to output the amplified differential signal.

[0053] Specifically, the differential amplifier circuit includes an operational amplifier U1, a first gain resistor Rg1, a second gain resistor Rg2, a first feedback resistor Rf1 and a second feedback resistor Rf2;

[0054] One end of the first gain resistor Rg1 is electrically connected to the first lead 181, and the other end of the first gain resistor Rg1 is electrically connected to the non-inverting input terminal of the operational amplifier U1; one end of the second gain resistor Rg2 is electrically connected to the second lead 182, and the other end of the second gain resistor Rg2 is electrically connected to the inverting input terminal of the operational amplifier U1; one end of the first feedback resistor Rf1 is electrically connected to the non-inverting input terminal of the operational amplifier U1, and the other end of the first feedback resistor Rf1 is grounded; one end of the second feedback resistor Rf2 is electrically connected to the inverting input terminal of the operational amplifier U1, and the other end of the second feedback resistor Rf2 is electrically connected to the output terminal of the operational amplifier U1. The positive power supply terminal of the operational amplifier U1 is electrically connected to the power supply VDD, and the negative power supply terminal of the operational amplifier U1 is grounded.

[0055] The common mode rejection ratio of the differential amplifier circuit is greater than or equal to 80 dB, for example, the common mode rejection ratio is selected to be greater than 100 dB.

[0056] The compensation circuit 152 includes a first compensation resistor R1 and a second compensation resistor R2. The first compensation resistor R1 is electrically connected between the first lead 181 and the in-phase input terminal of the operational amplifier U1 (or the first gain resistor Rg1), and the second compensation resistor R2 is electrically connected between the second lead 182 and the inverting input terminal of the operational amplifier U1 (or the second gain resistor Rg2).

[0057] The following combination Figure 6 For comparison:

[0058] exist Figure 6 No compensation circuit 152 is provided. Figure 5 or Figure 6In the formula, RP represents the equivalent resistance of the first lead 181 of the thermocouple 18, and RN represents the equivalent resistance of the second lead 182 of the thermocouple 18. Since the first lead 181 and the second lead 182 of the thermocouple 18 are made of two different metal materials, the resistivity ρ of the first lead 181 and the second lead 182 are different. It can be seen that even if the lead length L and the cross-sectional area s are the same, the resistance values ​​of the first lead 181 and the second lead 182 of the thermocouple 18 will be different. In particular, the longer the lead length L and the smaller the lead cross-sectional area s, the greater the resistance difference between the first lead 181 and the second lead 182 of the thermocouple 18. If there is electrical insulation between the thermocouple 18 and the heating element 14, the resistance difference between the first lead 181 and the second lead 182 of the thermocouple 18 can be ignored and does not affect the temperature measurement accuracy.

[0059] Taking the K-type thermocouple as an example, its positive lead is made of nickel-chromium material. Looking up relevant data shows that the resistivity is ρ = 70.6μΩ*cm; the negative lead is made of nickel-silicon material, with a resistivity of ρ = 29.4μΩ*cm. Assuming that the length L of the positive and negative leads of the thermocouple is 1000mm and the wire diameter (radius) is 0.05mm, it can be calculated that the equivalent resistance RP of the positive lead is about 90Ω, and the equivalent resistance RN of the negative lead is about 37.5Ω, and the resistance difference between the positive and negative leads is close to 53Ω. When the thermocouple leads are longer or the wire diameter is smaller, the resistance difference between the positive and negative leads will be greater, which seriously affects the ability of the differential amplifier circuit of the thermocouple to suppress common-mode voltage.

[0060] For thermocouples, what needs to be amplified is its differential signal, and what needs to be suppressed is its common-mode signal. The operational amplifier U1 used in the differential amplifier circuit generally has a low input impedance and is easily affected by the impedance of the peripheral input source. As mentioned above, operational amplifier U1 generally uses an operational amplifier with a relatively high common-mode rejection ratio, for example, a common-mode rejection ratio of 100dB. If the equivalent resistances RP and RN of the thermocouple 18 leads are ignored, the following formula (1) can be obtained:

[0061]

[0062] Ideally, the resistance of the first gain resistor Rg1 is the same as the resistance of the second gain resistor Rg2, and the resistance of the first feedback resistor Rf1 is the same as the resistance of the second feedback resistor Rf2. In fact, there will be some errors in the resistance of the above four resistors, but chip manufacturers will use special methods to basically ensure that Rg1 = Rg2, Rf1 = Rf2. Therefore, the above formula (1) can be simplified to:

[0063]

[0064] That is, the output voltage Vout is only related to the differential voltage V1-V2 of the thermocouple and has nothing to do with the common-mode voltage. Therefore, the common-mode rejection ratio of the circuit is 100dB, which is the common-mode rejection ratio of the operational amplifier U1 itself.

[0065] However, if the equivalent resistance of the thermocouple leads is considered, for example, the resistance difference between the positive and negative leads (or the first lead 181 and the second lead 182) is large, then Rg1 and Rg2 in the above formula (1) need to be replaced by Rg1+RP, Rg2+RN, and the following formula (2) is obtained:

[0066]

[0067] Since the formula is complicated, k is used instead. Then the above formula (2) can be simplified and written as the following formula (3):

[0068]

[0069] in, is the common mode gain Ac, is the differential mode gain Ad, according to the common mode rejection ratio formula (4):

[0070]

[0071] Assume Rg1=Rg2=1000kΩ, Rf1=Rf2=10kΩ, RP=90Ω, RN=37.5Ω, and substitute into formula (3) and (4), we get formula (5):

[0072]

[0073] That is, the CMRR at this time is 85.7dB, that is, due to the introduction of the equivalent resistance of the thermocouple lead, the circuit common mode rejection ratio has dropped by about 15dB from the original 100dB. This can easily cause the circuit output to be subject to greater common mode interference, which can affect the accuracy at a minor level and cause the output voltage measurement to be completely wrong at a serious level.

[0074] After the impedance between the first lead 181 and the second lead 182 is balanced by the compensation circuit 152, for example Figure 5 The compensation resistors R1 and R2 shown in the figure make R1+RP=R2+RN. Thus, the input impedance is balanced, and k in the above formula (3) is calculated to be 1. From formula (5), it can be seen that the common mode rejection ratio CMRR is ∞, so the common mode rejection ratio of the circuit is completely dependent on the common mode rejection ratio of the operational amplifier U1 itself, and has nothing to do with the input thermocouple loop.

[0075] Please refer to Figure 4As shown, in one example, a common mode signal detection circuit 154 is also included which is electrically connected between the compensation circuit 152 and the differential signal processing circuit 153, and the common mode signal detection circuit 154 is configured to detect a common mode signal between the first lead 181 and the second lead 182;

[0076] The control unit 151 is further configured to determine the temperature of the heating element 14 according to the differential signal output by the differential signal processing circuit 153 and the common mode signal detected by the common mode signal detection circuit 154 .

[0077] Specifically, the control unit 151 is configured to determine the error value corresponding to the differential signal output by the differential signal processing circuit 153 based on the common mode signal detected by the common mode signal detection circuit 154; after adding the error value to the differential signal output by the differential signal processing circuit 153, the temperature of the heating element 14 is determined.

[0078] like Figure 5 As shown, the common mode signal detection circuit is composed of a resistor R3, a resistor R4 and a resistor R5. Among them, one end of the resistor R5 is electrically connected between the first compensation resistor R1 and the in-phase input terminal of the operational amplifier U1 (or the first gain resistor Rg1), and the other end of the resistor R5 is grounded. One end of the resistor R3 is electrically connected between the second compensation resistor R2 and the inverting input terminal of the operational amplifier U1 (or the second gain resistor Rg2), and the other end of the resistor R3 is electrically connected to one end of the resistor R4, and the other end of the resistor R4 is grounded. The connection point between the resistor R3 and the resistor R4 is electrically connected to the control unit 151.

[0079] It should be noted that the sum of the resistance values ​​of resistor R3 and resistor R4 needs to be the same as the resistance value of resistor R5, so as not to introduce a new input impedance imbalance problem. In addition, the sum of the resistance values ​​of resistor R3 and resistor R4 needs to be relatively large, for example, above 1MΩ, so as to have a relatively small impact on the input impedance of the differential signal processing circuit 153. Generally, resistor R3 is set to a relatively large resistance value, and resistor R4 can be set to a relatively small resistance value, so that the ADC input impedance of the control unit 151 is relatively low, and the input impedance value of the ADC is approximately equal to the resistance value of the resistor R3 and the resistor R4 connected in parallel.

[0080] Based on the common-mode signal detection circuit 154, thermocouples of different lengths, wire diameters or materials can be flexibly used to achieve temperature measurement of the heating element 14. Specifically, the control unit 151 can sample the voltage division value of the resistor R3 and the resistor R4, and then obtain the common-mode voltage of the thermocouple. When the heating element 14 is not heated, for example, the control unit 151 controls the switch tube SW1 to be disconnected, that is, when there is no common-mode voltage, the differential signal processing circuit 153 outputs Vout1. Thereafter, a reference common-mode voltage VCM (for example, 10V) is given to the heating element 14, and the output is Vout2 after passing through the differential signal processing circuit 153. Since the temperature of Vout1 and Vout2 is the same, but it represents the voltage signal of the same temperature when there is no common-mode voltage and when there is a common-mode voltage, Vout1-Vout2 can represent the error at VCM (for example, equal to 10V). The subsequent control unit 151 also reads the voltage division signal of R3 and R4 at the output signal of the differential signal processing circuit 153, and the error caused by the common-mode signal can be corrected.

[0081] In a specific implementation, the error value Verr = Vout2 - Vout1, which can be determined by the above formula (3):

[0082]

[0083] in,

[0084] When the heating element 14 is working, the error voltage Verr = b*VCM can be obtained by measuring the actual VCM through the resistors R3 and R4. Then, the voltage Vout output by the differential signal processing circuit 153 is added to Verr to obtain the voltage signal corresponding to the actual temperature.

[0085] When calculating the temperature of a heating element through a voltage signal, it is also necessary to derive the differential voltage signal VIN (i.e., V1-V2) of the thermocouple after obtaining the voltage signal corresponding to the actual temperature. When the resistance of the thermocouple lead is small, Vout = (Rf2 / Rg2) * VIN can be used for derivation; if the resistance of the thermocouple lead is large, it is still necessary to measure the resistance of the thermocouple lead, write it into the software, and substitute it into the above formula (3) to calculate the thermocouple differential voltage signal VIN = V1-V2.

[0086] As mentioned above, when the thermocouple 18 is used for temperature measurement, the thermocouple 18 needs to be attached to the heating element 14. However, the heating element 14 is made of a conductive material, and the thermocouple 18 is also composed of two conductive metal leads. If the thermocouple 18 is directly attached to the heating element 14, the voltage provided to the heating element 14 is easily connected to the thermocouple. Generally, the voltage provided to the heating element 14 is above 5V, or even tens of volts, while the voltage signal converted by the thermocouple 18 is below tens of millivolts. Therefore, if the small voltage signal of the thermocouple 18 is connected to the high voltage signal of the heating element 14, the actual temperature signal cannot be measured, and even the components of the temperature measurement circuit may be damaged.

[0087] like Figure 7 As shown, in one example, the differential signal processing circuit 153 further includes a common mode signal suppression circuit 153 a , and the common mode signal suppression circuit 153 a is configured to suppress the common mode signal between the first lead 181 and the second lead 182 .

[0088] Specifically, the common-mode signal suppression circuit 153a includes a first voltage-dividing circuit and a second voltage-dividing circuit; the first voltage-dividing circuit is composed of a resistor R6 and a resistor R7, and the second voltage-dividing circuit is composed of a resistor R8 and a resistor R9.

[0089] One end of the first voltage divider circuit is electrically connected to the first lead 181, the other end of the first voltage divider circuit is grounded, and the voltage divider output end of the first voltage divider circuit (the connection point of the resistor R6 and the resistor R7 in the figure) is electrically connected to the differential amplifier circuit (the first gain resistor Rg1 in the figure);

[0090] One end of the second voltage divider circuit is electrically connected to the second lead 182, the other end of the second voltage divider circuit is grounded, and the voltage divider output end of the second voltage divider circuit (the connection point between resistor R8 and resistor R9 in the figure) is electrically connected to the differential amplifier circuit (the second gain resistor Rg2 in the figure).

[0091] The high common mode voltage on the thermocouple can be reduced by the common mode signal suppression circuit 153a. If the parameter values ​​of R6 to R9 are set reasonably, the common mode voltage below 15V can be reduced to below 3V. By using an ordinary operational amplifier U1 with a working power supply voltage of 3V, the differential voltage on the thermocouple can be accurately measured, avoiding damage to the components of the temperature measurement circuit. It can be understood that by adjusting the parameter values ​​of R6 to R9, a higher common mode voltage can be filtered out.

[0092] The figure also shows a filter circuit 153b, which is composed of a resistor R10 and a capacitor C1. The filter circuit 153b is used to filter the differential signal output by the differential amplifier circuit to obtain a smoother differential signal.

[0093] It should be noted that Figure 7 The compensation circuit 152 and the common mode signal detection circuit 154 are not shown in the figure, and can be understood by referring to the above content. It should also be noted that: Figure 7 In the differential signal processing circuit 153, the other end of the first feedback resistor Rf1 is connected to the reference voltage J1. In practice, different reference voltages J1 can be set according to the temperature measurement range, so that the output voltage VOUT fluctuates around the reference voltage J1. Generally, the reference voltage J1 is 0V. Figure 5 similar.

[0094] like Figure 8 As shown, in one example, the differential signal processing circuit 153 includes a current detection amplifier U2, which is configured to amplify the differential signal between the first lead 181 and the second lead 182 to output the amplified differential signal.

[0095] Specifically, the current detection amplifier U2 includes a first input terminal IN+, a second input terminal IN- and an output terminal OUT;

[0096] The first input terminal IN+ is electrically connected to the first lead 181 , the second input terminal IN− is electrically connected to the second lead 182 , and the output terminal OUT is used to output the differential signal after amplification.

[0097] It should be noted that the current detection amplifier U2 has the characteristics of being able to filter out common-mode voltages up to tens of volts and amplify differential-mode voltages. The current detection amplifier U2 can use chips commonly found on the market, such as the INA199 current detection amplifier, whose amplification factor can be between 50 and 200, specifically 100 times. When selecting the current detection amplifier U2, a current detection amplifier with a smaller low offset voltage (VOS), a larger high common-mode rejection ratio (CMRR), and a wider common-mode operating voltage range should be selected. The reference voltage J1 and the filter circuit 153b in the figure can be referred to Figure 7 and its description.

[0098] It should also be noted that Figure 7 akin, Figure 8 The compensation circuit 152 and the common mode signal detection circuit 154 are not shown in the figure, and can be understood by referring to the above content.

[0099] like Fig. 9 As shown, in one example, the differential signal processing circuit 153 includes a signal attenuation circuit 1531 and a proportional amplification circuit 1532;

[0100] The signal attenuation circuit 1531 is configured to attenuate the differential signal between the first lead 181 and the second lead 182 to output the attenuated differential signal;

[0101] The proportional amplifier circuit 1532 is configured to amplify the differential signal output by the signal attenuation circuit 1531 to output the amplified differential signal.

[0102] It can be understood that the signal attenuation circuit 1531 is also configured to attenuate the common mode signal between the first lead 181 and the second lead 182 .

[0103] Specifically, the signal attenuation circuit 1531 includes an operational amplifier U3, a first gain resistor R11, a second gain resistor R12, a first feedback resistor R13, and a second feedback resistor R14;

[0104] One end of the first gain resistor R11 is electrically connected to the first lead 181, and the other end of the first gain resistor R11 is electrically connected to the non-inverting input terminal of the operational amplifier U3; one end of the second gain resistor R12 is electrically connected to the second lead 182, and the other end of the second gain resistor R12 is electrically connected to the inverting input terminal of the operational amplifier U3; one end of the first feedback resistor R13 is electrically connected to the non-inverting input terminal of the operational amplifier U3, and the other end of the first feedback resistor R13 is grounded; one end of the second feedback resistor R14 is electrically connected to the inverting input terminal of the operational amplifier U3, and the other end of the second feedback resistor R14 is electrically connected to the output terminal of the operational amplifier U3. The positive power supply terminal of the operational amplifier U3 is electrically connected to the power supply VDD, and the negative power supply terminal of the operational amplifier U3 is grounded.

[0105] From the above, it can be seen that the signal attenuation circuit 1531 and Figure 5 The circuit structure of the differential amplifier circuit is similar, except that the common mode signal and the differential signal between the first lead 181 and the second lead 182 are attenuated by setting different parameters such as the first gain resistor R11, the second gain resistor R12, the first feedback resistor R13 and the second feedback resistor R14.

[0106] The proportional amplifier circuit 1532 in the figure adopts a common-phase proportional amplifier circuit, including an operational amplifier U4, a resistor R15, a resistor R16, a resistor R17 and a capacitor C2.

[0107] One end of resistor R15 is electrically connected to the output terminal of operational amplifier U3, and the other end of resistor R15 is electrically connected to the non-inverting input terminal of operational amplifier U4; one end of resistor R16 is grounded, and the other end of resistor R16 is electrically connected to the inverting input terminal of operational amplifier U4; one end of resistor R17 is electrically connected to the inverting input terminal of operational amplifier U4, and the other end of resistor R17 is electrically connected to the output terminal of operational amplifier U4; one end of capacitor C2 is electrically connected to the non-inverting input terminal of operational amplifier U4, and the other end of capacitor C2 is grounded.

[0108] The high common-mode voltage signal and differential signal are attenuated by the signal attenuation circuit 1531 of the previous stage, and the differential signal is amplified in the next stage. For example, if the attenuation coefficient of the signal attenuation circuit 1531 is set to 1 / 4 (R14 / R12), the common-mode voltage of VCC below 12V can be attenuated to below 3V, which is within the normal working voltage range of the operational amplifier U3. When VCC is higher than 12V, it is necessary to adjust the resistance values ​​of several resistors such as R11, R12, R13, and R14 to obtain a higher attenuation coefficient. Since the previous stage circuit attenuates the differential voltage of the thermocouple by 1 / 4, the next stage needs to be amplified 400 times, and the overall circuit amplifies the thermocouple signal by 100 times.

[0109] It is understandable that the above attenuation coefficient and amplification factor can be adjusted according to actual needs. Figure 7 akin, Fig. 9 The compensation circuit 152 and the common mode signal detection circuit 154 are not shown in the figure, and can be understood by referring to the above content.

[0110] It should be noted that the preferred embodiments of the present application are given in the specification and drawings of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described in the specification. These embodiments are not used as additional limitations on the content of the present application. The purpose of providing these embodiments is to make the understanding of the disclosure of the present application more thorough and comprehensive. In addition, the above-mentioned technical features continue to be combined with each other to form various embodiments not listed above, which are all regarded as the scope of the description of the present application; further, for ordinary technicians in this field, they can be improved or transformed according to the above description, and all these improvements and transformations should belong to the scope of protection of the claims attached to the present application.

Claims

1. An aerosol generating device, characterized in that: include: a heating element for heating the aerosol-forming substrate to generate an aerosol; a thermocouple comprising a first lead and a second lead; the thermocouple being in contact with a surface of the heating element; A differential signal processing circuit is configured to process a differential signal between the first lead and the second lead to output a processed differential signal; A compensation circuit electrically connected between the thermocouple and the differential signal processing circuit; the compensation circuit is configured to compensate for the impedance of the first lead and / or the second lead to balance the impedance between the first lead and the second lead; The control unit is configured to determine the temperature of the heating element according to the differential signal output by the differential signal processing circuit.

2. The aerosol generating device according to claim 1, characterized in that: The differential signal processing circuit includes a first input terminal electrically connected to the first lead, a second input terminal electrically connected to the second lead, and an output terminal for outputting the amplified differential signal; The compensation circuit includes a first compensation resistor and a second compensation resistor, wherein the first compensation resistor is electrically connected between the first lead and the first input terminal, and the second compensation resistor is electrically connected between the second lead and the second input terminal.

3. The aerosol generating device according to claim 1, characterized in that: Also included is a common mode signal detection circuit electrically connected between the compensation circuit and the differential signal processing circuit, the common mode signal detection circuit being configured to detect a common mode signal between the first lead and the second lead; The control unit is further configured to determine the temperature of the heating element according to the differential signal output by the differential signal processing circuit and the common mode signal detected by the common mode signal detection circuit.

4. The aerosol generating device according to claim 3, characterized in that: The control unit is configured to determine an error value corresponding to the differential signal output by the differential signal processing circuit based on the common mode signal detected by the common mode signal detection circuit; and determine the temperature of the heating element after adding the error value to the differential signal output by the differential signal processing circuit.

5. The aerosol generating device according to claim 1, characterized in that: The surface of the thermocouple is not insulated; and / or the surface of the heating element in contact with the thermocouple is not insulated.

6. The aerosol generating device according to claim 1, characterized in that: The differential signal processing circuit includes a differential amplifier circuit configured to amplify a differential signal between the first lead and the second lead to output the amplified differential signal.

7. The aerosol generating device according to claim 6, characterized in that: The common mode rejection ratio of the differential amplifier circuit is greater than or equal to 80 dB.

8. The aerosol generating device according to claim 6, characterized in that: The differential amplifier circuit includes an operational amplifier, a first gain resistor, a second gain resistor, a first feedback resistor and a second feedback resistor; One end of the first gain resistor is electrically connected to the first lead, and the other end of the first gain resistor is electrically connected to the non-inverting input terminal of the operational amplifier; One end of the second gain resistor is electrically connected to the second lead, and the other end of the second gain resistor is electrically connected to the inverting input terminal of the operational amplifier; One end of the first feedback resistor is electrically connected to the non-inverting input terminal of the operational amplifier, and the other end of the first feedback resistor is grounded; one end of the second feedback resistor is electrically connected to the inverting input terminal of the operational amplifier, and the other end of the second feedback resistor is electrically connected to the output terminal of the operational amplifier.

9. The aerosol generating device according to claim 6, characterized in that: The differential signal processing circuit further includes a common mode signal suppression circuit configured to suppress a common mode signal between the first lead and the second lead.

10. The aerosol generating device according to claim 9, characterized in that The common mode signal suppression circuit comprises a first voltage divider circuit and a second voltage divider circuit; One end of the first voltage divider circuit is electrically connected to the first lead, the other end of the first voltage divider circuit is grounded, and the voltage divider output end of the first voltage divider circuit is electrically connected to the differential amplifier circuit; One end of the second voltage divider circuit is electrically connected to the second lead, the other end of the second voltage divider circuit is grounded, and a voltage divider output end of the second voltage divider circuit is electrically connected to the differential amplifier circuit.

11. The aerosol generating device according to claim 1, characterized in that: The differential signal processing circuit includes a current detection amplifier configured to amplify a differential signal between the first lead and the second lead to output the amplified differential signal.

12. The aerosol generating device according to claim 11, characterized in that The current detection amplifier comprises a first input terminal, a second input terminal and an output terminal; The first input end is electrically connected to the first lead, the second input end is electrically connected to the second lead, and the output end is used to output the differential signal after amplification.

13. The aerosol generating device according to claim 1, characterized in that: The differential signal processing circuit includes a signal attenuation circuit and a proportional amplification circuit; The signal attenuation circuit is configured to attenuate the differential signal between the first lead and the second lead to output the attenuated differential signal; The proportional amplifier circuit is configured to amplify the differential signal output by the signal attenuation circuit to output an amplified differential signal.

14. The aerosol generating device according to claim 13, characterized in that: The signal attenuation circuit is further configured to attenuate a common mode signal between the first lead and the second lead.

Images