A surface acoustic wave driving control circuit and an electronic cigarette

Abstract

This invention discloses a surface acoustic wave (SAW) driving control circuit, comprising: a DC power supply circuit module (1), a microcontroller module (2), a high-frequency pulse generation circuit module (3), a bandpass filter circuit module (4), an adjustable switching power supply circuit module (5), a drive amplifier circuit module (6), a resonant network (7), an impedance matching network (8), a transmission line transformer coupler module (9), and a SAW atomizing chip (10). This invention also discloses an electronic cigarette incorporating the aforementioned SAW driving control circuit. The SAW driving control circuit of this invention exhibits high output frequency and power stability; when used in electronic cigarettes, it results in high smoke concentration and small smoke particle size.

Description

Technical Field

[0001] This invention relates to the field of electronic cigarettes, and more specifically to a surface acoustic wave (SAW) driving control circuit and an electronic cigarette containing the SAW driving control circuit. Background Technology

[0002] Electronic cigarettes, as a new type of low-harm alternative to traditional cigarettes, are increasingly favored by consumers. Currently, electronic cigarette atomization technology is mainly divided into three categories: The first is electrothermal atomization electronic cigarettes, which primarily use a battery to power a resistance wire made of nickel-chromium alloy, stainless steel alloy, or titanium alloy, causing the wire to heat up. This heat then conducts heat to the e-liquid, forming vapor for the user to inhale. This method has high conversion efficiency in driving the control circuit, but the resistance wire can continuously heat up to 500-600℃, causing the e-liquid to decompose at high temperatures and release harmful components such as aldehydes, posing both safety and health risks and affecting the user's vaping experience. The second type is ultrasonic atomization electronic cigarettes, which use an ultrasonic transducer to convert electrical energy into vibrational mechanical energy with a frequency of approximately kHz-3MHz, causing cavitation of the e-liquid film on the transducer surface, thus forming vapor. This method suffers from low e-liquid atomization efficiency and difficulty in refining vapor particle size due to the unconcentrated ultrasonic energy and low vibration frequency. The third type is surface acoustic wave (SAW) atomized e-cigarettes. Its principle is to convert electrical energy into high-frequency vibrational mechanical energy (frequency up to 20MHz and above) propagating along the surface of a piezoelectric material. The SAW waves generate a strong acoustic microfluidic effect with the e-liquid on the piezoelectric substrate surface, further exciting surface capillary waves. Under the ultra-high frequency oscillation of the surface capillary waves, the e-liquid forms smoke. The smoke particles produced by this method can reach the nanometer scale. The e-liquid does not directly contact the interdigital transducer, belonging to non-contact low-temperature atomization technology, and is currently the most promising e-cigarette atomization technology. The applicant first designed a surface acoustic wave e-cigarette system in 2018, as shown in Chinese Patent ZL201810076941.1.

[0003] Surface acoustic wave (SAW) atomizing e-cigarettes have significant advantages over heating and ultrasonic atomizing e-cigarettes. However, a key factor hindering the rapid industrialization of this technology lies in the low energy conversion efficiency of the ultra-high frequency drive control circuit. In existing technologies, most of the power is converted into heat, causing a significant increase in the temperature of the control circuit, leading to greater power dissipation and a higher probability of power device burnout. Consequently, the power output to the SAW atomizing chip decreases, gradually deteriorating the chip's performance and resulting in increasingly lower vapor concentration, directly impacting the user's vaping experience.

[0004] The present invention is proposed to solve the above problems. Summary of the Invention

[0005] The purpose of this invention is to address the problems of low energy conversion efficiency, low output power, poor power and frequency stability, and large overall size in existing ultra-high frequency surface acoustic wave (SAW) electronic cigarette drive control circuits. This invention provides a SAW electronic cigarette drive control circuit and the corresponding electronic cigarette. The SAW drive control circuit of this invention features high energy conversion efficiency, high output power, high power and frequency stability, low noise figure, compact size, low cost, and long lifespan. Electronic cigarettes using this circuit have low power consumption, low board temperature, are safe, stable, reliable, produce high smoke concentration, small smoke particle size, excellent inhalation experience, and are portable and compact.

[0006] The technical solution of the present invention is as follows:

[0007] The first aspect of the present invention discloses a surface acoustic wave (SAW) driving control circuit, characterized in that it comprises: a DC power supply circuit module 1, a microcontroller unit (MCU) module 2, a high-frequency pulse generation circuit module 3, a bandpass filter circuit module 4, an adjustable switching power supply circuit module 5, a drive amplifier circuit module 6, a resonant network 7, an impedance matching network 8, a transmission line transformer coupler module 9, and a SAW atomizing chip 10.

[0008] Preferably, the output terminal of the DC power supply circuit module 1 is electrically connected to the microcontroller module 2; the output terminal of the microcontroller module 2 is electrically connected to the control terminal of the high-frequency pulse generation circuit module 3 and the adjustable switching power supply circuit module 5; the output terminal of the high-frequency pulse generation circuit module 3 is electrically connected to the input terminal of the bandpass filter circuit module 4; the output terminals of the bandpass filter circuit module 4 and the adjustable switching power supply circuit module 5 are electrically connected to the input terminal of the drive amplifier circuit module 6; the output terminal of the drive amplifier circuit module 6 is electrically connected to the input terminal of the resonant network 7; the output terminal of the resonant network 7 is electrically connected to the input terminal of the impedance matching network 8; the output terminal of the impedance matching network 8 is electrically connected to the input terminal of the transmission line transformer coupler module 9; the feedback terminal of the transmission line transformer coupler module 9 is electrically connected to the signal acquisition terminal of the microcontroller module 2; and the output terminal of the transmission line transformer coupler module 9 is electrically connected to the surface acoustic wave atomizing chip 10 via a coaxial cable. With the above structure, the DC power supply circuit module 1 provides power signals to the microcontroller module 2 and the high-frequency pulse generation circuit module 3. The microcontroller module 2 controls the high-frequency pulse generation circuit module 3 to generate a high-frequency pulse signal with the same frequency as the characteristic response frequency of the surface acoustic wave (SAW) atomizing chip 10. The generated high-frequency pulse signal passes through the bandpass filter circuit module 4 to remove interference signals and obtain a pure sine wave signal. At the same time, the microcontroller module 2 controls the adjustable switching power supply circuit module 5 to amplify the sine wave signal from the input drive amplifier circuit module 6. The amplified signal passes through the impedance matching network 8 to achieve impedance matching with the load. The impedance-matched signal is synthesized into a complete radio frequency (RF) signal through the transmission line transformer coupler module 9. The RF signal is used to provide a high-frequency, high-voltage excitation signal for the SAW atomizing chip 10. The SAW atomizing chip 10 is used to excite and generate a surface acoustic wave vibration elastic wave signal that can atomize the e-liquid into smoke.

[0009] Preferably, the DC power supply circuit module 1 provides power signals to other circuit modules after the DC power supply is filtered by a capacitor and regulated by a voltage regulator; further, the DC power supply is preferably a 12V DC rechargeable battery.

[0010] Preferably, the high-frequency pulse generation circuit module 3 uses a direct digital synthesizer (DDS) to generate radio frequency signals, which has high frequency stability and fully meets the requirements of the power amplifier switch.

[0011] Preferably, the bandpass filter circuit module 4 adopts a multi-level feedback (MFB) active second-order bandpass filter with multiple negative feedback.

[0012] Preferably, the drive amplifier circuit module 6 adopts a Class D power amplifier, which consists of four metal-oxide-semiconductor field-effect transistors (MOSFETs) connected in parallel to form a push-pull resonant circuit. The signal processed by the bandpass filter circuit module 4 passes through the high-frequency transformer T1, which causes the two sets of parallel transistors to receive reverse excitation voltage and conduct alternately.

[0013] Preferably, the adjustable switching power supply circuit module 5 is provided with an adjustable resistor for each of the four MOSFET transistors in the drive amplifier circuit module 6, so as to adjust the bias voltage of each transistor to ensure that the final output of each transistor is the same and to keep the whole system stable.

[0014] Preferably, a cement resistor is connected in parallel between the drain and source of each of the four MOSFET transistors, which can effectively balance the power dissipation of the transistors. When a transistor burns out, the corresponding drain and gate will conduct, the drain voltage will be fed back to the gate, and the diode will be reverse-biased and cut off, thereby achieving the purpose of protecting the voltage regulator circuit.

[0015] Preferably, the output power of the two sets of parallel transistors is first impedance matched and then coupled to ensure the independence of each transistor, avoid output differences caused by individual differences of transistors, increase power supply stability, and make power synthesis easier by having each set of transistors output a standard sine wave signal before coupling.

[0016] Preferably, the two sets of power amplified signals output by the drive amplifier circuit module 6 are coupled into a complete radio frequency signal using a transmission line transformer. The transmission line transformer coupler module 9 has both transformer performance and transmission line characteristics, and has the advantages of wide bandwidth, small size and high isolation.

[0017] Preferably, the surface acoustic wave (SAW) atomizing chip 10 is composed of at least a piezoelectric substrate material and interdigital transducers attached to the surface of the piezoelectric substrate material; the piezoelectric substrate material can be piezoelectric crystals such as lithium niobate, lithium tantalate, and quartz, or piezoelectric thin film materials such as aluminum nitride and zinc oxide, or piezoelectric ceramic materials; the interdigital transducers can be straight or arc-shaped electrodes with interlaced fingers, and the electrode materials can be conductive metals with good conductivity such as gold, silver, aluminum, and copper.

[0018] Preferably, the output signal of the push-pull resonant circuit flows into the transmission line transformer coupler module 9 after passing through the resonant network 7 and the impedance matching network 8, and is coupled into a complete radio frequency signal. The synthesized radio frequency signal is connected to the input terminal of the surface acoustic wave atomizing chip 10.

[0019] A second aspect of the present invention discloses an electronic cigarette comprising the surface acoustic wave drive control circuit described in any of the preceding claims.

[0020] The beneficial effects of this invention are:

[0021] 1. Compared with the prior art, the surface acoustic wave drive control circuit of the present invention can not only realize the drive control of ultra-high frequency surface acoustic wave electronic cigarettes of about 30MHz, but also has a small overall size, energy conversion efficiency of over 80%, output power of up to 15W, high power and frequency stability, low noise figure, low cost and long life.

[0022] 2. The electronic cigarette using the drive control circuit of this invention not only has the advantages of surface acoustic wave non-contact low-temperature atomization technology, but also has low power consumption, low board temperature (<60℃), safety, stability and reliability, high smoke concentration, small smoke particle size (about 10nm, lower than the particle size of currently commercially available electronic cigarettes), good inhalation experience, and is portable and compact. Attached Figure Description

[0023] Figure 1 This is a block diagram of the surface acoustic wave drive control circuit of the present invention.

[0024] Figure 2 This is a schematic diagram of the bandpass filter circuit of the present invention.

[0025] Figure 3 This is a simplified schematic diagram of the driving amplifier circuit, impedance matching network, and coupling circuit of the present invention.

[0026] The attached diagram is labeled as follows: 1. DC power supply circuit module, 2. Microcontroller module, 3. High-frequency pulse generation circuit module, 4. Bandpass filter circuit module, 5. Adjustable switching power supply circuit module, 6. Drive amplifier circuit module, 7. Resonant network, 8. Impedance matching network, 9. Transmission line transformer coupler module, 10. Surface acoustic wave atomizing chip. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are merely some examples of the present invention, and not all examples. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] like Figure 1As shown, the high-efficiency surface acoustic wave electronic cigarette driving control circuit of the present invention includes a DC power supply circuit module 1, a microcontroller module 2, a high-frequency pulse generation circuit module 3, a bandpass filter circuit module 4, an adjustable switching power supply circuit module 5, a drive amplifier circuit module 6, a resonant network 7, an impedance matching network 8, a transmission line transformer coupler module 9, and a surface acoustic wave atomizing chip 10.

[0029] In an optional embodiment, the output terminal of the DC power supply circuit module 1 is electrically connected to the microcontroller module 2; the output terminal of the microcontroller module 2 is electrically connected to the control terminal of the high-frequency pulse generation circuit module 3 and the adjustable switching power supply circuit module 5; the output terminal of the high-frequency pulse generation circuit module 3 is electrically connected to the input terminal of the bandpass filter circuit module 4; the output terminals of the bandpass filter circuit module 4 and the adjustable switching power supply circuit module 5 are electrically connected to the input terminal of the drive amplifier circuit module 6; the output terminal of the drive amplifier circuit module 6 is electrically connected to the input terminal of the resonant network 7; the output terminal of the resonant network 7 is electrically connected to the input terminal of the impedance matching network 8; the output terminal of the impedance matching network 8 is electrically connected to the input terminal of the transmission line transformer coupler module 9; the feedback terminal of the transmission line transformer coupler module 9 is electrically connected to the signal acquisition terminal of the microcontroller module 2; and the output terminal of the transmission line transformer coupler module 9 is electrically connected to the surface acoustic wave atomizing chip 10 via a coaxial cable.

[0030] In an optional embodiment, the DC power supply circuit module 1 provides power signals to the microcontroller module 2 and the high-frequency pulse generation circuit module 3. The microcontroller module 2 controls the high-frequency pulse generation circuit module 3 to generate a high-frequency pulse signal with the same frequency as the characteristic response frequency of the surface acoustic wave (SAW) atomizing chip 10. The generated high-frequency pulse signal is filtered by the bandpass filter circuit module 4 to remove interference signals and obtain a pure sine wave signal. The microprocessor module 2 simultaneously controls the adjustable switching power supply circuit module 5 to amplify the sine wave signal from the input drive amplifier circuit module 6. The amplified signal is impedance matched with the load through the impedance matching network 8. The impedance-matched signal is synthesized into a complete radio frequency (RF) signal through the transmission line transformer coupler module 9. The RF signal is used to provide a high-frequency, high-voltage excitation signal for the SAW atomizing chip 10. The SAW atomizing chip 10 is used to generate a surface acoustic wave vibration elastic wave signal that can cause the e-liquid to form smoke.

[0031] In one embodiment, the DC power supply circuit module 1 provides power signals to other circuit modules after the DC power supply is filtered by a capacitor and regulated by a voltage regulator. The DC power supply is a 12V rechargeable DC battery, and the voltage regulator is a 78L05 three-port voltage regulator, which can output a stable 5V DC voltage to provide startup power to other power modules.

[0032] In an optional embodiment, the microcontroller module 2 is an STM32F103 microprocessor, and the high-frequency pulse generation circuit module 3 uses a direct digital frequency synthesizer (DDS) chip AD9850 to generate radio frequency signals, which has high frequency stability and fully meets the requirements of the power amplifier switch.

[0033] In an optional embodiment, the bandpass filter circuit module 4 adopts a multi-stage feedback MFB (Multi-stage Feedback Filter) type multi-channel negative feedback active second-order bandpass filter, as detailed in the following implementation: Figure 2 As shown, the amplifier uses the AD8008 chip. In order to eliminate the self-oscillation effect and work stably, a high-frequency decoupling capacitor C01 is directly connected between the power supply VCC and VEE, and another decoupling capacitor C02 is grounded.

[0034] like Figure 3 As shown, in an optional embodiment, the drive amplifier circuit module 6 adopts a Class D power amplifier, specifically composed of four MOSFET transistors (N1, N2, N3, N4), with N1 and N2 connected in parallel, and N3 and N4 connected in parallel, forming a push-pull resonant circuit. The signal processed by the bandpass filter circuit module 4 passes through the high-frequency transformer T1, causing the two sets of parallel transistors to obtain reverse excitation voltage and conduct alternately. That is, when N1 and N2 are on, N3 and N4 are off, and when N3 and N4 are on, N1 and N2 are off.

[0035] In an optional embodiment, the signal processed by the high-frequency transformer T1 is connected to the gate of the MOSFET transistor in the power amplifier circuit, the source of the MOSFET transistor is grounded, and the drain is connected to the impedance matching network 8 and the resonant network 7.

[0036] In an optional embodiment, the resonant network 7 is mainly composed of LC filters. Each MOSFET transistor has a set of LC resonant filter circuits at its drain. The resonant filter circuits connected to MOSFET transistors N1, N2, N3, and N4 are respectively denoted as XZ1, XZ2, XZ3, and XZ4. After being filtered by the resonant network, a standard sine wave signal can be output.

[0037] In an optional embodiment, the impedance matching network 8 is composed of LC circuits, and each MOSFET transistor has a set of impedance matching circuits at its drain. The impedance matching networks connected to MOSFET transistors N1, N2, N3, and N4 are respectively denoted as ZK1, ZK2, ZK3, and ZK4, which match the output impedance values ​​of each path to the characteristic impedance of the output line, 50Ω.

[0038] In an optional embodiment, a cement resistor (R12, R34) is connected in parallel to the drain and source of each of the two parallel MOSFET transistor groups (N1N2, N3N4) in the drive amplifier circuit module 6. This can effectively balance the power dissipation of the transistors. When a transistor burns out, the corresponding drain and gate will conduct, the drain voltage will be fed back to the gate, and the diode will be reverse-biased and cut off, thereby achieving the purpose of protecting the voltage regulator circuit.

[0039] In an optional embodiment, the adjustable switching power supply circuit module 5 is provided with an adjustable resistor RP1, RP2, RP3 and RP4 for each of the four MOSFET transistors (N1, N2, N3 and N4) in the corresponding drive amplifier circuit module 6, in order to adjust the bias voltage of each transistor to ensure that the final output of each transistor is the same and to keep the whole system stable.

[0040] In an optional embodiment, the output signal of the impedance matching network 8 is electrically connected to the input terminal of the transmission line transformer coupler module 9. The transmission line transformer coupler has both transformer performance and transmission line characteristics, and combines two reverse signals into a complete radio frequency signal to drive the surface acoustic wave atomizing chip 10. It has the advantages of wide bandwidth, small size and high isolation.

[0041] When used in electronic cigarettes, the surface acoustic wave (SAW) drive control circuit of this invention can achieve stable sinusoidal signal output at ultra-high frequencies and drive the SAW atomizing chip to stably atomize the e-liquid. Testing shows that at a frequency of 30MHz, the energy conversion efficiency can reach over 80%, and the output power can reach 15W. The vapor particle size used in electronic cigarettes is approximately 10nm, lower than that of currently commercially available electronic cigarettes. Due to the low-temperature characteristics of e-liquid atomization and the small vapor particle size, the vaping experience is improved.

[0042] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not limiting. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the scope of protection of the present invention.

Claims

1. A surface acoustic wave driving control circuit, characterized in that, include: DC power supply circuit module (1), microcontroller module (2), high frequency pulse generation circuit module (3), bandpass filter circuit module (4), adjustable switching power supply circuit module (5), drive amplifier circuit module (6), resonant network (7), impedance matching network (8), transmission line transformer coupler module (9), and surface acoustic wave atomizing chip (10). The output terminal of the DC power supply circuit module (1) is electrically connected to the microcontroller module (2). The output terminal of the microcontroller module (2) is electrically connected to the control terminal of the high-frequency pulse generation circuit module (3) and the adjustable switching power supply circuit module (5). The output terminal of the high-frequency pulse generation circuit module (3) is electrically connected to the input terminal of the bandpass filter circuit module (4). The output terminals of the bandpass filter circuit module (4) and the adjustable switching power supply circuit module (5) and the input terminal of the drive amplifier circuit module (6) are electrically connected. The output terminal of the drive amplifier circuit module (6) is electrically connected to the input terminal of the resonant network (7). The output terminal of the resonant network (7) is electrically connected to the input terminal of the impedance matching network (8). The output terminal of the impedance matching network (8) is electrically connected to the input terminal of the transmission line transformer coupler module (9). The feedback terminal of the transmission line transformer coupler module (9) is electrically connected to the signal acquisition terminal of the microcontroller module (2). The output terminal of the transmission line transformer coupler module (9) is electrically connected to the surface acoustic wave atomizing chip (10) via a coaxial cable. The drive amplifier circuit module (6) adopts a Class D power amplifier, which is composed of four metal-oxide-semiconductor field-effect transistors, and the two are connected in parallel to form a push-pull resonant circuit. The adjustable switching power supply circuit module (5) is provided with four adjustable resistors, which are respectively connected to the gates of four metal-oxide-semiconductor field-effect transistors in the drive amplifier circuit module (6); a cement resistor is connected in parallel to the drain and source of each of the four metal-oxide-semiconductor field-effect transistors. The output signal of the push-pull resonant circuit flows into the transmission line transformer coupler module (9) after passing through the resonant network (7) and the impedance matching network (8) to couple into a complete radio frequency signal. The synthesized radio frequency signal is connected to the input terminal of the surface acoustic wave atomizing chip (10).

2. The surface acoustic wave drive control circuit according to claim 1, characterized in that, The DC power supply circuit module (1) provides power signals to other circuit modules after the DC power supply is filtered by a capacitor and regulated by a voltage regulator.

3. The surface acoustic wave drive control circuit according to claim 1, characterized in that, The high-frequency pulse generation circuit module (3) uses a direct digital synthesizer to generate radio frequency signals.

4. The surface acoustic wave drive control circuit according to claim 1, characterized in that, The bandpass filter circuit module (4) adopts a multi-stage feedback active second-order bandpass filter with multiple negative feedback.

5. The surface acoustic wave drive control circuit according to claim 1, characterized in that, The surface acoustic wave atomizing chip (10) includes a piezoelectric substrate material and an interdigital transducer attached to the surface of the piezoelectric substrate material.

6. An electronic cigarette, characterized in that, It includes the surface acoustic wave drive control circuit according to any one of claims 1-5.

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