A piezoelectric ceramic air pump drive circuit

Abstract

This utility model discloses a piezoelectric ceramic air pump drive circuit, belonging to the technical field of piezoelectric ceramic air pump control. The circuit includes a main control processing unit, a program download unit, a low-dropout voltage regulator unit, an H-bridge piezoelectric ceramic air pump drive unit, and a DC-DC boost unit. The input terminals of the low-dropout voltage regulator unit and the DC-DC boost unit are connected to an external power supply, providing a stable low-voltage operating power supply to the main control processing unit and a high-voltage power supply to the H-bridge piezoelectric ceramic air pump drive unit. The H-bridge piezoelectric ceramic air pump drive unit uses complementary metal-oxide-semiconductor field-effect transistors to construct a full-bridge topology. The main control processing unit outputs complementary pulse width modulation signals to control the switching of the transistors in the H-bridge, generating a high-voltage alternating drive signal at the interface connecting to the air pump. This utility model features high integration, flexible control, and high drive efficiency, making it suitable for piezoelectric ceramic air pump applications requiring high-voltage, high-frequency drive.

Description

Technical Field

[0001] This utility model relates to the technical field of piezoelectric ceramic air pump control, and in particular to a high-frequency drive circuit for driving a piezoelectric ceramic air pump. Background Technology

[0002] Piezoelectric ceramic gas pumps operate using the inverse piezoelectric effect of piezoelectric ceramic materials. When a high-frequency alternating electric field is applied, the piezoelectric ceramic sheet undergoes periodic deformation, thereby pumping gas. These pumps offer advantages such as simple structure, no motor required, low electromagnetic interference, and ease of miniaturization, and are widely used in medical and aesthetic equipment, analytical instruments, and consumer electronics.

[0003] Driving a piezoelectric ceramic air pump requires a drive circuit capable of providing sufficiently high voltage (typically tens of volts) and a high-frequency AC signal. Traditional drive solutions may employ operational amplifiers with discrete component amplification or simple self-excited oscillating circuits, which suffer from problems such as fixed output voltage and frequency, inflexible adjustment, low efficiency, and inconvenient interface with the main control system. Especially for portable devices powered by a single lithium battery, efficiently, reliably, and controllably boosting the low voltage and converting it into the high-voltage AC signal required to drive the piezoelectric ceramic air pump has become a significant technical challenge.

[0004] Therefore, a dedicated drive circuit for piezoelectric ceramic air pumps is needed, which features higher integration, more intelligent control, and better energy conversion efficiency. Utility Model Content

[0005] The technical problem to be solved by this utility model is to provide a piezoelectric ceramic air pump drive circuit with high integration, flexible control and high driving efficiency, so as to overcome the shortcomings of the prior art.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A piezoelectric ceramic air pump drive circuit includes: a main control processing unit, a program download unit, a low differential pressure stabilizing unit, an H-bridge piezoelectric ceramic air pump drive unit, and a DC-DC boost unit;

[0008] The input terminals of the low-dropout regulator and the DC-DC boost converter are connected to an external power supply and defined as the first voltage network.

[0009] The output of the low-dropout voltage regulator unit is connected to the power input of the main control processing unit and is defined as the second voltage network;

[0010] The output of the DC-DC boost unit is connected to the power input of the H-bridge piezoelectric ceramic air pump drive unit and is defined as the third voltage network.

[0011] The control signal output terminal of the main control processing unit is connected to the control signal input terminal of the H-bridge piezoelectric ceramic air pump drive unit;

[0012] The signal port of the program download unit is connected to the debugging interface of the main control processing unit;

[0013] The H-bridge piezoelectric ceramic air pump drive unit includes a first high-pressure side P-type metal-oxide-semiconductor field-effect transistor, a first low-pressure side N-type metal-oxide-semiconductor field-effect transistor, a second high-pressure side P-type metal-oxide-semiconductor field-effect transistor, and a second low-pressure side N-type metal-oxide-semiconductor field-effect transistor. The drains of the first high-pressure side P-type metal-oxide-semiconductor field-effect transistor and the first low-pressure side N-type metal-oxide-semiconductor field-effect transistor are connected to form the midpoint of the first bridge arm. The drains of the second high-pressure side P-type metal-oxide-semiconductor field-effect transistor and the second low-pressure side N-type metal-oxide-semiconductor field-effect transistor are connected to form the midpoint of the second bridge arm. An air pump interface for connecting the piezoelectric ceramic air pump is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm.

[0014] The main control processing unit includes a microcontroller, a reset resistor, and a power supply decoupling capacitor; the microcontroller has multiple general-purpose input / output pins, of which four pins are configured as the first drive control pin, the second drive control pin, the third drive control pin, and the fourth drive control pin;

[0015] The main control processing unit is configured to output a first set of drive signals through the first drive control pin and the second drive control pin, and output a second set of drive signals through the third drive control pin and the fourth drive control pin; the first set of drive signals and the second set of drive signals are out of phase and are used to control the H-bridge piezoelectric ceramic air pump drive unit, so that the two ends of the air pump interface generate a high-frequency drive voltage with an amplitude equal to that of the third voltage network voltage and an alternating direction.

[0016] Furthermore, in the H-bridge piezoelectric ceramic air pump drive unit:

[0017] The gate of the first high-voltage side P-type metal-oxide-semiconductor field-effect transistor is connected to the first drive control pin through the eighth current-limiting resistor and to the third voltage network through the tenth pull-up resistor.

[0018] The gate of the first low-voltage side N-type metal-oxide-semiconductor field-effect transistor is connected to the second drive control pin through the second current-limiting resistor and to the ground network through the fourth pull-down resistor.

[0019] The gate of the second high-voltage side P-type metal-oxide-semiconductor field-effect transistor is connected to the fourth drive control pin through the ninth current-limiting resistor and to the third voltage network through the eleventh pull-up resistor.

[0020] The gate of the second low-voltage side N-type metal-oxide-semiconductor field-effect transistor is connected to the third drive control pin through the third current-limiting resistor and to the ground network through the fifth pull-down resistor.

[0021] Furthermore, the low-dropout voltage regulator unit includes a linear regulator, an input filter capacitor, and an output filter capacitor; the input terminal of the linear regulator and one end of the input filter capacitor are connected to a first voltage network; the output terminal of the linear regulator and one end of the output filter capacitor are connected to a second voltage network.

[0022] Furthermore, the DC-DC boost unit includes a boost controller, a power inductor, a Schottky rectifier diode, a voltage feedback network, an input filter capacitor, and an output filter capacitor. One end of the power inductor is connected to the input terminal of the boost controller, and the other end is connected to the pulse control output terminal of the boost controller. One end of the input filter capacitor is connected to a first voltage network. The first voltage network is connected to the input terminal and the enable terminal of the boost controller. One end of the output filter capacitor and the cathode of the Schottky rectifier diode are connected to a third voltage network. The other ends of the input filter capacitor and the other end of the output filter capacitor are both grounded to a network. The anode of the Schottky rectifier diode is connected to the pulse control output terminal of the boost controller. The voltage feedback network is connected to the cathode of the Schottky rectifier diode and the voltage feedback input terminal of the boost controller.

[0023] Furthermore, the voltage feedback network includes a first feedback resistor and a second feedback resistor connected in series. One end of the first feedback resistor is connected to a third voltage network, and one end of the second feedback resistor is connected to a ground network. The connection node between the first feedback resistor and the second feedback resistor is connected to the voltage feedback input terminal of the boost controller.

[0024] Furthermore, the program download unit includes a serial data line and a serial clock line that provides clock pulse signals to the serial data line; the serial clock line is connected to the serial line debug clock pin of the main control processing unit, and the serial data line is connected to the serial line debug data input / output pin of the main control processing unit.

[0025] The working principle of this utility model is briefly described as follows: The electrical energy provided by the external power supply (such as a +3.7V lithium battery) is divided into two paths. One path, after being regulated by the aforementioned low-dropout voltage regulator unit, provides a stable low-voltage operating power supply (such as +3.3V) to the aforementioned main control processing unit. The other path, after being efficiently boosted by the aforementioned DC-DC boost unit, generates the high-voltage power supply (such as +27V) required by the aforementioned H-bridge piezoelectric ceramic air pump drive unit. After the aforementioned main control processing unit is powered on, it generates two sets of complementary pulse width modulation control signals according to a preset program, which are respectively sent to the two bridge arms of the aforementioned H-bridge piezoelectric ceramic air pump drive unit. By precisely controlling the timing of the control signals, the first bridge arm and the second bridge arm are alternately turned on, forming an alternating high-voltage current path between the midpoints of the two bridge arms connecting the piezoelectric ceramic air pump, thereby driving the piezoelectric ceramic sheet to vibrate at high frequency.

[0026] As can be seen from the above, compared with the prior art, this utility model has the following advantages:

[0027] 1. Intelligent and highly flexible control: It adopts a programmable microcontroller as the control core, which can flexibly set key parameters such as the frequency, duty cycle and dead time of the drive signal through software, easily adapt to piezoelectric ceramic air pumps of different specifications, and easily realize advanced functions such as speed adjustment and soft start.

[0028] 2. Strong driving capability and high efficiency: The independent DC-DC boost unit adopts a switching power supply topology, which can efficiently boost the battery voltage to the high voltage required for driving; the H-bridge piezoelectric ceramic air pump drive unit uses a low on-resistance metal oxide semiconductor field-effect transistor as the switching element, and the overall circuit has high energy conversion efficiency, which is conducive to extending the battery life of portable devices.

[0029] 3. High integration and high reliability: The circuit modularly integrates functions such as power management, signal generation, and power drive, resulting in a clear structure. In the H-bridge piezoelectric ceramic air pump drive unit, each transistor gate is equipped with pull-up or pull-down resistors to ensure reliable turn-off. Combined with the dead time that can be set by the microcontroller software, the risk of bridge arm shoot-through short circuit is effectively prevented, improving system reliability.

[0030] 4. Convenient development and maintenance: It integrates a standard program download and debugging interface, which greatly facilitates the burning, debugging, and subsequent function upgrades and maintenance of the control program. Attached Figure Description

[0031] Figure 1 This is a schematic block diagram of the piezoelectric ceramic air pump drive circuit according to an embodiment of the present invention;

[0032] Figure 2 This is a circuit diagram of the main control processing unit in an embodiment of this utility model;

[0033] Figure 3 This is a circuit diagram of the program download unit in an embodiment of the present invention;

[0034] Figure 4 This is a circuit diagram of the low-dropout voltage regulator unit in an embodiment of this utility model;

[0035] Figure 5 This is a circuit diagram of the H-bridge piezoelectric ceramic air pump drive unit in this embodiment of the present invention;

[0036] Figure 6 This is a circuit diagram of the DC-DC boost unit in an embodiment of this utility model;

[0037] Figure 7 This is an example of an application scenario of this utility model in controlling liquid output in beauty instruments.

[0038] Description of main components in the diagram:

[0039] 1-Main control processing unit; 2-Program download unit; 3-Low differential voltage regulator unit; 4-H-bridge piezoelectric ceramic air pump drive unit; 5-DC-DC boost unit; U1-Microcontroller; U2-Serial line debugging connector; U3-Linear regulator; Q1-First low-voltage side N-type metal-oxide-semiconductor field-effect transistor; Q2-Second low-voltage side N-type metal-oxide-semiconductor field-effect transistor; Q3-First high-voltage side P-type metal-oxide-semiconductor field-effect transistor; Q4-Second high-voltage side P-type metal-oxide-semiconductor field-effect transistor; U4-Boost controller; CN1-Air pump interface. Detailed Implementation

[0040] The present invention and its beneficial technical effects will be further described in detail below with reference to the accompanying drawings and preferred embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0041] It should be noted that the use of terms such as "first" and "second" in this utility model is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those technical features.

[0042] like Figure 1 The schematic diagram shown illustrates that the piezoelectric ceramic air pump drive circuit provided in this embodiment of the invention mainly includes five functional units: main control processing unit 1, program download unit 2, low differential pressure stabilizing unit 3, H-bridge piezoelectric ceramic air pump drive unit 4, and DC-DC boost unit 5.

[0043] The positive terminal of an external power supply (e.g., a lithium battery with a nominal voltage of +3.7V) is connected to a first voltage network indicated by the network label "3.7V". This first voltage network simultaneously powers both the low-dropout regulator unit 3 and the DC-DC boost unit 5.

[0044] like Figure 4 As shown, the low-dropout voltage regulator unit 3 includes a linear regulator U3 (specifically, model XC6206P332MR), an input filter capacitor C1 (capacitance can be 10μF), and an output filter capacitor C2 (capacitance can be 10μF). A first voltage network of 3.7V is connected to the input terminal (VIN pin) of the linear regulator U3 and one end of the input filter capacitor C1. The output terminal (VOUT pin) of the linear regulator U3 and one end of the output filter capacitor C2 are connected to a second voltage network indicated by the network label "3.3V". The ground terminal (GND pin) of the linear regulator U3, the other end of the input filter capacitor C1, and the other end of the output filter capacitor C2 are all connected to the ground network (GND). This unit regulates the voltage from the first voltage network of 3.7V to the second voltage network of 3.3V.

[0045] like Figure 2 As shown, the main control processing unit 1 includes a microcontroller U1 (specifically, an STM32F030F4P6), an anti-interference resistor R1 (10kΩ), and a power decoupling capacitor C3 (100nF). A second voltage network, 3.3V, is connected to the power supply pin (VDD) of the microcontroller U1 to supply power. One end of the anti-interference resistor R1 is connected to the ground network GND, and the other end is connected to the power input / output pin (PA3) of the microcontroller U1. One end of the power decoupling capacitor C3 is connected to the power supply pin (VDD) of the microcontroller U1, and the other end is connected to the ground network GND. The microcontroller U1 has multiple general-purpose input / output pins. In this embodiment, pins PA7, PA5, PA6, and PA13 are configured as the first drive control pin MOTOR_1, the second drive control pin MOTOR_2, the third drive control pin MOTOR_3, and the fourth drive control pin MOTOR_4, respectively. The microcontroller U1 also features a serial line debug clock pin SWCLK and a serial line debug data input / output pin SWDIO for program debugging;

[0046] like Figure 3As shown, the program download unit 2 includes a 4-pin serial line debug connector U2 (specifically model ZX-MX1.25-4PZZ). Pin 2 (SWCLK) of connector U2 is connected to the SWCLK pin of microcontroller U1 via a serial clock line, and pin 3 (SWDIO) is connected to the SWDIO pin of microcontroller U1 via a serial data line. Pin 1 of connector U2 is connected to the second voltage network 3.3V, and pin 4 is connected to the ground network GND. Through program download unit 2, microcontroller U1 can be programmed and debugged online.

[0047] like Figure 6 As shown, the DC-DC boost unit 5 includes a boost controller U4 (specifically, an MT3608), a power inductor L1 (22μH), a Schottky rectifier diode D1 (SS34), a first feedback resistor R6 (100kΩ), a second feedback resistor R7 (4.7kΩ), an input filter capacitor C4 (10μF), and an output filter capacitor C5 (10μF). A first voltage network of 3.7V is connected to the power input pin (VIN) and enable pin (EN) of the boost controller U4, one end of the power inductor L1, and one end of the input filter capacitor C4. The other end of the power inductor L1 is connected to the switch pin (SW) of the boost controller U4; that is, the switch pin (SW) of the boost controller U4 serves as the pulse control output. The anode of the Schottky rectifier diode D1 is connected to the switch pin (SW) of the boost controller U4, and its cathode is connected to one end of the output filter capacitor C5, both connected to the third voltage network indicated by the network label "27V". The other end of the output filter capacitor C5 is connected to the ground network GND. One end of the first feedback resistor R6 is connected to the third voltage network 27V, and the other end is connected to one end of the second feedback resistor R7 and the feedback pin (FB) of the boost controller U4. The other end of the second feedback resistor R7 is connected to the ground network GND. The first feedback resistor R6 and the second feedback resistor R7 form the voltage feedback network of the boost controller U4. The other end of the input filter capacitor C4 is also connected to the ground network GND. This unit boosts and stabilizes the 3.7V voltage from the first voltage network to the 27V (approximately +27V) voltage of the third voltage network, and its output voltage value is determined by the ratio of the first feedback resistor R6 and the second feedback resistor R7.

[0048] like Figure 5As shown, the H-bridge piezoelectric ceramic air pump drive unit 4 includes a first high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q3 (specifically model SI2301), a first low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q1 (specifically model SI2302), a second high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q4 (SI2301), and a second low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q2 (SI2302). A third voltage network of 27V is connected to the source of the first high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q3 and the source of the second high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q4.

[0049] The drain of the first high-voltage side P-type MOSFET Q3 is connected to the drain of the first low-voltage side N-type MOSFET Q1, forming the midpoint of the first bridge arm, and is connected to pin 1 of the air pump interface CN1. The drain of the second high-voltage side P-type MOSFET Q4 is connected to the drain of the second low-voltage side N-type MOSFET Q2, forming the midpoint of the second bridge arm, and is connected to pin 2 of the air pump interface CN1. The piezoelectric ceramic air pump is connected between pins 1 and 2 of the air pump interface CN1.

[0050] The control signal connections are as follows:

[0051] The gate of the first high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q3 is connected to the first drive control pin MOTOR_1 (i.e., the PA0 pin of microcontroller U1) through the eighth current-limiting resistor R8 (the resistance value can be 100Ω), and is connected to the third voltage network 27V through the tenth pull-up resistor R10 (the resistance value can be 10kΩ).

[0052] The gate of the first low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q1 is connected to the second drive control pin MOTOR_2 (i.e., the PA1 pin of the microcontroller U1) through the second current-limiting resistor R2 (the resistance value can be 100Ω), and is connected to the ground network GND through the fourth pull-down resistor R4 (the resistance value can be 10kΩ).

[0053] The gate of the second high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q4 is connected to the fourth drive control pin MOTOR_4 (i.e., the PA3 pin of microcontroller U1) through the ninth current-limiting resistor R9 (the resistance value can be 100Ω), and is connected to the third voltage network 27V through the eleventh pull-up resistor R11 (the resistance value can be 10kΩ).

[0054] The gate of the second low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q2 is connected to the third drive control pin MOTOR_3 (i.e., the PA2 pin of microcontroller U1) through the third current-limiting resistor R3 (the resistance value can be 100Ω), and is connected to the ground network GND through the fifth pull-down resistor R5 (the resistance value can be 10kΩ).

[0055] The sources of both the first low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q1 and the second low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q2 are connected to the ground network GND.

[0056] The circuit operation process is explained in detail below:

[0057] After the system is powered on, the first voltage network of 3.7V begins supplying power. The low-dropout regulator unit 3 immediately starts working, establishing a stable second voltage network of 3.3V at the output of the linear regulator U3 to power the microcontroller U1 of the main control processing unit 1. At the same time, the DC-DC boost unit 5 starts working, controlling the energy storage and release of the power inductor L1 through the boost controller U4, and establishing a stable third voltage network of 27V at the output after rectification and filtering by the Schottky rectifier diode D1, preparing for the H-bridge drive.

[0058] After power-on reset, microcontroller U1 begins executing its internally stored control program. The program controls its first drive control pin (MOTOR_1), second drive control pin (MOTOR_2), third drive control pin (MOTOR_3), and fourth drive control pin (MOTOR_4) to output specific pulse-width modulation (PWM) signals. To achieve safe and efficient H-bridge driving, microcontroller U1 outputs two sets of complementary drive signals and typically includes a software dead time to prevent bridge arm shoot-through.

[0059] When it is necessary to drive the piezoelectric ceramic air pump to deform in the positive direction (corresponding to pin 1 of the air pump interface CN1 being positive and pin 2 being negative), the control logic of the microcontroller U1 is as follows: set the first drive control pin MOTOR_1 and the second drive control pin MOTOR_2 to low level, and the third drive control pin MOTOR_3 and the fourth drive control pin MOTOR_4 to high level.

[0060] When the first drive control pin MOTOR_1 (PA0) is low, the gate potential of the first high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q3 is pulled low, forming a negative voltage relative to its source (connected to the third voltage network 27V), and the first high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q3 is turned on.

[0061] When the second drive control pin MOTOR_2 (PA1) is low, the gate of the first low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q1 is low. Combined with the protection provided by the fourth pull-down resistor R4, the first low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q1 is reliably turned off.

[0062] When the third drive control pin MOTOR_3 (PA2) is high, the gate of the second low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q2 is high, and the second low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q2 is turned on.

[0063] When the fourth drive control pin MOTOR_4 (PA3) is high, the gate potential of the second high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q4 is raised to close to +27V. Since the voltage difference relative to its source is insufficient, the second high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q4 is reliably turned off under the protection of the eleventh pull-up resistor R11.

[0064] At this point, the current path is: third voltage network 27V → first high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q3 → air pump interface CN1 pin 1 → piezoelectric ceramic air pump → air pump interface CN1 pin 2 → second low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q2 → ground network GND. The piezoelectric ceramic air pump is subjected to a positive voltage of approximately 27V.

[0065] When the piezoelectric ceramic air pump needs to be driven to deform in the reverse direction (pin 2 of the corresponding air pump interface CN1 is positive and pin 1 is negative), the microcontroller U1 flips the control logic: sets the first drive control pin MOTOR_1 and the second drive control pin MOTOR_2 to high level, and the third drive control pin MOTOR_3 and the fourth drive control pin MOTOR_4 to low level.

[0066] When the first drive control pin MOTOR_1 is high, the first high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q3 is turned off.

[0067] When the second drive control pin MOTOR_2 is high, the first low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q1 is turned on.

[0068] When the third drive control pin MOTOR_3 is low, the second low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q2 is turned off.

[0069] When the fourth drive control pin MOTOR_4 is low, the second high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q4 is turned on.

[0070] At this point, the current path is: third voltage network 27V → second high-voltage side P-type metal-oxide-semiconductor field-effect transistor Q4 → air pump interface CN1 pin 2 → piezoelectric ceramic air pump → air pump interface CN1 pin 1 → first low-voltage side N-type metal-oxide-semiconductor field-effect transistor Q1 → ground network GND. The piezoelectric ceramic air pump is subjected to a reverse voltage of approximately 27V.

[0071] The microcontroller U1 periodically switches between the two driving states at high speed, using the ultrasonic operating frequency required by the piezoelectric ceramic air pump (e.g., 20kHz to 100kHz). This generates a square wave voltage of approximately 27V with alternating high-frequency polarity at the air pump interface CN1, driving the piezoelectric ceramic plate to produce mechanical vibrations at the same frequency, thus achieving the pumping function. By modifying the program of the microcontroller U1, the driving frequency can be precisely adjusted to match the mechanical resonant point of the air pump, and the signal duty cycle can be adjusted to control the air pump output intensity, achieving highly flexible and intelligent control.

[0072] See Figure 7 As an example of an application scenario for controlling liquid output in a beauty instrument, this utility model uses a piezoelectric ceramic pump drive circuit as the control circuit to control a miniaturized piezoelectric ceramic pump. The piezoelectric ceramic pump drive circuit is connected to the piezoelectric ceramic pump via an electrical connection wire. Gas is injected into the ampoule through the air inlet tube connecting the piezoelectric ceramic pump and the ampoule, causing the liquid inside the ampoule to flow out through the outlet tube connected to the ampoule outlet under air pressure to the corresponding functional head. The flow rate of the liquid can be adjusted by controlling the working state of the piezoelectric ceramic pump. The advantage is that the liquid inside the ampoule does not come into contact with the piezoelectric ceramic pump, thus preventing secondary contamination, and both the outlet tube and the ampoule can be used as disposable consumables.

[0073] In the above description of this utility model, in each circuit schematic, the same-named "network symbol" indicates an electrical connection between "connection ports". The specific models and parameters of the components selected in the circuit can be matched and adjusted according to the actual use. These are common techniques in the prior art. For the sake of brevity, the conventionally used contents in the prior art, such as structure and process, will not be described in detail. Undisclosed processing techniques and parts, and the connection relationships of resistors or commonly used electronic components not specifically described, can be handled according to conventional techniques in the prior art.

[0074] The above description and specific embodiments do not constitute any limitation on this utility model. This utility model is not limited to the specific embodiments disclosed and described above. Different implementations or changes of the control ideas and methods of this utility model should also fall within the protection scope of the claims of this utility model.

Claims

1. A piezoelectric ceramic air pump drive circuit, characterized in that, include: The system includes a main control processing unit, a program download unit, a low differential pressure stabilizing unit, an H-bridge piezoelectric ceramic air pump drive unit, and a DC-DC boost unit. The input terminals of the low-dropout regulator and the DC-DC boost converter are connected to an external power supply and defined as the first voltage network. The output of the low-dropout voltage regulator unit is connected to the power input of the main control processing unit and is defined as the second voltage network; The output of the DC-DC boost unit is connected to the power input of the H-bridge piezoelectric ceramic air pump drive unit and is defined as the third voltage network. The control signal output terminal of the main control processing unit is connected to the control signal input terminal of the H-bridge piezoelectric ceramic air pump drive unit; The signal port of the program download unit is connected to the debugging interface of the main control processing unit; The H-bridge piezoelectric ceramic air pump drive unit includes a first high-pressure side P-type metal-oxide-semiconductor field-effect transistor, a first low-pressure side N-type metal-oxide-semiconductor field-effect transistor, a second high-pressure side P-type metal-oxide-semiconductor field-effect transistor, and a second low-pressure side N-type metal-oxide-semiconductor field-effect transistor. The drains of the first high-pressure side P-type metal-oxide-semiconductor field-effect transistor and the first low-pressure side N-type metal-oxide-semiconductor field-effect transistor are connected to form the midpoint of the first bridge arm. The drains of the second high-pressure side P-type metal-oxide-semiconductor field-effect transistor and the second low-pressure side N-type metal-oxide-semiconductor field-effect transistor are connected to form the midpoint of the second bridge arm. An air pump interface for connecting the piezoelectric ceramic air pump is connected between the midpoint of the first bridge arm and the midpoint of the second bridge arm. The main control processing unit includes a microcontroller, a reset resistor, and a power supply decoupling capacitor; the microcontroller has multiple general-purpose input / output pins, of which four pins are configured as the first drive control pin, the second drive control pin, the third drive control pin, and the fourth drive control pin; The main control processing unit is configured to output a first set of drive signals through the first drive control pin and the second drive control pin, and output a second set of drive signals through the third drive control pin and the fourth drive control pin; the first set of drive signals and the second set of drive signals are out of phase and are used to control the H-bridge piezoelectric ceramic air pump drive unit, so that the two ends of the air pump interface generate a high-frequency drive voltage with an amplitude equal to that of the third voltage network voltage and an alternating direction.

2. The piezoelectric ceramic air pump drive circuit according to claim 1, characterized in that, In the H-bridge piezoelectric ceramic air pump drive unit: The gate of the first high-voltage side P-type metal-oxide-semiconductor field-effect transistor is connected to the first drive control pin through the eighth current-limiting resistor and to the third voltage network through the tenth pull-up resistor. The gate of the first low-voltage side N-type metal-oxide-semiconductor field-effect transistor is connected to the second drive control pin through the second current-limiting resistor and to the ground network through the fourth pull-down resistor. The gate of the second high-voltage side P-type metal-oxide-semiconductor field-effect transistor is connected to the fourth drive control pin through the ninth current-limiting resistor and to the third voltage network through the eleventh pull-up resistor. The gate of the second low-voltage side N-type metal-oxide-semiconductor field-effect transistor is connected to the third drive control pin through the third current-limiting resistor and to the ground network through the fifth pull-down resistor.

3. The piezoelectric ceramic air pump drive circuit according to claim 2, characterized in that, The low-dropout voltage regulator unit includes a linear regulator, an input filter capacitor, and an output filter capacitor; the input terminal of the linear regulator and one end of the input filter capacitor are connected to a first voltage network; the output terminal of the linear regulator and one end of the output filter capacitor are connected to a second voltage network.

4. The piezoelectric ceramic air pump drive circuit according to claim 3, characterized in that, The DC-DC boost unit includes a boost controller, a power inductor, a Schottky rectifier diode, a voltage feedback network, an input filter capacitor, and an output filter capacitor. One end of the power inductor is connected to the input terminal of the boost controller, and the other end is connected to the pulse control output terminal of the boost controller. One end of the input filter capacitor is connected to a first voltage network. The first voltage network is connected to the input terminal and the enable terminal of the boost controller. One end of the output filter capacitor and the cathode of the Schottky rectifier diode are connected to a third voltage network. The other ends of the input and output filter capacitors are both grounded to a ground network. The anode of the Schottky rectifier diode is connected to the pulse control output terminal of the boost controller. The voltage feedback network is connected to the cathode of the Schottky rectifier diode and the voltage feedback input terminal of the boost controller.

5. The piezoelectric ceramic air pump drive circuit according to claim 4, characterized in that, The voltage feedback network includes a first feedback resistor and a second feedback resistor connected in series. One end of the first feedback resistor is connected to a third voltage network, and one end of the second feedback resistor is connected to a ground network. The connection node between the first feedback resistor and the second feedback resistor is connected to the voltage feedback input terminal of the boost controller.

6. The piezoelectric ceramic air pump drive circuit according to claim 5, characterized in that, The program download unit includes a serial data line and a serial clock line that provides clock pulse signals to the serial data line; The serial clock line is connected to the serial debugging clock pin of the main control processing unit, and the serial data line is connected to the serial debugging data input / output pin of the main control processing unit.

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