PM2.5 detection device

Abstract

The utility model belongs to the technical field of particulate matter measurement, and provides a PM2.5 detection device which comprises a processing circuit, a PM2.5 concentration detection circuit and a conversion circuit, and the PM2.5 concentration detection circuit is connected with the processing circuit to transmit a detection feedback signal generated in a starting state. The processing circuit is connected with the conversion circuit to transmit a conversion voltage signal generated according to the detection feedback signal, the conversion circuit generates a target current signal through voltage-current conversion by using a target voltage signal gradually approaching the conversion voltage signal, and the current value of the target current signal is within a preset current range. A worker controls the starting state of the PM2.5 concentration detection circuit through the processing circuit, and by adjusting the voltage-current conversion proportion in the conversion circuit, a target current signal can adapt to industrial control equipment which needs to output analog quantity as a current signal.

Description

Technical Field

[0001] This utility model relates to the field of particulate matter measurement technology, specifically to a PM2.5 detection device. Background Technology

[0002] As environmental awareness deepens, PM2.5 levels have gradually become a common measurement standard in the industrial manufacturing sector. PM2.5 detection devices measure the concentration of fine particulate matter in the air and output an analog quantity corresponding to the concentration result according to the manufacturer's set standards. However, because different manufacturers of PM2.5 detection devices may have different standards, even the same analog quantity may correspond to different fine particulate matter concentrations. Therefore, commercially available PM2.5 detection devices are only suitable for industrial control equipment corresponding to their manufacturer's set standards and do not have broad applicability. Furthermore, the analog output of commercially available PM2.5 devices only supports voltage signals, which is not suitable for some industrial control equipment that requires current signals as PM2.5 sensing signals. Utility Model Content

[0003] The purpose of this application is to provide a PM2.5 detection device suitable for industrial control equipment that requires an analog output signal of current.

[0004] This application provides a PM2.5 detection device, which adopts the following technical solution:

[0005] A PM2.5 detection device includes a PM2.5 concentration detection circuit, a processing circuit, and a conversion circuit. The PM2.5 concentration detection circuit is connected to the processing circuit to transmit a detection feedback signal generated in the start-up state. The processing circuit is connected to the conversion circuit to transmit a conversion voltage signal generated based on the detection feedback signal. The conversion circuit is used to convert the conversion voltage signal into a target current signal, and the current value of the target current signal is within a preset current range.

[0006] Through the above technical solution, the PM2.5 concentration detection circuit, in its activated state, detects the fine particulate matter concentration in the environment and generates a corresponding detection feedback signal according to the manufacturer's set standards. This detection feedback signal is a directly detected electrical signal. The processing circuit processes the detection feedback signal to obtain a converted voltage signal, which fully reflects the fine particulate matter concentration. Subsequently, the conversion circuit converts the converted voltage signal to obtain a corresponding target current signal. This target current signal is an electrical signal in the form of current, suitable for industrial control equipment connected to analog current signals. Furthermore, operators can adjust the voltage-to-current conversion ratio in the conversion circuit to control the output range of the target current signal, ensuring that the target current signal is within a preset current range. This guarantees that the target current signal can be recognized and received by any industrial control equipment, and subsequent calculations and processing can be performed based on this target current signal indicating the fine particulate matter concentration (PM2.5). This solution enables the PM2.5 detection device to be widely used in industrial control equipment connected to analog current signals.

[0007] In one embodiment, the preset current range is 4-20mA.

[0008] Through the above technical solution, since 4-20mA analog input is a commonly used analog control method with good stability, reliability and high precision, it has been widely used in industrial control equipment. Therefore, this target current signal can be applied to a variety of industrial control equipment.

[0009] In one embodiment, the PM2.5 concentration detection circuit has a detection configuration terminal and a detection transceiver terminal, and the processing circuit has a control output terminal, a feedback input terminal, and a feedback output terminal.

[0010] The detection configuration terminal is connected to the control output terminal to receive control signals from the processing circuit, and the PM2.5 concentration detection circuit switches to the start state according to the control signal; the detection transceiver terminal is connected to the feedback input terminal to transmit the detection feedback signal generated by the PM2.5 concentration detection circuit in the start state; the feedback output terminal is connected to the input terminal of the conversion circuit to transmit the conversion voltage signal generated according to the detection feedback signal, and the output terminal of the conversion circuit outputs the target current signal.

[0011] Through the above technical solution, the processing circuit controls the PM2.5 concentration detection circuit to be in an active or inactive state via a control signal at its control output terminal. When active, the PM2.5 concentration detection circuit directly generates a detection feedback signal based on the concentration of fine particulate matter in the environment. The processing circuit then generates a conversion voltage signal indicating the fine particulate matter concentration based on this feedback signal. The conversion circuit further converts this conversion voltage signal to obtain the target current signal.

[0012] In one embodiment, the conversion circuit includes a comparator subcircuit, a control subcircuit, and an output subcircuit. The comparator subcircuit has a first comparator input terminal, a second comparator input terminal, and a differential output terminal. The control subcircuit has a first terminal, a second terminal, and a control terminal.

[0013] The first comparison input terminal is connected to the processing circuit to receive the converted voltage signal, the second comparison input terminal is connected to the input terminal of the output sub-circuit to receive the target voltage signal, and the differential output terminal is connected to the control terminal of the control sub-circuit to transmit the differential voltage signal generated based on the converted voltage signal and the target voltage signal. The first terminal is used to receive the source voltage signal, and the second terminal is connected to the output sub-circuit to receive the target voltage signal. When the voltage value of the differential voltage signal reaches a preset value, the first terminal and the second terminal are turned on to charge the target voltage signal from the source voltage signal. The output sub-circuit is used to convert the target voltage signal into the target current signal.

[0014] Through the above technical solution, when the voltage difference between the converted voltage signal and the target voltage signal is large, the voltage value of the differential voltage signal exceeds the preset value. The first and second terminals are then connected, and the source voltage signal charges the target voltage signal, causing the target voltage signal to gradually increase. This reduces the voltage difference between the target voltage signal and the converted voltage signal, gradually preventing the voltage value of the differential voltage signal from exceeding the preset value. The first and second terminals remain disconnected, and the output sub-circuit directly converts the target voltage signal to a voltage-to-current signal, thus obtaining the target current signal. This solution gradually adjusts the target voltage signal, making its value approach the converted voltage signal. Compared to directly converting the converted voltage signal, this avoids the impact of sudden voltage rises or falls caused by sudden voltage adjustments in the processing circuit, improving the overall circuit's anti-interference performance and enhancing the accuracy of the target current signal indicating the concentration of fine particulate matter.

[0015] In one embodiment, the conversion circuit further includes a conversion power supply circuit having a first resistor, one end of which is used to connect to a charging power supply to access the original voltage signal, and the other end of which is used to connect to the first end to transmit the source voltage signal generated based on the original voltage signal.

[0016] Through the above technical solution, the power conversion circuit transmits electrical energy from the charging power source to the first terminal through the first resistor, thereby realizing that under the control of the control sub-circuit, the charging power source supplies power to the target voltage signal with the source voltage signal through the power conversion circuit.

[0017] In one embodiment, the comparator circuit includes an amplifier, a second resistor, and a third resistor. The positive input terminal of the amplifier is connected to one end of the second resistor, the other end of the second resistor serves as the first comparator input terminal, the negative input terminal of the amplifier serves as the second comparator input terminal, the positive power supply terminal of the amplifier is connected to a third power supply voltage signal, the negative power supply terminal of the amplifier is connected to a reference ground signal, the output terminal of the amplifier is connected to one end of the third resistor, and the other end of the third resistor serves as the differential output terminal.

[0018] With the above technical solution, the amplifier operates under the third supply voltage signal. The amplifier receives the converted voltage signal through the second resistor, generates a differential voltage signal based on the voltage difference between the converted voltage signal and the target voltage signal, and then outputs it through the third resistor.

[0019] In one embodiment, the comparator circuit further includes a fifth voltage-regulating capacitor (C5), one end of which is connected to the positive power supply terminal of the amplifier, and the other end of which is connected to a reference ground signal.

[0020] Through the above technical solution, the fifth voltage regulator capacitor regulates the converted voltage signal, preventing sudden voltage changes in the converted voltage signal from damaging the amplifier in the comparator circuit.

[0021] In one embodiment, the control sub-circuit includes a semiconductor field-effect transistor (FET), with the gate of the FET serving as the control terminal, the source of the FET serving as the second terminal, and the drain of the FET serving as the first terminal.

[0022] Through the above technical solution, the gate of the semiconductor field-effect transistor is connected to the differential voltage signal. When the voltage value of the differential voltage signal reaches the preset value, the first terminal and the second terminal are connected, so that the source voltage signal charges the target voltage signal. The voltage value of the target voltage signal gradually approaches the conversion voltage signal, and the voltage value of the differential voltage signal decreases.

[0023] In one embodiment, the output sub-circuit includes a fourth resistor, a first end of which serves as the input terminal of the output sub-circuit to receive the target voltage signal, and the other end of which is connected to a reference ground signal. The resistance value of the fourth resistor is adjustable, and the current flowing through the fourth resistor serves as the target current signal.

[0024] Through the above technical solution, the output sub-circuit converts the target voltage signal into a target current signal via a fourth resistor and outputs it. Adjusting the fourth resistor changes the range of the output target current signal, making it suitable for various industrial control equipment. Furthermore, this solution generates the target current signal using the target voltage signal, which, compared to directly generating the target current signal from the converted voltage signal, avoids the impact interference caused by instantaneous voltage changes in the converted voltage signal, thus improving the overall output accuracy.

[0025] In one embodiment, the device further includes a power supply configuration circuit. The input terminal of the power supply configuration circuit is connected to a power supply to receive the original power supply signal. The first output terminal of the power supply configuration circuit is connected to the PM2.5 concentration detection circuit to transmit a first power supply voltage signal generated based on the original power supply signal. The second output terminal of the power supply configuration circuit is connected to the processing circuit to transmit a second power supply voltage signal generated based on the original power supply signal. The first power supply voltage signal and the second power supply voltage signal are different. The first power supply voltage signal powers the PM2.5 concentration detection circuit, and the second power supply voltage signal powers the processing circuit.

[0026] Through the above technical solution, the power supply configuration circuit generates a first power supply voltage signal and a second power supply voltage signal from the original power supply signal provided by the system power supply. The first power supply voltage signal powers the PM2.5 concentration detection circuit, and the second power supply voltage signal powers the processing circuit. This achieves different voltage power supplies for the processing circuit and the PM2.5 concentration detection circuit, ensuring their normal operation.

[0027] In one embodiment, the power supply configuration circuit includes a power supply control chip. The input terminal of the power supply control chip serves as the input terminal of the power supply configuration circuit to receive the original power supply signal. The input terminal of the power supply configuration circuit is connected to the first output terminal so that the voltage value of the first power supply voltage signal is equal to the voltage value of the original power supply signal. The ground terminal of the power supply control chip is connected to a reference ground signal. The output terminal of the power supply control chip serves as the second output terminal of the power supply configuration circuit. The voltage value of the first power supply voltage signal is 5V, and the voltage value of the second power supply voltage signal is 3.3V.

[0028] Through the above technical solution, the first output terminal directly outputs a first power supply voltage signal with the same voltage value as the original power supply signal, and the voltage value of the first power supply voltage signal is 5V. The power supply control chip converts the original power supply signal from 5V to a second power supply voltage signal of 3.3V, and uses the second power supply voltage signal to power the processing circuit.

[0029] In one embodiment, the power supply configuration circuit further includes a first voltage-stabilizing capacitor and a second voltage-stabilizing capacitor. One end of the first voltage-stabilizing capacitor is connected to the input terminal of the power distribution chip, and the other end of the first voltage-stabilizing capacitor is connected to a reference ground signal. One end of the first voltage-stabilizing capacitor is connected to the output terminal of the power distribution chip, and the other end of the first voltage-stabilizing capacitor is connected to a reference ground signal.

[0030] Through the above technical solution, the power supply configuration circuit stabilizes the original power supply signal input to the power supply control chip through the first voltage stabilizing capacitor and stabilizes the second power supply voltage signal through the second voltage stabilizing capacitor, thereby improving the circuit's anti-interference capability.

[0031] In one embodiment, the processing circuit includes a processor and a third voltage-stabilizing capacitor. The power supply input port of the processor is used to connect to the second power supply voltage signal. One end of the third voltage-stabilizing capacitor is connected to the power supply input port, and the other end of the third voltage-stabilizing capacitor is connected to a reference ground signal.

[0032] The PM2.5 concentration detection circuit includes a PM2.5 sensor and a fourth voltage-stabilizing capacitor. The power supply terminal of the PM2.5 sensor is used to connect to the first power supply voltage signal. One end of the fourth voltage-stabilizing capacitor is connected to the power supply terminal, and the other end of the fourth voltage-stabilizing capacitor is connected to the reference ground signal.

[0033] Through the above technical solution, the processing circuit stabilizes the second power supply voltage input to the processor using a third voltage-stabilizing capacitor, thereby improving the anti-interference capability of the power supply to the processor. Similarly, a fourth voltage-stabilizing capacitor stabilizes the first power supply voltage supplying power to the PM2.5 sensor, further enhancing the circuit's anti-interference capability. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a module of a PM2.5 detection device provided in this application.

[0035] Figure 2 This is a schematic diagram of another module of a PM2.5 detection device provided in this application.

[0036] Figure 3 yes Figure 2 The circuit diagram of the power supply configuration circuit.

[0037] Figure 4 yes Figure 1 The circuit diagram of the processing circuit in the middle.

[0038] Figure 5 yes Figure 1 A circuit diagram of a conversion circuit in [the context of a circuit].

[0039] Figure 6 yes Figure 1 A block diagram of a medium-voltage conversion circuit.

[0040] Figure 7 yes Figure 6 Circuit diagram of the intermediate conversion circuit. Detailed Implementation

[0041] Unless otherwise defined, the technical or scientific terms used in this specification and claims shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. Specific embodiments of this invention will be described below with reference to the accompanying drawings. It should be noted that, in order to provide a concise description, this specification cannot provide a detailed description of all features of the actual embodiments. Without departing from the spirit and scope of this invention, those skilled in the art can make modifications and substitutions to the embodiments of this invention, and the resulting embodiments are also within the protection scope of this invention.

[0042] This application provides a PM2.5 detection device. (Reference) Figure 1 As shown, the PM2.5 detection device 10 includes:

[0043] Processing circuit 11;

[0044] PM2.5 concentration detection circuit 12 is connected to processing circuit 11. It switches to the start state according to the control signal SET transmitted by processing circuit 11, and generates a detection feedback signal UASRT1_RX in the start state. The detection feedback signal UASRT1_RX is transmitted to processing circuit 11, so that processing circuit 11 can generate conversion voltage signal Vdac according to the detection feedback signal UASRT1_RX.

[0045] And a conversion circuit 13, connected to a processing circuit 11, converts the conversion voltage signal Vdac transmitted by the processing circuit 11 into a target current signal Iout, the current value of the target current signal Iout being within a preset current range.

[0046] The processing circuit 11 controls the operating state of the PM2.5 concentration detection circuit 12, switching it from standby to startup, or vice versa. In startup mode, the PM2.5 concentration detection circuit 12 detects the concentration of fine particulate matter in the environment and generates a corresponding detection feedback signal UASRT1_RX according to the manufacturer's set standards. This detection feedback signal UASRT1_RX is a directly detected electrical signal. For example, if the PM2.5 concentration detection circuit 12 uses the principle of light scattering for measurement, the built-in photodetector detects the intensity of scattered light generated by the light source after being scattered by fine particulate matter in the environment; in this case, the detection feedback signal UASRT1_RX is the electrical signal corresponding to that light intensity.

[0047] The processing circuit 11 processes the detection feedback signal UASRT1_RX to obtain the conversion voltage signal Vdac, which fully reflects the concentration of fine particulate matter. Continuing the previous example, the detection feedback signal directly reflects the intensity of scattered light generated by the scattering of fine particulate matter. The processing circuit 11 directly calculates the corresponding fine particulate matter concentration based on this light intensity, and generates the conversion voltage signal Vdac according to its own preset rules based on the fine particulate matter concentration. This conversion voltage signal Vdac directly reflects the fine particulate matter concentration, i.e., the PM2.5 value.

[0048] The conversion circuit 13 converts the voltage signal Vdac to obtain the corresponding target current signal Iout. This target current signal Iout is an electrical signal in the form of current, which is suitable for industrial control equipment where the analog quantity is a current signal. Furthermore, the operator can adjust the voltage-to-current conversion ratio in the conversion circuit to control the output range of the target current signal Iout, thereby ensuring that the target current signal Iout is within a preset current range. This ensures that the target current signal Iout can be recognized and received by any industrial control equipment, and subsequent calculations and processing can be performed based on this target current signal indicating the concentration of fine particulate matter (PM2.5).

[0049] In one example, the preset current range is 4-20mA. Since 4-20mA analog input is a commonly used analog control method with good stability, reliability and high precision, it has been widely used in industrial control equipment. Therefore, this target current signal can be applied to a variety of industrial control equipment.

[0050] In one example, continue to refer to Figure 1 The processing circuit 11 has a control output terminal, a feedback input terminal, and a feedback output terminal; the PM2.5 concentration detection circuit 12 has a detection configuration terminal and a detection transceiver terminal.

[0051] The control output terminal is connected to the detection configuration terminal of the PM2.5 concentration detection circuit 12 to transmit the control signal SET. The control signal SET controls the switching between the start-up and standby states of the PM2.5 concentration detection circuit 12. The feedback input terminal is connected to the detection transceiver terminal of the PM2.5 concentration detection circuit 12 to receive the detection feedback signal UASRT1_RX generated by the PM2.5 concentration detection circuit 12 in the start-up state. The feedback output terminal is connected to the power distribution input terminal of the conversion circuit 13 to transmit the conversion voltage signal Vdac generated based on the detection feedback signal UASRT1_RX. This voltage-to-current conversion of the conversion voltage signal Vdac by the subsequent conversion circuit 13 generates the target current signal Iout.

[0052] In one example, continue to refer to Figure 1 As shown, the PM2.5 concentration detection circuit 12 is connected to the first power supply voltage signal V1, the processing circuit 11 is connected to the second power supply voltage signal V2, and the conversion circuit 13 is connected to the third power supply voltage signal V3. The first power supply voltage signal V1 is different from the second power supply voltage signal V2, and the third power supply voltage V3 can be the same as or different from the first power supply voltage signal V1.

[0053] In this example, the first supply voltage V1 powers the PM2.5 concentration detection circuit 12, the second supply voltage V2 powers the processing circuit 11, and the third supply voltage powers the conversion circuit 13. The first supply voltage V1, the second supply voltage V2, and the third supply voltage V3 can be voltages output from three different power sources, or signals output from various output nodes after multiple voltage divisions from a single power source.

[0054] In one example, refer to Figure 2As shown, the PM2.5 detection device 10 also includes a power supply configuration circuit 14. The input terminal of the power supply configuration circuit 14 is used to connect to a power supply 20. The power supply 20 has a high-level output terminal VIP and a low-level output terminal VIN. The high-level output terminal VIP outputs the original power supply signal V0. The first output terminal of the power supply configuration circuit 14 is connected to the PM2.5 concentration detection circuit 12 to transmit a first power supply voltage signal V1 generated based on the original power supply signal V0. The second output terminal of the power supply configuration circuit 14 is connected to the processing circuit 11 to transmit a second power supply voltage signal V2 generated based on the original power supply signal V0. The first power supply voltage signal V1 and the second power supply voltage signal V2 are different. The first power supply voltage signal supplies power to the PM2.5 concentration detection circuit 12, and the second power supply voltage signal V2 supplies power to the processing circuit 11. Preferably, the voltage value of the first power supply voltage signal V1 is 5V, the voltage value of the second power supply voltage signal V2 is 3.3V, and the voltage value of the third power supply voltage signal V3 is equal to the voltage value of the first power supply voltage signal V1, and the voltage value of the third power supply voltage signal V3 is 5V.

[0055] In one example, refer to Figure 3 As shown, the power supply configuration circuit 14 includes a power supply control chip U1. The input terminal IN of the power supply control chip (i.e., pin 3 of U1) serves as the input terminal of the power supply configuration circuit to receive the original power supply signal V0. The input terminal of the power supply configuration circuit is connected to the first output terminal so that the voltage value of the first power supply voltage signal V1 is equal to the voltage value of the original power supply signal V0. The ground terminal GND of the power supply control chip U1 (i.e., pin 1 of U1) is connected to the reference ground signal. The output terminal OUT of the power supply control chip (i.e., pin 2 of U1) serves as the second output terminal of the power supply configuration circuit 14. In this example, the first output terminal directly outputs the first power supply voltage signal V1, which has the same voltage value as the original power supply signal V0, and uses the first power supply voltage signal V1 to power the PM2.5 concentration detection circuit 12. The power supply control chip U1 modulates the original power supply signal V0 into a second power supply voltage signal V2, and uses the second power supply voltage signal V2 to power the processing circuit 11. Preferably, the voltage value of the first power supply voltage signal V1 is 5V, and the voltage value of the second power supply voltage signal is 3.3V. Figure 3 The winning bid is for 3V3), and the power distribution chip U1 is an LM1117-3.3 chip.

[0056] As a preferred example of the above, please refer to [the example above]. Figure 3As shown, the power supply configuration circuit 14 includes a first voltage-stabilizing capacitor C1, a second voltage-stabilizing capacitor C2, and a power distribution chip U1. One end of the first voltage-stabilizing capacitor C1 is connected to the input terminal IN of the power distribution chip U1, and the other end of the first voltage-stabilizing capacitor C1 is connected to a reference ground signal. One end of the second voltage-stabilizing capacitor C2 is connected to the output terminal OUT of the power distribution chip U1, and the other end of the second voltage-stabilizing capacitor is connected to a reference ground signal. The power supply configuration circuit 14 stabilizes the original power supply signal V0 input to the power supply control chip U1 through the first voltage-stabilizing capacitor C1, and stabilizes the second power supply voltage signal V2 through the second voltage-stabilizing capacitor C2, thereby improving the circuit's anti-interference capability. Preferably, the capacitance values ​​of the first voltage-stabilizing capacitor C1 and the second voltage-stabilizing capacitor C2 are 2.2uF.

[0057] In one example, the power supply configuration circuit 14 includes a sliding resistor. The first end of the sliding resistor serves as the input terminal of the power supply configuration circuit to receive the original power supply signal V0, the other end of the sliding resistor is grounded, and the slider contact of the sliding resistor serves as the output terminal of the power supply configuration circuit to output a second power supply voltage signal V2. Operators can adjust the voltage value of the second power supply voltage signal V2 by adjusting the slider contact of the sliding resistor.

[0058] In one example, refer to Figure 4 As shown, the processing circuit 11 includes a processor U2 and a third voltage regulator capacitor C3. The processor U2 has a power supply input port, a control output port, an information transmission port, an information reception port, and a feedback control port. The power supply input port includes the processor U2's VDD and VDDA pins, both used to connect to the second power supply voltage V2. The control output port is one PA pin of the processor U2, used to transmit the control signal SET. The information transmission port is another PA pin of the processor U2, used to transmit UASRT1_TX. The information reception port is yet another PA pin of the processor U2, used to receive the detection feedback signal UASRT1_RX. The feedback control port is yet another PA pin of the processor U2, used to transmit the converted voltage signal Vdac. The control output port, information transmission port, information reception port, and feedback control port all utilize PA pins in the processor U2. The PA pin used for the feedback control port must also function as DAC1.

[0059] Preferably, the processor U2 uses an APM32F051K8U6 with 32 pins. Pin 1 is VDD, pin 2 is PF0 / OSC_IN, pin 3 is PF1 / OSC_IN, pin 4 is RST, pin 5 is VDDA, pin 6 is PA0, pin 7 is PA1, pin 8 is PA2, pin 9 is PA3, pin 10 is PA4 / DAC1, pin 11 is PA5, pin 12 is PA6, pin 13 is PA7, pin 14 is PB0, pin 15 is PB1, pin 16 is PA0, pin 17 is VDD, and pin 18 is PA8. Figure 4 Pin 19 is used to transmit the control signal SET. Figure 4 Pin 20 is used for transmitting UASRT1_TX and is the PA10 pin. Figure 4 Pin 21 is used to transmit the detection feedback signal UASRT1_RX. Figure 4 Pin 22 is used to transmit the reset signal RST. Pin 23 is the SWDIO pin, pin 24 is the SWCLK pin, pin 25 is the PA15 pin, pin 26 is the PB3 pin, pin 27 is the PB4 pin, pin 28 is the PB5 pin, pin 29 is the PB6 pin, pin 30 is the PB7 pin, and pin 31 is the BOOT0 pin. Figure 4 (BOOT0 is connected to the reference ground signal), pin 32 is pin PB8. Datasheets for each pin of this processor U2 can be found on the following webpage:

[0060] https: / / item.szlcsc.com / 4012207.html?lcsc_vid=TllXAlxQRwdfVVAFRwALVgVURVMPAVRWRlNeBFJfFlgxVlNSQ1dcVldfQlVWVDsOAxUeFF5JWAIASQYPGQZABAsLWA%3D%3D.

[0061] One end of the third voltage-stabilizing capacitor C3 is connected to the power input port VDD, and the other end is connected to the reference ground signal. The processing circuit 11 stabilizes the second power supply voltage V2 input to the processor U2 through the third voltage-stabilizing capacitor C3, improving the anti-interference capability of powering the processor U2. Preferably, the capacitance of the third voltage-stabilizing capacitor C3 is 100nF.

[0062] In one example, continue to refer to Figure 4As shown, the PM2.5 concentration detection circuit 12 includes a PM2.5 sensor P1 and a fourth voltage-stabilizing capacitor C4. The PM2.5 sensor P1 has a power supply terminal, a setting terminal, a transmission transmitting terminal, and a transmission receiving terminal. The power supply terminal is the VCC pin of the PM2.5 sensor P1, which serves as the detection power supply terminal for the PM2.5 sensor P1 and is connected to the first power supply voltage V1. The setting terminal is the SET pin of the PM2.5 sensor P1, which serves as the detection configuration terminal for the PM2.5 sensor P1 and the control output port of the processor U2 in the processing circuit 11. Figure 4 The P2.5 sensor P1 is connected to the PA8 pin of U2 to receive the control signal SET. Based on this SET signal, it controls the P2.5 sensor P1 to switch from standby to startup or vice versa under the first power supply voltage V1. The receiving end is the RXD pin of the PM2.5 sensor P1 to receive the signal UASRT1_TX. The transmitting end is the TXD pin of the PM2.5 sensor P1, serving as the detection transceiver for the PM2.5 sensor P1. It is connected to the information receiving port PA10 of the processor U2 in the processing circuit 11 to transmit the detection feedback signal UASRT1_RX generated by the PM2.5 sensor P1 when it is in startup mode. Preferably, the PM2.5 sensor P1 uses a PMS9103M and has a VCC pin, GND pin, SET pin, RXD pin, TXD pin, RST pin, and two NC pins, with the GND pin connected to the reference ground signal. For the datasheet of each pin of the PM2.5 sensor P1, please refer to the following webpage:

[0063] https: / / img.dfrobot.com.cn / wiki / 5d09937f437c63049d98b469 / 25823b35228503f1bb09ee05eb43ce67.pdf

[0064] One end of the fourth voltage-stabilizing capacitor C4 is connected to the power supply terminal, and the other end is connected to the reference ground signal. The fourth voltage-stabilizing capacitor C4 stabilizes the first power supply voltage V1 that powers the PM2.5 sensor P1, improving the circuit's anti-interference capability. Preferably, the capacitance of the fourth voltage-stabilizing capacitor C4 is 2.2uF.

[0065] In one example, refer to Figure 5As shown, the conversion circuit 13 includes an adjustable resistor R0. One end of the adjustable resistor R0 is connected to the feedback output terminal of the processing circuit 11 to receive the converted voltage signal Vadj, and the other end of the adjustable resistor R0 is connected to the reference ground signal. The conversion circuit 13 uses the current flowing through the adjustable resistor R0 as the target current signal Iout. In this example, the operator can control the output range of the target current signal by adjusting the resistance value of the adjustable resistor R0 in the conversion circuit 13 (i.e., the voltage-to-current conversion ratio), thereby ensuring that the target current signal is within a preset current range and that the target current signal can be recognized and received by any industrial control equipment.

[0066] In another example, refer to Figure 6 As shown, the conversion circuit 13 includes a comparator sub-circuit 131, a control sub-circuit 132, and an output sub-circuit 133. The comparator sub-circuit 131, which operates under the third power supply voltage signal V3, has a first comparator input terminal, a second comparator input terminal, and a differential output terminal. The control sub-circuit 132 has a first terminal, a second terminal, and a control terminal.

[0067] The first comparison input terminal is connected to the processing circuit 11 to receive the converted voltage signal Vdac. The second comparison input terminal is connected to the input terminal of the output sub-circuit 133 to receive the target voltage signal Vout. The differential output terminal is connected to the control terminal of the control sub-circuit 132 to transmit the differential voltage signal ΔV generated based on the converted voltage signal Vdac and the target voltage signal Vout. The first terminal is used to receive the source voltage signal V4, and the second terminal is connected to the output sub-circuit 133 to receive the target voltage signal Vout. When the voltage value of the differential voltage signal ΔV reaches a preset value, the first terminal and the second terminal are turned on to charge the source voltage signal V4 to the target voltage signal Vout. The output sub-circuit 133 is used to convert the target voltage signal Vout into a target current signal Iout.

[0068] Initially, the target voltage signal Vout has a small voltage value. When the voltage difference between the converted voltage signal Vdac and the target voltage signal Vout is large, the voltage value of the voltage difference signal ΔV exceeds the preset value. The first terminal and the second terminal are turned on, and the source voltage signal V4 charges the target voltage signal Vout, causing the voltage value of the target voltage signal Vout to gradually increase. This reduces the voltage difference between the target voltage signal Vout and the converted voltage signal Vdac, causing the voltage value of the target voltage signal Vout to gradually approach that of the converted voltage signal Vdac.

[0069] As the voltage value of the differential pressure signal ΔV gradually falls below the preset value, the first and second terminals remain disconnected, the source voltage signal V4 no longer charges the target voltage signal Vout, and the voltage value of the target voltage signal Vout approaches stability. The output sub-circuit 133 directly performs voltage-to-current conversion on the target voltage signal Vout to obtain the target current signal Iout, and the current value of this target current signal also approaches stability.

[0070] This case involves gradually adjusting the target voltage signal Vout until its value approaches that of the converted voltage signal, compared to... Figure 5 In this circuit, the direct conversion of the voltage signal Vdac avoids the impact of the sudden voltage rise or fall caused by the sudden voltage adjustment of the processing circuit 11, thereby improving the anti-interference performance of the overall circuit and making the target current signal Iout, which points to the concentration of fine particulate matter, more accurate.

[0071] In one example, the voltage value of the third supply voltage signal V3 is the same as that of the first supply voltage signal V1, and the voltage value of the third supply voltage signal V3 is 5V. The fourth source voltage signal V4 is provided by a dedicated charging power supply and directly charges the target voltage signal Vout through the control sub-circuit 132.

[0072] In one example, continue to refer to Figure 6 As shown, the conversion circuit 13 also includes a conversion power supply circuit 134. (See reference) Figure 7 As shown, the conversion power supply circuit 134 has a first resistor R1. One end of the first resistor R1 serves as the input terminal of the conversion power supply circuit 134, used to connect to a charging power supply. The charging power supply has a low-level output terminal VON and a high-level output terminal VOP. The high-level output terminal VOP outputs the original voltage signal VCC, which is fed into the first resistor R1. The low-level output terminal VON is connected to a reference ground signal. The other end of the first resistor R1 serves as the output terminal of the conversion power supply circuit 135, used to connect to the first terminal of the control sub-circuit 132 to transmit the source voltage signal V4 generated based on the original voltage signal VCC. The conversion power supply circuit 134 transmits electrical energy from the charging power supply to the first terminal via the first resistor R1, thereby realizing, under the control of the control sub-circuit 132, the charging power supply charges the target voltage signal Vout through the conversion power supply circuit 134 with the source voltage signal V4. The first resistor R1 serves as a protective resistor to extend the circuit's lifespan. Preferably, the resistance value of the first resistor R1 is 330Ω.

[0073] In one example, continue to refer to Figure 7As shown, the comparator circuit 131 includes an amplifier U3, a second resistor R2, a third resistor R3, and a fifth voltage-stabilizing capacitor C5. The positive input terminal of amplifier U3 is connected to one end of the second resistor R2, and the other end of the second resistor R2 serves as the first comparator input terminal to receive the conversion voltage signal Vdac. The negative input terminal of amplifier U3 serves as the second comparator input terminal to receive the target voltage signal Vout. The positive power supply terminal of amplifier U3 is connected to the third power supply voltage signal V3. The negative power supply terminal of amplifier U3 is connected to the reference ground signal. The output terminal of amplifier U3 is connected to one end of the third resistor R3, and the other end of the third resistor R3 serves as the differential output terminal to output the voltage difference signal ΔV. One end of the fifth voltage-stabilizing capacitor C5 is connected to the positive power supply terminal of amplifier U3, and the other end of the fifth voltage-stabilizing capacitor C5 is connected to the reference ground signal.

[0074] Amplifier U3 operates under the third supply voltage signal V3. Amplifier U3 receives the converted voltage signal Vdac through the second resistor R2, and generates a differential voltage signal ΔV based on the voltage difference between the converted voltage signal Vdac and the target voltage signal Vout, which is then output through the third resistor R3. The fifth voltage regulator capacitor C5 regulates the converted voltage signal Vdac to prevent sudden voltage changes in Vdac from damaging amplifier U3 in comparator circuit 131. Preferably, amplifier U3 uses an LTA8091, the third supply voltage signal V3 is 5V, the resistance of the second resistor R2 and the third resistor R3 is 100Ω, and the capacitance of the fifth voltage regulator capacitor C5 is 100nF.

[0075] In one example, continue to refer to Figure 7 As shown, the control sub-circuit 132 includes a semiconductor field-effect transistor (SFET) Q1. The gate of SFET Q1 serves as the control terminal, the source of SFET Q1 serves as the second terminal, and the drain of SFET Q1 serves as the first terminal. The gate of SFET Q1 is connected to a differential voltage signal ΔV. When the voltage value of the differential voltage signal ΔV reaches a preset value, the first terminal and the second terminal are connected, causing the source voltage signal V4 to charge the target voltage signal Vout. The voltage value of the target voltage signal Vout gradually approaches the conversion voltage signal Vdac, and the voltage value of the differential voltage signal ΔV decreases. Preferably, the SFET Q1 is an AO3400 NMOS transistor. Alternatively, the control sub-circuit 132 can also be implemented using a relay or other touch switch. The control terminal is connected to the differential voltage signal, the first terminal is connected to the source voltage signal V4, and the second terminal is connected to the target voltage signal Vout. When the voltage value of the differential voltage signal ΔV reaches a preset value, the first terminal and the second terminal are connected.

[0076] In one example, continue to refer to Figure 7As shown, the output sub-circuit 133 includes a fourth resistor R4. The first end of the fourth resistor R4 serves as the input terminal of the output sub-circuit to connect to the target voltage signal Vout. The other end of the fourth resistor R4 is connected to the reference ground signal. The resistance value of the fourth resistor R4 is adjustable. The current flowing through the fourth resistor R4 serves as the target current signal Iout.

[0077] The output sub-circuit 133 converts the target voltage signal Vout into a target current signal Iout through the fourth resistor R4 and outputs it. By adjusting the resistance value of the fourth resistor, the current value range of the output target current signal Iout can be changed, making the target current signal Iout suitable for various industrial control equipment. Furthermore, this invention generates the target current signal Iout using the target voltage signal Vout, which, compared to directly using the converted voltage signal Vdac to generate the target current signal Iout, avoids the impact interference caused by the instantaneous voltage value change of the converted voltage signal Vdac, thus improving the overall output accuracy.

[0078] The above description of the embodiments is intended to enable those skilled in the art to understand and apply this application. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without creative effort. Therefore, this application is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope and spirit of this application are within the scope of this application.

Claims

1. A PM2.5 detection device, characterized in that, It includes a PM2.5 concentration detection circuit, a processing circuit, and a conversion circuit. The PM2.5 concentration detection circuit is connected to the processing circuit to transmit a detection feedback signal generated in the start-up state. The processing circuit is connected to the conversion circuit to transmit a conversion voltage signal generated based on the detection feedback signal. The conversion circuit is used to convert the conversion voltage signal into a target current signal, and the current value of the target current signal is within a preset current range.

2. The apparatus as claimed in claim 1, characterized in that, The preset current range is 4-20mA.

3. The apparatus as described in claim 1, characterized in that, The PM2.5 concentration detection circuit has a detection configuration terminal and a detection transceiver terminal, and the processing circuit has a control output terminal, a feedback input terminal, and a feedback output terminal. The detection configuration terminal is connected to the control output terminal to receive control signals from the processing circuit, and the PM2.5 concentration detection circuit switches to the start state according to the control signal; the detection transceiver terminal is connected to the feedback input terminal to transmit the detection feedback signal generated by the PM2.5 concentration detection circuit in the start state; the feedback output terminal is connected to the input terminal of the conversion circuit to transmit the conversion voltage signal generated according to the detection feedback signal, and the output terminal of the conversion circuit outputs the target current signal.

4. The apparatus as claimed in claim 1, characterized in that, The conversion circuit includes a comparator subcircuit, a control subcircuit, and an output subcircuit. The comparator subcircuit has a first comparator input terminal, a second comparator input terminal, and a differential output terminal. The control subcircuit has a first terminal, a second terminal, and a control terminal. The first comparison input terminal is connected to the processing circuit to receive the converted voltage signal, the second comparison input terminal is connected to the input terminal of the output sub-circuit to receive the target voltage signal, and the differential output terminal is connected to the control terminal of the control sub-circuit to transmit the differential voltage signal generated based on the converted voltage signal and the target voltage signal. The first terminal is used to receive the source voltage signal, and the second terminal is connected to the output sub-circuit to receive the target voltage signal. When the voltage value of the differential voltage signal reaches a preset value, the first terminal and the second terminal are turned on to charge the target voltage signal from the source voltage signal. The output sub-circuit is used to convert the target voltage signal into the target current signal.

5. The apparatus as described in claim 4, characterized in that, The conversion circuit further includes a conversion power supply circuit having a first resistor, one end of which is used to connect to a charging power supply (VCC) to access the original voltage signal, and the other end of which is used to connect to the first end to transmit the source voltage signal generated according to the original voltage signal.

6. The apparatus as claimed in claim 4, characterized in that, The comparator circuit includes an amplifier (U3), a second resistor (R2), and a third resistor (R3). The positive input terminal of the amplifier is connected to one end of the second resistor, and the other end of the second resistor serves as the first comparator input terminal. The negative input terminal of the amplifier serves as the second comparator input terminal. The positive power supply terminal of the amplifier is connected to a third power supply voltage signal, and the negative power supply terminal of the amplifier is connected to a reference ground signal. The output terminal of the amplifier is connected to one end of the third resistor, and the other end of the third resistor serves as the differential output terminal.

7. The apparatus as claimed in claim 6, characterized in that, The comparator circuit also includes a fifth voltage regulator capacitor (C5), one end of which is connected to the positive power supply terminal of the amplifier, and the other end of which is connected to the reference ground signal.

8. The apparatus as claimed in claim 4, characterized in that, The control sub-circuit includes a semiconductor field-effect transistor (Q1), with the gate of the semiconductor field-effect transistor serving as the control terminal, the source of the semiconductor field-effect transistor serving as the second terminal, and the drain of the semiconductor field-effect transistor serving as the first terminal.

9. The apparatus as claimed in claim 4, characterized in that, The output sub-circuit includes a fourth resistor. The first end of the fourth resistor serves as the input terminal of the output sub-circuit to receive the target voltage signal. The other end of the fourth resistor is connected to a reference ground signal. The resistance value of the fourth resistor is adjustable. The current flowing through the fourth resistor serves as the target current signal.

10. The apparatus as claimed in claim 4, characterized in that, The device further includes a power supply configuration circuit. The input terminal of the power supply configuration circuit is used to connect to a power supply (VIP) to receive the original power supply signal. The first output terminal of the power supply configuration circuit is connected to the PM2.5 concentration detection circuit to transmit a first power supply voltage signal (V1) generated based on the original power supply signal. The second output terminal of the power supply configuration circuit is connected to the processing circuit to transmit a second power supply voltage signal (V2) generated based on the original power supply signal. The first power supply voltage signal and the second power supply voltage signal are different. The first power supply voltage signal powers the PM2.5 concentration detection circuit, and the second power supply voltage signal powers the processing circuit.

11. The apparatus as claimed in claim 10, characterized in that, The power supply configuration circuit includes a power supply control chip. The input terminal of the power supply control chip serves as the input terminal of the power supply configuration circuit to receive the original power supply signal. The input terminal of the power supply configuration circuit is connected to the first output terminal so that the voltage value of the first power supply voltage signal is equal to the voltage value of the original power supply signal. The ground terminal of the power supply control chip is connected to a reference ground signal. The output terminal of the power supply control chip serves as the second output terminal of the power supply configuration circuit. The voltage value of the first power supply voltage signal is 5V, and the voltage value of the second power supply voltage signal is 3.3V.

12. The apparatus as claimed in claim 11, characterized in that, The power supply configuration circuit also includes a first voltage-stabilizing capacitor and a second voltage-stabilizing capacitor. One end of the first voltage-stabilizing capacitor is connected to the input terminal of the power distribution chip, and the other end of the first voltage-stabilizing capacitor is connected to a reference ground signal. One end of the first voltage-stabilizing capacitor is connected to the output terminal of the power distribution chip, and the other end of the first voltage-stabilizing capacitor is connected to a reference ground signal.

13. The apparatus as claimed in claim 10, characterized in that, The processing circuit includes a processor and a third voltage-stabilizing capacitor. The power supply input port of the processor is used to connect to the second power supply voltage signal. One end of the third voltage-stabilizing capacitor is connected to the power supply input port, and the other end of the third voltage-stabilizing capacitor is connected to a reference ground signal. The PM2.5 concentration detection circuit includes a PM2.5 sensor and a fourth voltage-stabilizing capacitor. The power supply terminal of the PM2.5 sensor is used to connect to the first power supply voltage signal. One end of the fourth voltage-stabilizing capacitor is connected to the power supply terminal, and the other end of the fourth voltage-stabilizing capacitor (C4) is connected to the reference ground signal.

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