High-precision dust diameter measuring method and system based on automatic phase locking and temperature compensation

Abstract

The invention provides a high-precision dust diameter measuring method and system based on automatic phase locking and temperature compensation, and the method comprises the following steps: providing a power supply and a control signal for a laser head based on a laser control circuit, and controlling the laser head to emit laser to dust; according to the invention, the diameter of each piece of dust is automatically tracked and recorded, and then the diameter and the weight of each piece of dust are independently calculated, so that errors caused by neglecting the diameter difference of the dust in an interval are avoided, and the measurement accuracy is greatly improved; measurement precision is jointly guaranteed through stable power supply of the laser control circuit, accurate conversion of the photoelectric signal conversion circuit, effective processing of signals with different intensities by the amplification circuit, accurate position monitoring of the phase automatic tracking circuit, stable level holding of the phase holding circuit, high-precision analog-to-digital conversion and a scientific conversion relation. Through the temperature compensation circuit, the measurement accuracy can be ensured in different temperature environments, so that dust detection is more reliable in different temperature environments.

Description

Technical Field

[0001] The present invention relates to the technical field of dust detection, and particularly to a high-precision dust diameter measurement method and system based on automatic phase-locking and temperature compensation. Background Art

[0002] Dust detection plays a crucial role in many fields such as environmental monitoring, industrial production, and medical and health. In environmental monitoring, accurately detecting parameters such as the concentration and diameter of dust in the air helps to evaluate air quality and provides data support for the formulation and implementation of environmental protection policies; in industrial production, effective detection of dust can prevent safety accidents such as dust explosions and ensure that product quality is not affected by dust pollution; in the medical and health field, detecting the dust content and particle size distribution in the air can provide a reference basis for disease prevention and control. However, existing dust detection technologies have many defects.

[0003] Common detection methods generally only set several fixed channels, such as the six channels of 0.3um, 0.5um, 1.0um, 2.5um, 5um, and 10um. When calculating the dust weight of a certain channel (such as the 2.5um channel), it is based on the number of dust particles in a specific interval (such as 1.0um - 2.5um) and multiplied by a constant K value for calculation. However, this method does not consider the difference in dust diameters within the interval, resulting in a large error in the calculated dust weight, unable to accurately reflect the actual situation, and difficult to meet the application scenario requirements with increasing dust detection accuracy. Therefore, a high-precision dust diameter measurement method and system based on automatic phase-locking and temperature compensation are proposed. Summary of the Invention

[0004] In view of this, embodiments of the present invention hope to provide a high-precision dust diameter measurement method and system based on automatic phase-locking and temperature compensation to solve or alleviate the technical problems existing in the prior art and at least provide a beneficial choice.

[0005] To solve the above technical problems, a technical solution adopted by this application is: a high-precision dust diameter measurement method based on automatic phase-locking and temperature compensation, including the following steps:

[0006] Step 1: Provide power supply and control signals for the laser head based on the laser control circuit, and control the laser head to emit laser towards the dust;

[0007] Step 2: Power the photoelectric sensor through the photoelectric signal conversion circuit, and convert the laser scattered by the dust into an initial electrical signal;

[0008] Step 3: Amplify the initial electrical signal based on the amplifier circuit and convert it into a voltage signal for output;

[0009] Step 4: Automatically track the position of the dust in the housing based on the phase automatic tracking circuit and send a measurement signal to the microcontroller unit;

[0010] Step 5: Hold the measurement signal as a level signal based on the phase holding circuit;

[0011] Step 6: After receiving the measurement signal, the microcontroller unit converts the held level signal through the internal analog-to-digital conversion module, converting the level signal representing the dust diameter into a diameter value;

[0012] Step 7: The microcontroller unit converts the diameter value converted by the analog-to-digital conversion module into the dust weight and the number of particles one by one according to the pre-calibrated conversion relationship of dust characteristics and measurement environmental factors.

[0013] Preferably as a further improvement of this technical solution, in Step 1, the laser control circuit includes a constant current source module. If the control signal is 1, the constant current source module outputs a constant current to drive the laser head to work; if the control signal is 0, the constant current source module is turned off and the laser head stops emitting laser; the constant current source module provides a 5V power supply to make the constant current source module output a constant current.

[0014] Preferably as a further improvement of this technical solution, in Step 2, the conversion circuit of the optoelectronic signal supplies power to the optoelectronic sensor with a 3.3V voltage output by the constant voltage IC; after converting the laser scattered by the dust into an initial electrical signal, the initial electrical signal is filtered to remove the noise interference in the signal.

[0015] Preferably as a further improvement of this technical solution, in Step 3, the amplifier circuit includes two operational amplifiers and a signal mixing module. The two operational amplifiers amplify the initial electrical signal by different multiples respectively, and the signal mixing module mixes the amplified initial electrical signals and converts them into a voltage signal for output, so that signals with different intensities can be effectively processed within a range.

[0016] Preferably as a further improvement of this technical solution, in Step 6, after the analog-to-digital conversion module converts the held level signal, the microcontroller unit issues a clear signal to clear the held level signal.

[0017] Preferably as a further improvement of this technical solution, in Step 5, the phase holding circuit uses the principle of capacitor charge storage to hold the measurement signal as a level signal; the phase holding circuit has a temperature compensation function.

[0018] As a further preference of this technical solution, in step seven, the pre-calibrated conversion relationship between dust characteristics and measurement environmental factors is obtained through multiple measurement experiments on standard dust samples with various known diameters, densities, and shapes under different environmental conditions.

[0019] To solve the above technical problems, another technical solution adopted by this application is: a high-precision dust diameter measurement system based on automatic phase locking and temperature compensation. The system includes: a laser emission module, a photoelectric conversion module, a signal amplification module, a phase tracking module, a phase holding module, a data processing module, and a conversion module;

[0020] The laser emission module is configured to provide power and control signals to the laser head based on a laser control circuit, and control the laser head to emit laser towards the dust;

[0021] The photoelectric conversion module is configured to supply power to the photoelectric sensor through a photoelectric signal conversion circuit, and convert the laser scattered by the dust into an initial electrical signal;

[0022] The signal amplification module is configured to amplify the initial electrical signal based on an amplification circuit and convert it into a voltage signal for output;

[0023] The phase tracking module is configured to automatically track the position of the dust in the housing based on a phase automatic tracking circuit, and send a measurement signal to the micro control unit;

[0024] The phase holding module is configured to hold the measurement signal as a level signal based on a phase holding circuit;

[0025] The data processing module is configured to, after receiving the measurement signal from the micro control unit, convert the held level signal through its internal analog-to-digital conversion module, and convert the level signal representing the dust diameter into a diameter value;

[0026] The conversion module is configured to convert the diameter values converted by the analog-to-digital conversion module by the micro control unit into dust weights and particle numbers one by one according to the pre-calibrated conversion relationship considering dust characteristics and measurement environmental factors.

[0027] As a further preference of this technical solution, the system further includes a storage and display module. The storage and display module is configured to store the measured dust diameter, weight, and particle number data. At the same time, the storage and display module displays these data in an intuitive manner.

[0028] As a further preference of this technical solution, the system is also equipped with multiple communication interfaces. The multiple communication interfaces include an RS-485 interface, a Bluetooth interface, and a Wi-Fi interface.

[0029] Due to the adoption of the above technical solutions in the embodiments of the present invention, it has the following advantages:

[0030] 1. The present invention automatically tracks and records the diameter of each dust particle, and then calculates the diameter and weight of each dust particle separately, breaking the traditional method of only calculating the number of particles in a certain interval and then multiplying by a coefficient to calculate the dust weight, avoiding errors caused by ignoring the diameter differences of dust particles in the interval, and greatly improving the measurement accuracy;

[0031] 2. The present invention jointly ensures the measurement accuracy through the stable power supply of the laser control circuit, the accurate conversion of the photoelectric signal conversion circuit, the effective processing of signals with different intensities by the amplification circuit, the accurate position monitoring of the phase automatic tracking circuit, the stable level maintenance of the phase holding circuit, as well as high-precision analog-to-digital conversion and scientific conversion relationships;

[0032] 3. The present invention uses a temperature compensation circuit. For example, the phase holding circuit utilizes the characteristic that the diode voltage drop changes with temperature to achieve temperature compensation, ensuring the measurement accuracy in different temperature environments and making the dust detection more reliable in different temperature environments.

[0033] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0035] Figure 1 It is a schematic flowchart of the high-precision dust diameter measurement method based on automatic phase locking and temperature compensation of the present invention;

[0036] Figure 2 It is a schematic diagram of the functional modules of the high-precision dust diameter measurement system based on automatic phase locking and temperature compensation of the present invention;

[0037] Figure 3 It is a schematic diagram of the laser control circuit provided by the embodiments of the present invention;

[0038] Figure 4 It is a schematic diagram of the photoelectric conversion circuit provided by the embodiments of the present invention;

[0039] Figure 5Schematic diagram of the signal amplification and mixing circuit provided by the embodiment of the present invention;

[0040] Figure 6 Schematic diagram of the phase automatic tracking circuit and the phase level holding and clearing circuit provided by the embodiment of the present invention;

[0041] Figure 7 Functional framework diagram of the processor provided by the embodiment of the present invention. Detailed implementation manners

[0042] The embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings.

[0043] It should be clear that the embodiments of the present disclosure are described through specific specific examples below. Those skilled in the art can easily understand other advantages and effects of the present disclosure from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific implementation manners. Various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present disclosure without creative efforts belong to the scope of protection of the present disclosure.

[0044] It should be noted that the following describes various aspects of the embodiments within the scope of the appended claims. It should be obvious that the aspects described herein can be embodied in a wide variety of forms, and any specific structure and / or function described herein is illustrative only. Based on the present disclosure, those skilled in the art should understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects described herein can be used to implement the device and / or practice the method. In addition, this device and / or this method can be implemented using other structures and / or functions in addition to one or more of the aspects described herein.

[0045] It should also be noted that the diagrams provided in the following embodiments only illustrate the basic concept of the present disclosure in a schematic manner. The diagrams only show the components related to the present disclosure rather than being drawn according to the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in its actual implementation can be an arbitrary change, and the component layout type may also be more complex.

[0046] In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0047] Embodiment 1

[0048] Figure 1 is a schematic flowchart of a high-precision dust diameter measurement method based on automatic phase-locking and temperature compensation according to an embodiment of the present invention. It should be noted that if there are substantially the same results, the method of the present application is not limited to Figure 1 the process sequence shown. As Figure 1 shown: A high-precision dust diameter measurement method based on automatic phase-locking and temperature compensation includes the following steps:

[0049] Step 1: Provide power and control signals to the laser head based on the laser control circuit, and control the laser head to emit laser light towards the dust;

[0050] Specifically, first, select a constant current source IC (such as U4) as the core component of the laser control circuit. It has the characteristic of stable current output, which can ensure that the laser head obtains a stable driving current. Select a suitable model for the laser head (such as laser LED J2), and determine its power, wavelength and other parameters according to the measurement requirements. For example, in dust detection, it is necessary to ensure good scattering effect and penetration ability in the dust environment;

[0051] Then, connect a stable 5V power supply to the VCC pin of the constant current source IC. This is the energy source of the entire circuit. At the power input port, connect a filter capacitor (such as C2). Its function is to filter out the noise and interference signals in the power supply, prevent these interferences from affecting the normal operation of the constant current source IC, and thus ensure that the current output from the VOUT pin is pure and stable;

[0052] Next, connect the control signal EN to the corresponding control pin of the constant current source IC. When the EN signal is at a high level, the constant current source IC is activated, and the VOUT pin outputs a constant current; when the EN signal is at a low level, the constant current source IC is turned off, and the VOUT pin stops outputting current, so as to achieve precise control of the working state of the laser head;

[0053] When the control signal EN is 1 (i.e., high level), the internal circuit of the constant current source IC starts, so that the VOUT pin outputs a constant current. For example, if the design parameters of the constant current source IC make the VOUT pin output a constant current of 30mA, this current is sufficient to drive the laser head to emit light stably and ensure the stability of the laser emission power, providing a stable light source for subsequent dust detection;

[0054] When the control signal EN is 0 (i.e., low level), the control circuit inside the constant current source IC cuts off the current output path, the VOUT pin no longer outputs current, and the laser head turns off the light source. This design can not only effectively reduce the system power consumption and extend the service life of the device, but also avoid energy waste and device loss when laser emission is not required;

[0055] In the control software of the entire measurement system, write the corresponding code logic to control the level state of the EN signal. For example, in the system initialization stage, set the EN signal to low level to ensure that the laser head is in the off state; when dust measurement is required, set the EN signal to high level through software instructions to start the laser head to emit laser; the software also needs to set the collaborative working logic between the EN signal and other modules. When the phase automatic tracking circuit completes the tracking of the dust position and is ready for measurement, the software receives the corresponding feedback signal, and then controls the EN signal to remain high level to make the laser head continuously emit laser until this measurement is completed, and then control the EN signal to become low level according to the measurement process to turn off the laser head and wait for the next measurement instruction.

[0056] Step 2: Power the photoelectric sensor through the photoelectric signal conversion circuit, and convert the laser scattered by the dust into an initial electrical signal;

[0057] Specifically, first, select a suitable constant voltage IC, such as the constant voltage IC with the model number LM1117-3.3, which can provide a stable output voltage of 3.3V. Connect the input pin of the constant voltage IC to the power supply module of the system to ensure that the input voltage is within its acceptable range, for example, connect to a 5V power supply. Then, connect the output pin VOUT of the constant voltage IC to the power supply pin of the photoelectric sensor through a wire to provide a stable 3.3V working voltage for the photoelectric sensor. During the connection process, pay attention that the polarity cannot be reversed, and appropriate filter capacitors are connected in parallel at the power input and output ends respectively. For example, connect a 10μF electrolytic capacitor and a 0.1μF ceramic capacitor in parallel at the input pin, and connect a 4.7μF electrolytic capacitor and a 0.1μF ceramic capacitor in parallel at the output pin to filter out the noise in the power supply and ensure the stability of the power supply;

[0058] Next, select a suitable photoelectric sensor according to the measurement requirements. For example, select a silicon photodiode sensitive to a specific wavelength laser as the photoelectric sensor, and install the photoelectric sensor near the dust detection area to ensure that it can effectively receive the laser scattered by the dust. During installation, pay attention to avoiding the sensor from being affected by mechanical vibration, electromagnetic interference, etc. A shielding cover can be used to protect the sensor, and the shell of the sensor is grounded to reduce external interference;

[0059] Subsequently, connect the signal output pin of the photoelectric sensor to the subsequent signal processing circuit. If an operational amplifier is used for signal conversion, connect the output pin of the sensor to the inverting input terminal of the operational amplifier (such as U3_A). Connect a feedback resistor Rf between the inverting input terminal and the output terminal of the operational amplifier. At the same time, connect a resistor R1 to ground at the inverting input terminal. Calculate the resistance values of Rf and R1 according to the required amplification factor. For example, if the desired amplification factor is 100, Rf can be selected as 100 kΩ and R1 as 1 kΩ. Connect the non-inverting input terminal of the operational amplifier to a stable reference voltage source, such as 1.65 V (obtained from the 3.3 V power supply through resistor voltage division) to ensure the normal operation of the operational amplifier;

[0060] When the laser emitted by the laser emission module irradiates the area containing dust, the dust scatters the laser. After the photoelectric sensor receives the scattered laser, the internal photoelectric effect converts photons into electron-hole pairs, thereby generating a weak current signal. This weak current signal passes through the connected operational amplifier circuit. According to the working principle of the operational amplifier, the current signal is converted into a voltage signal. Assuming the weak current generated by the photoelectric sensor is I, according to Ohm's law and the amplification formula of the operational amplifier, the output voltage Vout = -I × Rf (the negative sign indicates that the output signal is out of phase with the input signal), thus realizing the conversion from optical signal to electrical signal;

[0061] To remove the noise interference in the converted initial electrical signal, connect a filter circuit at the output terminal of the operational amplifier. An RC filter circuit can be used. Select appropriate resistance R and capacitance C. For example, select resistance R as 10 kΩ and capacitance C as 0.1 μF. Connect the resistor R in series at the output terminal of the operational amplifier. One end of the capacitor C is connected between the resistor R and the subsequent circuit, and the other end is grounded. In this way, the high-frequency noise signal will bypass to the ground through the capacitor C, while the low-frequency effective signal will smoothly pass through the resistor R and be transmitted to the subsequent circuit, thereby improving the signal quality;

[0062] The weak voltage signal after filtering is connected to the input terminal of the next-stage signal amplification module through a wire. During the connection process, ensure reliable circuit connection and avoid problems such as poor soldering and short circuits. At the same time, to reduce interference during signal transmission, a shielded wire can be used for connection and the shielding layer is grounded to stably transmit the processed initial electrical signal to the subsequent signal amplification module for further processing.

[0063] Step 3: Amplify the initial electrical signal based on the amplifier circuit and convert it into a voltage signal for output;

[0064] Specifically, calculate the required amplification factor according to the initial amplitude of the initial electrical signal and the input requirements of the subsequent circuit;

[0065] For example, if the initial signal amplitude is between 1 - 10 mV and the subsequent circuit requires an input signal between 0.5 - 3 V, the total amplification factor can be set to 500 times;

[0066] Since the amplifier circuit consists of two operational amplifiers, the amplification factor needs to be reasonably distributed. Two - stage amplification can be adopted. For example, the amplification factor of the first - stage operational amplifier U3_B is set to 10 times, and the amplification factor of the second - stage operational amplifier U3_C is set to 50 times. In this way, through two - stage amplification, the total amplification factor reaches 500 times;

[0067] Build an amplifier circuit composed of two operational amplifiers and a signal mixing module according to the designed amplification factor. Taking U3_B as an example, connect its inverting input terminal to the initial electrical signal from the optoelectronic conversion module, connect the non - inverting input terminal to ground or a reference voltage, connect a feedback resistor Rf1 between the inverting input terminal and the output terminal, and connect an input resistor R1 between the input signal terminal and ground. Calculate the resistance values according to the amplification factor formula. For example, when the amplification factor is 10 times, if R1 is selected as 10 kΩ, then Rf1 is selected as 100 kΩ; similarly, build the amplifier circuit of U3_C;

[0068] Connect the signals amplified by U3_B and U3_C to the signal mixing module. The signal mixing module consists of resistors R12 and R13. Mix the amplified signals according to the principle of resistor voltage division; for example, R12 is set to 10 kΩ and R13 is set to 20 kΩ. By adjusting the ratio of these two resistors, mix the amplified signals in a certain proportion and finally output from the S_OUT port;

[0069] Select operational amplifiers with low noise and high gain - bandwidth product, such as LM358 or OP - 07, etc. These operational amplifiers can effectively amplify the initial electrical signal and introduce less noise during the amplification process, meeting the requirements of high - precision measurement;

[0070] Use metal - film resistors with higher precision, such as 1% precision resistors, to ensure the accuracy of the amplification factor; select capacitors with good stability and low leakage, such as ceramic capacitors, and connect appropriate decoupling capacitors at the power supply pins to filter out the noise in the power supply and ensure the stable operation of the operational amplifier;

[0071] When designing the circuit board, layout the components reasonably, try to shorten the signal transmission path, reduce signal interference, place the power supply pins of the operational amplifier close to the power supply, and separate the input and output pins to avoid crosstalk between signals;

[0072] The input end of the amplifier circuit is reliably connected to the output end of the photoelectric conversion module to ensure the smooth transmission of the initial electrical signal. When connecting, pay attention to the signal polarity and level matching to avoid signal distortion or loss. The output end S_OUT of the amplifier circuit is connected to the subsequent phase tracking module, providing an amplified and converted voltage signal to meet its requirements for signal amplitude and quality, so as to accurately track the dust position.

[0073] Step 4: Automatically track the position of the dust in the housing based on the phase automatic tracking circuit and send a measurement signal to the MCU (Microcontroller Unit).

[0074] Specifically, according to the selected design scheme of the phase automatic tracking circuit, build the corresponding hardware circuit, and accurately connect each component in the circuit, such as sensors, operational amplifiers, comparators, etc., according to the design schematic diagram. After the construction is completed, perform initialization settings on the circuit, such as setting the working parameters of the operational amplifier, the threshold of the comparator, etc., to ensure that the circuit is in a normal working state.

[0075] After the laser emission module emits laser light to the dust, the photoelectric conversion module converts the laser light scattered by the dust into an initial electrical signal. These initial electrical signals are input into the phase automatic tracking circuit. The sensor in the circuit is responsible for collecting signals related to the dust position, such as light intensity signals, phase signals, etc. The collected signals are amplified by an operational amplifier to increase the signal amplitude for better processing by subsequent circuits. Then, a filter is used to filter the amplified signal to remove noise and interference in the signal, obtaining a relatively pure signal related to the dust position.

[0076] The processed signal enters the position judgment circuit, usually implemented by components such as comparators. The processed signal is compared with a preset threshold. When the dust receives the maximum energy at the center of the laser light illumination, the signal characteristics at this time will meet specific conditions. For example, the light intensity signal reaches the maximum value or the phase signal is within a specific phase range. The comparator outputs a corresponding level change. According to the output result of the comparator, the working state of the laser emission module or other related components (such as mirrors, etc.) is adjusted through the feedback control circuit to achieve real-time tracking of the dust position and ensure that the dust is always near the optimal detection position.

[0077] When it is judged that the dust receives the maximum energy at the center of the laser light illumination, the phase automatic tracking circuit sends a measurement signal to the MCU. This measurement signal can be a level jump signal, such as changing from a low level to a high level, or a pulse signal with a specific frequency. The measurement signal is accurately transmitted to the corresponding pin of the MCU through the connection line, triggering the MCU to perform subsequent data acquisition and processing work.

[0078] According to the specific requirements of dust detection and environmental characteristics, select a suitable sensor to collect signals related to the dust position. For example, if the dust position is judged by the change in light intensity, a high-sensitivity photodiode can be selected as the sensor; if the phase difference is used to track the position, a sensor chip with phase detection function can be selected to ensure that the performance indicators such as the response speed and sensitivity of the sensor can meet the requirements of the system for the tracking accuracy and real-time performance of the dust position;

[0079] Select a low-noise and high-gain operational amplifier to amplify the weak signals collected by the sensor. For example, use high-precision operational amplifiers such as OP-07, which have the advantages of low offset voltage and low noise, can effectively amplify weak signals and reduce signal distortion. For the comparator, select a model with a fast response speed and high threshold accuracy, such as LM339, which can quickly and accurately compare the processed signal with the threshold and output a clear level signal;

[0080] During the circuit board design process, reasonably arrange each component. Place the sensor at a position where it can best receive signals related to the dust position, and try to reduce the interference in the signal transmission path. Components such as operational amplifiers and comparators should be close to the sensor to shorten the signal transmission distance, reduce signal attenuation and interference. At the same time, shield the sensitive signal lines to avoid interference from other strong electrical signals;

[0081] The phase automatic tracking circuit cooperates closely with the laser emission module. When the phase automatic tracking circuit detects a change in the dust position, it timely sends an adjustment signal to the laser emission module, so that the laser emission module can adjust parameters such as the emission angle or power of the laser according to the dust position, ensuring that the laser can always effectively irradiate the dust and improving the detection accuracy;

[0082] The phase automatic tracking circuit is connected to the photoelectric conversion module to receive the initial electrical signal output by the photoelectric conversion module as the original signal source for tracking the dust position. The connection with the photoelectric conversion module should ensure the stability and accuracy of signal transmission, avoid signal loss or distortion. Shielded wires can be used for connection, and appropriate filtering and buffering circuits can be set at the interface to enhance the anti-interference ability of the signal;

[0083] The phase automatic tracking circuit is connected to the MCU to accurately transmit the measurement signal to the MCU. In order to ensure that the MCU can correctly identify and process the measurement signal, appropriate level conversion circuits (if the levels do not match) and signal isolation circuits (to prevent interference) need to be set on the connection line.

[0084] Step Five: Based on the phase holding circuit, hold the measurement signal as a level signal;

[0085] Specifically, a circuit is built based on the principle of capacitive charge storage. The measurement signal output by the phase automatic tracking circuit is connected to the circuit composed of diode D2 and capacitor C7. When the measurement signal (S_OUT level) rises to the highest level, this high level charges capacitor C7 through diode D2. Assuming the highest level of S_OUT is 3V and the initial voltage of capacitor C7 is 0V, due to the unidirectional conductivity of the diode, the current flows from the measurement signal terminal through diode D2 to capacitor C7, causing the voltage across capacitor C7 to gradually increase and finally reach a level close to 3V. At this time, capacitor C7 stores the high-level state of the measurement signal and holds the measurement signal;

[0086] When the S_OUT level drops and is lower than the level stored in C7, for example, when the S_OUT level drops to 2V, the AD_EN signal in the circuit reverses, changing from 0 level to 1 level. This changing AD_EN signal is sent to the MCU as a trigger signal to notify the MCU to perform analog-to-digital conversion. After receiving the AD_EN signal, the MCU starts to perform analog-to-digital conversion on AD_IN (the analog-to-digital conversion input pin connected to the level stored in capacitor C7), converting the level signal stored in capacitor C7 representing the dust diameter into a digital signal;

[0087] After the analog-to-digital conversion is completed, the MCU discharges and clears the stored level of C7 by controlling S_C to be at a high level. Assuming the high level of S_C is 5V, when S_C becomes high, capacitor C7 quickly discharges through the discharge loop connected to S_C, causing the voltage across C7 to drop to 0V, preparing for the next measurement. After the discharge is completed, the MCU then resets S_C to a low level and waits for the next measurement signal to arrive;

[0088] Temperature compensation is carried out by using the characteristic that the voltage drop of diode D2 changes with temperature. In diode D2, its voltage drop decreases when the temperature rises. Assuming the voltage drop of D2 at room temperature is 0.7V, when the temperature rises, its voltage drop decreases to 0.6V. Since the voltage drop of diode D2 decreases, the voltage obtained by capacitor C7 during charging will increase, thereby compensating for the influence of temperature change on the measurement signal. For example, in a high-temperature environment, the level stored in capacitor C7 corresponding to the original measurement signal would decrease due to the temperature rise, but the decrease in the voltage drop of diode D2 makes capacitor C7 charge more fully and the level increases, ensuring the accuracy of the measurement result;

[0089] A diode with a stable forward voltage drop and good temperature characteristics is selected, such as a Schottky diode. The Schottky diode has the characteristics of a low forward conduction voltage drop and a fast switching speed, which can meet the requirements of the phase holding circuit for the diode. Its forward voltage drop is stable, which helps to accurately store the measurement signal level; it has good temperature characteristics and can effectively implement the temperature compensation function;

[0090] Select a capacitor with low leakage current and appropriate capacitance as the storage capacitor C7, such as a tantalum capacitor. Tantalum capacitors have the advantages of small size, large capacitance, and low leakage current, and can stably store charges for a long time to ensure that the measurement signal level remains stable during the analog-to-digital conversion process. Select a tantalum capacitor with an appropriate capacitance according to the circuit time constant and storage time requirements, such as a 0.1 μF tantalum capacitor;

[0091] During the circuit board design, place the diode D2 and the capacitor C7 as close as possible to shorten the signal transmission path and reduce signal interference. At the same time, avoid other high-power signal lines approaching this circuit to prevent affecting the stored measurement signal;

[0092] The input of the phase holding circuit is connected to the output of the phase automatic tracking circuit to receive the measurement signal output by the phase automatic tracking circuit, ensure reliable connection, avoid interference and distortion during signal transmission, and ensure that the measurement signal can be accurately stored by the phase holding circuit;

[0093] The phase holding circuit is connected to the MCU through the AD_EN signal to send an analog-to-digital conversion trigger signal to the MCU. At the same time, the MCU controls the clearing operation of the capacitor C7 in the phase holding circuit through the S_C signal to achieve coordinated work between the two. During the connection process, pay attention to level matching and signal timing to ensure that the data processing module can accurately obtain the measurement signal and perform subsequent processing.

[0094] Step 6: After receiving the measurement signal, the MCU converts the held level signal through its internal analog-to-digital conversion module, converting the level signal representing the dust diameter into a diameter value;

[0095] Specifically, a specific pin of the MCU is connected to the output terminal of the phase holding circuit. When the phase automatic tracking circuit detects that the dust is at the center of the laser light illumination and holds the measurement signal as a stable level signal through the phase holding circuit, this level signal is transmitted to the MCU pin. For example, assume that the PB0 pin of the MCU is configured as the input pin for receiving the measurement signal. When this pin detects a high level (representing the measurement signal is valid), it triggers an internal interrupt of the MCU (if configured in interrupt mode) or starts the analog-to-digital conversion related program flow;

[0096] Before performing analog-to-digital conversion, it is necessary to configure the analog-to-digital conversion module inside the MCU, and set parameters such as the conversion mode (such as single conversion, continuous conversion, etc.), conversion accuracy (such as 8-bit, 10-bit, 12-bit, etc.), and reference voltage through programming. If the level range of the measurement signal is 0 - 3V, an internal reference voltage of 3.3V can be selected and the conversion accuracy can be set to 12 bits to meet the measurement accuracy requirements and improve the measurement resolution;

[0097] After the configuration is completed, the MCU starts the internal analog-to-digital conversion module to convert the held level signal. The analog-to-digital conversion module converts the analog level signal into a digital quantity according to the set conversion accuracy. Taking 12-bit analog-to-digital conversion as an example, if the input level signal is 1.65V and the reference voltage is 3.3V, according to the analog-to-digital conversion formula, the converted digital quantity = 1.65 / 3.3 × 4095 (the full-scale digital quantity of 12-bit analog-to-digital conversion is 4095) = 2047;

[0098] After the analog-to-digital conversion is completed, the MCU reads the converted digital quantity. The result can be read through a specific register or function, and the digital quantity representing the dust diameter is stored in a variable inside the MCU for subsequent data processing and calculation;

[0099] Select an MCU with a high-performance analog-to-digital conversion module, such as the STM32 series of microcontrollers. The analog-to-digital conversion modules of such MCUs have the advantages of high conversion accuracy, high speed, and strong configurability, and can meet the requirements of high-precision dust diameter measurement. For example, STM32F407, its internal analog-to-digital conversion module can reach a maximum of 12-bit accuracy, and the conversion speed can meet the requirements of real-time measurement;

[0100] In the hardware circuit design, ensure that the connection between the MCU and the phase holding circuit is stable and reliable. On the signal transmission line, filtering capacitors and pull-up / pull-down resistors can be added to eliminate signal noise and stabilize the signal level. For example, a 10kΩ resistor is connected in series between the MCU pin and the output end of the phase holding circuit, and a 0.1μF filtering capacitor is connected in parallel to the ground at the pin to prevent interference signals from affecting the transmission of the measurement signal;

[0101] The MCU is closely connected to the phase holding module to ensure accurate reception of the held level signal. When connecting, pay attention to level matching. If the output level of the phase holding circuit does not match the input level of the MCU, a level conversion circuit needs to be designed. For example, if the output level of the phase holding circuit is 3.3V and the high-level threshold of the MCU pin input is 2V, a resistor voltage divider circuit can be used for level conversion; at the same time, the converted digital quantity (the value representing the dust diameter) is passed to the conversion module for subsequent calculation. In the software design, the data is passed to the program module responsible for conversion through function calls or data sharing to provide basic data for calculating the dust weight and the number of particles.

[0102] Step 7: The MCU converts the diameter values converted by the analog-to-digital conversion module into the dust weight and the number of particles one by one according to the pre-calibrated conversion relationship considering the dust characteristics and measurement environment factors;

[0103] Specifically, the MCU reads the values representing the dust diameter after conversion by the analog-to-digital conversion module from the internal storage area. These values are discrete and correspond to the dust diameters measured at different times. The MCU arranges these values in a certain order for subsequent unified conversion processing. For example, the diameter values at multiple measurement times are stored in an array for convenient traversal and calculation;

[0104] According to the settings of the measurement system, the MCU calls the pre-calibrated conversion relationships that consider dust characteristics and measurement environmental factors. These conversion relationships are usually stored in the internal memory or external storage device of the MCU in the form of formulas, tables, or algorithms. For example, they are stored as a series of coefficients and calculation steps for converting the diameter values into weight and particle number;

[0105] For each diameter value, the MCU calculates according to the conversion relationship. Assuming that in the conversion relationship, the dust weight calculation formula is:

[0106]

[0107] where W is the dust weight, ρ is the dust density (determined according to the pre-stored dust characteristics), d is the dust diameter (i.e., the value after analog-to-digital conversion), and n is the number of dust particles per unit volume (determined according to the measurement environmental factors and calibration data). The MCU substitutes the parameters such as the stored dust density and the number of particles per unit volume into the formula to calculate the weight of each dust particle;

[0108] While calculating the weight, the MCU counts the number of dust particles according to the conversion relationship and the measurement data. If the measurement system determines the total volume of the measurement through a certain method (such as setting the number of measurements per unit time and the volume of the measurement area), combined with the measured dust diameter distribution, according to the relevant rules in the conversion relationship, the number of dust particles in different diameter intervals is counted. For example, it is stipulated that the volume of the measurement area for each measurement is V, and according to the situation of the diameter values falling in different intervals, the number of particles N in each interval is calculated i 。

[0109] In one embodiment, specifically, in step one, the laser control circuit includes a constant current source module. If the control signal is 1, the constant current source module outputs a constant current to drive the laser head to work; if the control signal is 0, the constant current source module is turned off and the laser head stops emitting laser; the constant current source module plays a crucial role in the entire dust diameter measurement system; if the control signal is 1, this indicates that the system has issued an instruction to start laser emission. At this time, after receiving the high-level control signal, the internal circuit of the constant current source module responds quickly and outputs a constant current to drive the laser head to work; for example, in a specific measurement scenario, the constant current output by the constant current source module is 30 mA. This current value is determined through careful design and debugging. It can ensure that the laser head emits a laser beam with uniform intensity stably, laying a foundation for accurately measuring the dust diameter subsequently, because stable laser emission power is one of the key factors to ensure measurement accuracy. Only when the laser head works under the drive of a constant current can the intensity of the laser it emits be ensured to be stable, so that the dust scattering light signal is stable and the measurement accuracy is improved; if the control signal is 0, that is, the system issues an instruction to stop laser emission. After receiving the low-level control signal, the constant current source module immediately cuts off the internal current output path, and the laser head stops emitting laser due to the loss of current supply. This design can not only effectively reduce the system power consumption, but also avoid the ineffective operation of the laser head when it does not need to work, extending the service life of the laser head. For example, when the system is in standby or after the measurement task is completed, the control signal is set to 0, and the laser head stops emitting laser, reducing energy consumption and equipment loss;

[0110] The constant current source module provides a 5V power supply to make the constant current source module output a constant current; the 5V power supply provides stable energy support for various electronic components inside the constant current source module, ensuring the stable operation of its internal circuit, and then outputting a stable constant current. In practical applications, in order to further improve the stability of the constant current source module, filter capacitors and voltage stabilizing circuits are also added at the power input port. The filter capacitors can effectively filter out high-frequency noise and interference signals in the power supply, preventing these interferences from affecting the stability of the output current of the constant current source module; the voltage stabilizing circuit can ensure that the voltage input to the constant current source module is stable at about 5V. Even when the external power supply voltage fluctuates, it can ensure that the current output by the constant current source module is not affected and always remains constant, thus ensuring the stable operation of the laser head and improving the reliability and measurement accuracy of the entire dust diameter measurement system.

[0111] In one embodiment, specifically, in step two, the photoelectric signal conversion circuit supplies power to the photoelectric sensor with a constant voltage of 3.3V output by the constant voltage IC; the photoelectric signal conversion circuit plays a key role in the entire dust detection process. The constant voltage IC stably outputs a voltage of 3.3V to supply power to the photoelectric sensor. This stable power supply is the cornerstone to ensure the normal and accurate operation of the photoelectric sensor;

[0112] After converting the laser scattered by dust into an initial electrical signal, the initial electrical signal is filtered to remove the noise interference in the signal; since the converted initial electrical signal is extremely vulnerable to various noises, filtering must be performed to remove the noise.

[0113] In one embodiment, specifically, in step three, the amplifier circuit includes two operational amplifiers and a signal mixing module. The two operational amplifiers amplify the initial electrical signal by different multiples respectively, and the signal mixing module mixes the amplified initial electrical signal and converts it into a voltage signal for output. Through this design, signals of different intensities are effectively processed within a range. For weak signals, after two-stage amplification and mixing, they can reach the level range recognizable and processable by the subsequent circuit; for strong signals, by reasonably setting the amplification multiple and mixing ratio, distortion phenomena such as signal clipping are avoided, ensuring that the output signal can accurately reflect the characteristics of the dust scattered light signal, providing accurate data support for the subsequent measurement of the dust diameter. This design of the amplifier circuit greatly improves the adaptability and processing ability of the system to signals of different intensities, thus enhancing the performance of the entire dust diameter measurement system.

[0114] In one embodiment, specifically, in step six, after the analog-to-digital conversion module converts the held level signal, the MCU issues a clear signal to clear the held level signal. Through such a clearing operation, the phase holding circuit returns to its initial state, preparing for the holding of the next measurement signal. This process ensures the independence and accuracy of each measurement, avoids the interference of the residual signal of the previous measurement on the next measurement, and guarantees that the entire dust diameter measurement system can work continuously and stably, continuously obtaining new measurement data.

[0115] In one embodiment, specifically, in step five, the phase holding circuit uses the principle of capacitor charge storage to hold the measurement signal as a level signal; the phase holding circuit has a temperature compensation function.

[0116] Specifically, when the dust is at the center of the laser light illumination, the energy received by the sensor is the largest. At this time, the measurement signal (assumed to be the S_OUT level signal) will rise to the highest value. This high-level signal charges the capacitor C7 through the diode D2. Due to the unidirectional conductivity of the diode, the current can only flow from the signal source to the capacitor, causing the capacitor C7 to be quickly charged and the voltage across its two ends to gradually increase until it approaches the highest level of the measurement signal. For example, if the highest level of the measurement signal is 3V, after the capacitor C7 is fully charged, the voltage across its two ends will also reach about 3V, thus storing the measurement signal in the form of a level. In this process, the capacitor C7 is like a charge storage device. As long as there is no external interference, it will continuously maintain this level state, providing a stable signal input for the subsequent analog-to-digital conversion.

[0117] However, the change in ambient temperature will affect the performance of the capacitor, thereby affecting the accuracy of the measurement signal. To solve this problem, the phase-holding circuit has a temperature compensation function. This function mainly utilizes the characteristic that the voltage drop of diode D2 changes with temperature. At room temperature, diode D2 has a certain forward voltage drop, assumed to be 0.7V. When the ambient temperature rises, the forward voltage drop of diode D2 will decrease, for example, drop to 0.6V. Since the charging voltage of capacitor C7 is related to the voltage drop of diode D2, the decrease in the diode voltage drop will make capacitor C7 charge more fully under the same measurement signal, and its voltage across the two ends will increase accordingly. This seemingly leads to an error in the measurement signal. However, in fact, by reasonably designing the circuit parameters, this voltage change can exactly compensate for the attenuation of the measurement signal caused by the performance change of other circuit components due to the increase in temperature. On the contrary, when the temperature drops, the voltage drop of diode D2 will increase, and the charging voltage of capacitor C7 will decrease accordingly, which can also compensate for the change in the measurement signal caused by the temperature drop. In this way, the phase-holding circuit can automatically adjust the charging voltage of capacitor C7 in different temperature environments, keep the level of the measurement signal stable within a certain range, and effectively improve the accuracy and reliability of the measurement system.

[0118] In one embodiment, specifically, in step seven, the pre-calibrated conversion relationship considering the dust characteristics and measurement environment factors is obtained through multiple measurement experiments on standard dust samples with known diameters, densities, and shapes under different environmental conditions.

[0119] Specifically, to obtain this conversion relationship considering multiple factors, it is necessary to first prepare standard dust samples with known diameters, densities, and shapes. The selection of these samples should cover various dust situations encountered in practical applications. For example, select standard dust samples with different sizes in the range of 0.1μm - 10μm in diameter, covering various shapes such as spherical and irregular shapes, and at the same time select dust with different densities, such as common silica dust and coal dust.

[0120] Then, multiple measurement experiments are carried out on these standard dust samples under different environmental conditions. The environmental conditions mainly include factors such as temperature, humidity, and air pressure. Because in the actual measurement scenario, these environmental factors will have a significant impact on the measurement results. For example, set the temperature range to -20°C - 50°C, the humidity range to 20% - 90%RH, and the air pressure range to 80kPa - 106kPa. Under each combination of environmental conditions, multiple measurements are carried out on each standard dust sample.

[0121] During each measurement, according to the measurement method of the present invention, from laser emission, photoelectric conversion, signal amplification, to phase tracking, holding, and analog-to-digital conversion, a level signal representing the dust diameter is completely obtained and converted into a diameter value. These measured diameter values are compared and analyzed with the actual diameters of standard dust samples;

[0122] Through a large amount of such experimental data, using statistical methods and mathematical modeling means, the internal relationships among the measured diameter values, dust weight, and particle number are found. For example, through data analysis, it is found that within a certain temperature and humidity range, there is an approximately linear relationship between the dust weight and the cube of the diameter. Specific coefficients are obtained by fitting the curve. Finally, considering the dust characteristics (diameter, density, shape) and measurement environmental factors (temperature, humidity, air pressure, etc.), a set of accurate conversion relationships are established. Such conversion relationships can be a series of formulas, look-up tables, or algorithms, so that in actual measurement, the MCU can accurately convert the measured diameter values into dust weight and particle number one by one, thereby greatly improving the accuracy and reliability of the measurement results and meeting the high-precision requirements for dust measurement in different application scenarios.

[0123] In summary, the high-precision dust diameter measurement method based on automatic phase locking and temperature compensation provided in this embodiment uses the constant current source module in the laser control circuit to stably drive the laser head to emit laser, providing a stable light source for measurement; uses the photoelectric signal conversion circuit to accurately convert the scattered laser into an initial electrical signal and perform filtering processing; the amplification circuit performs two-stage amplification and mixing on the initial electrical signal to effectively process signals of different intensities; the phase automatic tracking circuit continuously tracks the dust position and sends a measurement signal when the dust is at the center of the light illumination; the phase holding circuit holds the signal based on the principle of capacitor charge storage and has a temperature compensation function; after receiving the signal, the MCU performs analog-to-digital conversion to convert the level signal into a diameter value, and also clears the held signal after conversion; finally, the MCU converts the diameter value into dust weight and particle number according to the pre-calibrated conversion relationship considering various factors, realizing high-precision dust diameter measurement, effectively solving the error problem of traditional measurement methods, and improving the accuracy of measurement and the reliability of the system.

[0124] Embodiment 2

[0125] Figure 2 is a schematic diagram of the functional modules of the high-precision dust diameter measurement system based on automatic phase locking and temperature compensation according to an embodiment of the present application. As Figure 2 shown, the high-precision dust diameter measurement system based on automatic phase locking and temperature compensation includes: a laser emission module, a photoelectric conversion module, a signal amplification module, a phase tracking module, a phase holding module, a data processing module, and a conversion module;

[0126] The laser emission module is configured to provide power and control signals to the laser head based on the laser control circuit, and control the laser head to emit laser towards the dust;

[0127] The photoelectric conversion module is configured to supply power to the photoelectric sensor through the photoelectric signal conversion circuit, and convert the laser scattered by the dust into an initial electrical signal;

[0128] The signal amplification module is configured to amplify the initial electrical signal based on the amplification circuit and convert it into a voltage signal for output;

[0129] The phase tracking module is configured to automatically track the position of the dust in the housing based on the phase automatic tracking circuit, and send a measurement signal to the MCU;

[0130] The phase holding module is configured to hold the measurement signal as a level signal based on the phase holding circuit;

[0131] The data processing module is configured to, after the MCU receives the measurement signal, convert the held level signal through the internal analog-to-digital conversion module thereof, and convert the level signal representing the dust diameter into a diameter value;

[0132] The conversion module is configured to the MCU convert the diameter value converted by the analog-to-digital conversion module into the dust weight and the number of particles one by one according to the pre-calibrated conversion relationship considering the dust characteristics and measurement environment factors.

[0133] In one embodiment, specifically, the system further includes a storage and display module, which is configured to store the measured dust diameter, weight, and number of particles data. Meanwhile, the storage and display module displays these data in an intuitive manner.

[0134] In one embodiment, specifically, the system is also equipped with multiple communication interfaces, and the multiple communication interfaces include RS-485 interface, Bluetooth interface, and Wi-Fi interface.

[0135] In summary, the high-precision dust diameter measurement system based on automatic phase locking and temperature compensation provided by this embodiment drives a laser head to emit laser through a laser emission module based on a laser control circuit; a photoelectric conversion module powers a photoelectric sensor and converts scattered laser into an initial electrical signal; a signal amplification module amplifies and converts the initial electrical signal; a phase tracking module tracks the dust position in real time and sends a measurement signal; a phase holding module holds the measurement signal as a level signal; an MCU of a data processing module performs analog-to-digital conversion to obtain a diameter value; a conversion module converts the diameter value into dust weight and the number of particles according to a calibration relationship; a storage and display module stores and visually displays measurement data; multiple communication interfaces (RS-485 interface, Bluetooth interface, and Wi-Fi interface) are used to implement data transmission. Each module works in coordination, effectively solving the defects of traditional dust detection technologies, achieving high-precision dust diameter measurement, and meeting the dust detection requirements in different scenarios.

[0136] For other details of the implementation technical solutions of each module in the high-precision dust diameter measurement system based on automatic phase locking and temperature compensation in the above embodiment, reference can be made to the description in the high-precision dust diameter measurement method based on automatic phase locking and temperature compensation in the above embodiment, and details will not be repeated here.

[0137] It should be noted that the embodiments in this specification are all described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The same or similar parts among the embodiments can be referred to each other. For system embodiments, since they are basically similar to method embodiments, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiments.

[0138] Embodiment III

[0139] As Figure 3As shown in the figure, an embodiment of the present invention provides a laser constant current source control circuit. In this circuit, the core component is the U4 constant current source IC. The VCC pin of U4 is connected to a 5V power supply to provide energy for the entire circuit. When the EN signal is at a high level, the U4 constant current source IC is activated and enters the working state. At this time, its VOUT pin will output a stable constant current, which is used to drive the laser LED (J2) to work. For example, assume that the constant current output by the VOUT pin of U4 is 30mA. This current can make the laser LED emit light stably and ensure the stable emission power of the laser, providing a stable light source for subsequent dust detection. C2 is used as a filter capacitor, and its function is to filter out the clutter and interference signals in the power supply, ensuring that the current output by VOUT is pure and stable, avoiding affecting the working stability of the laser LED due to current fluctuations, and further affecting the accuracy of dust detection. When the EN signal is at a low level, the U4 constant current source IC is turned off, the VOUT pin no longer outputs current, and the laser LED (J2) turns off the light source. This can effectively reduce the system power consumption, extend the service life of the device, and avoid energy waste when laser emission is not required.

[0140] Embodiment 4

[0141] As Figure 4 shown in the figure, an embodiment of the present invention provides a photoelectric conversion circuit. From the Figure 4 photoelectric conversion circuit, it can be seen that the constant voltage IC provides a stable 3.3V voltage for the entire circuit. This voltage is output through the VOUT pin to supply power to the photoelectric sensor SENSOR, ensuring that the sensor can work in a stable voltage environment. When the air containing dust enters the detection area, the dust scatters the laser. The photoelectric sensor SENSOR receives these scattered light signals and converts them into initial electrical signals. For example, in a certain actual application scenario, when the scattered light of dust with a specific concentration and particle size distribution irradiates the sensor, the sensor will generate a weak current signal, the magnitude of which is between a few microamperes and dozens of microamperes. This weak current signal is converted into a voltage signal by the U3_A operational amplifier. The U3_A operational amplifier, according to its internal circuit design and external connected resistors, capacitors and other components, amplifies the weak current signal and converts it into a voltage signal suitable for subsequent circuit processing, and then outputs it to the DUST_DEC signal line. During the conversion process, in order to improve the signal quality, the converted initial electrical signal will also be filtered. By setting a suitable filter circuit (such as an RC filter circuit), the noise interference in the signal can be effectively removed, making the output voltage signal more stable and accurate, providing a reliable basis for subsequent signal amplification and processing.

[0142] As Figure 5 shown in the figure, an embodiment of the present invention provides a signal amplification and mixing circuit. Refer to Figure 5The signal amplification and mixing circuit. The weak voltage signal input from DUST_DEC first enters the U3_B operational amplifier for the first amplification. The amplification factor of the U3_B operational amplifier is determined by its internal circuit structure and the externally connected resistors. Assuming the amplification factor of U3_B is set to 100, when the amplitude of the input weak voltage signal is 10 mV, after being amplified by U3_B, the signal amplitude becomes 1 V. The amplified signal then enters the U3_C operational amplifier for the second amplification. The amplification factor of U3_C is also set according to actual requirements, for example, set to 50. After being amplified by U3_C, the signal amplitude further increases. Then, the signal mixing module composed of R12 and R13 mixes the two amplified signals. The resistance values of R12 and R13 are selected according to the desired mixing ratio. For example, R12 is 10 kΩ and R13 is 20 kΩ. According to the principle of resistor voltage division, the amplified signals are mixed in a certain proportion and finally output from the S_OUT port. Such a design enables signals of different intensities to be effectively processed within a range. For weak signals, after two-stage amplification and mixing, they can reach the level range that can be recognized and processed by the subsequent circuit; for strong signals, by reasonably setting the amplification factor and mixing ratio, distortion phenomena such as signal clipping are avoided, ensuring that the output signal can accurately reflect the characteristics of the dust scattered light signal and providing accurate data for the subsequent measurement of the dust diameter.

[0143] Embodiment Six

[0144] As Figure 6 shown, an embodiment of the present invention provides a phase automatic tracking circuit and a phase level holding and clearing circuit. According to Figure 6The phase automatic tracking circuit and the phase level holding and clearing circuit. When the dust moves in the housing, the phase automatic tracking circuit will monitor the position of the dust in real time. When the dust is at the center of the laser light illumination, the energy received by the sensor is the largest at this time, and the S_OUT level rises to the highest. This highest level is transmitted to C7 through D2 and stored; for example, assuming the highest level of S_OUT is 3V, this voltage will charge the capacitor C7 through the diode D2, making the voltage across C7 reach 3V. When the S_OUT level drops and is lower than the level stored in C7, for example, when the S_OUT level drops to 2V, AD_EN is inverted, changing from a 0 level to a 1 level, and this signal is sent to the MCU. After receiving the AD_EN signal, the MCU starts the analog-to-digital conversion of AD_IN, converting the level signal representing the dust diameter into a digital signal. After the analog-to-digital conversion is completed, the MCU discharges and clears the stored level of C7 by controlling S_C to be at a high level; for example, when S_C is at a high level (assumed to be 5V), the capacitor C7 discharges rapidly through the discharge loop connected by S_C, reducing the voltage across C7 to 0V to prepare for the next measurement; in addition, this circuit also has a temperature compensation function. In the diode D2, its voltage drop decreases when the temperature rises; assuming the voltage drop of D2 at room temperature is 0.7V, when the temperature rises, its voltage drop decreases to 0.6V, which will increase the level of C7, thereby compensating for the influence of temperature changes on the measurement signal and ensuring the accuracy of the measurement result.

[0145] Embodiment Seven

[0146] As Figure 7 shown, the processor function framework diagram provided by an embodiment of the present invention, where AD_EN comes from the phase trigger signal. When the signal is high, the processor starts to convert the level stored on C7 of Figure 5 through the analog-to-digital conversion module and AD_IN. After the conversion is completed, control S_C to be at a high level to discharge the capacitor C7. After discharging, reset S_C to a low level to prepare for the next detection, and then convert the detected value into the dust particle diameter and weight, and finally output it to the outside.

[0147] The basic principles of the present disclosure have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, advantages, effects, etc. mentioned in the present disclosure are only examples and not limitations. It cannot be considered that these advantages, advantages, effects, etc. are essential for each embodiment of the present disclosure. In addition, the above-mentioned specific details of the disclosure are only for the purpose of illustration and easy understanding, rather than limitations. The above details do not limit the present disclosure to necessarily adopt the above specific details to implement.

[0148] In this disclosure, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. The block diagrams of devices, apparatuses, equipment, and systems involved in this disclosure are only illustrative examples and do not intend to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open-ended words, meaning "including but not limited to", and can be used interchangeably with each other. The words "or" and "and" used herein refer to the word "and / or", and can be used interchangeably with it, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to", and can be used interchangeably with it.

[0149] In addition, as used herein, "or" in a listing of items beginning with "at least one" indicates a disjunctive listing, so that for example, a listing of "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Further, the term "exemplary" does not mean that the examples described are preferred or better than other examples.

[0150] It should also be noted that in the systems and methods of this disclosure, each component or each step can be decomposed and / or recombined. These decompositions and / or recombinations should be regarded as equivalent solutions of this disclosure.

[0151] Various changes, substitutions, and alterations to the technologies described herein can be made without departing from the teachings defined by the appended claims. In addition, the scope of the claims of this disclosure is not limited to the specific aspects of the processes, machines, manufactures, compositions of events, means, methods, and acts described above. Current or later-developed processes, machines, manufactures, compositions of events, means, methods, or acts that perform substantially the same function or achieve substantially the same result as the corresponding aspects described herein can be utilized. Thus, the appended claims include such processes, machines, manufactures, compositions of events, means, methods, or acts within their scope.

[0152] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this disclosure. Therefore, this disclosure is not intended to be limited to the aspects shown herein, but rather to the broadest scope consistent with the principles and novel features disclosed herein.

[0153] The foregoing description has been presented for purposes of illustration and description. In addition, the description is not intended to limit embodiments of the present disclosure to the form disclosed herein. Although several example aspects and embodiments have been discussed above, those skilled in the art will recognize some variations, modifications, alterations, additions, and subcombinations thereof.

Claims

1. A high-precision dust diameter measurement method based on automatic phase locking and temperature compensation, characterized in that: The following steps are involved: Based on the laser control circuit, the laser head is provided with power and control signals to control the laser head to emit laser to the dust; The photoelectric sensor is powered by a photoelectric signal conversion circuit to convert the laser light scattered by dust into an initial electrical signal; Based on the amplifier circuit, the initial electrical signal is amplified and converted into a voltage signal for output; The phase automatic tracking circuit automatically tracks the position of the dust in the frame and sends a measurement signal to the micro control unit; Maintaining the measurement signal as a level signal based on a phase holding circuit; After receiving the measurement signal, the microcontroller unit converts the maintained level signal through its internal analog-to-digital conversion module, and converts the level signal representing the dust diameter into a diameter value; The microcontroller unit converts the diameter value converted by the analog-to-digital conversion module into dust weight and particle count one by one according to the pre-calibrated conversion relationship between dust characteristics and measurement environmental factors.

2. The high-precision dust diameter measurement method based on automatic phase locking and temperature compensation according to claim 1 is characterized in that: The laser control circuit comprises a constant current source module; the constant current source module provides a 5V power supply.

3. The high-precision dust diameter measurement method based on automatic phase locking and temperature compensation according to claim 1 is characterized in that: The photoelectric signal conversion circuit outputs a 3.3V voltage to power the photoelectric sensor when the constant voltage IC is used; after converting the laser light scattered by the dust into an initial electrical signal, the initial electrical signal is filtered.

4. The high-precision dust diameter measurement method based on automatic phase locking and temperature compensation according to claim 1 is characterized in that: The amplification circuit includes two operational amplifiers and a signal mixing module; The two operational amplifiers respectively amplify the initial electrical signal at different times, and the signal mixing module mixes the amplified initial electrical signals and converts them into voltage signals for output.

5. The high-precision dust diameter measurement method based on automatic phase locking and temperature compensation according to claim 1 is characterized in that: After the analog-to-digital conversion module converts the maintained level signal, the microcontroller unit sends a clear signal to clear the maintained level signal.

6. The high-precision dust diameter measurement method based on automatic phase locking and temperature compensation according to claim 1 is characterized in that: The phase holding circuit utilizes the capacitance charge storage principle to keep the measurement signal as a level signal; the phase holding circuit has a temperature compensation function.

7. The high-precision dust diameter measurement method based on automatic phase locking and temperature compensation according to claim 1 is characterized in that: The pre-calibrated conversion relationship between dust characteristics and measurement environmental factors is obtained by performing multiple measurement experiments on a variety of standard dust samples with known diameters, densities and shapes under different environmental conditions.

8. A high-precision dust diameter measurement system based on automatic phase locking and temperature compensation, applied to a high-precision dust diameter measurement method based on automatic phase locking and temperature compensation according to any one of claims 1 to 7, characterized in that: The system comprises: a laser emission module, a photoelectric conversion module, a signal amplification module, a phase tracking module, a phase holding module, a data processing module and a conversion module; The laser emission module is configured to provide power and control signals to the laser head based on the laser control circuit, and control the laser head to emit laser toward the dust; The photoelectric conversion module is configured to power the photoelectric sensor through a photoelectric signal conversion circuit to convert the laser light scattered by dust into an initial electrical signal; The signal amplification module is configured to amplify the initial electrical signal based on the amplification circuit and convert it into a voltage signal for output; The phase tracking module is configured to automatically track the position of the dust in the frame based on the phase automatic tracking circuit and send a measurement signal to the micro control unit; The phase holding module is configured to keep the measurement signal as a level signal based on the phase holding circuit; The data processing module is configured to convert the maintained level signal through the internal analog-to-digital conversion module after the microcontroller receives the measurement signal, and convert the level signal representing the dust diameter into a diameter value; The conversion module is configured as a microcontroller unit to convert the diameter values ​​converted by the analog-to-digital conversion module into dust weight and particle count one by one according to the pre-calibrated conversion relationship between dust characteristics and measurement environmental factors.

9. The high-precision dust diameter measurement system based on automatic phase locking and temperature compensation according to claim 8 is characterized in that: The system also includes a storage and display module, which is configured to store the measured dust diameter, weight and particle number data, and at the same time, the storage and display module displays these data in an intuitive manner.

10. The high-precision dust diameter measurement system based on automatic phase locking and temperature compensation according to claim 8, characterized in that: The system is also equipped with a variety of communication interfaces, including RS-485 interface, Bluetooth interface and Wi-Fi interface.

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