Particulate matter concentration detection device and method

Abstract

The embodiment of the specification provides a particulate matter concentration detection device and method, by integrating a laser emitting unit and a light signal receiving unit in the same package and sharing an optical lens assembly, a detection area is formed in the external open air, and a traditional active sampling mechanism such as a fan is abandoned, so that the sensor module is significantly miniaturized and low in power consumption. The design not only simplifies the structure, reduces the manufacturing cost and failure rate, but also realizes noiseless operation and longer service life. At the same time, the passive detection mode makes it more natural to respond to the real state of the environment air, and provides a key technical basis for realizing efficient and reliable particulate matter concentration detection in various compact electronic devices and scenes requiring long-term silent monitoring.

Description

Technical Field

[0001] The embodiments in this specification relate to the field of optical detection technology, and in particular to particulate matter concentration detection devices. Background Technology

[0002] Currently, the detection of particulate matter concentrations such as PM2.5 in the air commonly employs sensor solutions based on the principle of light scattering. These solutions typically design the laser emitter and photodetector as separate components, requiring mechanical power components such as fans or air pumps to actively draw air samples into a closed optical detection chamber. This discrete and active sampling design results in a large overall sensor size and high power consumption. Furthermore, it suffers from reduced reliability and increased noise due to wear or blockage of mechanical components, and is difficult to further miniaturize and integrate, limiting its application in space- and power-sensitive scenarios such as portable devices and embedded terminals.

[0003] Therefore, a better solution is urgently needed. Summary of the Invention

[0004] In view of this, embodiments of this specification provide a particulate matter concentration detection device to address the technical deficiencies existing in the prior art.

[0005] According to a first aspect of the embodiments of this specification, a particulate matter concentration detection device is provided, comprising: An integrated package, which contains a laser emitting unit and an optical signal receiving unit; An optical lens assembly is installed in front of the optical path of the integrated package. The light beam emitted by the laser emitting unit forms a detection area in the open air outside the device after passing through the optical lens assembly. The optical lens assembly also focuses the scattered light of the light beam by the particles in the detection area onto the optical signal receiving unit. A physical isolation structure is located within the integrated package and is positioned between the laser emitting unit and the optical signal receiving unit. The signal processing unit is electrically connected to the optical signal receiving unit. It is used to receive the electrical signal generated by the optical signal receiving unit based on the scattered light, amplify the electrical signal, and output the amplified electrical signal. The control unit is electrically connected to the signal processing unit and is used to receive amplified electrical signals and calculate particulate matter concentration data based on the amplified electrical signals.

[0006] In one possible implementation, the optical lens assembly includes a coaxial lens, through which the emitting optical axis of the laser emitting unit and the receiving optical axis of the optical signal receiving unit are aligned coaxially or quasi-coaxially.

[0007] In one possible implementation, the detection area relies on natural airflow to allow particulate matter to pass through.

[0008] In one possible implementation, the physical isolation structure is an opaque barrier that prevents the laser beam emitted by the laser emitting unit from directly illuminating the optical signal receiving unit.

[0009] In one possible implementation, the signal processing unit includes a transimpedance amplifier that converts the current signal output by the optical signal receiving unit into a voltage signal in the amplified electrical signal.

[0010] In one possible implementation, the control unit has pre-stored calibration data, and the control unit calculates particulate matter concentration data by comparing the amplified electrical signal with the calibration data.

[0011] In one possible implementation, the laser emitting unit is a side-emitting laser or a vertical-cavity surface-emitting laser, and the optical signal receiving unit is a photodiode or a phototransistor.

[0012] In one possible implementation, the control unit is also configured to analyze the pulse amplitude or pulse frequency distribution of the amplified electrical signal to distinguish signals generated by particles of different size ranges.

[0013] In one possible implementation, the device is a component of a portable air quality detector, an in-vehicle air monitoring module, or a smart home environment sensor.

[0014] According to a second aspect of the embodiments of this specification, a method for detecting particulate matter concentration is provided, employing the aforementioned particulate matter concentration detection device, the method comprising: The laser emitting unit emits a detection beam into open air through an optical lens assembly, forming a detection area; The optical signal receiving unit receives the scattered light generated by particles passing through the detection area through the optical lens assembly and generates an initial electrical signal; The signal processing unit amplifies the initial electrical signal to generate an amplified electrical signal; The control unit processes and amplifies the electrical signal to obtain particulate matter concentration data.

[0015] This specification provides a particulate matter concentration detection device. By integrating a laser emitting unit and a light signal receiving unit into the same package and sharing an optical lens assembly, a detection area is formed in open air. This eliminates the need for traditional active sampling mechanisms such as fans, thereby achieving significant miniaturization and low power consumption of the sensor module. This design not only simplifies the structure, reduces manufacturing costs and failure rates, but also achieves noiseless operation and a longer service life. Furthermore, its passive detection method allows for a more natural response to the actual state of the ambient air, providing a key technological foundation for efficient and reliable particulate matter concentration detection in various compact electronic devices and scenarios requiring long-term silent monitoring. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a particulate matter concentration detection device provided in one embodiment of this specification; Figure 2 This is a schematic diagram of a particulate matter concentration detection device provided in one embodiment of this specification; Figure 3 This is a circuit diagram of a particulate matter concentration detection device provided in one embodiment of this specification; Figure 4 This is a flowchart of a particulate matter concentration detection method provided in one embodiment of this specification. Detailed Implementation

[0017] Many specific details are set forth in the following description to provide a full understanding of this specification. However, this specification can be implemented in many other ways than those described herein, and those skilled in the art can make similar extensions without departing from the spirit of this specification. Therefore, this specification is not limited to the specific implementations disclosed below.

[0018] The terminology used in one or more embodiments of this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the one or more embodiments of this specification. The singular forms “a” and “the” as used in one or more embodiments of this specification and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used in one or more embodiments of this specification refers to and includes any or all possible combinations of one or more associated listed items.

[0019] It should be understood that although the terms first, second, etc., may be used to describe various information in one or more embodiments of this specification, such information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, first may also be referred to as second without departing from the scope of one or more embodiments of this specification, and similarly, second may also be referred to as first. Depending on the context, the word "if" as used herein may be interpreted as "when," "when," or "in response to a determination."

[0020] This specification provides a particulate matter concentration detection device, which will be described in detail in the following embodiments.

[0021] See Figure 1 , Figure 1This diagram illustrates a system schematic of a particulate matter concentration detection device according to an embodiment of this specification. Specifically, it includes an integrated package containing a laser emitting unit and a light signal receiving unit; an optical lens assembly mounted in front of the optical path of the integrated package, whereby the laser beam emitted by the laser emitting unit passes through the optical lens assembly to form a detection area in open air outside the device, and the optical lens assembly focuses the scattered light from the particulate matter within the detection area onto the light signal receiving unit; a physical isolation structure located within the integrated package and positioned between the laser emitting unit and the light signal receiving unit; a signal processing unit electrically connected to the light signal receiving unit, used to receive and amplify the electrical signal generated by the light signal receiving unit based on the scattered light, and output an amplified electrical signal; and a control unit electrically connected to the signal processing unit, used to receive the amplified electrical signal and calculate particulate matter concentration data based on the amplified electrical signal.

[0022] In this context, an integrated package can refer to a housing structure that encapsulates core optical and electronic components together. For example, a laser emitting unit and an optical signal receiving unit can be soldered together on the same printed circuit board using surface mount technology, and hermetically sealed with a plastic or ceramic shell to protect the internal components from dust and moisture. A laser emitting unit can refer to a light source capable of emitting a specific wavelength with good directionality, such as a semiconductor laser diode with a wavelength of 650 nanometers. An optical signal receiving unit can refer to a device capable of converting received optical signals into electrical signals, such as a photodiode sensitive to the aforementioned laser wavelength. An optical lens assembly can refer to an optical system composed of one or more lenses, such as an aspherical plastic lens used for collimating and focusing a laser beam. A detection area can refer to the spatial range in open air that is irradiated by a laser and forms an effective light spot; when suspended particles in the air pass through this range, they scatter the incident laser. A physical isolation structure can refer to mechanical components used to isolate the emission path and the receiving path in the optical path. A signal processing unit can refer to an analog circuit module used to process weak electrical signals. A control unit can refer to a microcontroller module that includes a processor and memory.

[0023] The present invention will be further described below through a detailed embodiment.

[0024] In one embodiment of this particulate matter concentration detection device, the integrated package is a black plastic shell measuring approximately 10mm x 10mm x 7mm. Inside the shell is a small printed circuit board, on which a side-emitting laser diode (SLED) as a laser emitting unit and a silicon photodiode (SPD) as a light signal receiving unit are soldered side-by-side. Between the laser diode and the SPD, a 0.5mm thick stainless steel spacer stands vertically, forming a physical isolation structure to ensure that the light emitted by the laser diode cannot directly illuminate the SPD.

[0025] At the front end of the integrated package, an optical lens assembly, comprising an aspherical lens, is fixedly mounted via a snap-fit. The diverging laser beam emitted by the laser diode is collimated into a parallel beam approximately 2 mm in diameter after passing through this aspherical lens. This beam exits the device housing and forms a cylindrical detection area in open air approximately 5 mm in front of the device. When the environment contains particulate matter such as PM2.5, the particles flow naturally through this detection area with the air, causing Mie scattering of the laser beam.

[0026] See Figure 2 A portion of the scattered light (backscattered light) returns along its original path, passing again through the aspherical lens. This lens converges the returned scattered light and guides it to the photosensitive surface of the photodiode. Due to the physical isolation structure, only scattered light returning from the external detection area can be converged by the lens to the receiving unit, while the direct light from the laser is effectively blocked, thus avoiding signal crosstalk.

[0027] A photodiode converts the received light signal, whose intensity varies with particulate matter concentration, into a weak photocurrent signal (typically in the nanoampere range). This current signal is transmitted through wires to a separate signal processing unit. The transimpedance amplifier in the signal processing unit linearly converts this current signal into a voltage signal and amplifies it thousands of times to obtain an amplified electrical signal. This amplified electrical signal is then input to a control unit (a microcontroller with an ARM Cortex-M0 core) via an analog-to-digital converter. The control unit internally stores a voltage-concentration curve calibrated using a standard dust concentration test chamber. By querying this curve, the real-time acquired amplified electrical signal value is converted into the corresponding PM2.5 mass concentration data (unit: micrograms per cubic meter), which can be output via a serial port.

[0028] For details, see Figure 3In this diagram, P1, P2, and P3 represent photodiodes, which effectively convert optical signals into electrical signals. V1 represents a laser chip that emits a laser beam. When this laser beam strikes particles in the air, it is reflected back. The photodiodes P1 and others receive this reflected laser beam and generate a photocurrent. This current signal, initially below 1µA, is amplified by a weak signal amplifier circuit into a voltage signal. This amplified signal is then transmitted thousands or tens of thousands of times to the ADC pin of the MCU (Microcontroller Unit). The ADC chip then acquires the amplified electrical signal and transmits it to the desired instrument via the MCU's UART or USB port.

[0029] The beneficial effect of this embodiment is that by integrating the laser emitting unit and the optical signal receiving unit into the same package and sharing the optical lens assembly, the optical structure is greatly simplified and the overall size of the device is reduced. The device utilizes natural airflow to perform detection in an open external space, eliminating the need for active sampling components such as fans and air pumps, thus reducing power consumption, noise, and mechanical failure rate. This makes the device very suitable for integration into portable or embedded devices that are sensitive to size and power consumption.

[0030] In one possible implementation, the optical lens assembly includes a coaxial lens, through which the emitting optical axis of the laser emitting unit and the receiving optical axis of the optical signal receiving unit are aligned coaxially or quasi-coaxially.

[0031] In this context, a coaxial lens can refer to a single lens element whose optical axis serves as the reference axis for both the emitted and received beams. Coaxial alignment refers to the complete coincidence of the emitted and received optical axes. Quasi-coaxial alignment refers to two optical axes that, while not completely coincident, have a very small angle (e.g., less than 5 degrees) and are designed to intersect near the detection area.

[0032] Based on the aforementioned particulate matter concentration detection device embodiment, the optical lens assembly employs a coaxial lens. During the integrated package design phase, precise optical simulation and mechanical positioning ensure that the light-emitting point of the laser emitting unit (laser diode) and the photosensitive center point of the light signal receiving unit (photodiode) are optically located near the focal plane of this coaxial lens and arranged symmetrically with respect to the lens's optical axis. Specifically, the laser diode's mounting position ensures its emission optical axis is precisely aligned with the lens's optical axis; the photodiode's mounting position allows for a slight offset between its receiving optical axis and the lens's optical axis, but this offset is designed to allow the photodiode to receive backscattered light returning from the lens's optical axis, thus achieving quasi-coaxial alignment. This design maximizes the overlap between the emission and receiving optical paths, improving light collection efficiency within the detection area while maintaining structural compactness.

[0033] The beneficial effects of this embodiment are that the coaxial or quasi-coaxial design significantly simplifies the difficulty and complexity of optical alignment and reduces manufacturing costs. Simultaneously, this design ensures perfect overlap between the emitted beam and the receiving field of view in the detection area, improving the system's ability to collect weak scattered light signals and thus enhancing the sensitivity of low-concentration particulate matter detection.

[0034] In one possible implementation, the detection area relies on natural airflow to allow particulate matter to pass through.

[0035] Natural air flow can refer to air convection caused by temperature difference, air pressure difference or ambient breeze, without the need for external power devices.

[0036] In the aforementioned particulate matter concentration detection device embodiment, the device itself does not contain any components for generating airflow. The detection area is completely exposed to ambient air. When PM2.5 particles in the environment randomly pass through the detection area formed by the laser under the influence of natural convection, breezes caused by people walking, or airflow caused by the device's own heat generation, they will be detected. The control unit reflects the average particulate matter concentration level within a certain time period (e.g., calculating the average pulse intensity or pulse count rate) by statistically processing multiple scattered light pulse signals collected over a period of time (e.g., 30 seconds). This method achieves truly passive, all-time monitoring.

[0037] The beneficial effects of this embodiment are that it completely eliminates moving parts such as fans and air pumps, giving the device outstanding advantages such as zero mechanical wear, long lifespan, zero operating noise, and ultra-low power consumption. The device structure is simpler and more reliable, making it very suitable for indoor environments (such as bedrooms and offices) that require long-term uninterrupted monitoring or have strict noise requirements.

[0038] In one possible implementation, the physical isolation structure is an opaque barrier that prevents the laser beam emitted by the laser emitting unit from directly illuminating the optical signal receiving unit.

[0039] Opaque materials can refer to any material that can effectively block lasers of a specific wavelength, such as black plastic, metal, or composite materials coated with light-absorbing coatings. Isolation walls can refer to sheet-like, wall-like, or cylindrical structures.

[0040] In the aforementioned particulate matter concentration detection device embodiment, the physical isolation structure is specifically a black polycarbonate isolation wall. This isolation wall is injection molded onto the inner base of the integrated package, located between the laser diode and the photodiode. The height of the isolation wall is slightly higher than the tops of the laser diode and the photodiode, and its thickness is sufficient to completely block any light that may leak from the side of the laser diode chip from directly reaching the photosensitive surface of the photodiode. Even in extreme cases where the laser beam is scattered at a small angle due to lens contamination, the isolation wall ensures that no direct light enters the receiving channel, thereby guaranteeing that the detection signal originates purely from the scattering of external particles, greatly reducing the system's background noise and false alarm probability.

[0041] The advantage of this embodiment is that it fundamentally solves the optical crosstalk problem between the emitted and received light through a simple mechanical isolation structure. This design is inexpensive and highly reliable, and is key to ensuring the signal-to-noise ratio and measurement accuracy of the detection signal.

[0042] In one possible implementation, the signal processing unit includes a transimpedance amplifier that converts the current signal output by the optical signal receiving unit into a voltage signal in the amplified electrical signal.

[0043] Among them, a transimpedance amplifier can refer to an operational amplifier circuit that converts input current into output voltage, and its gain is determined by the feedback resistor.

[0044] In the aforementioned particulate matter concentration detection device embodiment, the core of the signal processing unit is a transimpedance amplifier circuit built upon a precision operational amplifier. The nanoampere-level photocurrent generated by the photodiode when receiving scattered light is input as the inverting input of the transimpedance amplifier. The transimpedance amplifier linearly converts this current into a millivolt-level voltage signal through a high-resistance (e.g., 10 megohms) feedback resistor. This voltage signal is then further amplified by a multi-stage programmable gain amplifier, ultimately yielding an amplified electrical signal (e.g., 0-3.3V) suitable for the acquisition range of the analog-to-digital converter within the control unit. A low-pass filter network is also designed at the front end of the transimpedance amplifier to suppress high-frequency circuit noise.

[0045] The beneficial effect of this embodiment is that the transimpedance amplifier is one of the most effective and direct circuit solutions for processing the weak current signal output by the photodiode. It can convert the current signal into a voltage signal with high linearity and wide dynamic range, providing a high-quality analog signal foundation for subsequent accurate digitization and concentration inversion.

[0046] In one possible implementation, the control unit has pre-stored calibration data, and the control unit calculates particulate matter concentration data by comparing the amplified electrical signal with the calibration data.

[0047] Among them, calibration data can refer to a set of data that is established in advance through experiments and reflects the correspondence between particulate matter concentration and the output signal of the detection device, such as lookup table or fitting curve parameters.

[0048] In the aforementioned particulate matter concentration detection device embodiment, a calibration lookup table is pre-stored in the flash memory of the control unit. This lookup table is generated before shipment by placing the entire device in a standard dust concentration test chamber, introducing standard particles of different known concentrations (such as ISO 12103-1 A1 test dust), and recording the average voltage value of the amplified electrical signal output by the device at different concentrations. During actual operation, the analog-to-digital converter of the control unit periodically samples the amplified electrical signal and calculates a moving average voltage value. Subsequently, the processor queries the calibration lookup table and converts the current average voltage value into the corresponding PM2.5 mass concentration value using linear interpolation. This method based on pre-stored calibration data eliminates the need for complex real-time algorithm calculations, offers fast response speed, and ensures factory consistency.

[0049] The beneficial effect of this embodiment is that by using a pre-calibration method, the complex physical optical model and concentration inversion algorithm are simplified into a simple table lookup operation, which significantly reduces the computational load and software complexity of the control unit. This allows for the use of lower-cost, lower-power microcontrollers while ensuring measurement accuracy and consistency, facilitating large-scale production and application.

[0050] In one possible implementation, the laser emitting unit is a side-emitting laser or a vertical-cavity surface-emitting laser, and the optical signal receiving unit is a photodiode or a phototransistor.

[0051] Among these, a side-emitting laser refers to a laser diode that emits light from the side of a semiconductor chip. A vertical-cavity surface-emitting laser refers to a laser that emits light vertically from the surface of a chip. A phototransistor refers to a transistor device that uses the photoelectric effect to amplify optical signals and convert them into electrical signals.

[0052] In the aforementioned particulate matter concentration detection device embodiment, two optional core optoelectronic component combination schemes are provided. The first scheme uses a common combination of edge-emitting laser diodes and silicon photodiodes, which is cost-effective and technologically mature. The second scheme uses a combination of a vertical-cavity surface-emitting laser (VCSEL) and a phototransistor. VCSELs have a circularly symmetrical spot size and a lower divergence angle, resulting in higher coupling efficiency with the lens and contributing to a more uniform detection area. Compared to photodiodes, phototransistors have internal gain, enabling them to output stronger current signals and simplifying the design of subsequent signal amplification circuits. Both schemes can be integrated into the aforementioned package and optical path design, providing users with the flexibility to choose according to different performance requirements and cost budgets.

[0053] The beneficial effect of this embodiment is that it clarifies the selectable types of core optoelectronic components, thus broadening the implementation methods of the present invention. By employing high-performance components such as vertical-cavity surface-emitting lasers and phototransistors, detection performance can be further improved; while using traditional edge-emitting lasers and photodiodes can achieve lower costs while meeting basic detection requirements, thereby enhancing the market adaptability and feasibility of this technical solution.

[0054] In one possible implementation, the control unit is also configured to analyze the pulse amplitude or pulse frequency distribution of the amplified electrical signal to distinguish signals generated by particles of different size ranges.

[0055] The pulse amplitude refers to the peak voltage of the electrical pulse corresponding to the scattered light signal caused by a single particle passing through the detection area. The pulse frequency refers to the number of pulses detected per unit time.

[0056] In the aforementioned particulate matter concentration detection device embodiment, the control unit's software algorithm, in addition to calculating the average concentration, also possesses particle size analysis capabilities. When a single larger particle (such as PM10) passes through the detection area, it generates a high-amplitude scattered light pulse; while when multiple smaller particles (such as PM2.5) pass through rapidly, they may generate a series of low-amplitude but high-frequency pulses. The control unit monitors the amplified electrical signal in real time and counts and classifies the pulses by setting different amplitude thresholds. For example, all pulses are divided into two categories based on amplitude, and the count rate of each category of pulses within a fixed time window is statistically analyzed. Combining the pre-established correspondence between pulse amplitude / frequency and particle size distribution through calibration, the control unit can estimate the approximate proportion or concentration trend of PM2.5 and PM10 in the air, achieving a preliminary particle size resolution function.

[0057] The beneficial effect of this embodiment is that, based on a single optical structure, an upgraded signal processing algorithm enables a rough distinction of particulate matter size distribution. This provides richer ambient air quality information than a single PM2.5 concentration value, enhancing the product's functional value and user experience without incurring additional hardware costs.

[0058] In one possible implementation, the device is a component of a portable air quality detector, an in-vehicle air monitoring module, or a smart home environment sensor.

[0059] Portable air quality detectors can refer to handheld or portable standalone testing devices. Vehicle-mounted air monitoring modules can refer to dedicated components installed in vehicles to monitor in-vehicle air quality. Smart home environmental sensors can refer to sensor nodes that can connect to smart home systems to monitor indoor air parameters.

[0060] The aforementioned particulate matter concentration detection device, with its advantages of small size, low power consumption, and fanless operation, can be easily integrated into various terminal products as a core sensing module. For example, it can be installed in a handheld casing with a display screen and lithium battery to form a portable air quality detector. It can also be designed as a module with a CAN bus or automotive power interface, embedded in a car dashboard or air conditioning duct, becoming an in-vehicle air monitoring module. Furthermore, it can be packaged together with a temperature and humidity sensor in a small plastic shell, connecting to a smart home gateway via Wi-Fi or Bluetooth, serving as a smart home environmental sensor and reporting PM2.5 data to the user's mobile app or central control system in real time.

[0061] The beneficial effect of this embodiment is that it clarifies the wide range of application scenarios for the device of the present invention. Its high integration and passive detection characteristics enable it to flexibly adapt to product forms in various fields, from personal consumer electronics to automotive electronics and smart homes, greatly expanding the commercial application prospects and market potential of the technology.

[0062] This application also provides a method for detecting particulate matter concentration, using the particulate matter concentration detection device described above, the method comprising: Step S401: The laser emitting unit emits a detection beam into the open air through the optical lens assembly to form a detection area; Step S402: The optical signal receiving unit receives the scattered light generated by the particles passing through the detection area through the optical lens assembly and generates an initial electrical signal; Step S403: The signal processing unit amplifies the initial electrical signal to generate an amplified electrical signal; Step S404: The control unit processes the amplified electrical signal to obtain particulate matter concentration data.

[0063] The method will be further described below through a detailed embodiment.

[0064] This particulate matter concentration detection method is applied to the device described in any of the foregoing embodiments. The method begins with the device power-on initialization. First, the control unit activates the laser emitting unit. The laser emitting unit emits an infrared laser beam, which is collimated by a coaxial lens at the front end of the device to form a stable optical detection area outside the device. This area is exposed to ambient air, and particulate matter passes through it randomly due to natural air convection.

[0065] When PM2.5 and other particulate matter in the air pass through the detection area with the airflow, they scatter the laser light. The backscattered portion of the scattered light is collected and converged by the same coaxial lens. Due to the presence of physical isolation walls inside the device, only the scattered light returning from the outside can be guided to the photosensitive surface of the optical signal receiving unit. The optical signal receiving unit (photodiode) converts the received transient light intensity changes into a weak pulse current signal, i.e., the initial electrical signal.

[0066] The initial electrical signal is transmitted to the signal processing unit. The transimpedance amplifier circuit in the signal processing unit first converts the pulse current signal into a voltage pulse, and then the voltage pulse is amplified to a suitable amplitude range for acquisition by a programmable gain amplifier to form an amplified electrical signal.

[0067] The control unit periodically samples the amplified electrical signal. Within a preset measurement period (e.g., 30 seconds), the control unit acquires and stores a series of voltage sample values. Subsequently, the control unit executes the following processing steps: first, it digitally filters the sampled signal to reduce noise; then, it analyzes the amplitude and frequency distribution of the pulses, possibly based on preset thresholds; finally, it calculates the average intensity or RMS value of the signal within that period. The control unit compares and calculates the processed signal characteristic values ​​with the calibration data pre-stored in its memory, ultimately outputting a value representing the current concentration of particulate matter in the ambient air, completing one detection cycle. This method is repeated cyclically to achieve continuous monitoring.

[0068] The beneficial effect of this method embodiment is that it describes a passive detection process based on a highly integrated optical sensing device. The method has clear steps, is closely integrated with the device's hardware characteristics, and fully utilizes the advantages of common optical path, natural sampling, and signal processing to achieve stable, reliable, and low-power online monitoring of particulate matter concentration. It is simple to operate and requires no manual intervention.

[0069] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the embodiments in this specification are not limited to the described order of actions, because according to the embodiments in this specification, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in this specification are all preferred embodiments, and the actions and modules involved are not necessarily essential to the embodiments in this specification.

[0070] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0071] The preferred embodiments disclosed above are merely illustrative of this specification. The optional embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the embodiments described herein. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the embodiments, thereby enabling those skilled in the art to better understand and utilize this specification. This specification is limited only by the claims and their full scope and equivalents.

Claims

1. A particulate matter concentration detection device, characterized in that, include: An integrated package, wherein a laser emitting unit and an optical signal receiving unit are disposed within the integrated package; An optical lens assembly is installed in front of the optical path of the integrated package. The light beam emitted by the laser emitting unit forms a detection area in the open air outside the device after passing through the optical lens assembly. The optical lens assembly focuses the scattered light of the light beam by the particles in the detection area onto the optical signal receiving unit. A physical isolation structure is located within the integrated package and disposed between the laser emitting unit and the optical signal receiving unit; A signal processing unit, electrically connected to the optical signal receiving unit, is used to receive the electrical signal generated by the optical signal receiving unit based on the scattered light, amplify the electrical signal, and output an amplified electrical signal; The control unit is electrically connected to the signal processing unit and is used to receive the amplified electrical signal and calculate particulate matter concentration data based on the amplified electrical signal.

2. The particulate matter concentration detection device according to claim 1, characterized in that, The optical lens assembly includes a coaxial lens, and the emitting optical axis of the laser emitting unit and the receiving optical axis of the optical signal receiving unit are aligned coaxially or quasi-coaxially through the coaxial lens.

3. The particulate matter concentration detection device according to claim 1, characterized in that, The detection area relies on natural airflow to allow particulate matter to pass through.

4. The particulate matter concentration detection device according to claim 1, characterized in that, The physical isolation structure is an opaque isolation wall, which is used to prevent the light beam emitted by the laser emitting unit from directly illuminating the optical signal receiving unit.

5. The particulate matter concentration detection device according to claim 1, characterized in that, The signal processing unit includes a transimpedance amplifier, which converts the current signal output by the optical signal receiving unit into a voltage signal in the amplified electrical signal.

6. The particulate matter concentration detection device according to claim 1, characterized in that, The control unit has pre-stored calibration data, and the control unit calculates the particulate matter concentration data by comparing the amplified electrical signal with the calibration data.

7. The particulate matter concentration detection device according to claim 1, characterized in that, The laser emitting unit is a side-emitting laser or a vertical-cavity surface-emitting laser, and the optical signal receiving unit is a photodiode or a phototransistor.

8. The particulate matter concentration detection device according to claim 1, characterized in that, The control unit is also configured to analyze the pulse amplitude or pulse frequency distribution of the amplified electrical signal to distinguish signals generated by particles of different size ranges.

9. The particulate matter concentration detection device according to claim 1, characterized in that, The device is a component of a portable air quality detector, a vehicle-mounted air monitoring module, or a smart home environment sensor.

10. A method for detecting particulate matter concentration, characterized in that, The method using the particulate matter concentration detection device according to any one of claims 1 to 9 includes: The laser emitting unit emits a detection beam into the open air through the optical lens assembly, forming the detection area; The optical signal receiving unit receives the scattered light generated by the particles passing through the detection area through the optical lens assembly and generates an initial electrical signal; The signal processing unit amplifies the initial electrical signal to generate the amplified electrical signal; The control unit processes the amplified electrical signal to obtain the particulate matter concentration data.

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