Classroom air quality detection device

Abstract

The invention relates to the technical field of air detection equipment, and provides a classroom air quality detection device which comprises a packaging shell, and a control circuit board is arranged in the packaging shell; the control circuit board is provided with a plurality of sensors used for detecting air quality in a classroom, the control circuit board comprises a power supply circuit, a 4G communication module circuit, a sensor acquisition circuit, an expansion single-chip microcomputer control circuit and a main single-chip microcomputer control circuit, and the power supply circuit supplies power to the control circuit board; the 4G communication module circuit, the sensor acquisition circuit and the extended single-chip microcomputer control circuit are respectively connected with the main single-chip microcomputer control circuit, thereby realizing acquisition of classroom air quality and providing a data basis for effective monitoring of the classroom air quality.

Description

Technical Field

[0001] The invention belongs to the technical field of air detection equipment, and in particular relates to a classroom air quality detection device. Background Art

[0002] The quality of classroom teaching is increasingly closely related to the classroom environment. The classroom is densely populated, and the air quality is directly related to the health of teachers and students. For example, when the concentration of carbon dioxide exhaled by people in the classroom is too high, it will make people sleepy and lead to inattention, thus affecting the quality of students' listening and learning. In winter, when ventilation is poor, carbon dioxide is easy to accumulate. Indoor temperature and humidity also have an important impact on the comfort of students and teachers. Too high or too low temperature will affect the work and learning efficiency of teachers and students. If the humidity is too high, it will make people feel stuffy and sticky, and it is easy to breed bacteria and mold; too low humidity will cause problems such as dry skin and dry and itchy throat. Light intensity and quality play a key role in protecting students' eyesight and learning effects. According to national standards, the average illumination of classroom desks should not be less than 300 lux. Appropriate lighting can enable students to see the contents of books and blackboards more clearly and reduce visual fatigue. In newly renovated classrooms or classrooms with new furniture, these harmful gases may exceed the standard, causing serious harm to the health of teachers and students.

[0003] In summary, in view of the current air quality detection environment faced by classrooms, the existing detection equipment has the following defects: (1) Sensor detection accuracy and stability are crucial, but the sensors currently configured in classrooms are affected by transmission distance and signal interference during data transmission. (2) When selecting classroom power supplies, the power battery cannot work for a long time and requires frequent maintenance. Although an external power supply can solve the battery life problem, it has wiring difficulties and safety issues. Summary of the invention

[0004] In view of the defects in the prior art, the present invention provides a classroom air quality detection device, which aims to solve the problems of interference in sensor transmission data and inconvenient power supply configuration and wiring in the air quality detection equipment configured in the existing classroom.

[0005] The technical solution provided by the present invention is: a classroom air quality detection device, the classroom air quality detection device comprises a packaging shell, and a control circuit board is arranged in the packaging shell; The control circuit board is provided with several sensors for detecting the air quality in the classroom. The control circuit board includes a power supply circuit, a 4G communication module circuit, a sensor acquisition circuit, an extended single-chip control circuit and a main single-chip control circuit. The power supply circuit supplies power to the control circuit board. The 4G communication module circuit, the sensor acquisition circuit and the extended single-chip control circuit are respectively connected to the main single-chip control circuit.

[0006] As an improved solution, the power supply circuit includes a buck rectifier U5, the circuit led out from pin 5 of the buck rectifier U5 is connected to pin 1 of the connector VINI, a first circuit node is provided on the circuit between the pin of the buck rectifier U5 and pin 1 of the connector VINI, the circuit led out from the first circuit node is connected in series with a resistor R43 and then connected to pin 4 of the buck rectifier U5; the circuit led out from pin 6 of the buck rectifier U5 is connected in series with an inductor L2 and then set as a VDD5V voltage terminal, the inductor L2 and the pin 1 of the buck rectifier U5 are connected in series with each other, and the voltage terminal VDD5V is set as a VDD5V voltage terminal. A second circuit node is provided on the line between pins 6, and the line led out from the second circuit node is connected in series with a resistor R41 and then connected to pin 3 of the buck rectifier U5. A third circuit node is provided on the line between pin 3 of the buck rectifier U5 and the resistor R41, and the line led out from the third circuit node is connected in series with a resistor R42 and a capacitor C45 and then connected to the VDD5V voltage terminal. The line led out from the VDD5V voltage terminal is connected to pin 1 of the voltage regulating chip U6, and the line led out from pin 3 of the voltage regulating chip U6 is set to the VDD33V voltage terminal.

[0007] As an improved solution, the main single-chip microcomputer control circuit includes a single-chip microcomputer chip U1, the extended single-chip microcomputer control circuit includes an extended single-chip microcomputer chip U111, pin 5 and pin 6 of the single-chip microcomputer chip U1 are correspondingly connected to pin 6 and pin 5 of the extended single-chip microcomputer chip U111, the 4G communication module circuit includes a 4G communication chip U10, the line led out from pin 6 of the 4G communication chip U10 is connected to pin 48 of the single-chip microcomputer chip U1, and the lines led out from pin 2 and pin 3 of the 4G communication chip U10 are respectively connected to pin 46 and pin 45 of the single-chip microcomputer chip U1.

[0008] As an improved solution, the sensor acquisition circuit includes a temperature and humidity sensor circuit, a light sensor interface circuit, a spectrum sensor interface circuit, a formaldehyde sensor interface circuit, a PM2.5 sensor circuit and a carbon dioxide sensor interface circuit. The temperature and humidity sensor circuit, the light sensor interface circuit, the spectrum sensor interface circuit, the formaldehyde sensor interface circuit, the PM2.5 sensor circuit and the carbon dioxide sensor interface circuit are respectively connected to the single-chip microcomputer chip U1.

[0009] As an improved solution, the temperature and humidity sensor circuit includes a temperature and humidity sensor U3, a circuit led out from pin 1 of the temperature and humidity sensor U3 is connected to pin 35 of the single-chip chip U1, and is connected to the VDD33V voltage terminal after being connected in series with a resistor R2, a circuit led out from pin 6 of the temperature and humidity sensor U3 is connected to pin 36 of the single-chip chip U1, and is connected to the VDD33V voltage terminal after being connected in series with a resistor R1, a circuit led out from pin 5 of the temperature and humidity sensor U3 is connected to the VDD33V voltage terminal, a fourth circuit node is provided on the circuit between pin 5 of the temperature and humidity sensor U3 and the VDD33V voltage terminal, and the circuit led out from the fourth circuit node is connected in series with a capacitor C41 and then grounded; The light sensor interface circuit includes a light sensor slot GZ, the line led out from pin 1 of the light sensor slot GZ is connected to the VDD33V voltage terminal, the lines led out from pin 2 and pin 3 of the light sensor slot GZ are respectively connected to pin 10 and pin 9 of the single-chip chip U1, a fifth circuit node is provided on the line between pin 2 of the light sensor slot GZ and pin 10 of the single-chip chip U1, a sixth circuit node is provided on the line between pin 3 of the light sensor slot GZ and pin 9 of the single-chip chip U1, the line led out from the fifth circuit node is connected in series with a resistor R29 and then connected to the VDD33V voltage terminal, and the line led out from the sixth circuit node is connected in series with a resistor R30 and then connected to the VDD33V voltage terminal.

[0010] As an improved solution, the spectrum sensor interface circuit includes a spectrum sensor interface SCOM3, the line led out of pin 1 of the spectrum sensor interface SCOM3 is connected to the VDD5V voltage terminal, and the lines led out of pin 2 and pin 3 of the spectrum sensor interface SCOM3 are respectively connected to pin 43 and pin 44 of the single-chip microcomputer chip U1; The formaldehyde sensor interface circuit comprises a formaldehyde sensor interface S2COM4, ​​and the lines led out from pin 2 and pin 3 of the formaldehyde sensor interface S2COM4 are respectively connected to pin 45 and pin 46 of the extended single-chip microcomputer chip U111.

[0011] As an improved solution, the PM2.5 sensor circuit includes a PM2.5 sensor Sx2, wherein pin 1 and pin 2 of the PM2.5 sensor Sx2 are respectively connected to the VDD5V voltage terminal, and lines derived from pin 7 and pin 9 of the PM2.5 sensor Sx2 are respectively connected to pin 44 and pin 43 of the extended single-chip microcomputer chip U111; The carbon dioxide sensor interface circuit comprises a carbon dioxide sensor socket COCO2_2, and the lines led out from pins 3 and 2 of the carbon dioxide sensor socket COCO2_2 are correspondingly connected to pins 19 and 20 of the extended single-chip microcomputer chip U111.

[0012] As an improved solution, an indicator light circuit is also provided on the control circuit board, and the indicator light circuit includes a resistor R20 and a resistor R21. The circuit led out from one end of the resistor R20 is connected to the pin 21 of the single-chip chip U1, and the other end is connected in series with the light-emitting diode LD1 and then grounded. The circuit led out from one end of the resistor R21 is connected to the pin 22 of the single-chip chip U1, and the other end is connected in series with the light-emitting diode LD2 and then grounded.

[0013] As an improved solution, a buzzer circuit is also provided on the control circuit board, and the buzzer circuit includes a resistor R13 connected to the pin 31 of the single-chip microcomputer chip U1, the other end of the resistor R13 is connected to the gate of the transistor Q1, the collector of the transistor Q1 is connected to the speaker, and the emitter of the transistor Q1 is grounded.

[0014] As an improved solution, a Bluetooth interface circuit is also provided on the control circuit board, and the Bluetooth interface circuit includes a Bluetooth interface J2, the circuit led out from pin 3 of the Bluetooth interface J2 is connected to the VDD33V voltage terminal, the circuit led out from pin 6 of the Bluetooth interface J2 is connected to pin 47 of the microcontroller chip U1, and the circuit led out from pin 13 and pin 14 of the Bluetooth interface J2 is connected to pin 46 and pin 465 of the microcontroller chip U1 respectively.

[0015] In an embodiment of the present invention, a classroom air quality detection device includes a packaging shell, in which a control circuit board is arranged; a number of sensors for detecting the air quality in the classroom are arranged on the control circuit board, and the control circuit board includes a power supply circuit, a 4G communication module circuit, a sensor acquisition circuit, an extended single-chip microcomputer control circuit and a main single-chip microcomputer control circuit. The power supply circuit supplies power to the control circuit board, and the 4G communication module circuit, the sensor acquisition circuit, and the extended single-chip microcomputer control circuit are respectively connected to the main single-chip microcomputer control circuit, thereby realizing the collection of classroom air quality and providing a data basis for effective monitoring of classroom air quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0017] Figure 1 It is a structural block diagram of the classroom air quality detection device provided by the present invention; Figure 2 is a circuit diagram of a power supply circuit provided by the present invention; Figure 3 It is a circuit diagram of the main single-chip microcomputer control circuit provided by the present invention; Figure 4 It is a circuit diagram of the extended single-chip microcomputer control circuit provided by the present invention; Figure 5 is a circuit diagram of a 4G communication module circuit provided by the present invention; Figure 6 is a circuit diagram of a sensor acquisition circuit provided by the present invention; Figure 7 is a circuit diagram of a temperature and humidity sensor circuit provided by the present invention; Figure 8 is a circuit diagram of a light sensor interface circuit provided by the present invention; Fig. 9 is a circuit diagram of a spectrum sensor interface circuit provided by the present invention; Fig.10 is a circuit diagram of a formaldehyde sensor interface circuit provided by the present invention; Fig.11 is a circuit diagram of a PM2.5 sensor circuit provided by the present invention; Fig.12 is a circuit diagram of a carbon dioxide sensor interface circuit provided by the present invention; Fig.13 is a circuit diagram of an indicator light circuit provided by the present invention; Fig.14 is a circuit diagram of a buzzer circuit provided by the present invention; Fig.15 The present invention provides a circuit diagram of a Bluetooth interface circuit. DETAILED DESCRIPTION

[0018] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention.

[0019] Figure 1 4 is a structural block diagram of the classroom air quality detection device provided by the present invention. For the convenience of explanation, only the parts related to the embodiment of the present invention are shown in the figure.

[0020] The classroom air quality detection device comprises a packaging shell, in which a control circuit board is arranged; The control circuit board is provided with several sensors for detecting the air quality in the classroom. The control circuit board includes a power supply circuit 11, a 4G communication module circuit 12, a sensor acquisition circuit 13, an extended single-chip control circuit 14 and a main single-chip control circuit 15. The power supply circuit 11 supplies power to the control circuit board, and the 4G communication module circuit 12, the sensor acquisition circuit 13, and the extended single-chip control circuit 14 are respectively connected to the main single-chip control circuit 15.

[0021] In this embodiment, the control circuit board selects a microcontroller development board with powerful processing capabilities and supports 4G module expansion, which is responsible for coordinating the data collection, processing and communication with the external network of each sensor. Ensure that the development board has enough GPIO pins to connect various sensors, and its operating voltage is compatible with the subsequent circuit, usually adapting to the logic level of 3.3V - 5V.

[0022] like Figure 2 As shown, the power supply circuit 11 includes a buck rectifier U5, the line led out from the pin 5 of the buck rectifier U5 is connected to the pin 1 of the connector VINI, a first circuit node is provided on the line between the pin of the buck rectifier U5 and the pin 1 of the connector VINI, the line led out from the first circuit node is connected in series with a resistor R43 and then connected to the pin 4 of the buck rectifier U5; the line led out from the pin 6 of the buck rectifier U5 is connected in series with an inductor L2 and is set as a VDD5V voltage terminal, a second circuit node is provided on the line between the inductor L2 and the pin 6 of the buck rectifier U5, and the second circuit node leads out The line is connected in series with resistor R41 and then connected to pin 3 of the buck rectifier U5. A third circuit node is provided on the line between pin 3 of the buck rectifier U5 and the resistor R41. The line led out from the third circuit node is connected in series with resistor R42 and capacitor C45 and then connected to the VDD5V voltage terminal. The line led out from the VDD5V voltage terminal is connected to pin 1 of the voltage regulating chip U6. The line led out from pin 3 of the voltage regulating chip U6 is set to the VDD33V voltage terminal. The model of the buck rectifier U5 is JW5026, and the model of the voltage regulating chip U6 is LM1117-33.

[0023] The power supply circuit 11 is a 220V to 12DC voltage stabilization circuit, which can use linear voltage stabilization chips such as LM7805 and AMS1117 or high-efficiency DC-DC step-down chips. It ensures that the input 12V DC is stably converted into the working voltage required by the sensor and the main control board, providing reliable power protection for the entire device, and adding filter capacitors to reduce power ripple interference.

[0024] Combination Figure 3 and Figure 4As shown, the main single-chip control circuit includes a single-chip chip U1, and the extended single-chip control circuit 14 includes an extended single-chip chip U111. Pins 5 and 6 of the single-chip chip U1 are connected to pins 6 and 5 of the extended single-chip chip U111. Figure 5 As shown, the 4G communication module circuit 12 includes a 4G communication chip U10, the line led out of pin 6 of the 4G communication chip U10 is connected to pin 48 of the single-chip chip U1, and the lines led out of pins 2 and 3 of the 4G communication chip U10 are respectively connected to pins 46 and 45 of the single-chip chip U1. The 4G communication chip U10 selects a module that supports the mainstream 4G frequency band and has a standard TTL interface, such as Quectel EC20. It is connected to the control circuit board through the UART serial port (TTL level) to achieve high-speed docking between the device and the Internet, so as to upload the monitoring data to the cloud server or remote monitoring terminal in real time. Among them, the models of the above-mentioned single-chip chip U1 and the extended single-chip chip U111 can both use STC32G12K64.

[0025] Combination Figure 6 As shown, the sensor acquisition circuit 13 includes but is not limited to a temperature and humidity sensor circuit 16, a light sensor interface circuit 17, a spectrum sensor interface circuit 18, a formaldehyde sensor interface circuit 19, a PM2.5 sensor circuit 20 and a carbon dioxide sensor interface circuit 21. The temperature and humidity sensor circuit 16, the light sensor interface circuit 17, the spectrum sensor interface circuit 18, the formaldehyde sensor interface circuit 19, the PM2.5 sensor circuit 20 and the carbon dioxide sensor interface circuit 21 are respectively connected to the single-chip microcomputer chip U1.

[0026] like Figure 7 As shown, the temperature and humidity sensor circuit 16 includes a temperature and humidity sensor U3, a circuit led out from pin 1 of the temperature and humidity sensor U3 is connected to pin 35 of the single-chip chip U1, and is connected to the VDD33V voltage terminal after being connected in series with a resistor R2, a circuit led out from pin 6 of the temperature and humidity sensor U3 is connected to pin 36 of the single-chip chip U1, and is connected to the VDD33V voltage terminal after being connected in series with a resistor R1, a circuit led out from pin 5 of the temperature and humidity sensor U3 is connected to the VDD33V voltage terminal, a fourth circuit node is provided on the circuit between pin 5 of the temperature and humidity sensor U3 and the VDD33V voltage terminal, and a circuit led out from the fourth circuit node is connected in series with a capacitor C41 and then grounded; Among them, a high-precision temperature and humidity sensor model SHT20 is selected. The sensor integrates advanced sensing elements and can measure ambient temperature and humidity with high accuracy. The output digital signal can be directly connected to the GPIO pin of the control circuit board and adopts TTL communication protocol to facilitate data reading and processing.

[0027] like Figure 8 As shown, the light sensor interface circuit 17 includes a light sensor slot GZ, the line led out from pin 1 of the light sensor slot GZ is connected to the VDD33V voltage terminal, the lines led out from pin 2 and pin 3 of the light sensor slot GZ are respectively connected to pin 10 and pin 9 of the single-chip microcomputer chip U1, a fifth circuit node is provided on the line between pin 2 of the light sensor slot GZ and pin 10 of the single-chip microcomputer chip U1, a sixth circuit node is provided on the line between pin 3 of the light sensor slot GZ and pin 9 of the single-chip microcomputer chip U1, the line led out from the fifth circuit node is connected in series with a resistor R29 and then connected to the VDD33V voltage terminal, and the line led out from the sixth circuit node is connected in series with a resistor R30 and then connected to the VDD33V voltage terminal.

[0028] Among them, the silicon photocell light sensor is used, which works based on the principle of photoelectric effect. Different light intensities will cause the silicon photocell to generate different photocurrents. The measurement range is generally 0-20000 lux, with an accuracy of ±5%. It can accurately measure the light conditions at different times and locations in the classroom, providing a reliable basis for classroom lighting design and lighting adjustment. The light sensor is small in size and low in power consumption. It can measure the ambient light intensity and transmit data to the control circuit board in digital form through the TTL protocol, providing a basis for judging the lighting conditions in the classroom.

[0029] like Fig. 9 As shown, the spectrum sensor interface circuit 18 includes a spectrum sensor interface SCOM3, the line led out of pin 1 of the spectrum sensor interface SCOM3 is connected to the VDD5V voltage terminal, and the lines led out of pin 2 and pin 3 of the spectrum sensor interface SCOM3 are respectively connected to pin 43 and pin 44 of the single-chip microcomputer chip U1; Among them, the spectral sensor is a sensor that can cover the visible light band (for example, 350-1000nm) and has a certain spectral resolution. It can analyze the spectral components of light, judge the spectral quality of classroom lighting, and connect the output data to the control circuit board through TTL to help create a high-quality light environment.

[0030] like Fig.10 As shown, the formaldehyde sensor interface circuit 19 includes a formaldehyde sensor interface S2COM4, ​​and the lines led out of pin 2 and pin 3 of the formaldehyde sensor interface S2COM4 are respectively connected to pin 45 and pin 46 of the extended single-chip microcomputer chip U111, wherein an electrochemical formaldehyde sensor is used, which has high sensitivity to formaldehyde. The measurement range is 0-5ppm, and the accuracy is ≤0.01ppm. It can quickly detect formaldehyde released by decoration materials, furniture, etc., to ensure the safety of indoor air quality.

[0031] like Fig.11As shown, the PM2.5 sensor circuit 20 includes a PM2.5 sensor Sx2, pins 1 and 2 of the PM2.5 sensor Sx2 are respectively connected to the VDD5V voltage terminal, and the lines led out of pins 7 and 9 of the PM2.5 sensor Sx2 are respectively connected to pins 44 and 43 of the extended microcontroller chip U111; Among them, PM2.5 and PM10 sensors are sensors that use the principle of laser scattering. They can accurately measure the concentration of fine particles in the air, output digital signals and communicate with the control circuit board in TTL mode, and promptly remind teachers and students to pay attention to air quality.

[0032] like Fig.12 As shown, the carbon dioxide sensor interface circuit 21 includes a carbon dioxide sensor socket COCO2_2, and the lines led out from pins 3 and 2 of the carbon dioxide sensor socket COCO2_2 are correspondingly connected to pins 19 and 20 of the extended single-chip microcomputer chip U111.

[0033] Among them, the carbon dioxide sensor uses non-dispersive infrared absorption (NDIR) sensor, which has the characteristics of high precision and high stability. The measurement range is usually 0 - 5000ppm, and the accuracy can reach ± ​​(30ppm + 3% reading), which can effectively reflect the CO2 caused by breathing in the classroom. 2 The carbon dioxide sensor uses the chemical reaction principle to sense the change of carbon dioxide concentration (concentration range 0 - 5000ppm), and the output analog signal is connected to the control circuit board after ADC conversion. It follows the TTL communication specification and provides real-time feedback on the carbon dioxide content in the classroom, which is of great significance for the evaluation of ventilation conditions. Combination Figure 1 and Fig.13 As shown, an indicator light circuit 22 is also provided on the control circuit board, and the indicator light circuit includes a resistor R20 and a resistor R21. A line led out from one end of the resistor R20 is connected to the pin 21 of the single-chip chip U1, and the other end is connected in series with the light-emitting diode LD1 and then grounded. A line led out from one end of the resistor R21 is connected to the pin 22 of the single-chip chip U1, and the other end is connected in series with the light-emitting diode LD2 and then grounded. Combination Figure 1 and Fig.14 As shown, a buzzer circuit 23 is also provided on the control circuit board, and the buzzer circuit includes a resistor R13 connected to the pin 31 of the single-chip microcomputer chip U1, the other end of the resistor R13 is connected to the gate of the transistor Q1, the collector of the transistor Q1 is connected to the speaker, and the emitter of the transistor Q1 is grounded; Combination Figure 1 and Fig.15As shown, a Bluetooth interface circuit 24 is also provided on the control circuit board, and the Bluetooth interface circuit includes a Bluetooth interface J2, a circuit led out of pin 3 of the Bluetooth interface J2 is connected to the VDD33V voltage terminal, a circuit led out of pin 6 of the Bluetooth interface J2 is connected to pin 47 of the microcontroller chip U1, and a circuit led out of pin 13 and pin 14 of the Bluetooth interface J2 is connected to pin 46 and pin 465 of the microcontroller chip U1 correspondingly.

[0034] In the embodiment of the present invention, the classroom air quality detection device has the following specific features: (1) Software programming and debugging Development environment construction: Install an integrated development environment (IDE) suitable for the control circuit board on the computer, such as Keil, IAR, etc., and configure the corresponding compiler and debugging tools to ensure that the program can be written, compiled and downloaded to the main control board smoothly; (2) Sensor driver programming For each sensor, write the driver code according to its data sheet. Taking the temperature and humidity sensor as an example, read the temperature and humidity data output by the sensor according to a specific timing by controlling the GPIO pins of the circuit board and convert them into actual physical quantity values. The same is true for other sensors to ensure accurate and stable data acquisition.

[0035] (3) 4G communication program development By using the AT command set or SDK provided by the 4G module, a 4G communication program is developed on the control circuit board to achieve automatic networking and network registration after the device is turned on, and to package the collected environmental data in a predetermined format (such as JSON format) and upload it to the specified server address through the 4G network. At the same time, it can receive remote configuration instructions from the server to achieve remote control of the device.

[0036] (4) Data processing and alarm logic The data processing algorithm is set in the program of the control circuit board to analyze the collected environmental data in real time. For example, the average value of carbon dioxide concentration over a period of time is calculated, and the trend of PM2.5 concentration is determined. The alarm threshold of each parameter is set according to the education department or relevant standards. When the detection value exceeds the threshold, the alarm module is immediately activated and the alarm information is pushed to the server.

[0037] (5) Timing switch function realization The timing switch logic is integrated into the program to determine whether the current time is in the preset shutdown time period by reading the real-time clock (RTC) module or system time. If so, the shutdown command is executed to turn off the corresponding sensor or put the entire device into a low-power standby state; when the startup time is reached, the device is automatically awakened and normal monitoring is resumed.

[0038] (6) Assembly and packaging The selected control circuit board, sensor module, 4G module, power module, alarm circuit and other electronic components are neatly welded or connected to the customized printed circuit board (PCB) through connectors according to the circuit design layout. Pay attention to reasonable wiring, avoid signal interference, and try to shorten the length of power and signal lines to improve circuit stability.

[0039] Install the assembled control circuit board in the selected package shell. The size of the package shell can be designed according to actual needs. Generally, it is necessary to consider installation methods such as portability, wall mounting or desktop placement. The shell is made of insulating and durable materials, such as plastic ABS, and the sensor detection window, power interface, 4G antenna interface, and the installation positions of operating components such as indicator lights and buttons are reserved to ensure the overall appearance and practicality of the equipment.

[0040] In an embodiment of the present invention, the following are steps for using a classroom air quality detection device (hereinafter referred to as the device): (1) Equipment installation First, choose a suitable installation location based on the actual layout and usage requirements of the classroom. If you focus on monitoring the overall air quality, you can install the device in a higher position in the center of the classroom to avoid direct interference from human activities; if you are concerned about the impact of lighting on a specific area, such as near the podium, you can install the light sensor and spectrum sensor on a nearby wall facing the light source.

[0041] Use wall-mounted accessories (such as expansion bolts, hooks, etc.) or desktop brackets to fix the device in the selected location. Ensure that it is firmly installed and will not fall or be damaged due to accidental collisions. Connect the 12V DC power supply and pay attention to the correct positive and negative connection to avoid reverse connection of the power supply and burning the device.

[0042] (2) Device initialization and networking Turn on the power switch of the device and wait for the device to start. After the control circuit board starts, it will automatically initialize each sensor module. At this time, observe the status of the indicator lights on the device. Under normal circumstances, the indicator lights corresponding to each sensor will flash briefly, indicating that self-test is in progress.

[0043] After the device is started, the 4G communication module automatically searches for nearby 4G base stations and tries to connect to the Internet. Wait for a while, if the indicator light shows that the 4G network is successful (such as two consecutive beeps), it means that the device has successfully connected to the Internet and you can proceed to the next step.

[0044] (3) Parameter configuration and threshold setting Connect to the device through the computer management software (need to be installed and registered in advance). In the software interface, you can view real-time environmental monitoring data, such as current temperature and humidity, carbon dioxide concentration, etc.

[0045] According to the actual use scenarios and requirements of the classroom, the alarm thresholds of various environmental parameters can be set in the management software. For example, for classrooms with dense population, the alarm threshold of carbon dioxide concentration can be set at around 1500ppm; for classrooms with higher air quality requirements, the PM2.5 alarm threshold can be set at 35μg / m³. At the same time, the time interval of the timer switch can also be set, such as turning off unnecessary sensors from 10 pm to 6 am the next day to save energy.

[0046] (4) Daily use and monitoring During the teaching process, the device will automatically collect various environmental parameters at a set frequency (such as once every 5 minutes) and upload them to the cloud server in real time through the 4G network. Teachers, students or administrators can check the real-time environmental conditions of the classroom at any time through mobile phone APP or computer software.

[0047] When the device detects that an environmental parameter exceeds the alarm threshold, the mobile phone APP or computer software will receive a push notification to remind relevant personnel to take measures to improve the classroom environment, such as opening windows for ventilation to reduce carbon dioxide concentration, turning on air purifiers to deal with particulate matter pollution, etc.

[0048] (5) Maintenance and care Clean the device regularly (e.g. once a month) and wipe the housing and sensor detection window with a clean soft cloth to prevent dust accumulation that may affect sensor performance.

[0049] Check whether the power connection is firm, and tighten it in time if it is loose. Calibrate the equipment every six months or one year. You can contact the equipment manufacturer or a professional calibration agency to calibrate the carbon dioxide, temperature and humidity sensors using standard gas, temperature and humidity sources, etc. to ensure the accuracy of the monitoring data.

[0050] Through the above production methods and usage steps, this classroom environment monitoring equipment can effectively provide strong support for classroom environment management and help create a healthy, comfortable and intelligent teaching environment.

[0051] In an embodiment of the present invention, a classroom air quality detection device includes a packaging shell, in which a control circuit board is arranged; the control circuit board is provided with a plurality of sensors for detecting the air quality in the classroom, and the control circuit board includes a power supply circuit 11, a 4G communication module circuit 12, a sensor acquisition circuit 13, an extended single-chip microcomputer control circuit 14 and a main single-chip microcomputer control circuit. The power supply circuit 11 supplies power to the control circuit board, and the 4G communication module circuit 12, the sensor acquisition circuit 13, and the extended single-chip microcomputer control circuit 14 are respectively connected to the main single-chip microcomputer control circuit, thereby realizing the collection of classroom air quality and providing a data basis for effective monitoring of classroom air quality.

[0052] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and should all be included in the scope of the claims and specification of the present invention.

Claims

1. A classroom air quality detection device, characterized in that: The classroom air quality detection device comprises a packaging shell, wherein a control circuit board is arranged in the packaging shell; The control circuit board is provided with several sensors for detecting the air quality in the classroom. The control circuit board includes a power supply circuit, a 4G communication module circuit, a sensor acquisition circuit, an extended single-chip control circuit and a main single-chip control circuit. The power supply circuit supplies power to the control circuit board. The 4G communication module circuit, the sensor acquisition circuit and the extended single-chip control circuit are respectively connected to the main single-chip control circuit.

2. The classroom air quality detection device according to claim 1, characterized in that: The power supply circuit includes a buck rectifier U5, a circuit led out from pin 5 of the buck rectifier U5 is connected to pin 1 of the connector VINI, a first circuit node is provided on the circuit between the pin of the buck rectifier U5 and pin 1 of the connector VINI, a circuit led out from the first circuit node is connected in series with a resistor R43 and then connected to pin 4 of the buck rectifier U5; a circuit led out from pin 6 of the buck rectifier U5 is connected in series with an inductor L2 and then set as a VDD5V voltage terminal, and a voltage between the inductor L2 and pin 6 of the buck rectifier U5 is provided. A second circuit node is provided on the line, and the line led out from the second circuit node is connected in series with a resistor R41 and then connected to pin 3 of the buck rectifier U5. A third circuit node is provided on the line between pin 3 of the buck rectifier U5 and the resistor R41, and the line led out from the third circuit node is connected in series with a resistor R42 and a capacitor C45 and then connected to the VDD5V voltage terminal. The line led out from the VDD5V voltage terminal is connected to pin 1 of the voltage regulating chip U6, and the line led out from pin 3 of the voltage regulating chip U6 is set to the VDD33V voltage terminal.

3. The classroom air quality detection device according to claim 2 is characterized in that: The main single-chip microcomputer control circuit includes a single-chip microcomputer chip U1, the extended single-chip microcomputer control circuit includes an extended single-chip microcomputer chip U111, pin 5 and pin 6 of the single-chip microcomputer chip U1 are correspondingly connected to pin 6 and pin 5 of the extended single-chip microcomputer chip U111, the 4G communication module circuit includes a 4G communication chip U10, the line led out of pin 6 of the 4G communication chip U10 is connected to pin 48 of the single-chip microcomputer chip U1, and the lines led out of pin 2 and pin 3 of the 4G communication chip U10 are respectively connected to pin 46 and pin 45 of the single-chip microcomputer chip U1.

4. The classroom air quality detection device according to claim 3 is characterized in that: The sensor acquisition circuit includes a temperature and humidity sensor circuit, a light sensor interface circuit, a spectrum sensor interface circuit, a formaldehyde sensor interface circuit, a PM2.5 sensor circuit and a carbon dioxide sensor interface circuit. The temperature and humidity sensor circuit, the light sensor interface circuit, the spectrum sensor interface circuit, the formaldehyde sensor interface circuit, the PM2.5 sensor circuit and the carbon dioxide sensor interface circuit are respectively connected to the single-chip microcomputer chip U1.

5. The classroom air quality detection device according to claim 4, characterized in that: The temperature and humidity sensor circuit includes a temperature and humidity sensor U3, a circuit led out from pin 1 of the temperature and humidity sensor U3 is connected to pin 35 of the single-chip chip U1, and is connected to the VDD33V voltage terminal after being connected in series with a resistor R2, a circuit led out from pin 6 of the temperature and humidity sensor U3 is connected to pin 36 of the single-chip chip U1, and is connected to the VDD33V voltage terminal after being connected in series with a resistor R1, a circuit led out from pin 5 of the temperature and humidity sensor U3 is connected to the VDD33V voltage terminal, a fourth circuit node is provided on the circuit between pin 5 of the temperature and humidity sensor U3 and the VDD33V voltage terminal, and a circuit led out from the fourth circuit node is connected in series with a capacitor C41 and then grounded; The light sensor interface circuit includes a light sensor slot GZ, the line led out from pin 1 of the light sensor slot GZ is connected to the VDD33V voltage terminal, the lines led out from pin 2 and pin 3 of the light sensor slot GZ are respectively connected to pin 10 and pin 9 of the single-chip chip U1, a fifth circuit node is provided on the line between pin 2 of the light sensor slot GZ and pin 10 of the single-chip chip U1, a sixth circuit node is provided on the line between pin 3 of the light sensor slot GZ and pin 9 of the single-chip chip U1, the line led out from the fifth circuit node is connected in series with a resistor R29 and then connected to the VDD33V voltage terminal, and the line led out from the sixth circuit node is connected in series with a resistor R30 and then connected to the VDD33V voltage terminal.

6. The classroom air quality detection device according to claim 4, characterized in that: The spectral sensor interface circuit includes a spectral sensor interface SCOM3, a line led out of pin 1 of the spectral sensor interface SCOM3 is connected to a VDD5V voltage terminal, and lines led out of pin 2 and pin 3 of the spectral sensor interface SCOM3 are respectively connected to pins 43 and 44 of the single-chip microcomputer chip U1; The formaldehyde sensor interface circuit comprises a formaldehyde sensor interface S2COM4, ​​and the lines led out from pin 2 and pin 3 of the formaldehyde sensor interface S2COM4 are respectively connected to pin 45 and pin 46 of the extended single-chip microcomputer chip U111.

7. The classroom air quality detection device according to claim 4, characterized in that: The PM2.5 sensor circuit includes a PM2.5 sensor Sx2, wherein pin 1 and pin 2 of the PM2.5 sensor Sx2 are respectively connected to the VDD5V voltage terminal, and lines led out from pin 7 and pin 9 of the PM2.5 sensor Sx2 are respectively connected to pin 44 and pin 43 of the extended single-chip microcomputer chip U111; The carbon dioxide sensor interface circuit comprises a carbon dioxide sensor socket COCO2_2, and the lines led out from pins 3 and 2 of the carbon dioxide sensor socket COCO2_2 are correspondingly connected to pins 19 and 20 of the extended single-chip microcomputer chip U111.

8. The classroom air quality detection device according to claim 4, characterized in that: The control circuit board is also provided with an indicator light circuit, which includes a resistor R20 and a resistor R21. The circuit led out from one end of the resistor R20 is connected to the pin 21 of the single-chip chip U1, and the other end is connected in series with the light-emitting diode LD1 and then grounded. The circuit led out from one end of the resistor R21 is connected to the pin 22 of the single-chip chip U1, and the other end is connected in series with the light-emitting diode LD2 and then grounded.

9. The classroom air quality detection device according to claim 4, characterized in that: The control circuit board is also provided with a buzzer circuit, which includes a resistor R13 connected to the pin 31 of the single-chip microcomputer chip U1, the other end of the resistor R13 is connected to the gate of the transistor Q1, the collector of the transistor Q1 is connected to the speaker, and the emitter of the transistor Q1 is grounded.

10. The classroom air quality detection device according to claim 4, characterized in that: The control circuit board is also provided with a Bluetooth interface circuit, which includes a Bluetooth interface J2. The circuit led out of pin 3 of the Bluetooth interface J2 is connected to the VDD33V voltage terminal, the circuit led out of pin 6 of the Bluetooth interface J2 is connected to pin 47 of the microcontroller chip U1, and the circuits led out of pin 13 and pin 14 of the Bluetooth interface J2 are connected to pin 46 and pin 465 of the microcontroller chip U1 respectively.

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