Multispectral flame detection system

Abstract

The invention provides a multispectral flame detection system. Wherein multispectral flame detection can be realized through the Ga2O3 solar-blind ultraviolet photoelectric detector, the infrared detector and the visible light detector which are in contact with the high-work-function Pd electrode, so that flame source detection can be carried out in a complicated field environment or a factory or other scenes with special combustion materials without being influenced by a working environment. Besides, through the movable scanning platform, scanning type detection can be carried out, flame detection in a larger range is achieved, meanwhile, multi-point position confirmation can be carried out, and the specific flame position can be obtained. In addition, an Internet of Things function is added, data are transmitted to a cloud server, and remote monitoring operation is facilitated.

Description

Technical Field

[0001] The present application relates to a multi-spectrum flame detection system, belonging to the technical field of flame detection. Background Art

[0002] In the field of flame detection, most of them use infrared or camera algorithms for fire source detection, but this method will be interfered by sunlight, or the burning flame cannot be detected or identified by the naked eye. At this time, a flame detector that can detect in the full spectrum is needed. Otherwise, most detectors on the market cannot detect flame sources in complex field environments or in scenes with special burning materials such as factories.

[0003] Solar-blind ultraviolet photodetectors (SBPDs) are widely used in missile tracking, fire alarm, corona monitoring, ozone hole detection, offshore oil testing, biological detection and encrypted communications due to their low background noise, good reliability, high security and low false alarm rate. Among wide bandgap semiconductors (GaN, AlGaN, SiC, diamond, hBN, BiOCl, Ga2O3, etc.), Ga2O3 stands out with the following great advantages. It has an ultra-wide bandgap (4.5-5.3eV), which directly corresponds to the solar-blind band; it has excellent sensitivity in the solar-blind band; its large-size single crystals can be mass-produced at low cost by the melting method; it has high breakdown voltage, ultra-high power quality factor, low on-voltage, ultra-low specific on-resistance and good stability. Therefore, Ga2O3 is considered to be the most promising candidate material for the next generation of power electronics and SBPDs.

[0004] Ga2O3 has five different crystal structures: α, β, γ, δ and ε phases. Among them, the β phase has a monoclinic crystal structure and its thermochemical properties are the most stable. The other α, γ and ε phases are all metastable phases, and the δ phase is an unstable phase. Since gallium oxide has a structure similar to other wide bandgap materials (such as ZnO and AlN), it is often used to prepare gallium oxide photodetectors. However, the current gallium oxide photodetectors have disadvantages such as large dark current and poor photoelectric response.

[0005] The main methods for growing epitaxial films include molecular beam epitaxy (MBE); laser pulse deposition (PLD); magnetron sputtering (RFMS); hydride vapor phase epitaxy (HVPE); mist vapor deposition (Mist-CVD); atomic layer deposition (ALD); metal organic chemical vapor deposition (MOCVD), etc. Among them, MOCVD epitaxial growth film has a wide range of applications and can grow almost all compounds; the film thickness is controllable, suitable for the preparation of ultra-thin films; the composition and doping concentration are controllable; the purity is high and the uniformity is good; it is suitable for the growth of large-size films. It is suitable for growing large-area high-quality gallium oxide films, and the β-phase Ga2O3 can be directly grown by the MOCVD method without the need for a post-annealing process to transform it from other phases to the β-phase. However, the gallium oxide solar-blind ultraviolet photodetector prepared by the MOCVD method still has the disadvantages of high dark current and poor photocurrent response. Summary of the invention

[0006] The present application provides a multi-spectral flame detection system to solve the problems that existing flame detectors are unable to detect flame sources in complex field environments or in scenes with special combustion materials such as factories, and that existing gallium oxide photodetectors have large device dark current and poor photoelectric response.

[0007] In a first aspect, an embodiment of the present application provides a multi-spectral flame detection system, including a scanning platform, a processing device, and a cloud server;

[0008] The scanning platform includes a bracket and a vertical angle control steering gear and a horizontal angle control steering gear for driving the bracket to move. The bracket is provided with a Ga2O3 day-blind ultraviolet photodetector, an infrared detector and a visible light detector contacted with a high work function Pd electrode, which are respectively used to detect ultraviolet light, infrared light and visible light within a set range;

[0009] The processing device is connected to the vertical angle control steering gear and the horizontal angle control steering gear to control the operation of the vertical angle control steering gear and the horizontal angle control steering gear. The processing device is also electrically connected to the Ga2O3 day-blind ultraviolet photodetector contacted by the high work function Pd electrode, the infrared detector and the visible light detector to obtain and process the electrical signals output by the Ga2O3 day-blind ultraviolet photodetector contacted by the high work function Pd electrode, the infrared detector and the visible light detector;

[0010] The cloud server is in communication connection with the processing device and exchanges data and instructions with the processing device.

[0011] Based on the above multi-spectral flame detection system, optionally, through the movement of the vertical angle control servo and the horizontal angle control servo, the Ga2O3 day-blind ultraviolet photodetector contacted by the high work function Pd electrode, the infrared detector and the visible light detector can scan a spherical range to detect the flame in the spherical range.

[0012] Based on the above multi-spectrum flame detection system, optionally, the processing device includes: an IV amplification unit, a main control unit, a communication unit and a communication antenna;

[0013] The IV amplification unit is used to convert the current signal output by the Ga2O3 solar-blind ultraviolet photodetector and the visible light detector contacted by the high-work-function Pd electrode into a voltage signal and amplify it;

[0014] The main control unit is used to obtain and process the signals output by the IV amplification unit and the infrared detector, and send the processing results to the cloud server through the NB-Iot communication unit and the communication antenna.

[0015] Based on the above multi-spectral flame detection system, optionally, the Ga2O3 solar-blind ultraviolet photodetector contacted with a high work function Pd electrode comprises:

[0016] Insulating substrate;

[0017] A Ga2O3 thin film is disposed on the insulating substrate;

[0018] A plurality of Pd electrodes are arranged on the side of the Ga2O3 film away from the insulating substrate and are spaced apart from each other.

[0019] Based on the above multi-spectral flame detection system, optionally, when the processing device preliminarily determines that a flame is detected according to the processing result, it controls the scanning platform to scan the suspected flame area at multiple angles, and generates a final detection result according to the multiple scanning results.

[0020] Based on the above multi-spectrum flame detection system, optionally, the processing device further includes a smoke detector, a buzzer alarm and a light alarm;

[0021] When the processing device determines that smoke or fire is detected, it issues an alarm through the buzzer alarm and the light alarm, and sends an alarm signal to the cloud server.

[0022] Based on the above multi-spectrum flame detection system, optionally, it also includes: a mobile phone push platform and a remote website push platform that are communicatively connected to the cloud server;

[0023] The cloud server also pushes the processed data or results to the mobile phone push platform and the remote website push platform.

[0024] Based on the above multi-spectrum flame detection system, optionally, the cloud server periodically obtains the data transmitted by the processing device, stores it in the database of the cloud server, and distributes it to the mobile phone push platform and the remote website push platform through the MQTT protocol.

[0025] Based on the above multi-spectral flame detection system, optionally, the mobile phone push platform and the remote website push platform are also used to trigger control instructions according to user operations to control the working status and parameters of the multi-spectral flame detection system, including setting thresholds, releasing alarm information and adding new devices.

[0026] The above technical solution provided by this application has at least the following beneficial effects:

[0027] In the multi-spectral flame detection system provided by the present application, the Ga2O3 day-blind ultraviolet photodetector, infrared detector and visible light detector contacted by the high work function Pd electrode can realize multi-spectral flame detection, so that it can be unaffected by the working environment, and flame source detection can be performed in complex field environments or in scenes of special combustion materials such as factories. In addition, through a movable scanning platform, scanning detection can be performed to achieve flame detection in a larger range. At the same time, the orientation confirmation of multiple points can also be performed to obtain the specific flame orientation. In addition, the Internet of Things function is also added to transmit data to the cloud server for convenient remote monitoring operation. In addition, the Ga2O3 day-blind ultraviolet photodetector prepared by the MOCVD method still has the disadvantages of high dark current and poor photocurrent response. The introduction of high work function electrode Pd contact can solve the pinning problem of the Fermi level through a clean metal-semiconductor interface, effectively reduce the dark current of the device, obtain a better day-blind ultraviolet photoelectric response, and improve the photoelectric performance of the day-blind ultraviolet photodetector. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings herein are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present application, and together with the specification are used to explain the principles of the present application. In addition, these drawings and text descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application for those skilled in the art by referring to specific embodiments.

[0029] Figure 1 A schematic diagram of the structure of a scanning platform of a multi-spectral flame detection system provided in one embodiment of the present application;

[0030] Figure 2A schematic structural diagram of another angle of a scanning platform of a multi-spectral flame detection system provided by an embodiment of the present application;

[0031] Figure 3 A schematic diagram of the structure of a processing device provided in one embodiment of the present application;

[0032] Figure 4 A schematic structural diagram of a processing device provided by an embodiment of the present application from another angle;

[0033] Figure 5 A schematic diagram of the working principle of a multi-spectrum flame detection system provided by one embodiment of the present application;

[0034] Figure 6 A schematic diagram of the working principle of a processing device provided in one embodiment of the present application;

[0035] Figure 7 A schematic diagram of a communication principle between a main control unit and a cloud server provided in one embodiment of the present application;

[0036] Figure 8 A schematic diagram of another communication principle between a main control unit and a cloud server provided in one embodiment of the present application;

[0037] Fig. 9 A schematic diagram of the information push function of a cloud server provided in one embodiment of the present application;

[0038] Fig.10 A schematic diagram of the structure of a power management system for a multi-spectrum flame detection system provided by one embodiment of the present application;

[0039] Fig.11 A light-dark time-current characteristic curve of a Ga2O3 day-blind ultraviolet photodetector with a high work function Pd electrode contact provided in one embodiment of the present application without and with 255nm ultraviolet light.

[0040] Fig.12 A comparison diagram of the light-dark voltage-current characteristic curves of a Ga2O3 day-blind ultraviolet photodetector with a high work function Pd electrode contact provided in an embodiment of the present application without 255nm ultraviolet light and with 255nm ultraviolet light of different light intensities; wherein, the dark current of the device is 9.74×10-13A, the photocurrent is 3.67×10-9A, and the on-off ratio is 3764 at a bias voltage of 1.25V;

[0041] Fig.13 A graph of the responsivity of a Ga2O3 solar-blind ultraviolet photodetector with a high work function Pd electrode contact under different light intensities provided in one embodiment of the present application;

[0042] Fig.14 A detection diagram of a Ga2O3 solar-blind ultraviolet photodetector with a high work function Pd electrode contact under different light intensities provided by one embodiment of the present application;

[0043] Fig.15 A linear dynamic range diagram of a Ga2O3 solar-blind ultraviolet photodetector with a high work function Pd electrode contact provided by one embodiment of the present application;

[0044] Fig.16 A schematic diagram of the noise current of a Ga2O3 solar-blind ultraviolet photodetector with a high work function Pd electrode contact provided in one embodiment of the present application. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0046] In order to solve the problem of flame source detection in complex environments or special environments, the present application provides a multi-spectral flame detection system that can detect the location of fire sources in complex environments or environments with complex light, perform large-scale scanning, and perform remote monitoring of the Internet of Things.

[0047] like Figures 1 to 4 As shown, in some embodiments, a multi-spectrum flame detection system is provided, which includes: a scanning platform, a processing device and a cloud server 13.

[0048] Among them, Figure 1 and Figure 2As shown, the scanning platform includes a bracket and a vertical angle control steering gear 2 and a horizontal angle control steering gear 3 for driving the bracket to move. The bracket is provided with a Ga2O3 day-blind ultraviolet photodetector 1, an infrared detector 4 and a visible light detector 5 in contact with a high work function Pd electrode, which are respectively used to detect ultraviolet light, infrared light and visible light within a set range. The working principle of the scanning platform is: through the movement of the vertical angle control steering gear 2 and the horizontal angle control steering gear 3, the Ga2O3 day-blind ultraviolet photodetector 1, the infrared detector 4 and the visible light detector 5 in contact with a high work function Pd electrode can scan the set range, thereby detecting the flame. When there is a flame, the three detectors react differently according to different flames, and the current output by the detectors is different according to different reactions. Among them, the three detectors, namely, the Ga2O3 day-blind ultraviolet photodetector 1, the infrared detector 4 and the visible light detector 5, which are contacted by a high work function Pd electrode, can detect ultraviolet, infrared and visible light to achieve multi-spectrum flame detection. Moreover, because the detection band of the Ga2O3 day-blind ultraviolet photodetector 1 contacted by a high work function Pd electrode is in the day-blind zone, it is not affected by the ultraviolet rays of sunlight and has a strong ability to adapt to the environment.

[0049] Furthermore, by controlling the movement of the servo 2 at a vertical angle and the servo 3 at a horizontal angle, the Ga2O3 day-blind ultraviolet photodetector 1 contacted by the high work function Pd electrode, the infrared detector 4 and the visible light detector 5 can scan a spherical range to detect flames in the spherical range, that is, to achieve all-round detection in a range of 360°.

[0050] The signals output by the three detectors are transmitted to the processing equipment for processing. Figure 3 As shown, the processing device includes an IV amplifier unit 6, a main control unit 9, a communication unit 8 and a communication antenna 10. The IV amplifier unit 6 is used to convert the current signal output by the Ga2O3 day-blind ultraviolet photodetector 1 and the visible light detector 5 in contact with the high work function Pd electrode into a voltage signal and amplify it; the main control unit 9 is used to obtain the signal output by the IV amplifier unit 6 and the infrared detector 4 and process it, and send the processing result to the cloud server 13 through the NB-Iot communication unit 8 and the communication antenna 10. Among them, the main control unit 9 can include an ESP-Wroom-32 main control circuit.

[0051] When the Ga2O3 day-blind ultraviolet photodetector 1, infrared detector 4 and visible light detector 5 contacted with the high work function Pd electrode find a fire source, they can output current to the IV amplifier unit 6, which converts the current signal into a voltage signal, amplifies it, and transmits the output voltage signal to the main control unit 9. After processing, the main control unit 9 controls the movement of the vertical angle control servo 22 and the horizontal angle control servo 33 to make the detection directions of the three detectors point to the fire source, and uploads the data to the cloud server 13 through the communication unit 8 such as WIFI or NB-Iot module, and sends an alarm signal to the cloud server 13.

[0052] In some embodiments, a high work function Pd electrode-contacted Ga2O3 solar-blind UV photodetector comprises:

[0053] Insulating substrate;

[0054] A Ga2O3 thin film is disposed on the insulating substrate;

[0055] A plurality of Pd electrodes are arranged on the side of the Ga2O3 film away from the insulating substrate and are spaced apart from each other.

[0056] Among them, high work function Pd electrode contact detectors have good contact properties, can reduce contact resistance, improve current flow efficiency, and effectively reduce the dark current of the device. Pd electrodes also have excellent chemical stability and are suitable for a variety of environments.

[0057] In addition, if Figure 4 As shown, in some embodiments, the processing device further includes a buzzer alarm 11 and a light alarm 12. Based on this, when the processing device determines that smoke or fire is detected, the buzzer alarm 11 and the light alarm 12 perform an audible and visual alarm.

[0058] In addition, the processing device also includes a smoke detector 7, which can perform smoke detection and alarm.

[0059] The cloud server 13 can process, store, and display the received data.

[0060] In addition, in some embodiments, the multi-spectral flame detection system also includes a mobile phone push platform 14 and a remote website push platform 15 that are communicatively connected to the cloud server 13; the cloud server 13 can also push the processed data or results to the mobile phone push platform 14 and the remote website push platform 15.

[0061] like Figure 5 As shown, the overall working principle of the multi-spectrum flame detection system is as follows:

[0062] When the power is turned on, the system self-checks and verifies each module, and then selects the Internet access method. If the NB-IoT Internet access method is selected, an independent Internet of Things SIM card is required, and then wait for automatic connection. When the connection is completed, start connecting to the cloud server 13; if the WIFI Internet access method is selected, the network configuration method used is the SmartConfig network configuration method, and the network configuration can be performed through the mobile phone push platform 14 and other methods. If the network configuration has been completed before, the WIFI can be automatically connected and configured. After the connection is completed, it automatically starts to connect to the cloud server 13. When the cloud server 13 is successfully connected, it automatically enters the automatic inspection mode and starts the 360° scanning mode to find suspicious data points, that is, areas suspected of flames. During this period, the collected data will be uploaded to the cloud server 13 at regular intervals.

[0063] In some embodiments, when the processing device preliminarily determines that a flame is detected based on the processing results, that is, when an area suspected of a flame is found, the processing device controls the scanning platform to scan the suspected flame area at multiple angles, and generates a final detection result based on the multiple scanning results.

[0064] For example, in some embodiments, when the collected data is abnormal (when an area suspected of flame is found), the alert mode will be activated. After entering the alert mode, the suspicious data point will be re-scanned. The first horizontal angle controls the steering gear 3 to perform a horizontal scan. If a suspicious point is found again, the second scan will be entered, otherwise the automatic inspection mode will be restored. The second scan is a vertical scan of the steering gear 2 controlled by the vertical angle. If a suspicious point is found again in the vertical scan, it indicates that the fire source is confirmed to exist, and the alarm mode will be entered, otherwise the automatic inspection mode will be restored. After entering the alarm mode, the buzzer alarm 11 and the light alarm 12 will respond and send out an audible and visual alarm. At the same time, the alarm information will be quickly sent to the cloud server 13. At the same time, the cloud server 13 distributes the data to various message forwarding platforms, including the mobile phone push platform 14 and the remote website push platform 15. At this point, the system alarm is completed.

[0065] In the multi-spectral flame detection system provided by the present application, the Ga2O3 day-blind ultraviolet photodetector 1, the infrared detector 4 and the visible light detector 5 contacted by the high work function Pd electrode can realize multi-spectral flame detection, so that it can be unaffected by the working environment, and flame source detection can be performed in complex field environments or in scenes of special combustion materials such as factories. In addition, through a movable scanning platform, scanning detection can be performed to achieve flame detection in a larger range. At the same time, the orientation confirmation of multiple points can also be performed to obtain a specific flame orientation. In addition, an Internet of Things function is also added to transmit data to a cloud server 13, which is convenient for remote monitoring operations. In addition, the Ga2O3 day-blind ultraviolet photodetector prepared by the MOCVD method still has the disadvantages of high dark current and poor photocurrent response. The introduction of the high work function electrode Pd contact can solve the pinning problem of the Fermi level through a clean metal-semiconductor interface, effectively reduce the dark current of the device, obtain a better day-blind ultraviolet photoelectric response, and improve the photoelectric performance of the day-blind ultraviolet photodetector.

[0066] Furthermore, if Figure 6 As shown, the main sensor of the present invention is a Ga2O3 day-blind ultraviolet photodetector 1 with a high work function Pd electrode contact, and its detection range is in the 280nm day-blind wavelength range. At the same time, there is a visible light detector 5 for auxiliary scanning. The two sensors are connected to the IV amplifier unit 6 and the filter unit in turn, and finally transmitted to the ESP-Wroom-32 main control circuit of the main control unit 9 for processing.

[0067] For the IV amplifier unit 6, the amplifier type that can be used is AD825, which forms a current-to-voltage negative feedback amplifier circuit, converts the tiny current input by the detector into a voltage signal, and then cascades a conventional power amplifier LM353 in a cascade form to finally output the voltage. The signal output by the amplifier needs to be filtered by the filter unit and then connected to the main control unit 9. The filter unit can perform a capacitor-resistor filter on the voltage signal through a second-order RC low-pass filter, and then connect it to the ADC port of the ESP-Wroom-32 main control circuit of the main control unit 9. After reading, the ESP-Wroom-32 main control circuit performs a software filter. The filtering method uses a digital sliding window mean filter, and the data obtained at the end is the final data of the detector.

[0068] For the selection of infrared detector 4, the active infrared temperature detector MLX90614 can be used, which can be directly connected to the port of the main control unit 9 using the IIC bus communication method. Its detection temperature range is within the range of 0 to 400°, and it can also monitor the ambient temperature in real time. For the selection of smoke detector 7, the MQ-2 smoke alarm can be selected. This detector can respond quickly to gas, and its circuit is very simple. After the power is turned on, the pins are connected to the ADC port of the main control circuit of the main control unit 9 ESP-Wroom-32.

[0069] The communication between the processing device and the cloud server 13 may be NB-IoT narrowband Internet of Things or WIFI. Figure 7 As shown, for the NB-IoT narrowband Internet of Things Internet access method, the main core of the communication unit 8 used is the EA01-S module, which can quickly access the Internet and communicate with the module via the ESP-Wroom-32 main control circuit. The baud rate is 115200, and the text format supports the AT instruction set. Through the AT instruction, the address of the cloud server 13 to be connected is connected through the AT instruction, and then the Internet of Things SIM card is installed, and it is automatically connected to the cloud server 13 through the communication antenna 10.

[0070] like Figure 8 As shown, when using the WIFI mode of the ESP-Wroom-32 main control circuit, the connection method provided by Espressif, the SmartConfig network matching method, is used. The essence is to use the SmartConfig network matching mode in the mobile phone push platform 14 within a certain range of the present invention, select the specified connected network, and then query the device that is querying the SmartConfig network matching method through the WIFI broadcast mode, let the device return a response, handshake successfully, transmit network information, and then let the device successfully connect to the specified WIFI. After connecting to the Internet, data will be sent regularly to the specified cloud server 13.

[0071] like Fig. 9 As shown, when the device of the present invention successfully accesses the Internet, the cloud server 13 periodically obtains the data transmitted by the processing device, stores it in the database of the cloud server 13, and then distributes it to various platforms through MQTT, including the mobile phone push platform 14 and the remote website push platform 15. Users can access the remote website push platform 15 through IP or website web, and the website page can display ultraviolet intensity, ambient temperature, air quality, device information, etc. For the mobile phone push platform 14, the cloud server 13 can directly forward the data uploaded by the processing device to the mobile phone push platform 14 in real time. After receiving the information, the mobile phone push platform 14 will unpack and display the information of each detector.

[0072] In addition, the mobile phone push platform 14 and the remote website push platform 15 can also trigger control instructions according to user operations to control the working status and parameters of the multi-spectrum flame detection system, including setting thresholds, releasing alarm information and adding new devices.

[0073] like Fig.10 As shown, the multi-spectrum flame detection system of the present invention also includes a power management system, the power supply core of which is a battery management system 16, which has a wide voltage input and supports a voltage input in the range of 12V to 40V. The output is a multi-voltage conversion system 17, which can output 12V voltage to supply each chip, ±5V power supply to the dual power amplifier, and 3.3V power supply to the main control unit 9 and the communication unit 8.

[0074] The specific steps for using the system are as follows:

[0075] S1: Power on, the whole system starts self-checking, the main control unit 9ESP-Wroom-32 main control circuit starts to check the information of each detector, and selects the Internet access mode. When it detects that WIFI can be connected, use WIFI to access the Internet. If a SIM card is inserted, use NB-Iot Internet of Things to access the Internet. Send information to the cloud server 13 to check whether the data is normal and the network is smooth.

[0076] S2: In step S1, when the data of each detector is normal and the network link is normal, the initial normal data of the detector is sent to the cloud server 13, and the fire source coordinates are cleared. At the same time, the start instruction of the cloud server 13 is received.

[0077] S3: In step S2, when the data link is normal, the multi-spectral flame detection system starts to operate, and the vertical angle control servo 2 and the horizontal angle control servo 3 start to move. The scanning method is that the vertical angle control servo 2 scans 180° once, and then the horizontal angle control servo 3 rotates 1°, and then the vertical angle control servo 2 scans 180° again, scanning the entire hemisphere. At the same time, the ESP-Wroom-32 main control circuit obtains the data of each detector, and uploads the data to the cloud server 13 every 20S, and then the cloud server 13 distributes the data to the mobile phone push platform 14 and the remote website push platform 15, and displays it on the two platforms. If the multi-spectral flame detection system needs to be adjusted, it can be operated on the two platforms, and then forwarded to the multi-spectral flame detection system equipment through the cloud server 13 for operation.

[0078] S4: Scanning is performed under step S3. If abnormal data occurs continuously during the scanning, the device enters the alert state. The ESP-Wroom-32 main control circuit analyzes the position of the abnormal data, and then controls the horizontal angle control servo 3 to scan horizontally. If the abnormal data still exists, the vertical angle control servo 2 is controlled to scan longitudinally to confirm the position of the abnormal data. If abnormal data exists in both scans, the device enters the alarm mode, reports the target position, and reports the alarm information to the cloud server 13. The buzzer alarm 11 and the light alarm 12 work. If no abnormal data is found in these two scans, the device returns to step S3.

[0079] S5: After entering the alarm mode, alarm information will be continuously sent to the cloud server 13, and the cloud server 13 will also distribute the data. The processing device will not stop operating until it is restarted or the cloud server 13 sends a stop message, otherwise the alarm will continue.

[0080] In addition, in this example, the main communication network can be either self-built base stations or using third-party operators (such as China Unicom, China Mobile, and China Telecom).

[0081] For the first connection method, unlicensed frequency band network WIFI is used. This frequency band is used to communicate using the WIFI module of the ESP-Wroom-32 main control circuit. Users are required to build the IEEE802.11 wireless LAN environment of WIFI by themselves. Data is sent from the device to the wireless gateway, which is sent to the Internet public network, and then connected to the cloud server 13 on the Internet public network. The cloud server 13 then distributes the data to various platforms.

[0082] For the second connection method, NB-Iot Internet of Things is used for communication, and a wireless network with an authorized frequency band is used, that is, NB-Iot Internet of Things communication circuit is used for communication. The core of this module is EA01-S module. This communication method needs to be built by the operator. By purchasing the operator's Internet of Things SIM card and inserting the SIM card into the card slot, communication can be achieved. Data is sent from the device to the wireless base station, and then sent to the Internet public network through the base station. The Internet public network is connected to the cloud server 13, and the cloud server 13 distributes the data to various platforms.

[0083] In addition, experimental verification was performed to verify the effectiveness of the Ga2O3 solar-blind UV photodetector contacted with a high work function Pd electrode.

[0084] Firstly, a Ga2O3 solar-blind ultraviolet photodetector with high work function Pd electrode contact is prepared, and the preparation method comprises the following steps:

[0085] S1. Provide an insulating substrate, such as c-plane sapphire; ultrasonically clean the insulating substrate in acetone, anhydrous ethanol, and deionized water for 20 minutes respectively, and set aside;

[0086] S2. Place the cleaned substrate into the chamber of the MOCVD equipment. The MOCVD growth temperature is set to 800°C, the reaction chamber pressure is 40 torr, the Mo source is triethylgallium, the carrier gas is nitrogen 200 sccm, oxygen 3000 sccm, the growth rate is 180-200 nm / h, and the growth time is 1 hour.

[0087] S3, pre-treating the film to clean its surface to obtain better electrode contact, and after cleaning, placing the film in deionized water to isolate the surface from contamination by air and other impurities;

[0088] S4, covering the customized metal mask on the insulating substrate containing the Ga2O3 film and fixing it with a high temperature resistant tape;

[0089] S5. Place the c-plane sapphire substrate containing a clean gallium oxide film in an electron beam composite thermal evaporation coating machine, pre-evacuate for four hours, and after the vacuum degree reaches 3e-5, coat Pd on the gallium oxide film by electron beam thermal evaporation. After coating, remove the mask to complete the preparation of the Ga2O3 day-blind ultraviolet photodetector with high work function Pd electrode contact.

[0090] Based on the preparation of the Ga2O3 solar-blind ultraviolet photodetector with high work function Pd electrode contact prepared above, the verification results are as follows:

[0091] Fig.11 A light-dark time-current characteristic curve of a Ga2O3 day-blind ultraviolet photodetector with a high work function Pd electrode contact provided in one embodiment of the present application without adding 255nm ultraviolet light and with adding 255nm ultraviolet light. It is divided into rise time (tr) and fall time (td). The rise time is defined as the time required for the photocurrent of the detector to rise from 10% of the maximum value when stable to 90% under the condition of applied light, and the fall time is the time required for the maximum value to drop from 90% to 10% after the light is removed. The response time of the ultraviolet photodetector is also a very important parameter. It describes the reaction speed of the detector to changes in light. When the response time of the detector is very long, the detector will not be suitable for rapidly changing ultraviolet radiation. Generally, it is difficult to have both high sensitivity and high response speed of ultraviolet photodetectors. While the responsiveness is greatly improved, the response time is often extended to a certain extent. For example Fig.11 The figure shows a rising and falling process in the It curve of the device, wherein the rising response time is 64.95ms and the falling response time is 58.94ms.

[0092] Fig.12 A comparison of the light-dark voltage-current characteristic curves of a Ga2O3 solar-blind UV photodetector with a high work function Pd electrode contact provided in one embodiment of the present application without 255nm UV light and with 255nm UV light of different light intensities. The dark current of the device is 9.74×10 -13 A, photocurrent is 3.67×10 -9 A, the on / off ratio is 3764.

[0093] Fig.13 The responsivity diagram of the Ga2O3 solar-blind ultraviolet photodetector with high work function Pd electrode contact provided by one embodiment of the present application under different light intensities, the responsivity data is obtained by Fig.12 The light and dark data extraction calculation in the light intensity is as low as 300nW / cm 2 It still has 11.77A / W.

[0094] Fig.14 The detection rate diagram of the Ga2O3 solar-blind ultraviolet photodetector with high work function Pd electrode contact under different light intensities provided by one embodiment of the present application. Fig.16 The noise current and Fig.12 The noise equivalent power also involves the influence of detection area and bandwidth, which can better quantify the signal-to-noise ratio. 2 When up to 2.43 × 10 14 Jones.

[0095] Fig.15 The linear dynamic range diagram of the Ga2O3 day-blind ultraviolet photodetector with high work function Pd electrode contact provided for an embodiment of the present application. The linear dynamic range is generally determined by the photocurrent, dark current and incident light power intensity of the photodetector, which is 60dB. The linear dynamic range of the front device is good.

[0096] Fig.16 It is the noise current of the Ga2O3 solar-blind ultraviolet photodetector contacted with the high work function Pd electrode in the present invention.

[0097] It can be understood that the same or similar parts of the above embodiments can be referenced to each other, and the contents not described in detail in some embodiments can refer to the same or similar contents in other embodiments.

[0098] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0099] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A multi-spectral flame detection system, characterized in that: include: Scanning platforms, processing equipment and cloud servers; The scanning platform includes a bracket and a vertical angle control steering gear and a horizontal angle control steering gear for driving the bracket to move. The bracket is provided with a Ga2O3 day-blind ultraviolet photodetector, an infrared detector and a visible light detector contacted with a high work function Pd electrode, which are respectively used to detect ultraviolet light, infrared light and visible light within a set range; The processing device is connected to the vertical angle control steering gear and the horizontal angle control steering gear to control the operation of the vertical angle control steering gear and the horizontal angle control steering gear. The processing device is also electrically connected to the Ga2O3 day-blind ultraviolet photodetector contacted by the high work function Pd electrode, the infrared detector and the visible light detector to obtain and process the electrical signals output by the Ga2O3 day-blind ultraviolet photodetector contacted by the high work function Pd electrode, the infrared detector and the visible light detector; The cloud server is in communication connection with the processing device and exchanges data and instructions with the processing device.

2. The multi-spectrum flame detection system according to claim 1, characterized in that: By controlling the movement of the vertical angle servo and the horizontal angle servo, the Ga2O3 day-blind ultraviolet photodetector contacted by the high work function Pd electrode, the infrared detector and the visible light detector can scan a spherical range to detect flames within the spherical range.

3. The multi-spectrum flame detection system according to claim 1, characterized in that: The processing device includes: an IV amplification unit, a main control unit, a communication unit and a communication antenna; The IV amplification unit is used to convert the current signal output by the Ga2O3 solar-blind ultraviolet photodetector and the visible light detector in contact with the high work function Pd electrode into a voltage signal and amplify it; The main control unit is used to obtain and process the signals output by the IV amplification unit and the infrared detector, and send the processing results to the cloud server through the NB-Iot communication unit and the communication antenna.

4. The multi-spectrum flame detection system according to claim 1, characterized in that: The Ga2O3 solar-blind ultraviolet photodetector with high work function Pd electrode contact comprises: Insulating substrate; A Ga2O3 thin film is disposed on the insulating substrate; A plurality of Pd electrodes are arranged on the side of the Ga2O3 film away from the insulating substrate and are spaced apart from each other.

5. The multi-spectrum flame detection system according to claim 1, characterized in that: When the processing device preliminarily determines that a flame is detected based on the processing result, the processing device controls the scanning platform to scan the suspected flame area at multiple angles, and generates a final detection result based on the multiple scanning results.

6. The multi-spectrum flame detection system according to claim 1, characterized in that: The processing equipment also includes smoke detectors, buzzer alarms and light alarms; When the processing device determines that smoke or fire is detected, it issues an alarm through the buzzer alarm and the light alarm, and sends an alarm signal to the cloud server.

7. The multi-spectrum flame detection system according to any one of claims 1 to 6, characterized in that: It also includes: a mobile phone push platform and a remote website push platform that are communicatively connected to the cloud server; The cloud server also pushes the processed data or results to the mobile phone push platform and the remote website push platform.

8. The multi-spectrum flame detection system according to claim 7, characterized in that: The cloud server periodically obtains the data transmitted by the processing device, stores it in the database of the cloud server, and distributes it to the mobile phone push platform and the remote website push platform through the MQTT protocol.

9. The multi-spectrum flame detection system according to claim 8, characterized in that: The mobile phone push platform and the remote website push platform are also used to trigger control instructions according to user operations to control the working status and parameters of the multi-spectrum flame detection system, including setting thresholds, releasing alarm information and adding new devices.

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