Fire monitoring system

Abstract

The utility model relates to the technical field of safety monitoring, and provides a fire hazard monitoring system comprising a smoke detection module, the smoke detection module comprises a first smoke sensor, a second smoke sensor, a subtraction operation circuit and a first comparison circuit, and the first smoke sensor and the second smoke sensor have the same circuit structure. The first smoke sensor is arranged in a closed transparent shell, the output of the first smoke sensor is connected to the first input end of the subtraction operation circuit, the output of the second smoke sensor is connected to the second input end of the subtraction operation circuit, and the output end of the subtraction operation circuit is connected to the first input end of the first comparison circuit. The second input end of the first comparison circuit is connected with a first reference voltage, and the output end of the first comparison circuit is connected to the first input end of the controller. According to the technical scheme, the problem of poor reliability of a fire monitoring system in the prior art is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of safety monitoring, and in particular to a fire monitoring system. Background Art

[0002] Fire is a common disaster that can cause huge losses to people's lives, property and the environment. Fire monitoring systems sense the occurrence of fires and sound an alarm in time, reminding people to evacuate in time and reducing property losses. Fire perception is usually achieved by smoke sensors, temperature sensors or gas sensors. Among them, smoke sensors are the most common. They are based on the principle of light scattering. The specific working principle is: the sensor contains a transmitter and a receiver. The transmitter is used to emit light and the receiver is used to receive light. Under normal circumstances, when the light beam is not scattered by smoke particles, the light intensity received by the receiver is relatively high. However, when smoke particles exist, they scatter light, causing the light intensity received by the receiver to weaken. The presence of smoke is determined by continuously detecting and comparing the light intensity difference between the transmitter and the receiver.

[0003] In actual operation, smoke sensors will be affected by ambient light and their detection accuracy will be reduced, thereby reducing the reliability of the entire fire monitoring system. Utility Model Content

[0004] The utility model provides a fire monitoring system, which solves the problem of poor reliability of fire monitoring systems in related technologies.

[0005] The technical solution of the utility model is as follows: comprising a smoke detection module, the smoke detection module comprising a first smoke sensor, a second smoke sensor, a subtraction circuit and a first comparison circuit, the first smoke sensor and the second smoke sensor having the same circuit structure, the first smoke sensor being arranged in a closed transparent housing,

[0006] The output of the first smoke sensor is connected to the first input end of the subtraction circuit, the output of the second smoke sensor is connected to the second input end of the subtraction circuit, the output end of the subtraction circuit is connected to the first input end of the first comparison circuit, the second input end of the first comparison circuit is connected to a first reference voltage, and the output end of the first comparison circuit is connected to the first input end of the controller.

[0007] Further, the first smoke sensor includes a light emitting diode LED1, a resistor R1, a switch tube Q1, a photodiode PD1 and a resistor R4, the control end of the switch tube Q1 is connected to the first output end of the controller, the first end of the switch tube Q1 is connected to the power supply, the second end of the switch tube Q1 is connected to the anode of the light emitting diode LED1, and the cathode of the light emitting diode LED1 is grounded through the resistor R1.

[0008] The cathode of the photodiode PD1 is connected to a power source, the anode of the photodiode PD1 is grounded via a resistor R4, and the anode of the photodiode PD1 is the output of the first smoke sensor.

[0009] Furthermore, the subtraction circuit includes an operational amplifier U1C, an inverting input terminal of the operational amplifier U1C is a first input terminal of the subtraction circuit, a non-inverting input terminal of the operational amplifier U1C is a second input terminal of the subtraction circuit, an output terminal of the operational amplifier U1C is feedback-connected to the inverting input terminal of the operational amplifier U1C through a resistor R13, and an output terminal of the operational amplifier U1C is an output terminal of the subtraction circuit.

[0010] Further, the first comparison circuit includes a comparator U2A, the inverting input terminal of the comparator U2A is the first input terminal of the first comparison circuit, the non-inverting input terminal of the comparator U2A is the second input terminal of the first comparison circuit, and the output terminal of the comparator U2A is the output terminal of the first comparison circuit.

[0011] Furthermore, an operational amplifier U1A is provided between the first smoke sensor and the subtraction circuit, the non-inverting input terminal of the operational amplifier U1A is connected to the output terminal of the first smoke sensor, the inverting input terminal of the operational amplifier U1A is grounded through a resistor R5, the output terminal of the operational amplifier U1A is feedback-connected to the inverting input terminal of the operational amplifier U1A through a resistor R3, and the output terminal of the operational amplifier U1A is connected to the first input terminal of the subtraction circuit.

[0012] Furthermore, it also includes a temperature detection module, which includes a temperature sensor, an amplification circuit and a second comparison circuit.

[0013] The temperature sensor is used to detect the temperature of a set area, the output end of the temperature sensor is connected to the input end of the amplifier circuit, the output end of the amplifier circuit is connected to the first input end of the second comparison circuit, the second input end of the second comparison circuit is connected to the second reference voltage, and the output end of the second comparison circuit is connected to the second input end of the controller.

[0014] Furthermore, it also includes an alarm connected to the controller.

[0015] The working principle and beneficial effects of the utility model are:

[0016] In the utility model, the first smoke sensor and the second smoke sensor are both implemented based on the principle of light scattering. The circuit structures of the transmitter and the receiver inside the first smoke sensor and the second smoke sensor are the same. The only difference is that the first smoke sensor is arranged in a closed transparent shell, and its output signal will not change with the change of smoke concentration, and is only used to detect the change of surrounding light, while the second smoke sensor is used to detect the change of smoke concentration. When the surrounding light changes, the output signal of the first smoke sensor changes accordingly. The output signal of the first smoke sensor is connected to the first input end of the subtraction circuit, and the output signal of the second smoke sensor is connected to the second input end of the subtraction circuit. In this way, the output signal of the subtraction circuit is the difference between the output signals of the first smoke sensor and the second smoke sensor, that is, the influence of surrounding light is removed from the output signal of the subtraction circuit, and the smoke concentration can be accurately detected. The output signal of the subtraction circuit is connected to the first comparison circuit and compared with the first reference voltage. Under normal circumstances, the output signal of the subtraction circuit is less than the first reference voltage, and the first comparison circuit outputs a first level signal to the first input terminal of the controller. When the smoke concentration is greater than the set value, the output signal of the subtraction circuit is greater than the first reference voltage, and the first comparison circuit outputs a second level signal to the first input terminal of the controller. The controller can determine whether a fire has occurred based on the change in the output level of the first comparison circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0018] Figure 1 This is the circuit schematic diagram of the smoke detection module in the utility model;

[0019] Figure 2 This is the circuit schematic diagram of the temperature detection module in the utility model. DETAILED DESCRIPTION

[0020] The following will be combined with the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0021] The fire monitoring system of this embodiment includes a smoke detection module, such as Figure 1As shown, the smoke detection module includes a first smoke sensor, a second smoke sensor, a subtraction circuit and a first comparison circuit. The circuit structure of the first smoke sensor and the second smoke sensor is the same. The first smoke sensor is arranged in a closed transparent housing.

[0022] The output of the first smoke sensor is connected to the first input end of the subtraction circuit, the output of the second smoke sensor is connected to the second input end of the subtraction circuit, the output end of the subtraction circuit is connected to the first input end of the first comparison circuit, the second input end of the first comparison circuit is connected to the first reference voltage, and the output end of the first comparison circuit is connected to the first input end of the controller.

[0023] In this embodiment, the first smoke sensor and the second smoke sensor are both implemented based on the principle of light scattering. The circuit structures of the transmitter and the receiver inside the first smoke sensor and the second smoke sensor are the same. The only difference is that the first smoke sensor is arranged in a closed transparent shell, and its output signal will not change with the change of smoke concentration, and is only used to detect the change of ambient light, while the second smoke sensor is used to detect the change of smoke concentration. When the ambient light changes, the output signal of the first smoke sensor changes accordingly. The output signal of the first smoke sensor is connected to the first input end of the subtraction circuit, and the output signal of the second smoke sensor is connected to the second input end of the subtraction circuit. In this way, the output signal of the subtraction circuit is the difference between the output signals of the first smoke sensor and the second smoke sensor, that is, the influence of the ambient light is removed from the output signal of the subtraction circuit, and the smoke concentration can be accurately detected. The output signal of the subtraction circuit is connected to the first comparison circuit and compared with the first reference voltage. Under normal circumstances, the output signal of the subtraction circuit is less than the first reference voltage, and the first comparison circuit outputs a first level signal to the first input terminal of the controller. When the smoke concentration is greater than the set value, the output signal of the subtraction circuit is greater than the first reference voltage, and the first comparison circuit outputs a second level signal to the first input terminal of the controller. The controller can determine whether a fire has occurred based on the change in the output level of the first comparison circuit.

[0024] It should be noted that the controller in this embodiment can adopt a currently commonly used single-chip microcomputer, DSP, ARM and other microcontrollers, and no specific limitation is made here.

[0025] Further, if Figure 1 As shown, the first smoke sensor includes a light emitting diode LED1, a resistor R1, a switch tube Q1, a photodiode PD1 and a resistor R4, the control end of the switch tube Q1 is connected to the first output end of the controller, the first end of the switch tube Q1 is connected to the power supply, the second end of the switch tube Q1 is connected to the anode of the light emitting diode LED1, and the cathode of the light emitting diode LED1 is grounded through the resistor R1.

[0026] The cathode of the photodiode PD1 is connected to the power supply, the anode of the photodiode PD1 is grounded through the resistor R4, and the anode of the photodiode PD1 is the output of the first smoke sensor.

[0027] In this embodiment, the light emitting diode LED1 and the resistor R1 form the transmitter of the first smoke sensor. The controller sends a control signal to the control end of the switch tube Q1 at a fixed time, controls the switch tube Q1 to be turned on at a fixed time, and starts the light emitting diode LED1 to light up and emit an infrared light signal.

[0028] The photodiode PD1 and the resistor R4 form a receiver of the first smoke sensor. The infrared light signal emitted by the light emitting diode LED1 is received by the photodiode PD1. The conduction current of the photodiode PD1 is proportional to the intensity of the received light. Therefore, the conduction current of the photodiode PD1 can be obtained by detecting the terminal voltage of the resistor R4, and then the light intensity can be obtained.

[0029] Further, if Figure 1 As shown, the subtraction circuit includes an operational amplifier U1C, an inverting input terminal of the operational amplifier U1C is a first input terminal of the subtraction circuit, a non-inverting input terminal of the operational amplifier U1C is a second input terminal of the subtraction circuit, an output terminal of the operational amplifier U1C is feedback-connected to the inverting input terminal of the operational amplifier U1C through a resistor R13, and an output terminal of the operational amplifier U1C is an output terminal of the subtraction circuit.

[0030] In this embodiment, the operational amplifier U1C, the resistor R12 and the resistor R13 constitute a subtraction circuit for calculating the difference between the output signal of the first smoke sensor and the output signal of the second smoke sensor, and amplifying the difference signal. By adjusting the resistance values ​​of the resistor R12 and the resistor R13, the amplification factor of the subtraction circuit can be adjusted.

[0031] Further, if Figure 1 As shown, the first comparison circuit includes a comparator U2A, the inverting input terminal of the comparator U2A is the first input terminal of the first comparison circuit, the non-inverting input terminal of the comparator U2A is the second input terminal of the first comparison circuit, and the output terminal of the comparator U2A is the output terminal of the first comparison circuit.

[0032] In this embodiment, the comparator U2A is used to implement the function of the first comparison circuit. Under normal circumstances, the output signal of the subtraction circuit is less than the first reference voltage, and the comparator U2A outputs a high-level signal to the first input terminal of the controller. When the smoke concentration is greater than the set value, the output signal of the subtraction circuit is greater than the first reference voltage, and the comparator U2A outputs a low-level signal to the first input terminal of the controller. The controller can determine that a fire has occurred based on the low-level signal.

[0033] The first reference voltage is obtained by a series voltage divider circuit composed of resistors R16 and R17. The terminal voltage of resistor R17 is used as the first reference voltage. The first reference voltage can be adjusted by adjusting the resistance values ​​of resistors R16 and R17. The circuit structure is simple and easy to operate.

[0034] Further, if Figure 1 As shown, an operational amplifier U1A is provided between the first smoke sensor and the subtraction circuit, the non-inverting input terminal of the operational amplifier U1A is connected to the output terminal of the first smoke sensor, the inverting input terminal of the operational amplifier U1A is grounded through a resistor R5, the output terminal of the operational amplifier U1A is feedback-connected to the inverting input terminal of the operational amplifier U1A through a resistor R3, and the output terminal of the operational amplifier U1A is connected to the first input terminal of the subtraction circuit.

[0035] In this embodiment, the resistor R5, the resistor R3 and the operational amplifier U1A constitute a common-phase proportional amplifier circuit for amplifying the terminal voltage signal of the resistor R4 to facilitate the processing of the subsequent circuit. The amplification factor can be adjusted by adjusting the resistance values ​​of the resistor R5 and the resistor R3.

[0036] Furthermore, it also includes a temperature detection module, such as Figure 2 As shown, the temperature detection module includes a temperature sensor, an amplifying circuit and a second comparing circuit.

[0037] The temperature sensor is used to detect the temperature of a set area. The output end of the temperature sensor is connected to the input end of the amplifier circuit. The output end of the amplifier circuit is connected to the first input end of the second comparison circuit. The second input end of the second comparison circuit is connected to the second reference voltage. The output end of the second comparison circuit is connected to the second input end of the controller.

[0038] In this embodiment, in order to further improve the reliability of fire monitoring, a temperature detection module can be added to perform fire monitoring according to the temperature change when a fire occurs. Among them, the temperature sensor is used to detect the temperature of the set area and convert the temperature signal into a voltage signal. The voltage signal output by the temperature sensor is amplified by the amplifier circuit and connected to the second comparison circuit. Under normal circumstances, the output signal of the amplifier circuit is less than the second reference voltage, and the comparator U2B outputs a high-level signal to the second input terminal of the controller. When the temperature is greater than the set value, the output signal of the amplifier circuit is greater than the second reference voltage, and the comparator U2A outputs a low-level signal to the second input terminal of the controller. The controller can determine that a fire has occurred based on the low-level signal and the output signal of the smoke detection module.

[0039] The second reference voltage is obtained by a series voltage divider circuit composed of resistors R18 and R14. The terminal voltage of resistor R14 is used as the second reference voltage. The second reference voltage can be adjusted by adjusting the resistance values ​​of resistors R18 and R14. The circuit structure is simple and easy to operate.

[0040] Furthermore, it also includes an alarm connected to the controller.

[0041] In this embodiment, when the controller determines that a fire has occurred, it can control the alarm to sound an alarm to remind nearby people to call the police in time.

[0042] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. Fire monitoring system, characterized in that, The invention comprises a smoke detection module, wherein the smoke detection module comprises a first smoke sensor, a second smoke sensor, a subtraction circuit and a first comparison circuit, wherein the first smoke sensor and the second smoke sensor have the same circuit structure, and the first smoke sensor is arranged in a closed transparent housing. The output of the first smoke sensor is connected to the first input end of the subtraction circuit, the output of the second smoke sensor is connected to the second input end of the subtraction circuit, the output end of the subtraction circuit is connected to the first input end of the first comparison circuit, the second input end of the first comparison circuit is connected to a first reference voltage, and the output end of the first comparison circuit is connected to the first input end of the controller.

2. The fire monitoring system according to claim 1, characterized in that: The first smoke sensor includes a light emitting diode LED1, a resistor R1, a switch tube Q1, a photodiode PD1 and a resistor R4, wherein the control end of the switch tube Q1 is connected to the first output end of the controller, the first end of the switch tube Q1 is connected to a power supply, the second end of the switch tube Q1 is connected to the anode of the light emitting diode LED1, and the cathode of the light emitting diode LED1 is grounded through the resistor R1. The cathode of the photodiode PD1 is connected to a power source, the anode of the photodiode PD1 is grounded via a resistor R4, and the anode of the photodiode PD1 is the output of the first smoke sensor.

3. The fire monitoring system according to claim 1, characterized in that: The subtraction circuit includes an operational amplifier U1C, an inverting input terminal of the operational amplifier U1C is a first input terminal of the subtraction circuit, a non-inverting input terminal of the operational amplifier U1C is a second input terminal of the subtraction circuit, an output terminal of the operational amplifier U1C is feedback-connected to the inverting input terminal of the operational amplifier U1C through a resistor R13, and an output terminal of the operational amplifier U1C is an output terminal of the subtraction circuit.

4. The fire monitoring system according to claim 1, characterized in that: The first comparison circuit includes a comparator U2A, an inverting input terminal of the comparator U2A is a first input terminal of the first comparison circuit, a non-inverting input terminal of the comparator U2A is a second input terminal of the first comparison circuit, and an output terminal of the comparator U2A is an output terminal of the first comparison circuit.

5. The fire monitoring system according to claim 1, characterized in that: An operational amplifier U1A is arranged between the first smoke sensor and the subtraction circuit, the non-inverting input terminal of the operational amplifier U1A is connected to the output terminal of the first smoke sensor, the inverting input terminal of the operational amplifier U1A is grounded through a resistor R5, the output terminal of the operational amplifier U1A is feedback-connected to the inverting input terminal of the operational amplifier U1A through a resistor R3, and the output terminal of the operational amplifier U1A is connected to the first input terminal of the subtraction circuit.

6. The fire monitoring system according to claim 1, characterized in that: It also includes a temperature detection module, which includes a temperature sensor, an amplification circuit and a second comparison circuit. The temperature sensor is used to detect the temperature of a set area, the output end of the temperature sensor is connected to the input end of the amplifier circuit, the output end of the amplifier circuit is connected to the first input end of the second comparison circuit, the second input end of the second comparison circuit is connected to the second reference voltage, and the output end of the second comparison circuit is connected to the second input end of the controller.

7. The fire monitoring system according to claim 1, characterized in that: Also included is an alarm connected to the controller.

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