RU2279713C2 - Modulation indicator of infrared radiation - Google Patents

Abstract

FIELD: engineering of fire alarm devices.

SUBSTANCE: modulation indicator of infrared radiation, photo-electrical assembly of which is made with possible generation and transfer of signal through amplifier filter to digital part, input of analog-digital converter of which is meant for input of signal from amplifier filter, digital part is provided with guarding timer, connected to microcontroller, while signal generated by microcontroller is meant for sending to electromechanical modulator of photo-electric assembly, while signal transformed by analog-digital converter is meant for sending to microcontroller via optical isolation amplifiers, which microcontroller is meant for providing measurement results to transmitter-receiver of serial port to output of connecting device.

EFFECT: increased speed of operation, reliability and faultlessness of activation of fire-fighting systems and signalization.

1 dwg

Description

The invention relates to fire alarm devices and is intended to detect a source of ignition by infrared radiation of a source of elevated temperature. The invention can be used in automatic fire alarm and fire extinguishing systems to ensure explosion safety and fire safety in industrial premises and on industrial sites.

A pyrometric fire alarm sensor is known, which contains infrared photodetectors, light filters with different transmission spectra and amplifiers, the outputs of which are connected to the input of the actuating circuit, and a thermal stabilization unit for dark currents of photodetectors, a light flux splitter and an optical system for focusing the flux on sensitive windows of photodetectors are introduced into it , and the executive circuit contains a series-connected unit for calculating the ratio of two voltage values, an averaging unit, and a por a new detector, while a sequentially mounted optical system for focusing the flow on the sensitive windows of the photodetectors and a light splitter are optically connected to the photodetectors that are connected to the non-inverting inputs of the amplifiers, and the outputs of the thermal stabilization unit are connected to the inverting inputs of the amplifiers, the input of the unit for calculating the ratio of two voltage values is input executive circuit.

(RU patent No. 2109345, 04/20/1998).

The known solution is structurally complex and not reliable enough, it is limitedly applicable in extreme conditions at high temperature and dust, the presence of vibration.

Closest to the claimed one is a modulation flame sensor containing a sealed enclosure, inside which a filter is installed that transmits infrared radiation, an infrared radiation detector, a signal amplifier, a power generator, an electronic key that includes an automatic fire extinguishing system, while a pendulum modulator, a microlamp are introduced , a rectangular pulse shaper and a pulse counter, a pendulum infrared detector, a signal amplifier, a rectangular pulse shaper, a pulse counter and the electronic key is connected in series, the microlamp is shifted relative to the longitudinal axis of the housing so that the light signal from the microlamp, reflected from the filter, enters the infrared detector through the pendulum modulator, and the supply generator supplies voltage to the pendulum modulator, signal amplifier, square-wave pulse generator , pulse counter, electronic key and microlamp testing.

(RU Patent No. 2179743).

The known solution is excessively inertial and not reliable enough, limitedly applicable in extreme conditions at high temperatures and dust, the presence of vibration.

The objective of the invention is to increase the speed, reliability and error-free operation of fire extinguishing systems and alarm systems. The problem is solved in that in a modulation infrared sensor, which includes a housing, a photovoltaic assembly with an IR-transmitting light filter, a photoresistor and an electromechanical modulator, an analog part with an analog signal amplifier / filter, a digital part with an analog-to-digital converter, a serial port transceiver, and converters voltage, according to the decision of the photovoltaic unit is configured to generate and transmit a signal through an amplifier filter to a digital unit equipped with a watchdog timer and a microcontroller, the latter being connected to a photovoltaic unit, an amplifier filter connected to the digital unit via optocouplers, and a digital unit microcontroller connected to the watchdog timer, while the digital unit is configured to connect to the serial port of the fire fighting station.

Distinctive from the prototype are the following features:

- the photovoltaic unit is configured to generate and transmit a signal through an amplifier - filter to a digital part, the input of an analog-to-digital converter of which is designed to receive a signal from an amplifier-filter (which allows to obtain the values of the infrared signal in a digital code and provides an increase in the speed of obtaining and signal processing, reducing the inertia of the sensor);

- the digital part is equipped with a watchdog timer associated with the microcontroller, while the signal generated by the microcontroller is intended for receipt on the electromechanical modulator of the photovoltaic unit (which allows to increase noise immunity);

- the signal converted by an analog-to-digital converter is intended to be transmitted through optocouplers to a microcontroller, which is designed to transmit the measurement results to the serial port transceiver to the output of the connecting device (which provides the possibility of automatically transmitting the infrared value in digital form using standard protocols, increases noise immunity, reliability and speed);

Thus, the claimed solution meets the criterion of "novelty." Comparison of the proposed solutions with known analogues did not allow to identify in them the features that distinguish the claimed solution from the prototype, which allows us to conclude that the criterion of "inventive step"

The invention is illustrated in the drawing, which shows a diagram of a modulation sensor.

The infrared radiation modulation sensor contains a housing 1, a photovoltaic assembly 2 with a light filter 3, an analog part 4 with an amplifier — an analog signal filter 5, a digital part 6 with an analog-to-digital converter 7, a serial port 8 transceiver, voltage converters 9, a watchdog timer 10, a microcontroller 11, optocouplers 12, a connecting device 13, an electromechanical modulator 14, a photoresistor 15.

The device operates as follows. The signal with a frequency of 8 Hz generated by microcontroller 11 is fed to an electromechanical modulator 14 (PMT 2), while the photoresistor 15 of the photovoltaic unit 2 (PMT) is included in the feedback of the operational amplifier - an analog signal filter 5 (UFS). A reference voltage of 1.5 V is supplied to the positive input (UFS). A voltage of about 2-2.5 V is generated at the output of amplifier 5 (UFS). Thus, a stable current is set through the photoresistor 15, and the voltage at the output of the operational amplifier 5 (UFS) ) will depend on the change in the resistance of the photoresistor 15. When modulating the infrared radiation stream, a double frequency signal (16 Hz) is formed at the output of the operational amplifier 5 (UFS), the amplitude of which depends on the intensity of the infrared radiation stream. At the output of the UFS, the signal has a shape close to a sinusoidal shape.

A sinusoidal signal with a frequency of 16 Hz is fed to the input of an analog-to-digital converter 7. To reduce the time of measuring the signal amplitude (the need to measure rapidly changing processes), a quadrature measurement method is used. The sensor for the period of the measured signal generates four samples. The total time of one conversion and the technological pause, after which the conversion result can be read, does not exceed 2.5 μs. The conversion operation and the formation of the modulation frequency is performed in the interruption of the microcontroller 11, the priority of which is the highest. In the same interrupt, a reset is made to watchdog timer 10. In the interrupt with a lower priority, an exchange is made with the station (fire extinguishing station is not shown in the drawing) through the serial port 8 transceiver. The rest of the operations are performed during the interrupt-free operation time of the microcontroller 11. These include reading the conversion result from the data buffer of the analog-to-digital converter 7 (ADC) in the serial code, the mathematical operations necessary to calculate the amplitude of the measured signal. The results of measurements and subsequent calculations are stored in the data cell and are issued to the transceiver of serial port 8, when an address request is received from the control station.

The device allows you to measure the value of infrared radiation (background) at least 10 times per second and transmit this information in digital form via the RS-485 interface upon receipt of a request from the control station (fire fighting), which ensures speed and reliability of the system. The device allows you to programmatically adjust the allowable limits for the values of background illumination, because each sensor has its own address, which is configured on digital block 6, to monitor fire hazard and detect pre-emergency situations (dangerous overheating of bearings, conveyor belts and other equipment) of early detection of smoldering foci, fires and explosions of both technological rooms and in open areas, continuous automatic performance testing, which ensures the accuracy of the initiated information. The sensor is a technological device and works continuously in one mode, regardless of the detected information.

Claims (1)

Modulation infrared sensor, including a housing, a photovoltaic assembly with an IR-transmitting light filter, a photoresistor and an electromechanical modulator, an analog part with an analog signal filter amplifier, a digital part with an analog-to-digital converter, a serial port transceiver and voltage converters, characterized in that that the photovoltaic unit is configured to form and transmit a signal through an amplifier filter to the digital part, the input is analog-digital of the converter which is designed to receive the signal from the filter amplifier, the digital part is equipped with a watchdog timer connected to the microcontroller, while the signal generated by the microcontroller is intended to be fed to the electromechanical modulator of the photovoltaic unit, and the signal converted by the analog-to-digital converter is intended to be transmitted through the optocouplers to the microcontroller , which is designed to provide measurement results to the serial port transceiver on the output, connect nogo device.