RU2296370C2 - Infrared multirange flame and burst detector - Google Patents

Abstract

FIELD: fire and burst optical detectors.

SUBSTANCE: fire and burst IR detectors convert IR radiation from seat of fire, open flame or burst to electric signal. Radiation photovoltaic detectors are used in device, which detectors are made of solid solution formed by introduction of cadmium selenide into lead selenide. Six basic photoelectric elements with filters are developed. The combination of elements can be successfully used for optimal detection of typical types of flame at background of more characteristic optical noise.

EFFECT: improved reliability; higher speed of operation and sensitivity; adaptation to kind of ignition and kinds of optical noises; reduced cost.

15 cl, 6 dwg, 5 tbl

Description

FIELD OF TECHNOLOGY

The invention relates to optical flame and explosion detectors that convert infrared radiation from a fire, open flame or explosion into an electrical signal. Designed for use as devices that initiate the start of fire systems, fire extinguishing and explosion suppression, as well as to control the presence of flame.

BACKGROUND

Currently, two fundamental principles of flame identification are used, on which the fire and explosion detection equipment of most companies is based. These are the principles of frequency and spectral selection. With the frequency principle, the defining feature is the presence of low-frequency fluctuations in the radiation intensity of a controlled source. In the spectral principle, the defining feature is the presence in the radiation spectrum of a controlled source of spectral bands characteristic of combustion products (water vapor and carbon dioxide).

Obviously, the designs, circuits, and functionality of the sensors, their noise immunity, reliability, speed, consumer qualities, are mainly determined by the characteristics of infrared radiation receivers.

For the frequency principle of flame detection, radiation detectors are used that can detect low-frequency flame oscillations (from 2 to 20 Hz). Such receivers are, for example, pyrodetectors, photoresistors, photodiodes or photoelectric converters.

To implement the principle of spectral selection, several spectrally selective detectors that respond to radiation in different parts of the flame or explosion spectra are usually used, or one broadband radiation receiver is used, but then the necessary sections in the spectrum are isolated using optical filters. Sometimes spectral selection schemes complement frequency selection schemes. The most interesting of modern fire detectors are discussed below.

A technical solution is known (US patent No. 5850182A, priority 15.12.1998, applicant Detector Electronics Corporation, USA), where it is proposed to use two radiation detectors. The region of spectral sensitivity of the first coincides with the emission spectra of the flame, and the region of spectral sensitivity of the second should be outside the working spectral range of the first receiver. In this case, the first and second receivers carry out a frequency analysis of low-frequency signals from an oscillating flame and flickering optical noise, compare the amplitudes, phases, and frequencies of oscillations, detect the presence or absence of regular oscillations, evaluate their dynamics over time and draw a conclusion about the truth or falsehood of the fire signal . Here, pyrodetectors with two different interference filters are used as radiation detectors. This patent is used in the manufacture of detectors from Det-tronics, USA.

Solutions are also known when systems for the frequency analysis of a signal from an oscillating flame include three channels with different radiation detectors and complex algorithms for their mutual processing - US patent No. 5804825 (priority 08.09.1998) and application WO No. 9506927 (publ. 09.03.1995) . The basis of these decisions is the frequency analysis of signals in each channel, the receivers are pyrodetectors.

The simplest version of a detector based on spectral selection is the choice for a radiation receiver of a narrow range of spectral sensitivity that exactly matches the spectrum of the radiation of the flame. As a rule, the maximum radiation of the flame is at a wavelength of 4.4 microns, which corresponds to the "glow" of the combustion product - carbon dioxide. However, such a sensor is not sensitive enough and reliable, since it does not take into account other possible spectra of flame radiation and background optical noise.

UK patent No. 2281615 (A1) (publ. 03.09.93) offers a more complex combination of radiation detectors: along with the working channel tuned to emit flame at 4.4 microns, an additional channel at 3.8 micron tuned to emit foreign heated tel (optical background). Channel signals are compared. Radiation receivers are pyrodetectors.

In US patent No. 4101767 (publ. July 18, 1978), a spectral channel with a wavelength of 4.4 μm was used to detect flame, and sections of the spectrum with sensitivity maxima at 0.76 μm and 0.96 μm were used to isolate optical interference . Radiation receivers are also pyrodetectors.

It should be noted that the use of only the range with a maximum radiation of 4.4 μm for detection and identification of flame is not always sufficient, since no more than 1% of the energy emitted by the fires is concentrated in this spectral range, which means that serious difficulties arise in providing the necessary range of detection of the fire source.

US patent 6064064 (publ. 16.05.2000) solves the problem of "smoky flame" - a flame with a high content of fumes, such as decay. The detector contains three radiation detectors: two of them detect radiation from optical noise in the spectral range from 0.4 μm to 0.7 μm and from 0.7 to 1.1 μm, and the third, broadband, operates in the range 1.1– 3.5 microns and responds to flame radiation. As a broadband IR radiation detector, a lead sulfide photoresistor with a long-wavelength sensitivity limit of 3.5 μm was used. For the spectral ranges of 0.4-0.7 μm and 0.7-1.1 μm, silicon-based photodiodes are used, tuned to optical noise in the visible and near infrared spectral regions. The disadvantage of the proposed solution is the limited spectral range of the main channel of 3.5 microns. This makes it difficult to identify smokeless flames. In addition, interference associated with radiation from heated to relatively high temperatures of foreign bodies whose spectral region of radiation overlaps with the spectral range of a broadband radiation receiver is often included in the possible spectrum of optical interference. This gives a false signal.

A proposal is known to form the necessary spectral characteristics of the sensitivity of the radiation receiver by changing the composition of the semiconductor material. This adapts the receiver to the expected types of flame, and the process for manufacturing photodetectors is considered as part of the manufacturing process of the sensor as a whole (“Mercury cadmium telluride devices for detecting and controlling open flames”). In the patent US 005920071 (publ. 06/07/1999) as a semiconductor material of the photoresistor used SRT (cadmium-mercury-tellurium). When cadmium is replaced with mercury in the composition from 10 to 90 mol%, four spectral ranges of sensitivity are formed with the corresponding areas of photosensitive elements. These are ranges from 3 to 4 microns, from 4 to 5 microns, from 5 to 6.7 microns and from 6.7 to 20 microns. This approach to the design of sensors is very attractive. However, the CMT material is one of the most low-tech and expensive of industrial types of semiconductor materials. Additional difficulties arise due to the fact that multibandness (simultaneous reception of several spectral bands by a photoresistor) in this case is solved by multilayering the structure of optical filters, which excludes the possibility of accurately fixing the spectral sensitivity ranges of optical filters. In addition, the proposed radiation receiver is a photoresistor; for its operation, it requires pulsations of the intensity of flame radiation, which are difficult to separate from flickering optical noise.

A two-channel digital multi-frequency flame detector is known, in which photoconductors made of lead selenide are used as radiation detectors of both flame and optical noise (Patent US 6150659, publ. 21.07.2000). In this sensor, the flame is simultaneously identified by the frequency characteristics of the radiation sources. A range from 4.2 to 4.8 μm is selected as the spectral range of the flame registration channel, and a range from 2.0 to 2.4 μm is selected for the optical interference recording channel. Since the receivers are photoresistors, they require pulsations of the flame intensity for their operation, to distinguish them against the background of simultaneously operating flickering interference, the electronic circuit of the processing of channel signals is substantially complicated. In addition, the absence in the sensitivity spectrum of the region from 2.6 to 3.2 μm excluded the possibility of recording the combustion of substances not containing carbon. Finally, when choosing a channel for optical noise in the range of 2.0-2.4 μm, there was a threat of accepting a “smoky flame” for optical interference.

Known flame detector with the most fully applied method of spectral selection ("Dual channel multi-spectrum infrared optical fire and explosion detection system", US patent No. 5612676, publ. March 18, 1997). This is an infrared multi-band flame and explosion detector, the main channel of which is composed of two photosensitive elements with narrow-band optical filters, while the spectral characteristic of the channel sensitivity is formed by these filters and corresponds to the characteristic emission spectra of the flame and explosion, and the auxiliary channel is composed of three photosensitive elements homogeneous to the elements main channel, with narrow-band optical filters, while the spectral characteristic is sensitive The channel channel is formed by the indicated filters and corresponds to the characteristic emission spectra of optical interference, which contains a circuit for isolating low-frequency oscillations of radiation and a logic comparison circuit for the output signals of these channels and their low-frequency oscillations with the formation of a flame signal, and thermosensitive elements, pyrodetectors, and photoresistors from lead selenide, cadmium-tellurium photovoltaic cells, indium antimonide, gold-controlled germanium. In this two-channel sensor, the main channel has two spectral ranges with maximums of sensitivity at 2.9 microns and 4.4 microns, and the auxiliary (background) channel has three spectral ranges with maximums of sensitivity at 2.2 microns, 3.8 microns and 5, 6 microns. The main channel reacts mainly to the flame, and the auxiliary channel mainly to optical interference. A comparison of the channel signals makes it possible to fairly reliably detect the presence of a flame source sensor in the field of view. For both channels, a pair of the same type of radiation detectors is selected, having a sensitivity in the spectral range of 1.5 - 6.5 microns. The above spectral bands are formed using narrow-band interference filters. Thus, spectral analysis of the external radiation incident on the detector in five spectral ranges is simultaneously carried out. But in this sensor, as well as in the previous ones, it was not possible to completely abandon the principle of frequency selection and avoid the unpleasant consequences arising from it. Another difficulty is that the photoresistors recommended for use must be cooled with liquid nitrogen. Naturally, this makes the sensor design cumbersome, complex, expensive, limited in terms of continuous operation. The use of thermocouple batteries or pyrodetectors as radiation detectors dramatically reduces the speed of the system and reduces its sensitivity. In this case, the mode of explosion suppression is not possible. In addition, the rigid assignment of each of the spectral working ranges of the channels does not allow you to effectively adapt the proposed detector to the variety of possible types of foci of flame and interference. So, when choosing a maximum sensitivity of 2.2 μm for one of the spectral ranges of the auxiliary channel, it may be difficult to determine the presence of foci of flame, where the main emitting object is carbon particles heated to a temperature of 1500-2000 ° C (fire with a smoking flame) , and this variant of fire is more common in practice than others. Finally, apparently, due to the above reasons, specific types of sensors and companies that would use these inventions in their work are not known. Nevertheless, it is THIS SOLUTION - THE MOST CLOSE ANALOGUE OF THE DECLARED FLAME AND EXPLOSION DETECTOR, i.e. HIS PROTOTYPE.

One can not ignore another type of optoelectronic device, the principles of construction and functioning of which can be used to create flame and explosion sensors. These are matrix converters, which are the subject of mass research of an important practical application for creating solar batteries on their basis. A special place among them is occupied by cascade converters in which photovoltaic cells are created on the basis of semiconductor materials of various compositions (a review of such works is given in the monograph by T. Coates and J. Mikin “Modern Problems of Semiconductor Photovoltaics”, Moscow, Mir, 1988). In one embodiment of solar converters, solid solutions of gallium arsenide - phosphorus and gallium arsenide - antimony are used as semiconductor materials for photovoltaic cells operating in the visible spectrum. When forming panels from such series-connected elements, the total spectral sensitivity region of the converter significantly expands and, as a result, the efficiency of the solar battery increases. However, when designing flame sensors, an increase in conversion efficiency is not a determining factor. It is important that the formed spectral sensitivity regions of the photoelectric elements of the matrix converter correspond to the characteristic emission spectra of the flame sources and optical noise. Known matrix converters are not applicable for use in flame detectors without a significant change in the areas of their spectral sensitivity, switching circuits and the formation of the output signal.

The above review indicates that the well-known detectors considered above do not fully meet current practice requirements.

Lack of reliability. The main difficulties of the known solutions are due to the fact that the principle of frequency selection is adopted as at least one of the identifying principles of the flame. The frequency of vibration of the flame depends on the size of the fire and when certain areas are reached, the frequency of vibration becomes less than 0.1 Hz. The amplitude of irregular oscillations of a false source (for example, the reflection of sunlight from the surface of sea waves) can be many times greater than the signal from a flame. Heated rotating moving objects can emit in the "flickering" mode and in the spectral range that coincides with the spectral range of the flame. It is clear that this identification method is not reliable enough. Moreover, low-frequency fluctuations in flame intensity are generally not always present in practice. In particular, when burning gas burners in steam boilers, metallurgical furnaces, in household appliances, to ensure maximum efficiency, they achieve the most stable flame. In this case, the control of the flame using the frequency principle is not possible. For the same reason, it is difficult to detect smoldering fires.

Inadequate performance. The detectors used (described) cannot be used to suppress explosions. All flame detectors using pyrodetectors as radiation detectors detect flames in up to 20 seconds. Special settings of these sensors allow reducing the response time to 25-30 ms, but at the cost of a sharp decrease in sensitivity and noise immunity. As you know, the velocity of propagation of a fire front, for example, during a deflagration explosion, reaches 1500 m / s, and at such a speed of operation, thousands of square meters will already be in the zone of the explosion.

Narrow functionality. The analysis of industrial products manufactured according to the patents or their analogues considered above showed that the production of most of them has a narrow specialization and is focused on one of any possible practical applications, exclusively in its design, functional and operational characteristics, and therefore it is limited in scale of production.

All of the above makes us pay serious attention to another principle of identification - the principle of spectral selection in a variant that is not related to the need to supplement it with the principle of frequency selection. However, to implement this option, it is necessary to equip the sensors with special radiation detectors, which for their operation do not require modulation of the radiation intensity. Then it turns out to be possible to avoid the disadvantages resulting from the application of the frequency principle. At the same time, it is necessary to solve the problem of the multifunctionality of the sensors, the adequacy of their characteristics to various application conditions, and also to ensure the possibility of their mass production while ensuring high parametric characteristics and high reliability.

OBJECTS OF THE INVENTION

Objectives of the invention:

- increase in reliability (reliability of operation, noise immunity, explosion safety, the ability to test performance by control flame simulators, the emission spectrum of which is adequate to fire sources);

- expansion of functionality (detection of non-oscillating flame, flame of gas flames, decay of wood and cotton, large fire areas, speed - the ability to respond to the primary phases of the explosive process);

- universality (the ability to adapt the spectral characteristics of the detector to the expected type of ignition and the likely types of optical interference);

- an increase in sensitivity with respect to the fire sources resulting from the burning of wood, polymeric materials and fuels and lubricants;

- cheaper and the possibility of mass production and use.

SUMMARY OF THE INVENTION (SUMMARY OF THE INVENTION)

To solve these problems, the authors conducted in-depth studies and developed a new photoelectric semiconductor element, not used for flame detectors, based on solid solutions of chemical compounds of the A4B6 group, for example lead selenide, and compounds of the A2B6 group, for example cadmium selenide. The proposed element is a photo generator, i.e. directly converts the radiation from the fire sources and the primary phases of the explosion into a photo emf; it does not require external power sources and low-frequency flame oscillations for its operation. The use of such a photoelectric element made it possible to increase the sensitivity of the sensor, its reliability, reduced power consumption, and expanded functionality.

Studies of the proposed photovoltaic element revealed its most technologically advanced, inexpensive, and sensor-friendly form — in the form of thin polycrystalline layers in which the potential barrier that determines the appearance of photo emf is formed in the form of a MOS structure, and also established the dependence of the position of the maximum and the long-wavelength boundary of spectral sensitivity on concentration of cadmium selenide in a solid solution of lead selenide and cadmium selenide. All this made it possible to significantly simplify the formation of the spectral characteristics of the detector's optical channels and signal processing logic circuits.

To optimize the composition of the photovoltaic elements and the operating modes of the detectors, the characteristic spectra of six main types of fire sources were determined (in accordance with GOST R 50808-96) - Table 1 and the most likely types of optical interference - Table 2. Considering this knowledge and emerging technological capabilities, the options are considered the formation of spectral characteristics of the sensitivity of the main and auxiliary channels of the detectors using the proposed photovoltaic elements adequate to the expected types of fire sources and optical interference, i.e. having in the given operating conditions the greatest sensitivity and noise immunity.

In addition to this, on the basis of the proposed photovoltaic cells, optical filters, and previously not applied logic processing circuits, a new matrix multispectral (multiband) semiconductor converter was developed, which was the main functional element of the detector. As a result of the research:

The tasks are solved in that in order to increase reliability, speed, explosion safety, as well as simplify, reduce dimensions, energy consumption, cost in a well-known multi-band infrared flame and explosion detector, the main optical channel of which is composed of one or more photoelectric elements with optical filters, spectral characteristic the sensitivity of which corresponds to the characteristic emission spectra of the flame and explosion, and the auxiliary optical channel is composed of one or several There are significant changes and additions to the number of photovoltaic cells with optical filters, the spectral sensitivity characteristic of which corresponds to the characteristic emission spectra of optical noise, which contains a logical comparison of the output signals of these channels with the formation of a fire signal:

- photovoltaic cells are made of a semiconductor material based on solid solutions of chemical compounds of group A4B6 and group A4B6, for example, lead selenide and cadmium selenide.

To increase the reliability, manufacturability and lower cost of the detector, solid solutions of chemical compounds of the A4B6 and A2B6 groups used for photovoltaic cells are used in the form of thin polycrystalline layers in which the potential barrier that determines the appearance of photo emf is formed as a planar pn junction, a barrier Schottky or MOS structures.

To ensure that the spectral sensitivity ranges of the detector photoelectric elements correspond to the radiation spectra of various types of fires, the concentration of chemical compounds of the A2B6 group in the A4B6-A2B6 solid solution is set to a value ranging from 0.1 to 20 mol%, and the short-wavelength limit of their spectral sensitivity is determined by the short-wavelength the transmission limit of the optical filters installed in front of them.

To increase the reliability and simplify the design of the detector, the output voltages of the main and auxiliary channels are formed due to the serial electrical connection of the photoelectric elements in each channel and the corresponding summation of the photo emf generated by these elements, and the logical comparison circuit is made in the form of a circuit for subtracting the output voltages of the channels, with this criterion signal from the source of a fire or explosion is the excess voltage of the main channel over the voltage of the auxiliary channel but.

To reduce the dimensions, reduce the price and increase the reliability of the detector, the main and auxiliary channels, as well as a comparison circuit, can be formed on the basis of a single infrared semiconductor multi-band array transducer composed of photoelectric elements with optical filters installed in front of them, with the concentration of A2B6 material in A2B6 solid solution -A4B6, for example, cadmium selenide in a solid solution of lead selenide and cadmium selenide, and the pass band of the optical filter phot Of the electric elements in the main channel, a spectral sensitivity characteristic is formed corresponding to the characteristic radiation spectrum of the fire and explosion, and in the auxiliary channel, a spectral sensitivity characteristic corresponding to the characteristic optical radiation spectrum.

To simplify the design of the detector, expand its functionality and reduce the cost of production, the transducer matrix may contain two panels of elements. The first, the main panel, corresponds to the main optical channel of the sensor and is formed by photoelectric elements with filters, the sensitivity spectral characteristics of which correspond mainly to the characteristic emission spectra of one or more types of fire and explosion centers, and the second, auxiliary panel, corresponds to the auxiliary optical channel of the sensor and is formed by photoelectric elements with filters, the spectral sensitivity characteristic of which corresponds mainly arakternym emission spectra of one or more optical noise such as spectrum radiation from the sun or artificial light sources, electric welding, radiator and heater.

To increase manufacturability and reliability and reduce the dimensions of the detector, a logical comparison scheme can be made in the form of an internal serial electrical connection of the photovoltaic elements of each panel, providing a sum of their photo EMF, and subsequent electrical connection of the panels, which subtracts the total photo EMF of the main and auxiliary panels, thereby way comparison of the signals of the main and auxiliary channels.

In order to detect fires resulting from the combustion of mainly wood, polymeric materials, fuels and lubricants and flammable liquids with smoke, the photoelectric elements of the main channel of the detector can be made with a concentration of cadmium selenide in solid solution of 20 ± 3 mol% and with a short-wavelength transmission limit optical filter 1.6 microns. In this case, the maximum sensitivity is 2.9 μm.

Two types of photoelectric elements in the main channel of the detector were used to detect fires resulting from the combustion of predominantly flammable liquids without smoke, one of which was made with a cadmium selenide concentration in the solid solution of 0.1 ± 0.02 mol% and a short-wavelength optical transmission limit filter 4.2 microns, and the second is made with a concentration of cadmium selenide in solid solution of 10 ± 1.0 mol% and with a short-wavelength transmission limit of the optical filter of 2.6 microns. In this case, sensitivity maxima are found at 4.4 μm and 2.9 μm, respectively.

To detect fires of the type primarily predominantly smoldering wood and cotton, the photoelectric elements of the main channel of the detector can be made with a concentration of cadmium selenide in a solid solution of 0.1 ± 0.02 mol% and with a short-wavelength optical filter pass-through of 3.2 μm. In this case, the maximum sensitivity is 3.8 μm.

To detect fires of the type of combustion, mainly of carbon-free chemicals, the photoelectric elements of the main channel of the detector can be made with a cadmium selenide concentration in the solid solution of 10 ± 2 mol% and with a short-wavelength optical filter pass-through of 2.6 μm. In this case, the maximum sensitivity is 2.9 μm.

To detect optical interference with a radiation spectrum located mainly in the wavelength range 1.6-2.6 μm, for example from incandescent lamps, the photoelectric elements of the auxiliary channel of the detector can be made with a cadmium selenide concentration in the solid solution of 20 ± 3.0 mol % and an optical filter passband of 1.6 μm to 2.6 μm. In this case, the maximum sensitivity is 2.3 microns.

To detect optical interference with a radiation spectrum located mainly in the wavelength range 3.2–4.2 μm, for example, from heating batteries and heating devices, from electric incandescent lamps, the photoelectric elements of the auxiliary channel of the detector can be made with a concentration of cadmium selenide in solid a solution of 0.1 ± 0.02 mol%, and a short-wavelength optical filter passband of 3.2 μm. In this case, the maximum spectral sensitivity is at 3.8 μm.

To detect optical interference with a radiation spectrum located mainly in the wavelength range 1.0 μm - 1.4 μm, for example from the sun, artificial light sources, electric welding, the photoelectric elements of the auxiliary channel of the detector can be performed with a concentration of cadmium selenide in solid solution 20 ± 3.0 mol%, and an optical filter passband from 1.4 μm to 1.0 μm. In this case, the maximum sensitivity is 1.2 microns.

To increase the reliability and reliability of the detector, a control (testing) photoluminescent emitter placed in front of the sensor input window can be additionally introduced into its design. The emission spectrum of the control emitter is consistent with the emission spectra of the flame and explosion, for the detection of which the sensor is intended. The radiating element, like the photoelectric elements, is made of a semiconductor material based on a solid solution of lead selenide and cadmium selenide, and the source of the short-wave radiation is, for example, a gallium arsenide LED.

SUMMARY OF THE INVENTION.

The invention is illustrated in the following 5 tables and 6 figures:

table 1 - Characteristic emission spectra of the main types of fires (according to GOST R 50808-96);

table 2 - Typical emission spectra of the main types of optical interference;

table 3 - Examples of combinations of photovoltaic cells with filters, providing an adequate detector response, depending on the type of fire

table 4 - Recommended types of emission spectra of the control emitter, depending on the type of flame, for the detection of which the detector is intended;

table 5 - Comparison of the characteristics of the proposed detectors and foreign analogues;

figure 1 - dependence of the relative spectral sensitivity characteristic (UHF) of the proposed photovoltaic element on the concentration of cadmium selenide in solid solution;

figure 2 - the relative spectral characteristics of the sensitivity (UHF) of the basic photovoltaic cells with optical filters;

figure 3 is an example of the location of the photovoltaic cells in the matrix Converter of the detector;

figure 4 is an example of a detector;

5 is an example of the design of the control emitter of the detector;

6 - relative radiation spectra of the control emitter (OSIKI) of the detector depending on the concentration of cadmium selenide.

The following notation is used in the figures:

1, 2 - photoelectric elements of the main channel of the detector, 3, 4 - photoelectric elements of the auxiliary channel of the detector, 5 - contact pads for internal switching of photoelectric elements, 6 - contact pads for internal switching of the detector channels, 7 - contact pads - ends of external terminals, 8 - holder with cells for photovoltaic cells and optical filters, 9 - matrix converter housing, 10 - patch board, 11 - patch wires, 12-15 - optical filters, 16 - detector input window, 17 - external leads of the detector transducer, 18 - cap, 19 - case of the control emitter of the detector, 20 - LED for pumping, 21 - photoluminescent layer, 22 - cover of the control emitter of the detector, 23 - output window of the control emitter, 24 - external conclusions of the emitter, 25 - contact pads, 26 - contact conductors.

It is possible to produce photovoltaic cells from semiconductor materials based on solid solutions of chemical compounds of the A4B6 group, for example lead selenide, and the A2B6 group, for example cadmium selenide, as well as control photoluminescent emitters of the same type using typical technological methods adopted in microelectronics. This is vacuum deposition of polycrystalline films from semiconductor materials onto a dielectric substrate, traditional methods of doping in the synthesis of a material, or doping of formed polycrystalline layers from vapor or liquid phases when producing pn junctions, applying metal layers to obtain MOS structures, group methods for manufacturing photoelectric elements , their assembly, sealing and measurement of parameters. In particular, the synthesis of solid solutions of materials of the A2B6 and A4B6 groups is carried out by fusing the pure starting elements in a vacuum in a closed volume during preliminary purification of the starting material by zone melting. This technology is described in more detail, for example, in the patent of Gorbunov N.I., Diykova L.K., Varfolomeeva S.P., and others. "Photoluminescent emitter, semiconductor photocell and octron based on them" (patent No. 37575, priority from 05.02.2004), in the articles of Gorbunov NI., Diykova L.K. et al. "New octrons for spectral-analytical equipment" (the journal "Components and Technologies" No. 6, 2004) and Gorbunova NI, Diykova L.K. and others. "New optoelectronic flame sensors" (journal "Electronics" No. 2, 2005).

The concentrations of the additives introduced into lead selenide can be controlled by the method of emission spectral analysis, electronic spectral chemical analysis, and secondary ion mass spectrometry, and the content of the main components, selenium and lead, by the method of X-ray fluorescence analysis. The stated concentration limits introduced, for example, into the semiconductor material of cadmium selenide are due to the following factors: when the concentration of cadmium selenide is less than 0.1 mol%, the change in the band gap of the semiconductor material is insignificant and insignificant changes in the position of the wavelength of the maximum spectral sensitivity. Due to the limitation of the solubility of cadmium selenide in lead selenide from the side of lead selenide, the introduction of an additive in excess of 20 mol% is impractical, since at such concentrations no solid solutions of these compounds are formed.

At the same time, the amount of material spent, its low cost, the possibility of using group technologies adopted in microelectronics, their simplicity and high yield rate of products made it possible to organize a highly efficient and low-cost serial production of photovoltaic cells for multi-range transducers of detectors from materials based on solid solutions of lead and selenide selenide cadmium. In addition, the simplicity of processing EMF photo signals, achieved through internal switching of such photovoltaic cells, simplifies the electronic processing circuit and the detector tuning process. All of the above also allows you to organize the mass production of cheap flame detectors with high technical and operational characteristics, which can compete in scale with smoke and heat detectors. The use of a photovoltaic cell, which does not require a supply voltage — the main source and cause the degradation of the properties of photocells — also contributes to high reliability.

An example of the design of the main functional elements of the detector is presented in Figs. 3, 4, 5. For such a design, the applicant has a patent “Multi-range fire flame detector” (patent of the Russian Federation No. 53744 with priority dated June 18, 2002, applicant of the Research Institute “Girikond” , authors L.K.Diykov, A.L. Burkin, etc.)

The photovoltaic elements of the main (1, 2) and auxiliary (3, 4) channels are fixed in holders 8 with cells for installing the indicated photovoltaic elements and optical filters 12-15 on the patch board 10 located in the detector housing 10. Metallized on the patch board 10 pads 5, 6, 7 for internal switching by wires of 11 photovoltaic elements of channels, channels and external terminals, respectively. The housing has an input window 16. The internal switching of the photovoltaic elements of the channels, channels and external terminals is carried out by welding the switching wires 11 to pre-selected contact pads 5-7 on the circuit board 10. There is also such a design option when the ends of the external pads 5-7 the findings of the housing 9 in a number equal to the number of contact pads. In this case, the switching of the photoelectric elements 1-4 can be carried out outside the detector housing. Photovoltaic cells 1 and 2 form the main panel of the detector array, and photoelectric cells 3 and 4 form the auxiliary panel. The main and auxiliary panel are electrically connected by a wire 11.

A top view of the placement of the photovoltaic cells 1-4 on the circuit board 10 is shown in Fig.3. They form a four-element matrix and are squared in the cells of the holder 8 mounted on the circuit board 10. The contact pads 7, which are the ends of the output pins 17, are connected via contact wires 11 to the detector matrix panels through the contact pads 6. The output pins 17 are electrically connected with electronic elements located on the sensor circuit board. It is possible to set a light indication that the detector is turned on, about the “fire” mode and about the malfunction of the detector.

The electrical signals of the main and auxiliary channels in the detector are formed by several series-connected photoelectric elements with filters, the spectral sensitivity characteristics of which correspond to the characteristic spectra of the expected types of flame and optical interference. The excess of the signal of the main channel (main panel) over the signal from the auxiliary channel indicates the presence of a fire.

The applicant revealed the dependence of the wavelength of the maximum spectral sensitivity of the photoelectric element on the concentration of cadmium selenide in the solid solution (Fig. 1) and used it to form the spectral characteristics of the detector elements. In this case, the short-wavelength boundaries of their spectral sensitivity are determined by the short-wavelength transmission limits of the optical filters installed in front of the photoelectric elements.

Depending on the operating conditions of the detector, its optical channels can be formed from one, two, or three photoelectric elements with optical filters. If it is necessary to increase the sensitivity in any of the selected parts of the spectrum, it is possible to series-connect the same photovoltaic cells with the same CXF.

Typical flame and interference spectra are presented in tables 1 and 2.

Table 1. - Characteristic emission spectra of the main types of fire sources (according to GOST R 50808-96) Type of TP-1 TP-2 TP-3 TP-4 TP-5, explosion TP-6
explosion Another explosion Fire source Wood burning Smoldering wood Smoldering cotton Burning polymer materials Combustion of flammable liquids and fuels and lubricants with smoke Flaming LVH without smoke Combustion of hydrocarbon-free substances, explosion Maximum emission wavelength, 2.9 μm 4.4 μm
3.8 μm 4.4 μm
3.8 μm 2.9 μm 2.9 μm 4.4 μm
2.9 μm 2.9 μm OSHCH number of the base element 3 1 and 4 1 and 4 3 3 1 and 3 3

Table 2 - Characteristic emission spectra of the main types of optical interference Optical Interference Source Incandescent light bulbs Sun, electric welding, fluorescent lamps Heated bodies The wavelength of the maximum radiation, microns 2 1,2 3.8 OSHCH number of the base element 5 6 four

The applicant has developed six basic photovoltaic cells with filters, a combination of which can cover the most popular cases of fire detectors against typical optical interference. Figure 2 shows their relative spectral characteristics of sensitivity (UHF). Table 3 shows the combinations of series connections of the basic photovoltaic cells with filters in the main and auxiliary channels, respectively, providing an adequate response of the detector to a flame or explosion in the presence of optical interference.

Table 3
Examples of combinations of photovoltaic cells with filters that provide an adequate detector response depending on the type of fire source. No. Type of fire according to GOST R 50808-96 The number of the type of the frequency response of the basic photovoltaic cells according to Fig 1 No. 1 Number 2 Number 3 Number 4 Number 5 Number 6 one TP-1, TP-4, TP-5, explosion + 2 TP-2, TP-3 + + 3 TP-6, explosion + + four Combustion of hydrocarbon-free substances, explosion + 5 Optical interference: radiation from the sun, fluorescent lamps, electric welding + 6 Optical interference: radiation from heated bodies and incandescent lamps + +

Typical fuels and lubricants (fuels and lubricants) burning with smoke (TP-5): diesel fuel and gasoline, jet engine fuel, transformer oil and compressor and pump working oils.

Typical types of flammable liquids (LVH) burning without smoke (TP-6): methane, ethane, propane, butane, alcohols - methanol, ethanol, propanol, acetone.

Typical flammable substances (LVH) that do not contain carbon: hydrogen, ammonia, hydrazines, sodium azide and others, in which water vapor is the emitting combustion product.

Below are frequently used options for the selection and switching of basic photovoltaic cells 1-4 with optical filters 12-15 to obtain a given frequency response. In this case, the basic elements of each channel (panel), taking into account the sign of the photo EMF, are connected in series, and the channels (panels) are in opposite directions. To detect the burning of fuels and lubricants, without the emission of smoke, for example methane, ethane, propane, butane, alcohols, in the presence of high-temperature objects in the field of view, radiation from the sun and incandescent lamps (fire center type TP-6): basic elements for the main channel - elements with a frequency response number 1 and with a frequency response number 3, for the auxiliary channel - elements with a frequency response number 4 and with a frequency protection number 6.

To detect the burning of wood, polymer compounds and fuels and lubricants with smoke emission in the presence of a large-area heated bodies detector and solar radiation in the field of view (fire sources of the type TP-1, TP-4. TP): basic elements for the main channel are elements with SINR No. 2 and with SINR No. 2, for the auxiliary channel - elements with SINR No. 4 and with SINR No. 6.

To detect a fire source of the TP-2 and TP-3 type (for example, wood and cotton smoldering) when there are electric incandescent and radiation lamps in the field of view of the detector: the basic elements for the main channel are elements with a frequency response number 1 and a frequency response number 4 , for the auxiliary channel - elements with a frequency response number 5 and with a frequency response number 6.

To detect a fire source in which combustible substances do not contain carbon, and radiation from the sun and incandescent lamps can get into the field of view of the detector: the basic elements for the main channel are elements with SINR No. 3 and SINS No. 3, for the auxiliary channel - elements with OSHKh No. 5 and with OSHKh No. 6

Note that an increase in the concentration of cadmium selenide introduced into the semiconductor material allows not only to control the position of the long-wavelength boundary in the spectral characteristics of the photoelectric elements and the position of the emission spectra of the control emitters, but also significantly increases their sensitivity and emissivity, respectively, as can be seen from figure 1 and figure 6.

The detector operates as follows (Fig.3, 4).

Radiation from foci of flame, explosion, and from optical interference in the field of view of the detector, through the input window 16 of the detector transducer, falls on the group of photovoltaic cells 1-4 placed in the holder 8 with cells, while optical filters 12-15 are installed in front of the photovoltaic elements . External radiation cannot get into each cell except once passing through the corresponding optical filter. Moreover, each photoelectric element 1-4 generates a photo-emf, the value of which is proportional to the radiation power of the external optical signal and the reception of which this photoelectric element with a filter is configured. According to the preliminary application of the consumer, the detectors are made to detect the alleged types of fires and the expected optical interference. With this in mind, as we described above, the selection of photovoltaic cells 1-4, filters 12-15 and their switching using pads 5-7 and switching wires 11. Electrical signals (photo EMF) from photovoltaic cells 1,2 of the main channel (main panel) are summarized and the total photo EMF value will be proportional to the radiation intensity from the source of the fire or explosion. In turn, the electrical signals (photo EMF) from the photoelectric elements 3 and 4 of the auxiliary channel (auxiliary panel) are added up and the total value of the photo EMF will be proportional to the radiation intensity from optical interference. The total signals from the main and auxiliary channels using the pads 6 and the patch wire 11 are subtracted due to their oncoming switching. As a result, an electrical signal is generated at the contact pads 7 and the external terminals 17 of the sensor, which is supplied for subsequent amplification and inclusion of control, signal or actuating devices. If the signal of the main channel is greater than the signal of the auxiliary channel, the detector is triggered. It detects a fire source both against the background of optical interference, and in their absence. When the signal of the main channel is less than the auxiliary one, the detector does not work. So there is no flame or it is small compared to the optical background.

Figure 5 shows an example of the design of the control emitter, which is made as follows: a short-wave radiating element - LED 20 for "pumping" is glued to the housing 19 using heat-conducting glue. The contact pads 25 of the LED 20 through the conductors 26 are connected to the electrical inputs 24. A long-wave emitting element — a photoluminescent layer 21 — is glued to the radiating surface of the LED 20 with a transparent adhesive. A cover 22 with a window 23 is attached to the housing 19 with the radiating elements 20 and 21 glued to it. from a material transparent in the spectral range of 1-4.8 microns.

To maximize the approximation of the emission spectra of the control emitter to the spectral characteristics of possible flame sources, a photoluminescent emitter 21 based on a solid solution of lead selenide and cadmium selenide excited by an LED 20 from gallium arsenide was used as an emitter. the emitter is made on the basis of the same semiconductor materials as the photoelectric elements of the sensor.

The output window 23 of the control emitter is located in front of the input window 16 of the detector and emits in the spectral range consistent with the spectral sensitivity characteristic of the photovoltaic elements of the main channel, which respond mainly to radiation from the fire source. Thus, a flame simulator with optical characteristics as close as possible to the expected type of ignition is realized. At the same time, the contamination of the input window of the detector and the operability of the electronic circuit are checked.

The control emitter operates as follows. When applied through electrical inputs 24, conductors 26 to the contact pads 25 of a constant or pulse voltage of 2-2.5 V, the LED 20 begins to emit in the spectral range of 0.8-0.9 μm. This radiation enters the photoluminescent layer 21 from a semiconductor material based on solid solutions of lead selenide - cadmium and excites radiation in the spectral range that coincides with the spectral sensitivity regions of the photoelectric elements and flame emission spectra. When this radiation subsequently hits the detector input window 16 and the photoelectric elements 1.2 of the main channel, its operability is checked.

The emission spectrum of the control emitter of the detector can be changed by changing the concentration of cadmium selenide in the solid solution (Fig.6), which is used in sensors configured to detect certain types of fires.

Table 4 shows the recommended relative radiation spectra of the control emitter, depending on the type of fire source for which the detector is intended to be detected. The numbers of recommendations correspond to Fig.6. The manufacturing technology and characteristics of the control emitter are similar to those given in the patent of the Russian Federation No. 37575 (priority from 02/05/2004) or in the article by Gorbunov NI, Diykova LK, Varfolomeeva SP, Medvedeva F.K. “New octrons for spectral-analytical equipment” (“Components and Technologies” journal, No. 6 of 2004).

Table 4 - Recommended types of relative radiation spectra of the control emitter (OSIKI) depending on the type of fire source for detection of which the detector is intended (according to Fig.6) No. Type of fire according to GOST R 50808-96 Type number SIFI photoluminescent emitter according to Fig.6 No. 1 Number 2 Number 3 eleven TP-1, TP-4, TP-5, explosion + 22 TP-2, TP-3 + 33 TP-6 + 34 Combustion of hydrocarbon-free substances, explosion +

INDUSTRIAL APPLICABILITY

The claimed infrared multi-range flame and explosion detectors are investigated in detail by the applicant in laboratory conditions and mastered by him in serial production. For the first time in domestic and foreign practice, OJSC “Research Institute“ Girikond ”implemented a technical solution for fire detectors when a receiving optical unit detecting infrared radiation from fires and optical noise, and an electronic signal processing unit that processes electrical signals from the receiving optical unit and emitting a fire signal, are made in a single small-sized matrix infrared multi-band two-panel uncooled converter, in which as a photoelectric of their elements, thin-film polycrystalline MOS structures based on solid solutions of the A2B6 and A2B4 group were used, and when the manufacture of such photovoltaic cells and converters was one of the elements of the detector production technology as a whole.

The algorithm of the detector development process for a specific fire and explosion safety facility provides for: analysis of the possibility of a fire or explosion in a guarded object, prediction of the most likely types of fire or explosion outbreaks, identification of areas on the territory of the protected facility that are subject to protection from a possible explosion or fire, project development fire and explosion safety systems for the facility, manufacture of detectors with characteristics that ensure their adaptation to possible real threats of fire or explosion at the protected facility.

This is exactly the scheme that operates at the enterprise of the Research Institute “Girikond”. The mastered production of detectors currently provides annual output in excess of 10,000 pcs. In particular, these are NABAT type detectors (IP-332 1/1, IP-332 1/2 SK, IP-332 1/3). During their development and production, the spectral identification method was fully used, which became possible thanks to the use of photovoltaic cells made on the basis of solid solutions of materials of the A2B6 and A2B4 groups in a single small-sized matrix infrared multi-band two-panel uncooled converter. At the same time, it was possible to solve a number of technical problems, the overcoming of which until recently was difficult or impossible.

The main problem of the considered technical direction is the variety of requirements that constantly arise from the consumer who needs cheap small-sized reliable sensors that are fully adapted to specific operating conditions, and which should be used not only at strategically important facilities, but also wherever fires and there is a chance of an explosion. At the same time, questions of optimal adaptation are usually solved by creating numerous design options and types of detectors with specific and well-defined parameters. Given that most of them have energy consumption of up to 10-15 watts, weight up to 6.5 kg, and cost up to 2000 dollars, it becomes clear that their mass use is impossible.

Table 5 shows a comparison of the parameters of declared and foreign fire detectors, which are most widely used in domestic and foreign markets.

Table 5
Comparison of the characteristics of the proposed and foreign fire detectors Detector PROPERTIES Det-tronics Det-tronics Det-tronics Siemens, Cerberus Division Spectrex Inc Cedar rove NJ Research Institute "Girikond" Sensor type U7602 UV U7698 IR U7652 UV / IR S121,122 IR 20/201
IR ³ ALARM
IR Type of radiation receiver UV Photocell Pyroelectric receiver UV Photocell, Pyrodetector Pyroelectric receiver Pyroelectric receiver Semiconductor multi-band photocell Spectral range, microns
Identification principle 0.18-0.24
flame swing 4.2-4.7
flame swing 0.18-0.24
4.45
flame swing 4.4
4.2-4.7
flame swing 4.0-5.0
flame swing According to table 4 Spectral selection Sensitivity to the fire source type TP-1, TP-4, TP-5, meters 6-27 6-25 fifteen 18-25 60 25-60 Sensitivity to the fire source, type TP-2, TP-3 NO NO NO NO NO YES Explosion suppression
Speed, ms Limited
thirty Limited
thirty Limited
thirty NO 3000 NO 5000 YES 0.1 Sensitivity to combustion of substances not containing C YES NO NO NO NO YES Resistance to modulated infrared radiation YES NO YES NO NO YES Resistance to sunlight or electric welding NO YES YES YES YES YES Ability to register a flame of a gas burner NO NO NO NO NO YES Health testing NO NO NO NO NO YES Power consumption 2-4.5 2-4.5 2-5 50 mW four 30 mW Weight kg 4,5 4,54 6.3 2 3,5 0.3 Operating temperature range, С -40 ÷ + 75
(125) -40 ÷ + 75
(125) -40 ÷ + 75
125) -20 ÷ + 75
(one hundred) -40 ÷ + 75
(one hundred) -60 ÷ + 80
(90) Type and level of explosion protection Flameproof enclosure (IN) or intrinsically safe circuit (IC) 1E _xd IIBT6
IN 1E _xd IIBT6
IN 1E _xd IIB + H ₂ T6
IN - 1E _xd IIB +
H ₂ T6
IN _1Е xib IIСТ6
IC Sheath protection IP66 IP66 IP66 - IP67

From table 5 it follows that the claimed detectors in most characteristics (reliability dimensions, sensitivity, speed, noise immunity, power consumption, temperature range) are superior to known ones. In addition, the claimed detectors have much greater variability in the formation of specified spectral characteristics of the sensitivity of photovoltaic cells, which means that they are more adapted to the variety of conditions for their use.

Some of their modifications are currently successfully used at dozens of enterprises in Russia and the CIS.

Thus, in our opinion, the claimed detector meets all the requirements for the invention - it is new, non-obvious and industrially applicable.

Claims (15)

1. An infrared multi-band flame and explosion detector, the main optical channel of which is composed of one or more radiation detectors with optical filters, the spectral sensitivity characteristics of which correspond to the characteristic radiation spectra of the fire and explosion centers, and the auxiliary optical channel is composed of one or more radiation receivers with optical filters whose spectral sensitivity characteristics correspond to the characteristic emission spectra of optical noise, with holding a logical comparison circuit of the output signals of these channels with a fire signal conditioner, characterized in that photovoltaic radiation detectors are used, which are made of a solid solution formed by the introduction of cadmium selenide into lead selenide. 2. The device according to claim 1, characterized in that the solid solution used to manufacture the radiation detector is applied in the form of a thin polycrystalline layer in which the potential barrier that determines the appearance of photoEMF is formed in the form of a planar pn junction, Schottky barrier, or MOS structures. 3. The device according to claim 1, characterized in that the maximum wavelength and long-wavelength border of the spectral sensitivity of each photovoltaic detector is determined by the concentration of cadmium selenide in the specified solid solution in the range from 0.1 to 20 mol.%, And the short-wavelength limit of its spectral sensitivity is determined short-wavelength transmission limit of the optical filter installed in front of it. 4. The device according to claim 1, characterized in that the output voltages of the main and auxiliary channels are formed by the serial connection of the outputs of the photovoltaic receivers in each channel, and the circuit for their logical comparison is made in the form of a circuit for subtracting the output voltages of the channels, with the selected signal or flame criterion excess voltage of the main channel over the voltage of the auxiliary channel. 5. The device according to claim 1, characterized in that its main and auxiliary channels are formed in the form of a single infrared semiconductor multi-band array transducer composed of radiation receivers with optical filters installed in front of them, with the concentration of cadmium selenide in the solid solution from which it is made each radiation receiver, and the passband of the optical filter mounted in front of it, a spectral sensitivity characteristic is formed corresponding to the character polar range and explosion of flame radiation or the characteristic spectrum of the optical interference radiation. 6. The device according to claim 5, characterized in that the matrix converter contains two panels of elements, the first panel is formed by radiation detectors with filters, the spectral sensitivity characteristic of which corresponds mainly to the characteristic radiation spectra of one or more types of flame and explosion, and the second panel is formed by radiation receivers with filters, the spectral sensitivity characteristic of which corresponds mainly to the characteristic emission spectra of one or more optical interferences Such as radiation from the sun or artificial light sources, electric welding, radiator and heater. 7. The device according to claim 6, characterized in that the logical comparison circuit is made in the form of an internal serial connection of the radiation receivers of each panel and a counter connection of the total signals of the panels. 8. The device according to claim 3, characterized in that for the detection of fires resulting from the burning of mainly wood, polymeric materials, fuels and lubricants and flammable liquids with smoke, the concentration of cadmium selenide in the solid solution from which the main radiation detector is made channel, selected within (20 ± 3) mol.%, and the short-wavelength transmission limit of the optical filter of 1.6 microns. 9. The device according to claim 3, characterized in that the concentration of cadmium selenide in the solid solution of which one radiation detector of the main channel is made is selected to detect fire sources resulting from the combustion of predominantly flammable liquids without emitting smoke, within the range of (0.1 ± 0.02) mol.%, The short-wavelength limit of transmission of its optical filter is 4.2 μm, and the concentration of cadmium selenide in the solid solution from which the other radiation detector is made is selected in the range (10 ± 1.0) mol.% With a short-wavelength boundary about letting its optical filter 2.6 microns. 10. The device according to claim 3, characterized in that for the detection of fires, formed mainly during decay of wood and cotton, the concentration of cadmium selenide in the solid solution from which the radiation detector of the main channel is made is selected in the range (0.1 ± 0, 02) mol.%, And the short-wavelength transmission limit of its optical filter 3.2 microns. 11. The device according to claim 1, characterized in that for the detection of fires resulting from the combustion of predominantly carbon-free chemicals, the concentration of cadmium selenide in the solid solution from which the radiation detector of the main channel is made is selected within (10 ± 2 ) mol%, and the short-wavelength transmission limit of its optical filter is 3.2 μm. 12. The device according to claim 1, characterized in that for detecting optical interference with a radiation spectrum located mainly in the wavelength range of 1.6-2.6 μm, for example from incandescent lamps, the concentration of cadmium selenide in a solid solution, from which an auxiliary channel radiation detector was manufactured, selected within (20 ± 3.0) mol%, and the bandwidth of its optical filter from 1.6 to 2.6 μm. 13. The device according to claim 3, characterized in that for the detection of optical interference with a radiation spectrum located mainly in the wavelength range of 3.2-4.2 μm, for example from heating radiators, heating appliances and electric incandescent lamps, the concentration of selenide cadmium in the solid solution from which the auxiliary channel radiation detector is made is selected in the range of (0.1 ± 0.02) mol%, and the short-wavelength transmission limit of its optical filter is 3.2 μm. 14. The device according to claim 3, characterized in that for detecting optical interference with a radiation spectrum located mainly in the wavelength range of 1.0 - 1.4 μm, for example from the sun, artificial light sources and electric welding, the concentration of cadmium selenide in solid the solution of the photoelectric element of the auxiliary channel is selected in the range of (20 ± 3.0) mol.%, and the bandwidth of its optical filter from 1.4 to 1.0 μm. 15. The device according to claim 1, characterized in that it is supplemented by a control photoluminescent emitter placed in front of the sensor input window made of a solid solution formed by the introduction of cadmium selenide into lead selenide, while the emission spectrum of the emitter is consistent with the emission spectra of the fire and explosion centers.

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