Security volumetric optical-electronic detector - the principle of operation. Passive infrared motion detectors Smoke detectors

In security systems, the volumetric optical-electronic security detector is an integral element.

It is also used in "smart home" technology, where, when warm-blooded objects are detected, lighting is turned on for a while in a room or in an adjacent area.

It gained popularity due to its simplicity of design and low cost. The operation of the sensor is based on the sensor's response to infrared radiation.

Since man is a warm-blooded creature, he reacts to his presence.

Types of detectors

On the market, the optoelectronic security detector is represented by a large number of devices that differ in characteristics and purpose.

According to the way they work with radiation, they are divided into active and passive.

The former themselves emit IR radiation and determine the presence or absence of a person in the protection zone by the received reflected energy. The second work only on reception.

According to the configuration of the controlled area, they are divided into volumetric, surface and linear. The optical-electronic surface security detector responds to changes in radiation only in one plane.

They are used to control openings, doors, windows. Linear are used in the protection of perimeters. The volumetric optoelectronic detector is used when it is necessary to control any sector of space, usually indoors.

Advantages of optoelectronic detectors

The advantages of IR detectors include:

1. accurate determination of the range and angle of the controlled area;
2. the ability to work outdoors;
3. absolute safety for human health.

The disadvantages of IR detectors are:

• false alarms that occur when bright light hits the lens due to warm air currents;
• work in a narrow temperature range.

A conventional pulse-counting sensor can be fooled when moving slowly.

These shortcomings are deprived of an optical-electronic detector on a microprocessor. He is able to compare the radiation from a real object with the patterns embedded in the memory, due to this, the number of false positives is sharply reduced.

Principle of operation

The main element of an optical-electronic detector is a pyroelectric converter, which converts infrared radiation into an electric current.

A faceted Fresnel lens is used to hit the pyro receiver.

With the help of many small prisms, IR radiation from each sector of the controlled space enters the photodetector.

The signal level at the output of the device is constantly monitored for exceeding the threshold value. When this happens, it means that an object with a temperature above the background has appeared in the protection zone.

The sensor sends an alarm signal to the control panel. To reduce the amount of false noise, 2-4 sensors and digital signal processing are used.

Detector design

The detector is a small box with a lens on the front surface. The lens is molded from plastic in the form of many small lenses.

Each of them has a certain shape and orientation in space, depending on which sensor is volumetric, surface or linear.

In any case, all lenses direct the collected radiation to the pyro receiver. It is located on a printed circuit board mounted on the back of the case.

When the case is opened, a tamper is activated, which sends a signal to the control panel. An anti-masking circuit is used to protect the sensor during the "disarmed" mode. She reports about the gluing of the lens with adhesive tape or other material.

In lighting control devices, there is a powerful relay controlled by a sensor in the housing. In addition, there is a photocell that allows the inclusion of light lamps only in low light.

Features of use

When using IR sensors, it must be taken into account that they must be located in areas where there are no heat fluxes or bright light sources.

Devices must be mounted on solid surfaces, without strong vibration. In permanent structures, the sensor is mounted on a wall or ceiling. In rooms made of light metal structures, they are mounted on the load-bearing elements of the building.

When used as a lighting control device, it is necessary to coordinate the power of light lamps with the capabilities of a relay or an electronic key. The mounting point is chosen in such a way that there are no obstacles in the control zone.

To increase the reliability of intruder detection, it is recommended to use it in tandem with a microwave sensor. When monitoring window openings, it is necessary to use it together with an acoustic detector.

IR sensors can be used together with video cameras, cameras, light and sound annunciators, turning them on when the control zone is violated by a warm-blooded object.

TOP 5 models

Pyronix

Pironix has been operating on the Russian market for a very long time and has established itself as an excellent manufacturer of inexpensive and reliable IR sensors for security systems.

It provides protection against animals up to 20 kg. It has increased noise immunity from electromagnetic interference, background radiation fluctuations and convective heat flows.

Protection against opening is provided. Has the ability to work in address security systems.

Range 10 m. Captures objects moving at a speed of 0.3-3 m/s. Operates in the range -30+50 ⁰С. Service life 10 years.

Optex

Powered by two alkaline batteries. Radio communication range in open area 300 m.

Operating frequency 868.1 MHz. The sector of control is 110⁰ with a radius of 12 m.

Designed for indoor use. Additional lenses are provided that provide the “corridor”, “curtain” mode and protection from animals.

Video: Surveillance detector volumetric optical-electronic street "Piron-8"

Optoelectronic detectors.

Optoelectronic There are two fundamentally different types of detectors: passive and active. In this lecture, we will consider only detectors used for burglar alarm purposes. The fire component will be discussed in a lecture on fire detectors. Let me remind you that passive detectors do not emit anything into the environment, but only analyze the incoming information. Active for the purpose of detecting penetrations, they radiate something into the environment and, based on the response, draw the appropriate conclusions. Active detectors can be either monoblock (emitter and receiver in one housing), or two or more block ones, when the emitter and receiver are separated.

Consider first

Passive optoelectronic detectors

Currently passive optoelectronic infrared ( IR) detectors occupy a leading position in the choice of protection of premises from unauthorized intrusion at the objects of protection. Aesthetic appearance, ease of installation, configuration and maintenance make them a priority compared to other detection tools.

The principle of operation of passive optical-electronic IR detectors is based on the perception of changes in the level of infrared radiation of the temperature background, the sources of which are the body of a person or small animals, as well as all kinds of objects in their field of vision.

Infrared radiation is heat that is emitted by all heated bodies. In passive optical-electronic IR detectors, infrared radiation enters the Fresnel lens, after which it is focused on a sensitive pyroelectric element located on the optical axis of the lens

Passive IR detectors they receive infrared energy flows from objects and are converted by the pyro receiver into an electrical signal that enters through the amplifier and the signal processing circuit to the input of the alarm generator.

Passive infrared detectors are designed to detect a person who is within the sensitivity zone. The main task of the detector is to detect the infrared radiation of the human body. As can be seen from Figure 1, the thermal radiation of the human body is within the spectral range electromagnetic radiation with wavelengths of 8-12 microns. This is the so-called equilibrium glow of the human body, the maximum radiation length of which is completely determined by temperature and for 37°C corresponds to approximately 10 microns. Exists whole line physical principles and related devices that are used to detect radiation in the specified spectral range. For PIR detectors, a sensitive element with an optimal sensitivity/cost ratio should be used. Such a sensitive element is a pyroelectric photocell.

Rice. Fig. 1. Spectral dependence of the luminescence intensity: the sun, a fluorescent lamp, an incandescent lamp, the human body and the transmission spectrum of a number of filters blocking visible light: a silicon filter, a coated silicon filter, a filter with a cutoff wavelength of 5 μm and a filter with a cutoff wavelength of 7 μm.

The phenomenon of pyroelectricity consists in the occurrence of an induced potential difference on opposite sides of a pyroelectric crystal during its nonequilibrium short-term heating. With time electric charges from external electrical circuits and redistribution of charges inside the crystal lead to relaxation of the induced potential. From the above it follows:

interruption frequency (Hz).

Rice. Fig. 2. Dependence of the value of the pyroelement response signal on the interruption frequency of the recorded thermal IR signal.

1. For effective pyroelectric registration of thermal radiation, it is necessary to use a chopper with an optimal radiation interruption frequency of about 0.1 Hz (Fig. 2). On the other hand, this means that if a lensless design of the pyroelectric element is used, it will be able to register a person only when he enters the radiation pattern (Fig. 3, 4) and exits it at a speed of 1 - 10 centimeters per second.

Rice. 3, 4. Paired pattern shape corpsed pyroelectric element in horizontal (Fig. 3.) and vertical (Fig. 4.) planes.

2. To increase the sensitivity of the pyroelectric element to the temperature difference (the difference between the background temperature and the temperature of the human body), it is necessary to design it, maintaining the minimum possible dimensions, in order to reduce the amount of heat required for a given increase in the temperature of the sensitive element. The dimensions of the sensitive element must not be excessively reduced, as this will lead to an acceleration of the relaxation characteristics, which is equivalent to a decrease in sensitivity. There is an optimal size. The minimum sensitivity is usually around 0.1°C for a 1 x 2 mm pyro element, a few microns thick.

Rice. Fig. 5. Appearance of the sensitive element of the pyroelectric passive IR detector.

You can clearly formulate the conditions for detecting a person using an infrared detector. The infrared detector is designed to detect moving objects with a temperature different from the background value. Range of recorded movement speeds: 0.1 - 1.5 m/sec. Thus, the infrared detector does not register stationary objects, even if their temperature exceeds the background level (still person) or if an object with a temperature different from the background moves in such a way that it does not cross the detector's sensitive zones (for example, it moves along the sensitive zone). Of course, strictly speaking, the sensitive element does not register movement at all, it registers the temperature measurement in a single part of space, which is a consequence of a person's movement. It must always be remembered that the sensitive element detects movement not “on the detector”, but across. Getting rid of this disadvantage occurs due to the design of the lenses.

Naturally, the high sensitivity of the infrared detector is achieved by using a lens system for the concentration of incoming radiation (Fig. 6). In an infrared detector, the lens system performs two functions.

Rice. 6. Options for forming the directional diagram of IR detectors depending on the type of lens system.

First, the lens system serves to focus the radiation on the pyroelectric element.

Secondly, it is intended for spatial structuring of the detector sensitivity. In this case, spatial zones of sensitivity are formed, which ,e as a rule, they have the form of "petals", and their number reaches several tens. The object is detected every time it enters and exits sensitive areas.

Usually, the following types of sensitivity diagram are distinguished, which is also called a radiation pattern.

one). The standard one is fan-shaped in azimuth and multi-tiered in elevation (Fig. 6a).

2). Narrowly directed - single- or double-beam long-range in azimuth and multi-tiered in elevation (Fig. 6b).

3). Curtain-like - narrowly focused in azimuth and fan-shaped in elevation (Fig. 6c).

There is also a circular pattern (in particular, for detectors installed on the ceiling of the room), as well as a number of others.

Consider the options for the design of the beamforming system (Fig. 7). This optical system can be either lens or mirror. The manufacture of a conventional lens system, taking into account the requirement for the formation of a spatially structured radiation pattern, is an expensive task, so conventional lenses are not used in passive infrared sensors. The so-called Fresnel lenses are used. In a conventional lens, a special spherical surface shape is used for directional light deflection (focusing), the lens material has an optical refractive index that is different from the refractive index of the environment. The Fresnel lens uses the phenomenon of diffraction, which manifests itself in particular in the deflection of a light beam when passing through a narrow slit. The Fresnel lens is made by stamping and is therefore cheap. The disadvantage of using a Fresnel lens is the inevitable loss of half of the radiation energy as a result of its diffraction deflection by the lens in a direction other than the direction to the pyroelectric element.

Rice. 7. Design options for security passive IR detectors: with a Fresnel lens and with a mirror focusing system.

The mirror lens is more efficient than the Fresnel lens. It is made of plastic mass by stamping followed by coating the structured surface with a reflective coating that does not change its properties over time (up to 10 years). Gold is the best plating. Hence the higher, approximately twice, the cost of passive infrared detectors with a mirror system compared to a lens one. In addition, detectors with a mirror system are larger than detectors equipped with Fresnel lenses.

Why use more expensive detectors with a mirror system for concentrating incoming radiation? The most important characteristic the detector is its sensitivity. Sensitivity is practically the same in terms of unit area of ​​the detector's input window. This, in particular, means that if a passive infrared detector is designed with increased sensitivity, then they are forced to increase the size of the radiation concentration zone - the area of ​​\u200b\u200bthe entrance window, and, therefore, the detector itself (the maximum sensitivity of modern passive infrared detectors allows detecting a person at a distance up to 100 meters). If we assume the presence of losses of the useful signal due to the imperfection of the lens, then it is necessary to increase the gain of the electronic circuit for processing the electrical signal generated by the sensitive element. Under the condition of the same sensitivity, the gain electrical circuit in a mirror detector, it is two times less than in a detector with a Fresnel lens. This means that in detectors with a Fresnel lens, there is a higher probability of false alarms caused by interference in the electronic circuit. Quite often, both technologies are used together, so in the Astra-5sp detector. And the main zone is formed by zones of Fresnel lenses, the anti-sabotage zone directly under the detector is a small mirror made in a rather handicraft way. In general, the market for security detectors is filled with fairly cheap products, the price of which ranges from 300-900 rubles apiece with a significant advantage towards the lowest price. Naturally, in such conditions, it is not possible to talk about some kind of gilded mirrors.

Once again, let's return to the optical scheme of the detector. In addition to the lens system and the optical “cut-off” filter installed directly in the sensor housing, various optical filter elements (“white” filter, “black” mirror, etc.) are used to reduce false positives caused by various radiation sources. which minimize the incidence of extraneous optical radiation on the surface of the pyroelectric element.

The entrance window of most IR detectors is made in the form of a "white" filter. This filter is made of a material that scatters visible light, but at the same time does not affect the propagation of infrared radiation. Due to their low cost, cheap detectors use polyethylene similar in properties to those used for food bags, while more expensive ones are milky in color, which transmits IR rays well, but a poorly visible spectrum, which is what we need.

Fresnel lenses are constantly being improved. First of all, by giving the lens a spherical shape that minimizes aberrations compared to the standard cylindrical shape. In addition, additional structuring of the radiation pattern in the vertical plane is used due to the multifocal geometry of the lens: in the vertical direction, the lens is divided into three sectors, each of which independently collects radiation on the same sensitive element.

I will dwell in more detail on the structure of that part of the detector, which most electricians call the lens. This is a piece of polyethylene, on which rectangles of various sizes are squeezed out, inside which some concentric circles, or parts of them, are visible. In most cases, we see about 12-15 vertically elongated rectangles in the upper part, 5-6 more square-like rectangles in the middle part, and usually 3 practically square rectangles in the lower part. It is necessary to correctly understand that each of these rectangles is a Fresnel lens, so we have a matrix of lenses. In order to distinguish an intruder at the edge of the detection zone, and this is usually 10-12 meters, it must be divided into the number of elementary zones we need, which is what the upper set of rectangles does. The number of elementary zones will correspond to the number of rectangles. Naturally, in the middle part of the detector detection zone, it is no longer necessary to divide into such a number of elementary zones, and their number is already reduced to 5-6, and in the near zone - to 3. When considering a matrix of lenses, pay attention to important feature– the vertical sides of the rectangles in different tiers are always shifted relative to each other. This was done specifically to be able to detect the intruder in the worst movement for the detector "to the detector". Even if the intruder accidentally hit exactly in the middle of the elementary sensitive zone and moves directly to the detector, then in another tier he will not be able to get into the middle of the elementary zone in the same way and will be detected by it. When placing the detector, it must be taken into account that its maximum detective abilities precisely when the intruder moves across sensitive zones.

Very relevant is the problem of counteracting the physical shielding of the detector, which comes down to installing a screen in front of it that overlaps its “field of view” (the so-called “masking”). Technical means of counteracting masking constitute a system antimasking detector. Some detectors are equipped with built-in IR LEDs. If an obstacle appears in the detection zone of the detector, and therefore in the LED coverage area, then the reflection of the LED radiation from the obstacle is perceived by the detector as an alarm signal. Moreover, periodically (in existing models - once every 5 hours) the detector self-tests for the presence of reflected radiation from IR LEDs. In the event that during self-testing, the required signal does not appear at the output of the electrical circuit, then the alarm generation circuit is triggered. Detectors with functions antimasking and self-testing are installed at the most critical facilities, in particular, where it is possible to counteract the operation of the security system.

Another way to increase the noise immunity of the detector is the use of a quadratic sensitive pyroelement in conjunction with the use of microprocessor signal processing. Different firms solve the problem of creating a quadratic element in different ways. For example, the OPTEX company uses two conventional dual pyroelements located side by side. The main task of the system is to isolate and “screen out” events caused by the simultaneous illumination of both pyroelements (for example, headlights) or electrical interference.

Quite a lot of companies use a special design of a quad pyro receiver, where four sensitive elements are located in one housing.At the same time, pyroelements are turned on in the opposite direction, located both in horizontal plane, as well as vertically. Such a detector will not respond to small animals (mice, rats), which are often found in warehouses and are one of the causes of false alarms (Fig. 8). The use of a bipolar connection of sensitive elements in such a detector makes it impossible for "noise" false alarms.

ADEMCO is so confident in the perfection of the quadratic detector developed by it that it announced the payment of a bonus if the owner of the detector fixes its false operation.

Another precaution is the use of conductive film coatings applied to the inside surface of the entrance window to counteract RF interference.

An effective method of increasing the noise immunity of detectors is the use of the so-called "double technology", which consists in using a combined detector that implements passive infrared and active radio wave (sometimes ultrasonic) principles of operation. Such detectors will be discussed in the following lectures.

Rice. 8. The operation of a multi-channel system for selecting noise pulses on the example of the operation of a quadratic security passive IR detector.

Due to the principle of detection, it is very difficult for such detectors to detect an intruder if the ambient temperature approaches the temperature of the human body. In such cases, the detector simply goes blind, and for our southern region, a temperature of 35-40 degrees in summer is not at all uncommon, especially in closed, unconditioned rooms with insufficiently insulated roofs and walls. To combat this problem, a thermal compensation. The essence of its work lies in the fact that when the temperature in the room approaches the critical one (37 degrees Celsius), the detector increases sensitivity stepwise (usually by an order of magnitude). Of course, this reduces its noise immunity, but it allows you to detect an intruder in these extreme conditions. When the temperature drops, the detector returns sensitivity to normal.

We examined the basics of operation and design of passive infrared security detectors. In general, all constructive tricks used by certain companies have one goal - to reduce the likelihood of a false alarm, since a false alarm leads to unjustified costs for responding to an alarm, and also causes moral damage to the owner of the protected property.

Detectorsare constantly being improved. At the present stage, the main directions for improving detectors are increasing their sensitivity, reducing the number of false alarms, and differentiating moving objects on the basis of authorized or unauthorized presence in the detection zone.

As a source of electrical signal, each sensitive pyroelectric element is also a source of random noise signals. Therefore, the problem of minimizing fluctuation interference, which can be solved by circuitry, is topical. Are used different methods noise control.

Firstly, electronic discriminators of the input signal are installed in the detector for the upper and lower levels, which minimizes the frequency of interference (Fig. 9).

Rice. 9. Threshold system for two-way limitation of the noise signal level of a security passive IR detector.

Secondly, the mode of synchronous counting of pulses coming from both optical channels is applied. Moreover, the circuit is designed in such a way that a useful optical signal at the input leads to the appearance of a positive electrical pulse in one channel and a negative one in another. The subtraction scheme is applied at the output. If the source of the signal is a noise electrical signal, it will be identical for two channels and at the output the resulting signal will be missing. If the signal source is an optical signal, then the output signal will be summed.

Thirdly, the pulse counting method is applied. The essence of this method is that a single object registration signal does not lead to the formation of an alarm signal, but sets the detector into the so-called "pre-alarm state". If within a certain time (in practice it is 20 seconds) the object registration signal is not received again, the pre-alarm state of the detector is reset (Fig. 10). This method must be used with caution and only when warranted. It must be remembered that the detector may not have a chance to fix the second impulse, and it will rest peacefully covered with a cardboard box.

Rice. 10. Operation of the pulse counter system.

The remarkable property of forming a detection zone with a matrix of Fresnel lenses allowed manufacturers to create a unified detector design and change its properties by replacing the matrix. Thus, the same detector can be made voluminous, it is possible to create a “long beam” zone - it sees far, but narrowly, it is possible to create a detector - a “curtain”, with which we can cut off the necessary parts of the object using a detection zone similar to a curtain.

As a rule, all detectors require a 12 V DC power supply. The current consumption of a typical detector is in the range of 15 - 40 mA. The alarm signal is generated and transmitted to the security control panel by means of an output relay with normally closed contacts.

The use of solid-state relays instead of conventional relays also made it possible to reduce energy consumption. Let me remind you that these detectors are passive, which also allows you to have a minimum current consumption. Like most security detectors, PIR detectors are recoverable, i.e. when an intruder is detected, it will go into the "alarm" state, in the absence of further movement registration, it will be restored to the "normal" state. Usually, for ease of maintenance, the detector has a built-in red LED that signals the "alarm" state, but can also transmit other additional messages.

For the normal placement of the detection zone in space, it is necessary to take into account the detector installation height recommended by the manufacturer, which is usually 2.2-2.5 meters for a wall-mounted version. Let me also remind you that reorientation of the detector (sideways, upside down) is not allowed.

When choosing a detector, it must be remembered that they have different temperature ranges, and if you install a detector that operates up to 0 degrees in an unheated room, then you can expect problems in operation in winter with frost.

The industry produces detectors for installation indoors, as well as outdoors; the latter have the appropriate climatic design.Typical service life of passive infrared detectors is 5 - 6 years.

Detector examples

With a detection zone of the "long beam" type: Astra-5 isp. V, Photon-10A, Photon-15A, Photon-16.

With a detection zone of the "curtain" type: Astra-5 isp. B, Astra-531 isp. IR, Ikar-Sh, Ikar-5B, Photon-10B, Photon-10BM, Photon-15B, Photon-16B, Photon-20B, Photon-22B, Photon-Sh, Photon-Sh-1, Photon-Sh2.

With volumetric detection zone: Astra-5 isp. A, Astra-5 isp. AM, Astra-511, Astra-512, Astra-7 isp. A, Astra-7 isp. B, Photon-9, Photon-9M, Photon-10, Photon-10M, Photon-10M-01, Photon-12, Photon-12-1, Photon-15, Photon-16, Photon-17, Photon-19, Photon-20, Photon-21, Photon-22, Ikar-1A, Ikar-2/1, Ikar-5A, Ikar-7/1.

Active optical-electronic detectors.

Linearoptoelectronic detectors (active IR detectors), as a rule, have a two-block design and consist of an emitter unit (BI) and a photodetector unit (BF), forming an optical system. The emitter generates a stream of infrared radiation (infrared beam) with specified characteristics, which falls on the receiver. The appearance of an optically opaque object in the detection zone of the detector causes an interruption of the IR beam (or a decrease in its power) that enters the receiver, which analyzes the magnitude and duration of this interruption and, in accordance with the specified algorithm, generates an alarm notification by changing the resistance of the contacts connected to the alarm loop. There are also detectors that have a single-block design, the optical system of which consists of an emitter and a photodetector combined in one housing, as well as a reflector (reflector). The input windows of the BI and BF are usually closed with special filters (sometimes these filters are made as one piece with the cover of the detector housing). The scheme of the active IR detector is shown in Figure 11.

The advantage of active IR detectors is that they detective the ability does not depend on the characteristics of the thermal radiation of a person (intruder). They are also insensitive to changes in the characteristics of the thermal radiation of surrounding objects (background) and the resulting thermal interference, which is very important when operating in open areas.

Figure 11 - Diagram of an active IR detector

The disadvantages of active IR detectors include their ability to form only a linear detection zone, which leads to a narrow scope. In part, this problem can be solved by organizing a surface detection zone through the use of detectors that form several IR beams, or by building an IR barrier from several detectors. But at the same time, the size of the detection zone for the first option will be small, and the second option will require an increase in financial costs. The disadvantages include sensitivity to optical illumination.

Recently, some manufacturers have made attempts to create an active security detector using an infrared laser. So, the Japanese company Optex has recently launched a detector that uses the principle of scanning the surrounding space with a laser beam.

Main functional characteristics active IR detectors and their impact on the use and tactics of protection

Active IR detectors form a linear detection zone. They can be used to organize the first line of protection of objects (blocking of extended engineering fences (fences), windows or doors outside the building, gates, ventilation shafts and channels, etc.). Because active infrared detectors form a linear detection zone, their use will be influenced by the shape of the protected object, depending on the characteristics of the landscape and the object itself. Protected objects must be straight, otherwise, the object is divided into several straight sections, to block which a separate detector is used (see Figures 12, 13).

Figure 12 - Incorrect use of an active IR detector

Figure 12 shows the incorrect use of an active IR detector. In zones A and B, an intruder can enter through a guarded fence. At the same time, in zone B, the detection zone of the detector is located outside the protected object, where there is a high probability of its accidental overlap (swaying tree branches, actions of random passers-by, etc.), which will lead to the formation of a false alarm notification.

Figure 13 - Scheme of protection of an object of complex shape

Figure 13 shows an exemplary scheme for protecting an object of complex shape with the help of several detectors. The breakdown of the object into sections should be done in such a way that the intruder could not penetrate the object without blocking the IR beam, i.e. the maximum distance between the fence sheet and the IR beam (an imaginary line between the BI and the BP) should be less than the dimensions of a person (approximately 300 - 350 mm).

The main functional characteristics of an active IR detector are the maximum operating range, safety factor, sensitivity and noise immunity.

The maximum operating range is the maximum possible distance at which the emitter and receiver of the detector can be separated, provided that it complies with the requirements of the national standard.

The safety factor is the maximum value of the reduction in the flow of infrared energy, which does not lead to the formation of an alarm notification. This coefficient characterizes the resistance of the detector to meteorological factors (rain, snowfall, fog). The minimum allowable safety factors depend on the operating range and are given in the national standard. Because does not happen in the premises precipitation, the requirements for the safety factor of detectors intended for indoor operation are significantly lower than those for detectors intended for operation outdoors. outdoors.

Specific values ​​of the maximum operating range and safety factor for each detector model are set by the manufacturer.

To ensure the possibility of use on various objects, most modern active IR detectors have the ability to adjust the range. As a rule, the adjustment is discrete, each of its values ​​corresponds to a certain range of range. It is not allowed to operate the detector if the actual range does not match the range set during the adjustment. If the actual range exceeds the set one, the safety factor may turn out to be insufficient, which, in the presence of precipitation (intense snow, rain, dense fog), may lead to a malfunction of the detector (manifested in the form of a false alarm notification and the impossibility of arming). If the actual range is below the set power of the IR radiation falling on the receiver, it will be excessive, which in some cases may lead to the intruder being missed. Excessive signal power is also due to the fact that active IR detectors have a minimum range. The distance between the BI and the BF must not be less than the value specified in the operational documentation attached to the detector.

The sensitivity of an active IR detector is the duration of the interruption of the infrared beam, above which the detector should generate an alarm notification. The minimum allowable sensitivity value for detectors operated in open areas is regulated by the national standard and is 50 ms.

This value is determined taking into account the anthropometric characteristics of a person and corresponds to the intruder crossing the detector detection zone by running at maximum speed. Modern detectors provide discrete sensitivity adjustment up to 400 - 500 ms.

It is recommended to set the sensitivity value taking into account the most probable time the intruder stays in the detection zone, which depends on its size and movement speed. For example, if the detector is set to open space, where the intruder will be able to run up and cross the zone at high speed, you should set high sensitivity (50 ms). If the intruder does not have the opportunity to take off and move at high speed (for example, when blocking a narrow space between two fences), the sensitivity value can be set in the range of 100 - 200 ms. If the intruder is forced to stay in the zone for a sufficiently long time, for example, when crawling over a blocked area or climbing a fence (fence), the sensitivity value can be set in the range of 400 - 500 ms. The correctness of the sensitivity value selection must be checked after installing and configuring the detector on the object by performing test crossings of the zone in the most probable ways and at the highest possible speed. After each crossing of the detection zone, the detector must generate an alarm notification. Except in justified cases, it is not recommended to set the maximum sensitivity (50 ms), because. this reduces the noise immunity of the detector.

Interference immunity is the duration of the interruption of the infrared beam, in the absence of which the detector does not generate an alarm notification. The minimum permissible value of noise immunity for detectors operated in open areas is regulated by the national standard and is 35 ms. This value is determined taking into account the size and speed of movement of the most likely obstacles, such as falling leaves, flying birds, etc.

In modern domestic detectors, the change in noise immunity occurs automatically simultaneously with the change in sensitivity in the process of its adjustment. An increase in the noise immunity of the detector is facilitated by the use of a dual (synchronized) IR beam in it. The relationship between sensitivity and noise immunity for modern domestic active IR detectors is shown in Table 1.

Table 1

Parameter	Meaning
Sensitivity, ms
Noise immunity, ms

Influence external factors on the operation of active IR detectors and recommendations for its reduction

1) temperature factor. The ambient temperature has Negative influence on the performance of the detector, if its value exceeds the allowable values ​​of the operating temperature set for this detector. To reduce the possibility of overheating of the detector, if possible, avoid installing it in places where it will be exposed to direct sunlight for a long time, and also use protective visors. For operation in areas where very low temperatures are often observed in winter (minus 40 ° C and below), it is necessary to choose detectors that have built-in automatic heating of the board and optics. The lower value of the operating temperature range for modern domestic detectors is minus 40 °С, in the presence of built-in heating it drops to minus 55 °С. If the air temperature has dropped below the admissible values ​​of the detector, it must be taken into account that it may not detect the intruder, it is advisable to organize the protection of the object by patrolling.

2) Optical flare. The reason for high illumination can be both the sun and sources artificial lighting. The presence of a light detector at the input window of the BF, the actual value of which exceeds the norms established in the national standard (more than 20,000 lux from natural light and light sources powered by DC sources, and 1000 lux from light sources (including fluorescent lamps) mains powered alternating current), may cause false positives or miss the intruder. To exclude the influence of this factor on the operation of the detector, it must be installed in such a way that direct sunlight does not fall on the BF entrance window (this is especially important during sunset or sunrise, when various protective visors are ineffective) and radiation from powerful lighting devices (spotlights, powerful fluorescent lamps, etc.). Most of the active IR detectors included in the "List of ..." today are resistant to natural light up to 30,000 lux.

3) Precipitation. Atmospheric precipitation has a negative effect on the safety factor of the detector due to the attenuation of radiation due to scattering by water drops or snowflakes. They can also cause moisture to appear in the housings of the detector blocks, which can cause the loss of its performance. In winter, the input windows of the detector units may also become iced. The safety factor of modern detectors, as a rule, allows them to function properly in the presence of precipitation, but in the case of their special intensity, a malfunction of the detector may occur (manifested in the form of a constant generation of an alarm notification and the impossibility of arming). In this case, you should organize the protection of the object by patrolling. To reduce the harmful effects of precipitation, protective visors can be used, more frequent maintenance (cleaning the entrance windows from ice and snow) of the detector should be carried out. It is necessary to use detectors with more a high degree protection of the shell (not lower than IP54 in accordance with GOST 14254), carefully seal the inlet technological openings in the housings of the blocks during installation. If the detector is installed at a low height from the ground or other surface (for example, directly above the fence), a gradually increasing layer of snow (snowdrift) can block the detector's detection zone, which will cause a constant generation of a false alarm. The detection zone of the detector can also be blocked by the formed icicles if it is located under any protruding structures and their elements. To prevent a malfunction of the detector, it is necessary to clear the snow accumulating in the detection zone and remove the formed icicles in a timely manner. If the detector is installed along the upper edge of the fence, it is recommended to move it from the axis of the fence into the object.

4) Electromagnetic interference(EMP). The source of EMF that can affect the operation of the detector can be both operating high-power electrical equipment and atmospheric electrical discharges (thunderstorm). For outdoor use, detectors should be used that have resistance to EMF according to GOST R 50009 (electrostatic discharge, electromagnetic field, electrical impulses in the power supply circuit) of at least 3 degrees. When installing detectors outdoors, it is necessary to lay long connecting lines exposed to EMF. To reduce the effect of EMF on the operation of the detector, it is necessary to lay all connecting lines in metal hoses (steel pipes) and use grounding.

5) Changing the position in space of structures on which the detector blocks are fixed. These changes can be both natural and man-made. They can be caused, for example, by vibration due to the operation of any mechanisms or the movement of heavy vehicles, seasonal ground movements, repair and other work carried out in the immediate vicinity of the detector installation site. Their consequences may be false positives and a decrease in the safety factor. To prevent the influence of this factor on the operation of the detector, it is necessary, if possible, to install it on foundations that are not subject to vibration, deformation, and have a stable foundation (bearing walls of permanent structures, etc.).

6) The presence of solid fine particles in the air. These particles can be of both natural (dust, plant pollen) and technogenic (dust, soot, etc.) origin. Their settling on the input window of the detector leads to a decrease in the safety factor. To combat this phenomenon, at sites with a high content of dust or soot in the air, more frequent maintenance of the detector should be carried out. Operational features of active IR detectors.

Power supply of active detectors, as a rule, is allowed to be carried out from a direct current source with a rated voltage of 12 or 24 V. For power supply of detectors operated in open areas (especially with a large length of power loops), it is recommended to use sources with a rated voltage of 24 V. Power supply of built-in heating (if any), as a rule, is carried out from a separate source connected to terminals specially designed for this purpose.The output power of the sources must match the load.

Features of the organization of the IR barrier

The interval between the detectors should be chosen in such a way that the intruder does not have the opportunity to crawl between the IR beams without blocking them. For outdoor applications, a spacing of about 350 mm can be recommended. To organize an infrared barrier, detectors with several operating frequencies can be used. This is necessary to exclude the influence of the radiation of one detector on the operation of the neighboring one. If it is necessary to use detectors in the barrier in excess of the number of operating frequencies, they must be installed in such a way that the IR beams of the detectors operating at the same frequency are directed towards each other (Figure 14). In the same way, it is possible to organize a two-beam barrier of detectors having one operating frequency.

Figure 14 - Example of barrier IR detectors operating at the same frequency

If it is necessary to create an IR barrier in the horizontal plane, the detectors must be installed in such a way that the radiations of the same operating frequency of closely located PIs are multidirectional and cannot simultaneously fall on the input window of one BP (Figure 15).

Figure 15 - An example of an IR barrier in the horizontal plane

Setting the parameters of the detector, necessary for operation at each specific object, is carried out either using switches or by programming. The process of programming parameters is described in the operational documentation attached to the detector. After installing the detector on the object and connecting the power supply, it is necessary to adjust the relative position of the emitter and detector receiver. Coarse adjustment is carried out visually by approximate alignment of their optical axes or according to the indications of the IR radiation indicator (if this indicator is available). In some models of detectors (for example, IO209-32 "SPEK-1115"), a special optical sight is provided for this purpose. After completion of coarse adjustment, it is necessary to perform adjustment (fine adjustment) of the blocks. It is carried out by smoothly turning the block in different directions at a small angle in the horizontal and vertical planes using the adjustment devices (screws or flywheels) provided for by the design of the detector. The adjustment process is controlled, depending on the specific detector model, either by the readings of a voltmeter connected to a special connector, or by a change in the built-in light indication. Adjustment is considered completed at the maximum readings of the voltmeter or in the presence of light indication, the type of which is indicated in the operational documentation. ATTENTION. Alignment of the detector blocks ensures the presence of the necessary IR radiation power at the BF input window, as well as the achievement of the maximum safety factor and is a necessary and mandatory procedure, even if, after a rough adjustment, the detector goes into standby mode and is able to generate an alarm notification when crossing the zone detection.

Remote operation control is designed to check the detector's performance from the central monitoring console. It is carried out by short-term switching of the output specially designed for this purpose and the positive output of the power supply. As a result, a short-term interruption of the BI radiation occurs, after which the detector must issue an alarm notification. This feature requires padding additional wire, but may be useful when perimeter security long or difficult access to the detector (for example, in winter). If the detector is installed in such a way that its detection zone is directed along an extended surface (fences, walls, etc.) .P), the effect of re-reflection may appear, which consists in the fact that, in addition to direct IR radiation, re-reflected radiation will also fall on the input window of the BF (Figure 16). As a result, with sufficient power re-reflected radiation, the detector will not generate alarm notifications when the main one is blocked. This effect can also manifest itself during low-intensity precipitation, when IR radiation is reflected from snowflakes and water drops.

Figure 16 - Reflection effect

To eliminate the negative impact of the reflection effect in modern domestic detectors, it is possible to turn on the so-called. “intelligent signal processing mode”, the essence of which is that the detector generates an alarm notification when the IR radiation power at the BF input window decreases by about 70%.

On the domestic market active IR detectors are currently represented mainly by the products of the Russian company SPEC CJSC (St. Petersburg), Japanese firms Optex and Aleph, German Bosch and some others.

To date, only detectors manufactured by CJSC "SPEK" fully comply with the requirements of domestic national standards and ETT. Below are recommendations for their selection for the protection of various objects, taking into account the main features and characteristics. It should be noted that the design features of active IR detectors, especially those intended for operation in open areas, determine their high cost. Therefore, the use of most of them will be most appropriate at fairly important facilities.

The selection of single beam detectors (or dual synchronized IR beam) is generally based on the maximum operating range. It is not advisable to use a detector with a maximum operating range that significantly exceeds the actual size of the protected object. For operation in areas where very low temperatures are often observed in winter (minus 40 ° C and below), it is necessary to choose detectors that have built-in automatic heating of the board and optics. Installation, connection, configuration and operation of the detectors must be carried out in strict accordance with the attached operational documentation. Some detectors can also be used indoors. In this case, their maximum operating range is increased due to the lower requirements for the safety factor, which should be reflected in the operational documentation. Each active IR detector included in the list is assigned a symbol of the type "IO209-XX / U", where "I" means the type of product (detector), "O" - scope (security), "2" - characteristic of the detection zone ( linear), "09" - the principle of operation (optical-electronic), "XX" - the serial number of the development, registered in in due course, through the oblique fraction "Y" - the serial number of the design modification (if there are several modifications).

Figure 17 - IO209-16 "SPEK-7"

IO209-16 "SPEK-7".The multibeam detector is available in two versions (modifications) IO209-16/1 "SPEK-7-2" (forms 2 beams with an interval of 350 mm) and IO209-16/2 "SPEK-7-6" (forms 6 beams with an interval of 70 mm). The emitters and photodetectors are mounted in single housings (the so-called KI and KF columns). The detector is recommended to be used to protect gate openings, gates, blocking access to windows and doors of the building from the outside. At the same time, IO209-16/2 "SPEK-7-6" is able to detect a hand extended through the detection zone. Both versions of the detector have an operating range of 0.4 to 15 m (outdoors), 4 sensitivity settings. It is possible to use up to 5 detectors in the IR barrier. In this case, the CIs are combined by a synchronization line. CFs can be both synchronized and each work with its own settings. The maximum length of the synchronization line between adjacent CIs or CFs is no more than 10 m. Synchronization allows you to save money by laying a smaller number of loops. It is possible to set the number of IR rays, the simultaneous intersection of which is necessary to generate an alarm notification, which increases the detector's resistance to crossing the detection zone by small animals, birds, etc. The detector can also be used indoors.

IO209-17 "SPEK-8" The detector has a double infrared beam in the horizontal plane, 4 operating frequencies, 4 sensitivity values, built-in heating. The range of the detector is from 35 to 300 m. The detector is recommended for blocking straight sections of long perimeters, incl. in areas with cold climates.

Figure 18 - IO209-17 "SPEK-8"

Figure 19 - IO209-22 "SPEK-11"

IO209-22 "SPEK-11"The maximum operating range is 150 m (outdoors). The detector has 1 IR beam, 2 operating frequencies, 2 sensitivity values. This detector is intended for use in explosive zones of class 1 and 2 of premises and outdoor installations in accordance with GOST R 52350.14 (classes B-Ia, B-Ib, B-Ig according to PUE) and other regulatory documents regulating the use of electrical equipment in explosive zones. Explosion-proof design of the "flame-proof shell" type. Explosion protection marking 1 Ex d IIB T5 X. The detector can also be used indoors. Application on other objects is impractical due to the high cost.

IO209-29 "SPEK-1112" Detector with two horizontal out of sync IR rays. Due to the presence of two output relays, the detector allows you to determine the direction of the EA crossing by the intruder (when the beams cross in one direction, one relay opens, and when the beams cross in the other direction, the second one). Operating range - from 10 to 150 m. The detector has built-in heating, 4 operating frequencies, 2 sensitivity values. Recommended for the protection of various objects, incl. in areas with cold climates.

Figure 20 - IO209-29 "SPEK-1113"

IO209-29 "SPEK-1113" The detector has a single block design with a reflector, 5 operating frequencies, 4 sensitivity values. Operating range - from 5 to 10 m (outdoors). There is no built-in heating. It is recommended to use for blocking gate openings, gates, air duct outlets, ventilation shafts and other small objects. Due to the relatively low cost, it would be advisable to use the detector, incl. for the protection of ordinary objects, individual housing construction objects, etc. The detector can be used indoors.

Figure 21 - IO209-32 "SPEK-1115"

IO209-32 "SPEK-1115"It is produced in four versions, differing in the maximum working range and the presence of built-in heating:

a) IO209-32/1 "SPEK-1115" has a range of 1 to 75 m;

b) IO209-32/2 "SPEK-1115M" has a range of 1 to 75 m and built-in heating;

c) IO209-32/3 "SPEK-1115-100" has a range of 1 to 100 m;

d) IO209-32/4 "SPEK-1115M-100" has a range of 1 to 100 m and built-in heating.

detectorhas a dual IR beam in the vertical plane, 4 operating frequencies, 4 sensitivity values. Recommended for the protection of various objects, incl. in areas with a cold climate (for versions with the letter "M").

IO209-29 "SPEK-1117"This detector is a simplified modification of the "SPEK-1115" detector and has a lower cost, due to which it will be advisable to use it, incl. and for the protection of ordinary objects, individual housing construction objects, etc. The detector has a double infrared beam in the vertical plane, 1 operating frequency, 2 sensitivity values.

Imported detectors present on the domestic TCO market often do not comply with the current national standard and ETT in terms of resistance to impact low temperatures environment and switching parameters of output relays. Also, foreign manufacturers in the technical characteristics of their detectors do not give the value of the safety factor.

A list of regulatory and technical documentation, the requirements of which must be taken into account when studying this topic.

1. R78.36.026-2012 Recommendations. The use of technical detection tools based on various physical principles for the protection of fenced areas and open areas.

2. R78.36.028-2012 Recommendations. Technical means of detecting intrusions and threats various kinds. Features of selection, operation and application depending on the degree of importance and danger of objects.

3. R78.36.013-2002 - “Recommendations. False alarms of technical means of protection and methods of dealing with them.

4. R78.36.036-2013 "Methodological guide for the selection and use of passive optical-electronic infrared detectors".

5. R78.36.031-2013 "Survey of objects, apartments and MHIG accepted as a centerlysed security."

6. R78.36.022-2012 "Methodological guide for the use of radio wave and combined detectors in order to increase the detecting ability and noise immunity."

7. GOST R 50658-94 Alarm systems. Part 2. Requirements for burglar alarm systems. Section 4. Ultrasonic Doppler detectors for enclosed spaces.

8. GOST R 50659-2012 Doppler radio wave detectors for indoor and outdoor areas. General technical requirements and test methods.

9. GOST R 54455-2011 (IEC 62599-1:2010) Intrusion alarm system. Test methods for resistance to external influencing factors, modified in relation to the international standard IEC 62599-1:2010 Alarm systems. Part 1: Environmental test methods.

10. GOST R 50777-95 Alarm systems. Part 2. Requirements for burglar alarm systems. Section 6. Passive optical-electronic infrared detectors for enclosed spaces.

11. GOST R 51186-98 Passive burglar alarms for blocking glazed structures in enclosed spaces. General technical requirements.

12. GOST R 54832-2011 Security point detectors magnetic contact. General technical requirements.

13. GOST R 52434-2005 Optoelectronic active security detectors. General technical requirements.

14. GOST 31817.1.1-2012 Alarm systems. Part 1. General requirements. Section 1. General Provisions.

15. GOST 52435-2005 Technical means of security alarms. Classification. General technical requirements and test methods.

16. GOST R 52551-2006 Security and safety systems. Terms and Definitions.

17. GOST R 52650-2006 Combined radio wave and passive infrared security detectors for enclosed spaces. General technical requirements and test methods.

18. GOST R 52651-2006 Linear radio wave security detectors for perimeters. General technical requirements and test methods.

19. GOST R 52933-2008 Surface capacitive security detectors for rooms. General technical requirements.

20. GOST R 53702-2009 Vibrating surface security detectors for blocking building structures of enclosed spaces and safes.

21. GOST 32321-2013 Shock-contact surface security detectors for blocking glazed structures in enclosed spaces.General technical requirements.

22. A list of technical security equipment that satisfies the "Unified technical requirements for centralized surveillance systems intended for use in private security units" and "Unified technical requirements for object security subsystems intended for use in private security units."

23. www.ktso.ru

24. www.guarda.ru

Questions for self-examination.

1. What is a sensitive element in PIR detectors?

2. Why is the detection zone of the PIR detector divided into tiers?

3. What are the main types of detection zones for PIK detectors?

4. What type of detection zone does the active infrared detectors we have reviewed have?

5. Give an example of an active infrared detector.

Every mother of a baby knows how difficult it is sometimes for him to measure the temperature. Not only do you need to keep the child, but also for at least 5-8 minutes. An infrared thermometer in such a situation will become indispensable assistant. This is a non-contact thermometer that fixes the temperature using a laser beam on any part of the body. It is convenient to use, just direct the beam or touch any part of the body to get the exact value within 2-8 seconds.

Most infrared thermometers require batteries to operate. More expensive models have the ability to charge from the network. For ease of choice, we have compiled a rating of the best models based on user reviews and expert recommendations.

	Name	price, rub.	Briefly about the main
			The fastest temperature measurement in the frontal, temporal and ear zones - only 2 seconds.
			The most budgetary in the line of non-contact measuring instruments.
			Can be calibrated with a mercury thermometer.
			The most accurate temperature measurement.
			Convenient application robust construction, and interference protection.
			Takes measurements from a distance of 15 cm, even in complete darkness.
			Multifunctional thermometer - for body, air, food.
			Choice of Celsius or Fahrenheit temperature measurement system.
			The results of the last 32 measurements remain in memory.

Varieties of infrared thermometers

The main difference between all non-contact thermometers is the method of measurement. So, non-contact, ear and forehead ICTs are on sale that measure the temperature in the corresponding zone. This is due to the fact that a certain model is calibrated for a specific zone (by the way, the amount of heat in each zone is different).

ear

The principle of operation is also based on infrared radiation, but this is still a contact device - it is tedious to insert a thermometer into the ear and hold it there for 3-4 seconds. Among the entire arsenal of measuring instruments, this one is the most dangerous, as it can injure the baby's eardrum.

Frontal

Depending on the length of the beam, it is possible to take measurements from a distance of 5-15 cm without touching the body. The functionality of the meter is not limited to this - it can be used to measure the air temperature in the house, food for the child, etc.

Contactless

The most convenient and safe to use. No need to “aim” anywhere to hit exactly on the forehead and even more so to put it in the ear. Pointed at the body and got the value on the display. If used only to measure human body temperature, calibration can be done once and for all. If you have to do other measurements - calibrate each time.

Direct the pyrometer to the forehead or ear for measurement. Other parts of the body, even in a healthy person, may have a temperature that is significantly different from the usual 36.6 ° C.

The IR thermometer is a device designed for remote temperature measurement - fast, simple and absolutely safe. Below are the top 3 ratings of infrared thermometers for kids.

B.Well WF-1000

The temperature measurement speed is only 2 seconds. The streamlined shape and special sensor allow you to measure the temperature in the ear or on the forehead.

It is very easy to transfer the pyrometer from one mode to another: if a special nozzle is put on the sensor, the thermometer is automatically set to measure in the forehead area, if the nozzle is removed, the bi-well thermometer is ready to measure the temperature in the auricle.

• measurement speed;
• functional;
• screen tips.

• not calibrated;
• accurately measures only at certain points.

The second model in the line - B.Well WF-2000, is designed only for forehead measurement, it is also convenient to use. Power supply type CR2032.

Appearance - the form of a gun. The handle has three-finger grooves for a more comfortable grip, and the button to start measurements is made in the form of a trigger. Powered by two AA batteries.

There are two measurement modes: medical is designated as Body (that is, “body”), the accuracy in it is increased, but the measurement range lies between 35 and 43 ° C, lower or higher temperatures are simply not displayed, only the letters Lo (Low) are displayed on the screen , low) or Hi (High, high).

To attract attention in case of elevated temperature, the color of the screen backlight also changes: up to 37.5 ° C it is green (there is no particular cause for concern), between 37.5 and 37.9 it is already orange (dangerous, but not very), and above - red, and beeps five times (serious danger!).

In the second mode - Surface (surface) the range is wider: from 0 to 100   ° C (Hi or Lo will also be displayed above and below), but the error is larger. There is no color differentiation - the backlight is always green.

• backlight;
• design in the form of a pistol;
• auto shutdown.

• error, especially noticeable when the batteries are discharged.

Another pistol-shaped model, which is very convenient for non-contact measurements. It has two measurement modes: body temperature and object surface temperature. Inner memory on the last 32 measurements allows you to track the dynamics of temperature changes. The voice announcement function reproduces the measurement results in speech form.

The body temperature measurement range is 32°С-42.5°C, with an increase in the backlight of the LCD screen (it is convenient to use even in complete darkness). Measurement range of surrounding objects: from 0°C to +60°C - in this case, the backlight remains invariably blue.

Pros of Sensitek:

• minimum error;
• light weight - only 15 gr.

• although it is indicated that it is designed for 10,000 measurements, after 6 months the batteries need to be changed.

In the same category, it is worth mentioning the IR Thermometer non contact pyrometer - it is the most inexpensive in the line, it will cost only 550 rubles. It is also convenient to use, but it “sins” with incorrect measurements. It is advisable at the very beginning to determine the error using a mercury thermometer and try to change the batteries more often.

The principle of operation of all pyrometers is the same. Only functions and design change. Almost all devices measure not only body temperature (Body, medical), but also the surface of objects. Calibration, depending on the model, is carried out manually or automatically.

Medisana FTN

German pyrometer, one of the best in its class. It is used for forehead, rectal, axillary measurements. Readings are ready in 2 seconds from a distance of up to 15 cm, so no hygienic caps are required. It gives very accurate data (when compared with a mercury thermometer, the error was 0.02 ° C), which, in general, is rare for contactless devices.

The form is convenient, the LCD screen makes it possible to use the pyrometer even in complete darkness. It is convenient to measure the temperature of indoor air, baby bath water, etc.

Body measurement range up to 43.5°C, surface - up to 100°C. The memory stores data on the last 30 readings, which is convenient for health dynamics. Alarm by changing the color of the display from green to bright red at > 37.5°C. Stored in a handy case. Weighs 48 g, powered by 2 AAA batteries, LR03 1.5 V.

• convenience;
• measurement accuracy.

• price.

There are two measurement modes: medical is designated as Body temp (that is, “body”), the accuracy in it is increased, but the measurement range lies between 32 and 42.9 ° C, lower or higher temperatures are simply not displayed. To measure the pyrometer, direct the pyrometer to the forehead or ear. Theoretically, it is possible to measure in the armpits, but the indications will not change from this.

The second mode ms 302 Object temp - to obtain data about the environment. In this case, the range is from 0°C to 118°C.

There is a choice of temperature measurement system in Celsius or Fahrenheit.

Stores information about the last 64 changes in Body temp mode. The error is minimal. But it increases as the battery drains.

• high measurement accuracy;
• the ability to work in Fahrenheit.

DT-8836

It is made in a convenient form of a pistol, it receives information from a distance of 15 cm. The LCD displays data - the backlight is blue in the "healthy" range - up to 37.5 °, above - it lights up in red. The backlight is dim, the numbers are large, which makes it possible to use in the dark. For convenience, you can switch measurements from Celsius to Fahrenheit and vice versa.

The measurement time is 2 sec., after 8 sec. Inactivity, the device turns off. Range for the body: +32°-42.5°С, for objects and air - from +10°С to 99°С. Recommended measuring distance: from 5 to 15 cm. Power supply: 9V, 6F22 (Krona type). Weight 172 grams.

• measurement accuracy;
• low price;
• convenient form;
• flashlight.

• you can't turn off the sound.

Pyrometers are a simple and easy-to-use household device designed to measure body temperature in the range from 35 to 43 °C and surfaces of various objects in a much wider range - from 0 to 100 °C.

AND DT-635

Designed to instantly measure the temperature of a person's body in the ear or on the forehead and the environment. It also combines the functions of a clock and a room thermometer. Can be used on the human body in the ear and forehead, any object within the temperature range of the device (up to 50°C), alcohol before serving, indoor air, food storage in the refrigerator, etc.

Only the last reading is stored in the device memory. Convenient case-stand and case for storage and transportation included. Gives sound signals about the termination of measurement and at a temperature above 38 °C. Power supply: 1 lithium battery type CR2032.

• clock and room thermometer functions;
• 2 measuring methods.

• an error that increases as the batteries are discharged.

A new model with similar specifications, but with a different body shape, powered by AAA batteries, not AA like the IT-1, so it's slightly lighter. Designed to measure the temperature of the body, surfaces and air. This device has a wide measurement range and high accuracy, easy to use. Does not require skin contact, so there is no need to change hygienic caps.

Displays the saved data of the last measurement. The high-speed sensor ensures fast and accurate measurement. Information is displayed on the liquid crystal display Automatically turns off after 8 seconds of inactivity. Power type: 2 x LR03.

• quality assembly;
• ease of use;
• minimal deviations;
• very convenient and practical.

Chinese pyrometer for remote measurement of body temperature, air, objects. Information is displayed on a large LCD display with backlight. The memory stores the results of the last 32 measurements. Sound signalization of the end of the measurement. Laica sa5900 Automatically turns off after 10 seconds of inactivity.

Power is supplied by 2 AA 1.5V batteries. It is recommended to change the batteries after 6 months of use. Remove the batteries for extended periods of inactivity.

• convenient form;
• fast information.

• after a long period of inactivity measurement errors.

All manufacturers are trying to make devices as convenient and accurate as possible, although, admittedly, not everyone succeeds.

When operating, follow certain rules:

1. Monitor the condition of the batteries - as soon as information about the discharge appears, you should replace it.
2. The IR sensor lens must always be kept clean.
3. A wet forehead gives large errors.
4. Measurement in the ear in 9 cases out of 10 will be inaccurate - it is difficult to direct the beam into the opening of the ear canal. It is best to measure the temperature on the forehead.
5. Take 2-3 measurements at once with an interval of a minute and a half.
6. In children, heat exchange is more intense than in adults, so it is best to use contact thermometers.

VIDEO: How to choose a non-contact thermometer - Komarovsky's advice

These instruments are devices that use optical instruments and sensors to detect an unauthorized event. The final analysis of the signal takes place in the electronic circuit. Optoelectronic detectors are often used in security and fire alarm systems.

The main reasons why they are so popular are:

1. high efficiency;
2. different areas of location;
3. small cost.

The optical part of these devices operates in the infrared region of radiation. There are many ways to install infrared devices.

Passive

Applied in security systems. The main advantages are low price and a wide range of applications. Passive devices analyze changes in IR radiation.

Active

The principle of operation consists of estimating the difference in the intensity of the IR beam, which is produced by the emitter. The emitter and receiver can be in different blocks and in one. In the first case, only that part of the territory that is between them is protected.

If both devices are in the same module, then a special reflector is used.

There are also addressable optoelectronic devices that transmit the control panel signal and indicate a code that is unique for any device. Thanks to this, you can accurately find out the place where the sensor worked. However, the price of such devices is higher, but if you want reliable system, then this is the best option.

There is another type of detectors - addressable analog. This option transmits the digitized information to the control panel, where it is decided whether to apply the alarm signal.

There are several options for transferring data: wired and radio channel.

Security detectors

The location zones of these devices can be volumetric, surface, and linear. Any of these types is a motion sensor, it turns out that it detects movement in a protected area.

The use of surface devices is constrained by the blocking of structures indoors. Linear are usually used for outdoor areas.

Optoelectronic devices are negative to the presence of air currents and to extraneous light sources.

Active linear devices are smaller than others, dependent on the influence of external factors. But they are difficult to set up, especially when using devices with a large radius of action.

Fire detectors

This type of device is divided into turned and linear detectors. In the first case, the device has a smoke block and is a labyrinth with a transmitter and receiver at the ends. If smoke penetrates inside, then the IR radiation is scattered and this is noted by the receiver.

Such devices are used in many facilities, mainly service, that is, offices, shops, and so on. According to the type of data signal sending, optoelectronic detectors are divided into threshold, and addressable analog. And according to the method of connection with the devices of the fire system, they are divided into wired and radio channel.

Such devices are quite versatile and help in providing fire safety. But for large rooms this species detectors should not be used.

In such cases, linear optoelectronic devices are better suited. They control the air density by processing the IR parameters. Line detectors include a transmitter and a receiver and are active devices.

Popular Models

Arton-IPD 3.1M

Optical spot fire smoke detector SPD-3.1 (IPD-3.1M). The device is designed to detect fires in enclosed spaces of buildings and structures, accompanied by the appearance of smoke. When triggered, it transmits a signal to the control panel.

Designed for continuous round-the-clock operation on a direct current or alternating two-wire loop fire alarm. The rated supply voltage of the loop is 12 or 24 V. To operate the detectors with the control panel according to the four-wire scheme for connecting the detectors, the MUSH-2 loop matching module is used.

Astra-7B (IO409-15B)

The announcer is security volumetric optical-electronic. Designed to detect penetration into the protected area and generate an alarm notification by opening the output contacts of the alarm relay.

Mounted on the ceiling, the detection zone is circular, maximum height installations up to 5 meters. Microprocessor-based signal analysis, temperature compensation, resistance to external illumination, case opening control, optoelectronic relay. It can work at temperatures from -30 to +50 C and humidity up to 95%.

AMBER

Designed to detect intrusion into the protected area of ​​a closed room. Generates an alarm by opening the relay contacts. Widely used in security alarm systems.

It detects movement in a zone with a range of 12m and a width of 20m, a viewing angle of 90 degrees. The recommended installation height is 2.4m. Supply voltage 12V, operates at temperatures from -30 to +55C. Detects movement at speeds of 0.3..3 m/s.

Useful video

The video explains in detail the device and the principle of operation of devices using the example of a smoke autonomous detector DIP-34AVT from the company.

Conclusion

Optoelectronic emitters are a common and effective component for fire and security alarm systems. Their main advantages include relatively low price, versatility, and reliability.

The main limitation on the use of such devices is problems when working in an environment with a high content of dust, that is, in industrial premises. Optoelectronic detectors are also subject to electromagnetic interference.

Optoelectronic detectors are devices in which optical devices and sensors of various designs are used to detect an alarm event. Further processing of the received signal is carried out by an electronic circuit. Such devices are widely used in both security and fire alarm systems.

The main reasons for their popularity are:

• high efficiency;
• the possibility of forming detection zones of various configurations;
• relatively low price.

The optical part of these detectors operates in the infrared (IR) range of radiation. Exists various options versions of infrared sensors, differing in the principle of operation, purpose and application features.

Passive.

Used in security alarm systems. Their main advantages are economic availability and a wide range of applications. The principle of operation is based on the analysis of the difference in IR radiation between the sectors formed by special lenses (Fresnel).

The receiver of the infrared stream is a pyroelectric module that generates electrical impulses processed by electronics.

Modern detectors quite often use microprocessor signal processing, which increases their reliability, efficiency and resistance to interference.

Active.

They evaluate changes in the intensity of the IR beam generated by their transmitter. Structurally, the receiving and transmitting parts can be placed in separate blocks installed opposite each other. In this case, the part of the space between them is controlled.

With a monoblock design, a special reflector is used to return the beam to the device. Such detectors are used in security and fire systems.

The operation of such devices is considered in sufficient detail in the article about linear sensors used in fire alarms.

In addition to the "classic" wired devices that use relays to transmit information about their state, there are addressable optoelectronic detectors. By transmitting a signal to the receiving and control device, they add their own code, unique for each product, to the information.

Due to this, it becomes possible to localize an alarm event with an accuracy up to the location of the sensor installation. Their cost, of course, is higher, but in some cases it is worth it.

Another technology is addressable analog. It implies the transmission of digitized data of the scanned parameter, on the basis of which the decision to generate an alarm is made by the control panel. Such detectors are mainly used in fire protection systems.

The last thing worth noting is the signal transmission methods. There are actually two of them:

• wired;
• radio channel.

SECURITY OPTO-ELECTRONIC DETECTORS

The principle of operation of security optoelectronic devices is described at the beginning of this article. As for detection zones, passive infrared detectors allow you to use all possible options:

• bulk;
• surface (curtain);
• linear (beam).

Active ones work according to the last (ray) principle.

All of them are inherently motion sensors, that is, they detect the movement of an object in a protected area. For surface and linear, it would be more correct to say - the intersection of the detection zone. You can see more about how it works.

FIRE OPTO-ELECTRONIC DETECTORS

Optoelectronic devices used in fire alarm systems and automatic fire extinguishing installations belong to smoke detectors. According to the type of detection zone, they are divided into:

• point;
• linear.

Point ones incorporate a smoke chamber. It is a kind of labyrinth at the beginning and end of which an emitter and a photodetector are installed. When smoke gets inside, IR radiation is scattered, which is recorded by the electronic circuit of the device.

The scope of such detectors is very wide, they are installed in offices, shops, hotels and other similar facilities. According to the type of information signal formation, they are divided into:

• threshold;
• targeted;
• addressable analog.

According to the method of communication with fire alarm devices, these detectors are wired and wireless (radio channel).

In general, these are quite universal sensors that allow solving various issues of fire safety. Somewhat inconvenient, and sometimes not economically feasible, to use them for indoor installation large area and (or) a large distance to the ceiling.

In this case, linear optoelectronic detectors are used in fire alarm systems. They do not have a gas chamber and control the optical density of the medium by analyzing the parameters of the infrared beam. For these purposes, a receiver and a transmitter are required, that is, such devices are active.

A general limitation on the use of optoelectronic fire detectors is rooms with a high dust content. In addition, such devices may be affected by electromagnetic interference. But this largely depends on the model of the sensor.

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