What Are the Different Types of IR Detectors?

An infrared detector (Infrared Detector) is a device that converts an incident infrared radiation signal into an electrical signal output. Infrared radiation is an electromagnetic wave with a wavelength between visible light and microwaves, which is imperceptible to the human eye. To detect the presence of this radiation and measure its strength, it must be transformed into other physical quantities that can be detected and measured. Generally speaking, any effect caused by infrared radiation irradiating an object can be used to measure the intensity of infrared radiation as long as the effect is measurable and sufficiently sensitive. Modern infrared detectors use mainly infrared thermal effects and photoelectric effects. The output of these effects is mostly electricity, or it can be converted into electricity by appropriate methods.

Infrared Detectors

(Products on display at Asia Consumer Electronics Show 2015)

An infrared detector (Infrared Detector) is a device that converts an incident infrared radiation signal into an electrical signal output. Infrared radiation is an electromagnetic wave with a wavelength between visible light and microwaves, which is imperceptible to the human eye. To detect the presence of this radiation and measure its strength, it must be transformed into other physical quantities that can be detected and measured. Generally speaking, any effect caused by infrared radiation irradiating an object can be used to measure the intensity of infrared radiation as long as the effect is measurable and sufficiently sensitive. Modern infrared detectors use mainly infrared thermal effects and photoelectric effects. The output of these effects is mostly electricity, or it can be converted into electricity by appropriate methods.

Chinese name

Infrared Detectors

Foreign name

Infrared Detector

Use

Detect human movement, illegal intrusion and alarm

False alarm rate

low

The wireless infrared detector is an intelligent dual element detector developed by using the most advanced digital processing technology in the world. It mainly uses a dual element passive infrared pyroelectric sensor and a special photo series analysis judgment, with microcomputer digital signal processing. Perfect temperature compensation, unique anti-false alarm algorithm, low power consumption, stable performance, strong anti-interference, it is a cost-effective wireless infrared anti-theft detector.

1. Turn the power switch on the left side of the detector to the bottom. At this time, the detector is powered on, and the alarm indicator on the face case lights up for about 3 seconds. At the same time, a wireless signal is also emitted. , The time is about 50 seconds, the stabilization time is up, and start to enter the next round of detection and monitoring.
2. When someone enters the detection range of the detector, the detector alarm indicator lights up and emits a wireless signal at the same time.
3. As long as the alarm is issued, it will wait for 50 seconds before entering the next round of alarm. If the detector is always in the monitoring state, the alarm will be generated immediately whenever someone enters the monitoring area.

In the infrared detector, the thermoelectric element detects the presence or movement of the human body, and converts the output signal of the thermoelectric element into a voltage signal. Then, waveform analysis is performed on the voltage signal. Therefore, a detection signal is output only when a waveform generated by a human body is detected through waveform analysis. For example, voltage signals are amplified in two different frequency ranges, and the amplified signals are used to identify signals caused by the human body. Therefore, it is possible to prevent noises such as popcorn noise of thermoelectric elements from being generated by the human body and being prepared for detection.

The infrared detector includes an infrared transmitter, a receiver, and a signal processor. A signal output terminal of the signal processor is connected to the infrared transmitter through an infrared transmitting circuit; a signal input terminal is connected to the infrared receiver through an infrared receiving circuit, and a feedback signal is provided. The output is connected to the peripheral control circuit.

This technology uses a micro single chip microcomputer as a signal processor to generate an encoded signal, drives an infrared transmitter to emit an infrared signal with an encoded signal, and detects the reflected signal processed by the amplification circuit in real time. The encoded signal can ensure that multiple sensors of the same model are simultaneously Work in the same place without interfering with each other. And the operating frequency is consistent, high reliability, low power consumption.

An infrared detector has at least one pair

The infrared light bands emitted by different kinds of objects have their specific bands, and the infrared light in this band is outside the visible light band. Therefore, people can use this kind of infrared light to detect and track objects. The technology that detects invisible infrared radiation and converts it into a measurable signal is the application of infrared detection technology. From the perspective of infrared detection technology, infrared detection has the following advantages: environmental adaptability is better than visible light, especially at night and Ability to work in bad weather; good concealment, generally passively receiving the signal of the target, safer and more confidential than radar and laser detection, and difficult to be interfered with; due to the temperature difference between the target and the background and the emissivity difference The infrared radiation characteristics are used to detect, so the ability to identify camouflage targets is better than visible light. Compared with radar systems, infrared systems are smaller, lighter, and have lower power consumption. The spectral response of the detector extends from short to long waves; Units have developed to multiple, from multiple to focal planes; a wide variety of detectors and systems have been developed; from single-band detection to multi-band detection; from refrigeration-type detectors to room-temperature detectors.

Proximity detector

It is a detection device that can trigger an alarm when an intruder approaches it. In the proximity detector, there is usually a high-frequency LC oscillating circuit, and the LC circuit of the oscillating circuit is connected to external metal parts through wires. When the human body approaches,

Detect human movement, illegal intrusion and alarm. It has high sensitivity, low false alarm rate, compact appearance, beautiful appearance, and easy installation ^[1]

In 1800, FW Herschel discovered the presence of infrared radiation in the solar spectrum. At the time, he was using

(1) There are two types of pillars, circular and square, which are popular in pillar installations. Round cross-section pillars were more popular in the early days. The situation is just the other way round. Square pillars are becoming more and more popular in the engineering world. The main reason is that the detector is installed on a square pillar without rotation and difficult to move. In addition, it is also one of its advantages to have a wide choice of stainless steel, alloy and aluminum alloy profiles. Another method is to use angle steel as a pillar. If the wiring cannot be effectively covered by the pipe, the wiring will be exposed in the air. This method is not acceptable. The key point is that the fixing of the pillar must be firm and solid, without displacement or shaking, in order to facilitate installation and fortification and reduce false alarms.

(2) Infrared detectors that can provide a full 180 ° horizontal rotation angle and a tilt angle of 20 ° or more, such as the ALEPH active infrared detector HA, ABT, ABF series products, can support the probe directly on the building's outer wall or fence, fence installation.

(3) General Principles of Detector Installation Detectors installed on the aisle are mainly used to prevent illegal traffic. In order to prevent false alarms caused by pets and small animals, the position of the probe should generally be 50 above the ground. The shading time should be adjusted to a faster position to respond quickly to illegal intrusions. The main function of the detector installed on the fence is to prevent man-in-the-middle overturning. It can be installed on the top or side. For detectors installed on the top, the position of the probe should be higher than the fence and the top of the fence should be 25 to reduce false alarms caused by birds and kittens moving on the wall. The four-beam detector's ability to prevent false alarms is stronger than that of dual beams, which are stronger than single beams. For side installation, the probe is installed on the fence, and the side of the fence near the top is generally wall-mounted, and it is mostly installed on the outside. This way can avoid the interference of birds and kittens. Each method has its own advantages or disadvantages, and engineering companies have their own preference for each installation method. Users should choose according to the characteristics of their buildings and anti-theft requirements.

(4) Special reminder: The line must not be applied directly, and it must be installed through a pipe. This is the minimum requirement for the safety of the detector.

The maximum horizontal distance of the detector installed on the fence wall from the edge of the wall cannot be greater than 30. This point needs special attention where the fence bends in an arc. After the wiring is connected, please use the resistance of the multimeter to test the power terminals and of the probe, and make sure that there is no short-circuit fault before turning on the power for debugging.

(1) Adjust the optical axis of the light projector. Open the cover of the probe, point the eye at the sight, and observe the effects in the sight. The optical lens of the probe can be adjusted by hand directly to the left and right within the range of 180 °. Adjust the screw. The lens system has an adjustment range of up to 12 °. Repeatedly adjust the impact of the counterpart detector in the sight to the central position. Be careful not to cover the optical axis during the adjustment process, so as not to affect the adjustment work. The adjustment of the optical axis of the projector has a great impact on the sensitivity performance of the zone. Please be sure to carefully and repeatedly follow the correct steps.

(II) Adjusting the optical axis of the receiver The first step is to perform preliminary adjustment of the optical axis of the receiver according to the same method as "adjusting the optical axis of the projector. At this time, the red warning indicator on the receiver is off, the green indicator is on, and there is no flicker, which indicates that the optical axis of the head is normal, and the emitter and receiver functions normally.

The second step: there are two small holes on the receiver, marked with "+" and "-" respectively, for testing the intensity of the infrared light felt by the receiver. Insert the test leads (red "+", black "-") of the multimeter into the photoreceptor voltage of the measuring receiver. Repeatedly adjust the lens system to reach the maximum value of the photosensitive voltage. In this way, the working state of the probe has reached the optimal state.

Note: The four-beam detector has two sets of optical systems, which need to cover the upper and lower lenses of the receiver respectively and adjust until the upper and lower photosensitive voltages are consistent. The two optical systems of the older four-beam detector are adjusted separately. Due to the corresponding relationship between the four optical systems of the two probes of the transmitter and receiver, it is quite difficult to adjust, and it needs to be adjusted carefully. False positives or dead zone protection. The ABF four-beam detector has integrated two parts into one body for adjustment, making engineering construction much easier. (3) Shading time adjustment There is a shading time adjustment button on the receiver. Generally, the shading time of the probe is adjustable between 50m / s ~ 500m / s. When the probe is shipped from the factory, the shading time of the probe is adjusted to a standard in the factory. In terms of position, under normal circumstances, this position is a relatively moderate state, taking into account the environmental conditions and the characteristics of the probe itself, so there is no special reason, and there is no need to adjust the shading time. If you need to adjust the shading time due to fortification reasons, to adapt to changes in the environment. Generally speaking, the shorter the light-shielding time, the faster the sensitivity of the probe, but the sensitivity to falling leaves, flying birds, etc. is also strong, increasing the possibility of false alarms. Long shading time reduces the sensitivity of the probe and increases the possibility of false negatives. The engineer should adjust the shading time according to the actual needs of the fortification.

(4) After setting the connection probe with the anti-theft host, connect the tamper switch to the input circuit of the defense zone. After the connection is completed, cover the housing of the probe and tighten the fastening screws. It is required that the warning light of this zone on the anti-theft host computer is not flashing or lit, and there is no alarm indication output in the zone. Indicates that the entire zone is set normally. Otherwise, check the line, re-adjust the probe, and confirm the zone status again.

(5) Anti-theft performance test After the working area of the defense zone is normal, according to the requirements of fortification, all possible size and shape objects similar to the defense should be used to cover the optical axis of the probe with different speeds and different methods. The radio talks to the control center to check whether the alarm condition is normal. At the same time, pay careful attention to whether the alarm host is flashing or unstable. So as not to leave hidden dangers to the alarm system. We call this process verbally. The purpose of the firing test is to test whether the defense zone has the ability to alarm normally, to test whether the scope of the defense zone can meet the predetermined requirements, and whether there is a dead zone of protection.

In the daily work of the detector, because it has been working outdoors for a long time, it is unavoidably affected by the dust, microorganisms, snow, frost and fog in the atmosphere. For a long time, a layer of dust-like hard materials has often accumulated on the outer wall of the detector. In the shell, a thick layer of moss will grow in relatively humid places, and sometimes birds will also pull excrement onto the detector, which will hinder the emission and reception of infrared rays and cause false alarms.