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    • PIR Motion Sensor

      Infrared sensors (IR Sensors) are the sensors that work on Infrared sensing technology to detect the motion of objects. There exist two types of sensors which detect motion with the help of Infrared, one is Active Infrared sensor (AIR sensor) and another one is Passive Infrared sensor (PIR sensor).

      Table of Contents

      • What is a PIR Motion Sensor ?

        Passive Infrared Sensor (PIR sensor) or PIR motion sensor is the kind of IR sensor that measures the Infrared radiations released from objects and thus identify them as moving or still objects. This type of motion sensor is only the receptor of infrared waves and does not release any infrared beam like that is done in Active Infrared sensors.

      • Types of Passive Infrared Sensors (PIR sensors)

        The PIR sensors are of two types:-

        Thermal Infrared Sensors- Thermal Infrared sensors (IR Sensors) or Pyroelectric Infrared sensors (IR Sensors ) use Infrared as the source of heat energy for the detection of objects and their sensitivity is independent of the wavelength. These sensors are slow with their detection time and responsiveness.

        Quantum Infrared sensors- Quantum sensors detect photons and are dependent on the wavelength and are highly sensitive than those sensing heat. These sensors are fast in their detection time and responsiveness but require frequent cooling for precise measurement.

      • Passive Infrared Sensor (PIR Sensor) Components

        A PIR sensor is made from a Pyroelectric component (combination of metal and crystal) and other essential electrical components like circuits, resistors, capacitors. The sensor is enclosed in a metal sheet protector and a silicon window is provided in that to allow the infrared radiations to pass through it. The PIR motion sensors are mostly rectangular in shape irrespective of the device they are installed in. To increase the detection sensitivity, the motion detector devices cover the PIR sensor with lenses to focus more energy on it.

      • PIR Beam Pattern

        As the PIR sensor is covered with the lenses to increase the focus, the detection view becomes a beam pattern.

      • Working Principle of PIR motion sensor

        All the objects, living things having a temperature more than absolute zero emit infrared radiations in their surroundings. Warmer the object, more the infrared radiations are emitted.

        The Passive Infrared sensor is a thermal infrared sensor (IR Sensor) which detects the motion of objects on reading these infrared radiations’ variations in its nearby environment.

        The sensor has two equal slots made up of Pyroelectric material that is very sensitive to Infrared. When the sensor is not active, both its slots sense the same amount of Infrared radiations coming from any object, door or wall, etc.

        When a warm body comes in the range of the PIR motion sensor, it passes through both the slots one after the other. The moment it intercepts the first half of the sensor, a positive differential change is caused between the two halves. Similarly, when it leaves the detection area a negative differential change occurs between both the slots. These changes in the pulses are the indication to the sensor that there is some motion in its detecting zone.

      • Motion Sensor Alarm

        A motion sensor alarm is the integrated component of a security solution installed at premises that on detecting the motion in its vicinity alerts the security personnel or the owners for suspicious activity.

      • Motion Sensor Alarm Working

        A motion sensor alarm does not have its own detection method. It only alerts about the intrusion attempt being made that is actually detected by the different sensors like PIR sensor, AIR sensor, Microwave sensor, LASER (LiDAR) sensor, etc. Whenever any suspicious activity is detected by any of these sensors, it sends a warning signal to the Control Panel. The control panel on receiving the warning from the sensor activates the alarm or hooter to alert the deployed security and take necessary action.

      • Advantages of PIR Motion Sensors

        • PIR motion sensors can detect moving objects even in dark with great accuracy.
        • PIR sensors can detect the motion of objects without coming in contact with them.
        • They are very easy to install and do not require much wiring.
        • They reduce a lot of human efforts by making things to work automatically.
        • They consume very less energy and thus reduce electricity bills a lot.

        Disadvantages of PIR Motion Sensors

        • PIR motion sensors are a bit costly and can not be afforded by a majority of people.
        • Passive Infrared Sensors sometimes behave abnormally during bad weather conditions.
        • PIR sensors sometimes become incapable of detecting a very slow-moving object.
        • Home security systems with PIR motion detectors sometimes trigger false alarms due to no reason.
        • PIR motion sensors have a very short detection range and thus sometimes it leads to a loophole in Burglar alarm systems because of incomplete coverage issue.

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      • Applications

        • Burglar Alarm Systems or Intrusion Detection System
        • Automated Home Appliances
        • Automated Doors
        • Parking Areas
        • Automated Lightings
        • IR Thermometers
        • Night Vision Cameras
        • Gas Analyzers
        • Moisture Analyzers
        • Smoke and Fire Detectors

      • FAQs

        • How are PIR sensors different from AIR sensors ?

          PIR sensors only detect the infrared waves coming from humans but the AIR sensors release the infrared by themselves through a transmitter and send it to the receiver.

        • As we know that PIR sensors respond to the heat radiations and generate alarms, then it will also give false alarms in hot weather conditions. How do Optex products deal in such a situation ?

          PIR sensors work on the principle of scanning the nearby area and then responding to change in the temperature. In hot weather condition, the temperature of the environment does not change too quickly and hence there is no effect on the sensor. But, whenever any human comes into the detection region of the PIR sensor present in the same hot weather, there comes a quick change in the nearby environment and thus the sensor comes into action.

        • I have pre-installed PIR sensors of some other brand and now I want some more to be installed. Can Optex PIR sensors be integrated with my pre-installed sensors ?

          Optex products are compatible with products from other brands as well and hence can be integrated with each other to work parallelly.

        • What if anyone tries to trick the Optex PIR sensor by covering it with some cloth, tape, paper, etc. ?

          Optex products have a special feature called Anti-Masking that makes the PIR sensor to give an alarm if someone tries to trick it by covering it with anything like cloth, tape, paper, etc.

        • I have heard from many people that their PIR sensors give alarms when pets come into the detection region. Are Optex sensors also the same ?

          Optex sensors have been designed to tackle this problem of people by incorporating the technology that makes the sensor immune to the presence of pets in the detection region.