Motion detection refers to the process of detecting a change in the position of an object over time. This can be done using various techniques, such as infrared sensing, acoustic sensing, or image processing.
Humans perceive motion through visual and vestibular cues, with the brain using information from the eyes and inner ear to detect changes in the visual field to sense movement. Similarly, passive infrared (PIR) motion sensors detect changes in the infrared radiation (IR) emitted by all objects above absolute zero.
How Do PIR Sensors Work?
A PIR motion sensor primarily consists of two parts: a pyroelectric sensor that detects infrared radiation and an optical lens that focuses the infrared radiation onto the sensor. PIR sensors detect changes in infrared radiation (radiant heat) by measuring the objects’ temperature and surface characteristics in their field of view. The term “passive” in PIR refers to the fact that these devices do not emit energy to detect motion. Instead, they detect changes in the infrared radiation emitted or reflected by objects in their field of view. When an object, like a person, moves in front of a background, like a wall, the temperature at that point in the sensor’s field of view increases from room temperature to body temperature and then back again. The sensor converts this change in incoming infrared radiation into a change in output voltage, triggering a detection signal to an alarm system or other device to indicate motion. PIR motion sensors are commonly used in security systems, lighting controls, and other applications where motion detection is needed. Additionally, objects that have similar temperatures but different surface characteristics may emit different infrared patterns, causing a detection when moved in relation to the background.
Demand for PIR Sensors
The market for PIR motion sensors is strong, with a wide range of applications, including security systems, lighting control systems, HVAC systems, and smart home devices. The market is expected to continue growing in the future as the demand for smart home and building automation products increases.
PIR Sensor Solutions
ams OSRAM SFH 4172 OSLON® P1616 is a high-power infrared emitter in a clear silicone package. It has an 850nm centroid wavelength, an operating temperature range of -40°C to 105°C, and a 2kV ESD rating. The P1616 sensor is ideal for access control & security, body tracking, home/building/factory automation, and building lighting applications.
The STEVAL-BLUEPIRV1 evaluation board from STMicroelectronics is a wireless motion detector based on a PIR sensor and features Bluetooth® Low Energy wireless connectivity. The design uses IRA-S210ST01 by Murata and has a detection range of up to 5m. The whole design has been built by focusing on low-power consumption with an expected lifetime of around a year while powered via a CR2032 coin-cell battery.
Author :
Rudy Ramos, Member of the Technical Content Marketing team, Mouser Electronics
