About infrared wave

Infrared wave has wavelength greater than visible light and less than electric wave. It is invisible to the naked eye, but has thermal energy that makes people perceive heat. Whether human or objects in the nature, flames or ice, will emit infrared varying waves consistent with their temperature and surface state.

Work Principle

Pyroelectric sensors use the pyroelectric effect of piezoelectric element (ceramics) as the principle of infrared wave detection. When infrared rays enter the PIR sensor, a temperature change occurs and raises the surface temperature of the pyroelectric element (ceramic), and generates surface electric charge and output signal accordingly.

According to Wien displacement law, human body emits infrared waves between 9-10 µm. PIR sensor is equiped with a filter in the light window to allow enterance of infrared waves of human body or constant temperature animals.

PIR sensor is passive infrared motion detection sensor, and it

  • can detect only when temperature change occurs
  • not able to detect when there is no temperature changes or motion happens.
  • can be ajusted the detection distance(2-10m) matching with different Fresnel lenses.

PIR sensor application

PIR sensors has great potential and wide variety of use. It’s able to detect human body infrared wave changes with no need of direct contact, and output enlarged voltage signal that can drive various control circuits. Smart lighting control, security alarm, automatic door, motion induction toys, smart building, household appliances, and smart pet keeping, etc.

Smart Lighting Control

With PIR human inductive motion sensor, automatic lighting control can be realized in multiple scenarios such as entrances, aisles, cabinets, wardrobes, bedrooms, bathrooms, etc., turning on lights when people come and turn them off when people leave.

Smart Home Appliances

With the increasing of smart home appliances, PIR sensors can be integrated in range hood, air conditioner, electric fan, toilet to realize many functions such as hand motion control, avoiding direct wind blow or wind follows human motion, and automatic cover open, etc.

Smart Pet Keeping

Smart pet keeping is a new hot trend. PIR sensor can also detect motion of endotherms (constant temperature animals), and used for devices such as smart cat litter box, automatic food feeder, etc.

Smart Security

PIR sensor has a mature use in security field. Welcome door bell, infrared alarm are the common devices with PIR sensors. Besides, it can be combined with other technologies to build up integrated smart security solutions for home, building, residential community.

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