Why Infrared

Advantages of using Passive Infra-red sensor in Watchman People Counter:

The Passive Infra-red (PIR) sensor detects people by sensing the heat emitted from the human body, (heat is in the invisible infra-red part of the light spectrum).

When an individual comes within the range of the PIR sensor, it picks up the latest source of heat (infra-red) because there is temperature difference between the background and the person.

This sensor has advantages over other types of sensors used to count people because it is simple, cost effective, unobtrusive and easy to install / use.

Our Passive Infra-Red sensors are superior to other type of sensors which:

  • Emit infra-red light that is reflected by a reflecting surface but can get obstructed by people or other objects. It is also difficult to align the sensor and the reflector.
  • Use tread mats to count people as they step on it. The mats can be damaged from abuse and weather conditions. They can also give multiple readings or missed readings in crowded environments.
  • Use technology like dual element sensor (which use two different types of sensors in one housing) or image signal processing and counting are expensive and complex solutions which require more sophisticated installation, monitoring and maintenance.  

Our capabilities include designing microprocessors with programmed code to achieve the solution. We also make printed circuit boards with SMD (surface mount device) technology and thick film multilayer printed hybrid ceramic technology. This technology provides both security and intellectual property protection as it makes it impossible to copy data and designs incorporated into the electronics without destruction of the target.

Businesses worldwide turn to Watchman Products for simple, dependable and low cost electronics products.

How Our Infrared Sensors Work

The above diagram shows how the People Counter (or sensor unit) should be installed.

1. The first diagram on the left illustrates the narrow depth “curtain” covering the entrance (side view) which ensures that only people who walk through the doorway are sensed.  The sensor will not pick up pedestrians in the walkway or inside the aisles of a store

2. The second diagram illustrates the (front view) broad span across the doorway that ensures complete coverage of a doorway.

3. The third diagram illustrates the front view of an installed sensor on a doorway – which has a maximum range of 13 feet.

4. The fourth diagram illustrates the side view of an installed sensor on a doorway