PIR detectors explained

Access & Identity Management Handbook 2005 Perimeter Security, Alarms & Intruder Detection

Elvey Security Technologies is a proud distributor of the high performance intruder detectors from Optex. Optex products are most reliable, easy to install and affordable. All Optex detectors are 100% tested before being introduced to the market and with continuous R&D, Optex is constantly improving its existing detectors to meet the needs of the security market.

Elvey Security Technologies, together with Optex, would like to add some insight to the mechanisms behind the Optex detectors.

How do PIR detectors work?

Passive infrared (PIR) detection is achieved by monitoring changes of the far infrared levels in the sensors field of view. All objects emit infrared radiation at or around a wavelength of 10 µm. The sensor activates when a human being moves against a background that is emitting more or less radiation. Effective detectors are able to discriminate between humans and other sources of infrared.

Conventional models
Conventional models

Unique technologies

Using a number of unique technologies, many of which are patented, Optex detectors are able to discriminate between human and other sources of infrared such as moving curtains or blinds, radiators, office equipment, pets, sunlight and reflections. The aim of all the technologies is to reduce the incidence of a false alarm.

Double conductive shielding

Double filtering and conductive metal shielding cover the pyroelectric sensor, blocking and grounding out visible light and radio frequency interference (RFI). Only infrared energy passes through the filter, minimising false alarms from direct or reflected sunlight and car headlights.

Quad zone logic

These create an extremely high vertical zone density; two or three times the size of that in conventional PIRs. These taller zones capture the entire body mass of a person and enable detection of the smallest temperature contrast between them and the background. In addition, the vertical detection density takes into account dead zones created by furniture or partitions.

Quad zone logic
Quad zone logic

Multifocus technology

Multifocus technology creates zones with high vertical density, optimising detection sensitivity and enabling detection to remain stable even in high temperature conditions.

Temperature compensation

Temperature compensation increases detection capability in high temperature conditions, where the background temperature is similar to that of the human body. It maintains a high level of false alarm protection and helps prevent valid alarms being missed by automatically adjusting sensitivity according to the environmental temperature.

Spherical lens design

Traditional PIR detectors use a flat lens bent into a curve to focus infrared energy onto the pyroelectric sensor. This is not the most accurate method, because the distance between the lens and the pyroelectric sensor (the focal length) varies for each detection zone, creating distortion. The Optex spherical lens design eliminates distortion by providing a uniform focal length for every detection zone. Additionally, the sphere is one of the strongest geometrical structures, making spherical lenses superior both optically and mechanically.

Conventional structure
Conventional structure

Sealed optics

With conventional PIR detectors, small inserts and draughts can cause false alarms by getting between the lens and the pyroelectric sensor. This is prevented by 'sealed optics', which make this space separate sealed optical compartment ensuring that it remains empty and undisturbed at all times.

Sealed optics
Sealed optics

For more information contact Elvey Security Technologies, 011 401 6700, sales@elvey.co.za, www.elvey.co.za



Credit(s)




Share this article:
Share via emailShare via LinkedInPrint this page



Further reading:

Hikvision alarms improve protection
Residential Estate Security Handbook 2020, Hikvision South Africa , Perimeter Security, Alarms & Intruder Detection
Hikvision has created a broad portfolio of innovative alarm solutions that are sophisticated, automated, and always fit for purpose.

Read more...
Thermal cameras with artificial intelligence
Residential Estate Security Handbook 2020, Dahua Technology South Africa , Perimeter Security, Alarms & Intruder Detection
Dahua Technology showcased solutions that are important to residential estates, namely perimeter protection.

Read more...
Securing estate perimeters
Residential Estate Security Handbook 2020, Nemtek Electric Fencing Products , Perimeter Security, Alarms & Intruder Detection
Nemtek has a range of products designed to secure the perimeters of estates, however its display at the conference focused on its Network Energizer and its Dual-Action Tension Sensor.

Read more...
Take estate security seriously
Residential Estate Security Handbook 2020 , Perimeter Security, Alarms & Intruder Detection
While the growth in residential estates continues, crime syndicates continue to target lifestyle estates, more often than not using inside information to gain access.

Read more...
Catching the intruder vibes
Residential Estate Security Handbook 2020 , Perimeter Security, Alarms & Intruder Detection
While a fence or wall of some sort is still the foundation for a perimeter solution, a simple barrier is not a sufficient defence against the continual criminal onslaught against estates.

Read more...
Perimeter security decisions
Residential Estate Security Handbook 2020 , Perimeter Security, Alarms & Intruder Detection
There are many options when it comes to perimeter security; Stafix offers some advice to guide estates through the decision-making process.

Read more...
Improved perimeter security with IoT
Residential Estate Security Handbook 2020, Vox Telecom , Perimeter Security, Alarms & Intruder Detection
Vox has introduced an Internet of Things (IoT) solution that helps better protect perimeters by providing notifications when boundary fences have been cut or tampered with.

Read more...
Vehicle and driver identification
Residential Estate Security Handbook 2020, Protoclea Advanced Image Engineering , Products, CCTV, Surveillance & Remote Monitoring, Perimeter Security, Alarms & Intruder Detection
Detecta features vehicle identification (make and model), automated number plate recognition (ANPR), vehicle colour recognition, driver identification, high speed and free flow detection.

Read more...
Wide-area surveillance with early detection
Residential Estate Security Handbook 2020, Protoclea Advanced Image Engineering , Products, CCTV, Surveillance & Remote Monitoring, Perimeter Security, Alarms & Intruder Detection
Being aware of a threat beforehand allows landowners to implement the necessary steps and alert security personnel, and thereby prevent threats from reaching the property.

Read more...
Watch your perimeter
Access & Identity Management Handbook 2020 , Perimeter Security, Alarms & Intruder Detection
SqwidNet collaborated with Teqcon, a South African mechanical and electronic design company, to address the problem of perimeter security in remote locations.

Read more...