The umbrella term ‘motion sensor’ applies to any form of technology that has something to do with the automatic regulation of lighting within (and outside of) your home. Motion sensors don’t only increase comfort and convenience (no need to go out of your way to switch on the light), they also provide an element of safety (such as in the garage entryway or to keep burglars at bay) – and that’s not all.

Lights employing this technology save on energy use and therefore energy costs. This is because these lights only switch themselves on when they are needed, avoiding unnecessary use of light and therefore electricity.

 

infographic on motion detectors

The different forms of technology that fall under the category ‘motion sensors’ are divided into the following areas of use:

Motion detectors with infrared sensors…

are ideal for both outdoor and indoor use.

Presence detectors…

that is, motion sensors with very finely tuned infrared sensors – are only used for indoor lighting.

High-frequency (‘HF’) sensors…

are another excellent option for reducing energy use indoors. These sensors are capable of registering even the subtlest of movements.

 

Motion detectors with infrared sensors react to motion and warmth

A motions sensor using infrared technology (also called PIR – passive infrared – sensors) reacts to heat, thanks to a so-called ‘Pyrosensor’ within the light. Moving bodies are recognised by a segmented lens because their body temperature causes a change in the thermal image within the light when the body passes into or leaves one of the ‘fingers’ of the sectioned detection range. This thermal pulse is what switches the light on.

When the light switches itself off is determined by a set length of time, which can be adjusted in most models between a few seconds of light, up to a few minutes.

For a PIR sensor to function correctly two aspects are important: correct installation and adjustment of the detection range, and the differentiation between static heat sources (sunlight) and dynamic heat sources (cars, animals, people).

Please note! When approaching an infrared sensor, the Pyrosensor only registers a change in the thermal image when the heat source moves between the ‘fingers’ of the detection range. This means that the motion detector only notices dynamic changes in the thermal image when a heat source enters or leaves one of the sections of detection range. Therefore, a body moving diagonally in front of the sensor will be recognised sooner than a body moving directly toward the motion sensor, as this body may not leave or enter one of the fanned out fingers of the detection range until close to the PIR sensor. For example, if the detection range is set to a width of 12 metres, the sensor would not register a directly frontal approaching heat source until it was but 5 metres away from the sensor.

 

outdoor lights fitted with motion detector

Motion sensors detect diagonally approaching movement sooner as directly frontal approaching movements. Item number at Lights.co.uk: 9619029

 

Motion detectors vs. presence detectors: What’s the difference?

Both motion detectors and presence detectors operate using PIR sensors, however the areas in which these sensors are used is different.

While the motion detectors with PIR sensors are also excellent for outdoor use, they are most commonly installed indoors, such as at a desk or workspace in the office.

Presence detectors also make use of thermal imaging to know when to switch on and off; however presence detectors are much more finely tuned to catch very small movements of heat sources. This is because the detection range is not fanned out in ‘finger’ sections as with a simple infrared sensor, but rather divided into a chess board-type grid. Because of this, a presence detector can register small movements like typing on a keyboard as a change in the thermal image and switch on/sustain the illumination until the motion stops. If the presence detector registers that a desk is unoccupied it will automatically switch off the light. This is also the case if there is already enough light (artificial or natural) in the room – a presence detectors also has an integrated sensor which automatically measures the brightness levels in the room.

 

Motion detectors with high-frequency (‘HF’) sensors

In contrast to infrared sensors, HF or high-frequency motion sensors do not use changes in thermal imagery to register movement. Instead, they rely on echo imagery. For this, HF motion sensors send out a signal that is undetectable by the human ear. This signal creates an ‘echo image’ of the space for the light, letting it know if there has been movement in the area.

Any changes in the echo image (i.e. movement) will activate the motion sensor and therefore the light.

Just as with other motions sensors, the settings on HF sensors can be adjusted to suit their surroundings as well, such as in the size of the detection range. HF sensors are also ideal for installation in basement spaces, transition/hallway areas, or other spaces where the installation of an infrared sensor wouldn’t provide an optimal performance but where constant illumination is nevertheless required.

Please note! Due to their level of sensitivity, high-frequency sensors are not suitable for outdoor use.

Discover our selection of outdoor lighting and ensure safety on your property, or learn more about how lights with motion detectors can be used as anti-burglary protection.

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