ADVERTISEMENT FEATURE COVER STORY WHO TURNED OUT THE LIGHTS?
Energy efficiency in buildings has received much attention over recent years as energy prices have hiked and the drive for energy efficiency has become a necessity. Now the latest occupancy/absence detection – PIR’s from Panasonic are delivering something of renaissance, enabled by miniature sensors. Here’s more
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uilding Services Management has become an evolving area of high interest in the last few years. But there is a basic requirement in that the various systems need to identify the presence or absence of people in the controlled areas. The most obvious example of this is in the control of lighting, enabled by integrating some form of occupancy sensor to detect the presence of people in an area. This information can then be used to decide where lighting is needed. This can be extended to allow very precise detection within larger areas so that lighting can be controlled down to a single source if necessary. There are a number of different types of occupancy sensor, ranging from very basic on/off switches, that maybe are connected to sense the opening of an area doorway, to very advanced thermopile sensors that can detect not only a presence in an area but also very precise location information within that area. However the occupancy sensor type most widely used in the building services management industry is the PIR (Passive Infrared) sensor. PIR motion sensors use electromagnetic radiation in the low infrared spectrum in which radiation emitted by human movement is identified using a PIR detector. Objects that are located within the area of sensitivity generate electromagnetic radiation in the low infrared range and project an image through the focus line of the sensor onto the internal heat- sensitive element.
12 SEPTEMBER 2017 | ELECTRONICS
SIGNAL PROCESSING The signal processing electronics then convert the images into electrical signals. If the heat image remains the same, the output signal of the sensor remains unchanged. If the heat image changes, because the object moves within the area of sensitivity, the optical imaging changes accordingly. This movement results in a change of the output signal that in turn can be evaluated by a window comparator that specifies upper and lower thresholds. However miniaturisation of PIR devices can prove problematic when compared to the usual miniaturisation of other electronic control devices. Many of these problems arise due to the structure and characteristics of the sensor device since PIR motion detectors use thermal sensors to detect the small temperature increases present when the sensor element is exposed to radiation. In addition the required lens array needed for the focus and detection/elimination of any returning light sources are increasingly difficult to manufacture to the necessary tolerance limits the smaller the overall size. Of equal importance is the necessity to produce control circuits that take the lowest quiescent currents possible. Over the years Panasonic has developed a number of miniature PIR products. A good example is the company’s PaPir sensor – combining state of the art miniaturisation with practical specifications that allows a whole host of new applications to be realised.
Figure 1: Panasonic’s PaPir sensor range covers detection distances from 2m through to 12m and beyond with versions to detect slight body movements, focused spot areas and general area movement
The company’s PaPir sensor range covers detection distances from 2m through to 12m and beyond with versions to detect slight body movements, focused spot areas and general area movement. This is to cover a wide area of internal building control. Detection of movement in corridors may require a long distance version whilst occupation of a room may call for a general area type. New applications such as repeated slight movement detection within a sheltered accommodation environment or spot check areas in doorways for counting purposes push the sensor to offer reliable detection within an often difficult environment. Special ultra-low power versions allow long life use in remote wireless detection systems with minimal current drain taken from the power source. The future of miniature PaPir sensors is secure but even so many new versions are continually being developed or improved. The company’s latest innovation in PIR motion sensors includes the new Dual Zone Lens type and “Approach Sensing Technology”, Horizontally Wide Detection type. Panasonic PIRs unique design concept goes from the production of the sensing devices to the internal signal processing, thus guaranteeing an optimal detection capability and high reliability. Panasonics original NaPiOn & new
PaPIR sensors all have a standard three pin footprint, two pins for power supply and one pin for output signal, the circuit design once approved can use any of the 71+ standard sensor variations depending on applications sensing/trigger requirements. This allows product designers to finalise hardware in reduced timescales and concentrate on the firmware/software offering of their application. Many projects succeed because Panasonic sensors allow for quick and easy product hardware development enabling engineers to work on the behavioural pattern modelling associated with their application.
Panasonic Electric Works UK
www.panasonic-electric-works.com/uk T: 01908 231555
/ ELECTRONICS
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