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News Fraunhofer IMS Develops Wireless Window Sensors With EnergyHarvesting Technology (22/9/2011) Window contacts tell us which of a house"s windows are openor closed. Researchers have now developed a fail-safe system thatis particularly easy to use and needs no wiring or batteries. Thesensors harvest the energy they need to run from ambient radiosignals. It is 7:30 a.m. and high time she left the house; she mustn"tbe late for her 8 o"clock appointment. But the young ladystill feels the need to check that she closed all her windows,because the forecast is for thunderstorms that afternoon. Later, inthe car, she realizes that she forgot to check one of the roomswhen she went round the house. In situations like this, windowcontacts can make life easier and give peace of mind. These littleelectronic helpers are fitted onto window handles, and they cantell from the position of the handle whether the window is wideopen, tilted open or closed. They transmit this information to abase station, and the house"s occupants can then see at aglance which windows are open. Research scientists at the Fraunhofer Institute for MicroelectronicCircuits and Systems IMS in Duisburg have now developed a versionof this sensor arrangement that is particularly reliable and easyto use and which needs no wiring or batteries. "Our wirelesswindow contacts draw all their energy from ambient radiosignals," explains Dr. Gerd vom Bögel, a scientist atthe IMS. Until now, wireless models have been reliant on eitherbatteries or solar cells, but both of these approaches havedrawbacks. Batteries need to be changed regularly to keep windowcontacts operational. Solar-powered systems avoid this problem, butthey too are liable to fail: all it takes is for the sunlight to beblocked by something casting an unintentional shadow over the solarcell. Solar systems are also aesthetically less pleasing becausethey cannot be tucked away in a dark corner of the window. Whichleaves the classic setup: window contacts with cable connections.Such systems have been on the market for years. The main argumentagainst these is the effort it takes to install them – quiteapart from the fact that it is often impossible to retrofit them toexisting buildings. The new system, however, can be fitted with little effort –and they can be positioned very discreetly. Aside from windowcontacts, each room is equipped with a room controller. Thistransmitter module not only receives the data from individualwindow contacts, it also actively provides the sensors with energyvia its radio signal. The room controller also has the function ofpassing the sensor data on to a central base station in thebuilding, from which users can query the status of all windows.Alternatively, the system can be configured to permit remotequerying, for instance from a user"s smartphone. The onlyprerequisite for this is a DSL connection for the base station. Energy management was the issue which caused the most headachesduring development. "Room controllers, too, have to complywith certain limits on the strength of their radio output. Thismakes it particularly tricky to get enough energy to all the windowcontacts in bigger rooms," vom Bögel points out."But we have made sure all the sensor modules, antennas andcomponents are so finely tuned to each other that the system worksreliably even over considerable distances." The IMS research scientists have already constructed an initialprototype, and they know which way they want to head next: They arehoping to integrate other types of sensor into the system along thesame lines – to regulate room temperature, for example. Atthe moment, thermostats are generally fitted somewhere just insidethe room. If a door is open, the temperature by the door will belower than in the middle of the room. As a result, the thermostatwill then unnecessarily regulate the temperature upwards. The newsystem would allow a temperature sensor to be placed unobtrusivelyprecisely where a particular temperature is desired – forinstance on the display cabinet by the dining room table. www.fraunhofer.de Visit our featured links Visit our sponsors and showcases. We are high quality suppliers, our products such as Hydraulic Crawler Crane Manufacturer , Waterwell Drilling Rig for oversee buyer. To know more, please visits drilling rigs suppliers.
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