Single-element weather sensor for automatic windows

The thermal impedance of a self-heating probe gives information about the inside structure, the temperature distribution and the environment conditions in which the probe works. In case of large temperature dependencies of the resistor, sufficiently high periodic power supply causes a delayed heating of the resistor and results in a periodic change of its temperature T and therefore resistivity and power P. The evaluation of the mean value and expansion of the measured (T,P)-characteristics allows various sources of influence like ambient temperature, wind, rain drops or snow on the device´s surface to be separated and delivers explicit information about the wind velocity and the presence of rain or snow and ice and as well as about the surrounding temperature. This information is sufficient to trigger an impulse to an automatically inclined window to be closed in case of strong wind or rain or snow fall. Prototype sensors have been developed and evaluated with satisfactory results.