Measuring unit for a rain sensor for detecting of moisture on a surface, moisture sensor, as well as a method for measuring the degree of moisture on the surface

摘要

The present invention relates to a measuring unit for a rain sensor for detecting of moisture on a surface and for outputting a periodic output signal, with a radiation receiving means, in order to provide a of the degree of moisture on the surface to receive radiation which is dependent on, and with a measuring device, which is connected with the radiation receiving means and the comprises a capacitor with one of the proportion of the received radiation dependent measurement current can be recharged, wherein said measuring device is constructed in such a way that the capacitor to a periodically from a predetermined reference potential can be charged to a specific potential and then to be discharged, and in order to output a periodic output signal whose period duration is determined by the charging and discharging, and depends on the measure of the received radiation.