Sensor zur Detektion von Feuchtigkeitstropfen und/oder Schmutzpartikeln auf einer Scheibe und Verfahren zum Betreiben eines solchen Sensors

摘要

The invention relates to a sensor (1) for detecting humidity drops (7) and/or dirt particles (8) on a glass surface (2), especially a windscreen of a motor vehicle. The sensor (1) is provided with at least one emitting element (3) for emitting optical beams (4) onto the glass surface. The sensor is also provided with at least one receiving element (10) for receiving at least a portion of the beams (9) which are reflected by the humidity drops (7) and/or the dirt particles (8) and for generating a receiving signal (11) which depends upon the received beams (9). The sensor is further provided with evaluation means for evaluating the receiving signal (11). The invention also relates to a method for operating such a sensor (1). The aim of the invention is to reduce fabrication costs for such a sensor (1) and to enable digitalisation of the receiving signal (11) of the sensor (1) with a sufficiently high resolution and dynamic. The or each emitting element (3) emits optical beams (4) in a temporally successive manner, whereby said beams have different intensities. The evaluation means allocate the intensities of the emitted optical beams to the receiving signal (11). The intensities are considered during evaluation of the receiving signal (11).