Deposit detector for outer surface of pane - uses radiation source and receiver at right angles to pane esp. windscreen to detect rain drops

摘要

A system for detecting a coating on an outer surface of a pane (21), esp. moisture (26), uses at least one optical radiation source, the radiation of which falls vertically on an incident surface of a radiation conducting body (16) to arrive at a limit point (17) reflecting the radiation, and at a specified angle in the panel (21) which leads to a toal reflection of radiation at the outer clean pane surface within a detection zone to be taken from the radiation conducting body to act on a radiation receiver (25). The radiation source (11) and receiver are arranged on an axis rrunning vertical to the pane surface (23). A reflector (13) is aligned rotationally symmetrical to this axis in the beam path between the radiation source and the light incidence surface of the radiation conducting body. The reflector (13) and the radiation conducting body are positioned in such as way that the radiation (12) from the radiation source enters the radiation conducting body at specified solid angle ranges and establishes the detection zone corresp. to the solid angle ranges on the outer surface. ADVANTAGE - Information signal/interference signal ratio of known unit, e.g. rain sensor, improved.