Patent ID: 7429745

Claim:
A sensor device for detecting a wetting on a windshield comprising: a light emitter that emits a reference light; and a reflective device for reflectively redirecting, toward the windshield, reference light emitted from the light emitter along a first light path; a light receptor for receiving reference light from the light emitter, wherein the reference light in the first light path is redirected by the reflective device toward the windshield and is then redirected by the windshield to the light receptor, wherein the reference light in the first light path is redirected by an outer side of the windshield after being reflected by the reflective device, and wherein reference light emitted from the light emitter along a second light path passes to the windshield without reflection by the reflective device and is then redirected by the outer side of the windshield to the light receptor; and a determination unit that determines wetting on the windshield based on an amount of the light received by the light receptor.