Water drop detection sensor

摘要

A water drop detection sensor for detecting water drops W adhering to or present upon a windshield by detecting changes in an amount of reflection light and also for detecting the ambient brightness outside of a car or other vehicle, comprising: a windshield 2; a light emitting means 5 for introducing detection light into the windshield 2; and a light receiving means 6 for detecting reflected detection light. The reflected detection light is reflected by total internal reflection within the windshield 2, and the light emitting means 5 and said light receiving means 6 are provided on the windshield 2.