Patent ID: 8914197

Claim:
An optical raindrop detector, comprising: a light source; a light control unit configured to control the light source to emit light with a first brightness value and a second brightness value; a light guide comprising an incident surface, a detection surface and an ejection surface, wherein the light source is configured to emit incident light into the light guide via the incident surface and a plurality of microstructures are formed on the ejection surface configured to reflect the incident light to become scattered light toward the detection surface; an image sensor configured to receive reflected light formed by raindrops in front of the detection surface reflecting the scattered light to penetrate the light guide and eject from the ejection surface, and to generate a first image frame corresponding to the first brightness value and a second image frame corresponding to the second brightness value; and a processing unit configured to calculate a differential image of the first image frame and the second image frame and to identify rain intensity according to the differential image.