Windshield wiper controller, optical raindrop detector and detection method thereof

Abstract

There is provided an optical raindrop detector including a light source, a light guide, an image sensor and a processing unit. The light source alternatively emits light with different brightness values. The light guide has an incident surface, a detection surface and an ejection surface, wherein the light source emits incident light into the light guide via the incident surface, and a plurality of microstructures are formed on the ejection surface to reflect the incident light to become scattered light toward the detection surface. The image sensor receives 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 generates image frames corresponding to the different brightness values of the light source. The processing unit calculates differential images of the image frames to accordingly identify rain intensity.