Patent ID: 6239444
Filing Date: 2001-05-29
Classification: B60S,Y10S

Abstract:
A water drop detection device for a transparent substrate, for detecting an amount of water drops adhering to or present upon a surface of said transparent substrate, comprising:a light emitting means for guiding light into said transparent substrate so as to cause internal reflection to occur upon interior surfaces of said transparent substrate, and including a driver circuit therein; anda light receiving means for receiving the light reflected within said transparent substrate, wherein said light emitting means comprises:a light emitting element; anda receiving light sensing element, located in close proximity to the light emitting element, detects light output from said light emitting element, and further comprising:means for modulating the light output from said light emitting element with a predetermined frequency, wherein only the modulated component is detected by said light receiving means;means for separating a signal corresponding to the modulated component from the output signal of said receiving light sensing element; andmeans for controlling an output of light emission of said light emitting element at a desired value by feeding the separated signal back to the driver circuit of said light emitting element.