Patent ID: 7348586

Claim:
An exterior element sensor for use with a window that has an interior surface and an exterior surface, the window separating an exterior atmosphere from an interior atmosphere, comprising: a light source capable of emitting light; a sensing optical element including an incident optical element portion configured to allow the emitted light to enter into the window from the interior surface of the window and at an angle larger than a critical angle, and an emissive optical element portion configured to allow the emitted light that is reflected from the exterior surface of the window to exit from the window towards the interior atmosphere, wherein the sensing optical element is located adjacent an incident position of light on the interior surface of the window and an emissive position of light on the interior surface of the window to measure the amount of the light totally reflected from the exterior surface of the window and exiting from the window, thereby measuring an amount of exterior elements located on the exterior surface of the window, wherein the sensing optical element of the exterior element sensor further includes a connection portion having one end portion serving as the incident optical element portion and the other end portion serving as the emissive optical element portion, the one end portion and the other end portion both being convex in shape, and a central planar portion of the sensing optical element extends continuously from the one end portion to the other end portion to provide a substantially flat surface between the one end portion and the other end portion; a first photoreceptor located opposite to the emissive optical element portion such that it can receive the light that is totally reflected from the exterior surface of the window; and a second photoreceptor serving as an exterior light sensor located opposite to the connection portion and between the incident optical element portion and the emissive optical element portion.