Illumination device

Abstract

A transparent, generally wedge-shaped linear illuminator is used to provide a uniform level of illumination suitable for performing various functions in a reproduction device. One function is to provide uniform illumunination of a charged surface so as to selectively erase charge on said surface. Another is to illuminate a document in an illumination plane. In a specific embodiment, the illuminator consists of a glass or plastic body having a first sector formed with parallel sides and a second sector having a wedge-shaped configuration. Light is introduced into the first sector and is coupled along the length of the second sector by internal reflection. As the distance between the slope and base surfaces of the wedge sector decreases in the direction of the wedge end, the angles of incidence of the incident light decrease proportionately. As the angles made by internally reflecting light drop below the critical angle of the illuminator, the light begins to exit the body at the base surface providing a uniform band of illumination along the linear length of the wedge sector. Depending upon the output power of the illumination source, the light may be used for charge erase or document illumination purposes. In one variation, reflective segments surround the inclined wedge portions of the illuminator to redirect the light back into the member thereby improving efficiency.