Bar-shaped light guide, illumination unit and image-scanning device

摘要

A bar-shaped light guide is provided to allow its emitting surface to be exposed from a white casing and is provided with a pattern for scattering and reflecting the light on a bottom surface opposite to the emitting surface. This pattern is formed by a white paint or minute irregularities. Further, an end face of the bar-shaped light guide opposite to the incident side is made cube-corner shaped. In other words, the end face is made chevroned by mirror-finished flat surfaces. These flat surfaces are tilted at such an angle that an incident angle theta of the rays of light traveling through the bar-shaped light guide parallel to the longitudinal direction of the bar-shaped light guide is smaller than a critical angle.