Light guide and line illuminating device

Abstract

A light guide 1 is provided at the reverse side thereof with triangular uneven surfaces 1b at a predetermined pitch. The uneven surfaces 1b are integrally formed with the light guide 1 when the latter 1 is injection-molded. Incident light from a light incident plane is caused to be totally reflected within the light guide and to spread in a main scanning direction (the longitudinal direction), wherein the light reaching the uneven surfaces 1b is scattered and caused to be totally reflected at the uneven surfaces 1b. The light scattered and totally reflected at the uneven surfaces 1b is emitted from an emission plane. Intensity of light in the main scattering direction can be made uniform by lengthening the uneven surfaces 1b as the uneven surfaces extend from the light incident plane. A position where the light intensity becomes maximum in a sub-scanning direction can be changed by adjusting an angle between the ridgeline of the uneven surfaces 1b and the sub-scanning direction, and distributed characteristics of the light intensity in the sub-scanning direction can be also changed.

Dependencies are inferred from the claim text.