this invention discloses an illumination device for use in image reading applications . the illumination device comprises a light guide and a light source attached to one end of the light guide , which consists of a rod - shaped body with two end light reflectors made of metal clips . the two lateral surfaces of the light guide causes total internal reflection of light rays impinging upon the surface from within the light guide . the curved top surface of the light guide serves the function of focusing . the narrow bottom surface along the light guide reflects the light with a series of highly reflective paint stripes of varying widths applied upon it . the light source comprises a plurality of light emitting elements and at least a center of the light emitting elements is placed along a normal line passing through a center of the reflection area when viewed in a longitudinal direction of the light guide . a light beam applied from the light source is scattered and reflected by a scatter and reflection area of the light guide to illuminate an original document .