Light guide and line illuminator

An image reader comprising an illuminating unit including:

• an elongate light guide having an end face on a longitudinal end thereof, an elongate emitting face extending longitudinally of the guide and an internal face extending longitudinally of the guide, the light guide emits lights incident on the end face from the emitting face in a line shape, while the lights are reflected by the internal face, wherein a sectional shape of the light guide in a direction orthogonal to the longitudinal direction of this light guide has two opposite parabolas or two oval curves, a line segment connecting the focal points of said two opposite parabolas or the focal points of said two oval curves, and a line segment corresponding to said emitting face, a light source on an end face of the light guide, a lens array for converging on a light receiving element lights radiated from the illuminating unit toward a document and reflected by the document or transmitted by the document, and a box housing the illuminating unit and the lens array.

An image reader comprising an illuminating unit including:

• an elongate light guide having an end face on a longitudinal end thereof, an elongate emitting face extending longitudinally of the guide and an internal face extending longitudinally of the guide, the light guide emits lights incident on the end face from the emitting face in a line shape, while the lights are reflected by the internal face, wherein a sectional shape of the light guide in a direction orthogonal to the longitudinal direction of this light guide has two opposite parabolas or two oval curves, a line segment connecting the focal points of said two opposite parabolas or the focal points of said two oval curves, and a line segment corresponding to said emitting face, and a light source on an end face of the light guide, a lens array for converging on a light receiving element lights radiated from the illuminating unit toward a document and reflected by the document or transmitted by the document, and a box housing the illuminating unit and the lens array, wherein a side face of the light guide on a side of said emitting face is substantially parallel to the optical axis.