Light guide and image reading apparatus

An image reading apparatus comprising two light guides, a first light guide and a second light guide,

• wherein each of the two light guides comprises:
• a rod-shaped light guide main body extending in a longitudinal direction;
• a first end face that is an end face of the light guide main body along a transverse direction intersecting the longitudinal direction;
• a light scattering pattern formed in the light guide main body along the longitudinal direction, the light scattering pattern scattering light that enters the light scattering pattern from the first end face and is guided inside the light guide main body;
• a light emission surface portion formed on the light guide main body along the longitudinal direction, the light emission surface portion being a surface from which the light scattered at the light scattering pattern is emitted to outside the light guide main body after being reflected on a wall surface of the light guide main body;
• and
• a paraboloidal surface having a parabolic cross section taken along the transverse direction, the paraboloidal surface being the wall surface contiguous with the light emission surface portion,
• wherein the light guide main body of the first light guide and the light guide main body of the second light guide are arranged to face each other outwardly directing the paraboloidal surfaces on a cross section along the transverse direction;
• wherein the image reading apparatus further comprises:
• a lens array extending in the longitudinal direction disposed between the light guide main body of the first light guide and the light guide main body of the second light guide, the lens array converging the light emitted from the light emission surface portion and reflected by an object to be read;
• and
• a light receiving element array, extending in the longitudinal direction, to receive the light converged by the lens array,
• wherein each of the light emission surface portions comprises:
• a first light emission surface that is disposed near the first end face in the longitudinal direction;
• and
• a second light emission surface contiguous with the first light emission surface in the longitudinal direction,
• wherein a width of the first light emission surface in the transverse direction is shorter than a width of the second light emission surface in the transverse direction,
• wherein the light scattering pattern is formed at a focal point of the paraboloidal surface on the cross section along the transverse direction,
• wherein the light emission surface portion on the cross section along the transverse direction is a straight line, and
• wherein a normal direction of the straight line and an optical axis direction of the light reflected on the paraboloidal surface are parallel.