Illumination apparatus and image reading apparatus

An image reading apparatus, comprising:

• an illumination apparatus configured to illuminate a surface to be illuminated from a first side and a second side different from the first side, the illumination apparatus comprising:
• a light guide;
• and
• a reflecting member,
• wherein the light guide comprises:
• an incident surface into which a light beam from a light source arranged in a one-dimensional direction enters;
• a side surface for totally reflecting a portion of the light beam which enters the incident surface;
• a reflecting surface arranged on an opposite side of the incident surface with respect to the side surface;
• a first exit surface for causing a light beam reflected by the reflecting surface to exit as a converging light beam, the first exit surface having a condensing action in a plane orthogonal to the one-dimensional direction, the converging light beam emitted from the first exit surface illuminates the surface to be illuminated as a light beam from the first side;
• and
• a second exit surface for causing a light beam from the light source, which is not reflected by the reflecting surface, to exit as a converging light beam, the second exit surface having a condensing action in the plane orthogonal to the one-dimensional direction, and
• wherein the reflecting member is configured to reflect the light beam from the second exit surface to the surface to be illuminated as a light beam from the second side;
• an original table;
• a reading unit;
• and
• an image forming optical system configured to image the light beam reflected by a surface of an original as the surface to be illuminated on the reading unit,
• wherein the light guide comprises a separating boundary between the first exit surface and the second exit surface, the separating boundary defining a concave portion.

A light guide comprising:

• an incident surface, elongated in a first direction, configured to allow a light beam to enter the light guide;
• a side surface configured to totally reflect the light beam from the incident surface;
• a reflecting surface configured to reflect the light beam from the side surface;
• a first exit surface configured to allow the light beam from the reflecting surface to exit;
• and
• a second exit surface configured to allow a light beam from the incident surface, which is not reflected on the reflecting surface, to exit,
• wherein the first and second exit surfaces are disposed adjacent to each other and have a condensing function in a first section perpendicular to the first direction, and
• wherein a separating boundary between the first exit surface and the second exit surface defines a concave portion.

An illumination apparatus which illuminates a surface to be illuminated, comprising:

• a plurality of light sources arranged in a first direction;
• an incident surface configured to allow light beams from the plurality of light sources to enter;
• a side surface configured to reflect the light beams from the incident surface;
• a reflecting surface configured to reflect the light beams from the side surface;
• a first exit surface configured to allow the light beams from the reflecting surface to exit;
• and
• a second exit surface configured to allow light beams from the incident surface, which are not reflected on the reflecting surface, to exit,
• wherein the first and second exit surfaces are disposed adjacent to each other and have a condensing function in a first section perpendicular to the first direction, and
• wherein a separating boundary between the first exit surface and the second exit surface defines a concave portion.