Patent ID: 7057778

Claim:
An image reading apparatus comprising: a line sensor which reads an image and outputs an image signal corresponding thereto; a light source: a light guide member which illuminates an original in a line shape along a first reading direction which corresponds to a longitudinal direction of said line sensor, wherein said light source is arranged on an end surface of said light guide member, in the longitudinal direction thereof, said light guide member has a light emitting surface for illuminating the original in the line shape in the first reading direction of said line sensor and a reflection portion which is arranged on a surface different from said light emitting surface and along the first reading direction across the length of said light guide member so as to diffuse and/or reflect the light from said light source along the first reading direction, and said light guide member is arranged relative to said light source so that a line normal to an elongated area of said light guide member and passing through a center of the width of said reflection portion at a portion thereof which is relatively close to said light source is offset from a line extending in the longitudinal direction of said light guide member and passing through the center of said light source, when viewed from said light source; a drive unit which moves a relative position between the image illuminated along the first reading direction by said light guide member and said line sensor, in a second reading direction different from the first reading direction; and a control circuit which controls said light source, said line sensor and said drive unit, wherein said reflection portion is arranged across the length of said light guide member so that at least the portion of said reflection portion is arranged so as to be offset from a center of a cross-section of said light guide member.