Patent ID: 8908239

Claim:
An image reading device comprising: an illumination unit that has a light guide body guiding light of a light source to an object to be read and illuminates the object; and an image forming optical device that is disposed parallel to the light guide body, has a lens array provided with an incidence surface in which a plurality of lens surfaces are arranged in the same direction as a longitudinal direction of the light guide body, and condenses reflected light from the object which is incident on the incidence surface, thereby forming an erect equal-magnification image on a sensor, wherein the light guide body is formed of a transparent member, and includes a reflecting surface in which a reflection structure reflecting the light of the light source, which is incident into the light guide body, is formed, and a light emitting surface from which the light reflected by the reflecting surface is emitted toward the object, wherein the light guide body tapers in the longitudinal direction toward the light emitting surface to reduce the size of the light emitting surface, wherein the lens array tapers toward the incident surface to reduce the size of the incident surface, and wherein the illumination unit contacts the image forming optical device in an area where a tapered portion of the light guide body faces a tapered portion of the lens array.