To provide an illumination device which uses a white LED light source and a rod lens, suppresses color non-uniformity inside an illumination area within an allowable range, is reduced in size and cost, and has high illuminance and also to provide an image reading apparatus and image forming apparatus.
An image reading apparatus is provided with an illumination device 18, which illuminates an illumination area on a document surface of a document, and an image reader for reading reflection light from the illumination area. The illumination area consists of an illumination area width A and a predetermined illumination area length. The illumination device includes: light sources of a plurality of white LEDs 40 disposed linearly in a direction of the illumination area length; and a condenser for converging light emitted from the plurality of white LED light sources in a direction of the illumination area width. The condenser is a rod lens having a diameter D disposed in such a way that the axial direction thereof is matched with the direction of the illumination area length, and satisfies D≥2.5A.
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ONO NOBUAKI
TAKAURA ATSUSHI
MIYAGAKI KAZUYA
SAKURAI YASUO
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