Patent ID: 7498553

Claim:
An image reading device comprising: a plurality of light sources each of which illuminates a document surface as a target for reading with illuminating light of a color different from the other light sources; an image pick-up section that images light radiated from the plurality of the light sources and reflected on the document surface; a controlling unit that makes the plurality of the light sources emit light with any one of the plurality of the light sources as a reference light source so that light amounts of the light sources other than the reference light source are in a predetermined ratio with respect to a light amount of the reference light source; an adjusting unit that lowers a current value of a power source which makes the reference light source emit light when an amount of light imaged in the image pick-up section exceeds a threshold value as a predetermined upper limit value at the time only the reference light source illuminates a predetermined reference surface, so that the amount of light imaged in the image pick-up section is equal to or smaller than the threshold value; a first illumination unit that has a light transmission tube of a white type including the red LED, the green LED, and the blue LED as the light source, and illuminates the document surface from a direction inclining toward the document surface for a predetermined angle; and a second illumination unit that has an LED array including the yellow-green LED as the light source, and a spectral characteristic different from the first illumination unit, and illuminates the document surface from a direction substantially symmetrical to the first illumination unit with respect to a normal line to the document surface, and the controlling unit controls light emission of the light sources included in the first and the second illumination units.