Patent ID: 8368974

Claim:
An image reading apparatus comprising: a light source that is configured to light up at luminance associated with supplied electric current; an electric-current supplying section that is configured to supply the light source with electric current; a control section that is configured to control the electric-current supplying section; a reading section that is configured to read at least one sheet of an original document on which light from the light source is irradiated and to generate image data; and a determining section that is configured to determine whether a change in the electric current flowing through the light source is large, based on a predetermined criterion, during a period when the reading section reads the at least one sheet of the original document, wherein, when the reading section reads the at least one sheet of the original document, the control section is configured to increase electric current supplied to the light source if the determining section determines that the change is large relative to electric current supplied to the light source when the determining section determines that the change is small, wherein the reading section comprises a line sensor that is configured to read the original document one line at a time by moving relative to the original document, and wherein the control section is configured to control the electric-current supplying section such that a product is constant regardless of whether the determining section determines that the change is large or small, the product being a magnitude of the electric current supplied to the light source multiplied by a time period of lighting of the light source per line.