Patent ID: 7388691

Claim:
An apparatus comprising: a light-emitting module comprising a first light source having a first illuminating range capable of illuminating a front surface of a document being scanned, and a second light source having a second illuminating range and capable of illuminating a back surface of said document, wherein said first light source comprises a first light element configured to emit light of a first color and a second light element configured to emit light of a second color that is different from the first color, and wherein said second light source comprises a third light element configured to emit light of a third color and a fourth light element configured to emit light of a color that is different from the third color; a first light sensor having a first scanning range and capable of scanning said front surface of said document; and a second light sensor having a second scanning range and capable of scanning said back surface of said document; wherein said first scanning range does not overlap with said second illuminating range and said second scanning range does not overlap with said first illuminating range; and wherein said apparatus is configured to control a timing of said scanning such that said first light source and said second light source do not emit light from light elements of the same color simultaneously.