Patent ID: 8842303

Claim:
An image reading device, comprising: a light source that includes a first block and a second block arranged alternately, both blocks including a plurality of light-emitting elements arranged linearly, the first block and the second block lighting independently, and the light-emitting elements in a same block of the first block and the second block lighting at a same time; a scanning unit that scans a document by irradiating the document with light from the light source; a lighting control unit that lights one of the first block and the second block of the light source and then lights the other; a peak level acquiring unit that acquires a peak level of scanned data of each of the first block and the second block while the blocks are lit by the lighting control unit; and an abnormality determining unit that determines that the first block is abnormal when the peak level of the first block becomes equal to or smaller than a given value, and determines that the second block is abnormal when the peak level of the second block becomes equal to or smaller than the given value, wherein the peak level is the scanned data of a light-emitting element positioned at a center of the corresponding first block and second block, and a light-emitting element positioned at an end of the first block is provided so that an emitted light area thereof does not reach the light-emitting element positioned at the center of the adjacent second block, and a light-emitting element positioned at an end of the second block is provided so that an emitted light area thereof does not reach the light-emitting element positioned at the center of the adjacent first block.