Patent ID: 8367997

Claim:
An image reading device comprising: a light source comprising a plurality of light-emitting elements that are arrayed along a predetermined direction, the plurality of light-emitting elements emitting illumination light and being grouped into a plurality of groups, each group having a predetermined first number of adjacent light-emitting elements; a detection unit that detects light amounts of illumination light, the illumination light being emitted from the plurality of light-emitting elements and reflected by a reference plate positioned on an opposite side of a platen glass from the light-emitting elements; a derivation unit that derives difference amounts for each group of light-emitting elements between a pre-defined reference value and an average value of light amounts detected by the detection unit for the group; an adjusting unit that, on the basis of the difference amounts derived by the derivation unit, adjusts light amounts per group of light-emitting elements such that the average value becomes the reference value; and a memory that stores, in correspondence with the difference amounts, adjustment amounts for making the average values be the reference value, wherein the adjusting unit reads out from the memory the adjustment amounts that correspond to the difference amounts derived by the derivation unit, and adjusts the light amounts per group of light-emitting elements by using the read-out adjustment amounts, wherein the memory stores first adjustment amounts that are set at a first interval that corresponds to difference amounts of magnitudes outside of a predetermined range and second adjustment amounts that are set at a second interval that is narrower than the first interval and that corresponds to difference amounts of magnitudes within the predetermined range, and wherein in a case in which magnitudes of the difference amounts are within the predetermined range, the derivation unit derives subdivision difference amounts that are difference amounts between subdivision average values and the reference value by using, as the average values, the subdivision average values that average light amounts per predetermined second number of adjacent light-emitting elements obtained by dividing each of the groups of light-emitting elements into a plurality of subdivisions, and the adjustment unit reads out from the memory the second adjustment amounts that correspond to the subdivision difference amounts derived at the derivation unit, and adjusts the light amounts per subdivision by using the read-out second adjustment amounts.