Patent ID: 8824024

Claim:
An image reading device comprising: a moving unit configured to make relative movements of a sheet with respect to a predetermined reading position to move the sheet in a predetermined direction; a reading unit configured to read an image from the sheet disposed at the predetermined reading position, the reading unit including: a light-emitting unit configured to emit a plurality of lights of different colors toward the predetermined reading position; and a light-receiving unit configured to receive a light; an opposing member disposed opposite the reading unit with the predetermined reading position interposed therebetween, a distance between the reading unit and the opposing member being longer than a distance between the reading unit and the predetermined reading position; and a controller configured to: control the light-emitting unit to emit the plurality of lights and control the light-receiving unit to receive the plurality of lights, thereby acquiring an intensity of each of the plurality of lights received by the light-receiving unit; and determine whether or not a sheet is present at the predetermined reading position, the controller determining that the sheet is not present when relationships among intensities of the plurality of lights are same as the first intensity relationships, the controller determining that the sheet is present when relationships among intensities of the plurality of lights are different from the first intensity relationships, the first intensity relationships being defined by intensities of the plurality of lights that are emitted from the light-emitting unit, reflected by the opposing member, and received by the light-receiving unit, the first intensity relationships being different from second intensity relationships, the second intensity relationships being defined by intensities of the plurality of lights that are emitted from the light-emitting unit, reflected by a sheet present at the predetermined reading position and received by the light-receiving unit.