Image reading device and image forming apparatus for detecting dirt at a document reading position

An image forming apparatus comprising an image reading device and an image forming section,

• the image reading device comprising:
• a housing forming an outer covering of the image reading device;
• a document conveyance section including a document loading chute and configured to convey an original document placed on the document loading chute;
• an original glass plate allowing the original document being conveyed from the document conveyance section to pass thereover;
• a reading unit including a light-emitting part and a light-receiving part, the light-emitting part including first light source, second light source, and third light source and configured to emit light toward the original document at a predetermined document reading position, the light-receiving part being configured to receive light reflected on the original document;
• an operation control section configured to control a light emitting operation of the light-emitting part;
• and
• a foreign matter detecting section configured to detect a foreign matter on the original glass plate,
• wherein the housing is provided with a hollow capable of letting part of the light emitted from the light-emitting part out of the image reading device, and
• the operation control section is further configured to, when the foreign matter detecting section detects the foreign matter on the original glass plate, allow the light-emitting part to emit light of a different color from the light emitted during reading of the original document, and
• the image forming section is configured to form an image on a recording paper sheet based on image data read by the image reading device.