DOCUMENT READER AND IMAGE FORMATION APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a document reader capable of detecting the size of a document whatever color and pattern the document has without raising the cost of the document reader.SOLUTION: A document reader detects a main scanning-directional size of a document in a process of closing a document cover when performing size detection of the document placed on a document platen. Specifically, a light source irradiates a platen surface with light when the document cover reaches a predetermined specific angle (S4), and an imaging element reads light from the document platen a plurality of times in predetermined line read cycles during a period of light irradiation by the light source (S5). The document reader detects the main scanning-directional size of the document and/or whether the document is present on the document platen on the basis of whether density change is caused in a sub scanning direction of image data read by the imaging element (S6).