| 摘要 |
A document reading unit (150) includes an original document table (155), a moving irradiation unit (152) having multiple block light sources (152a) moving in a sub scanning direction while irradiating an original document (MS), an image sensor (153) receiving reflected light, and a controller (170) that starts a length specifying operation with the moving irradiation unit (152) located at a position facing the original document (MS), sequentially turns on the block light sources (152a), obtains an amount of reflected light under lighting conditions of each block light sources (152a), and determines the length of the original document (MS) in the main scanning direction. While the moving irradiation unit (152) is moving in the sub scanning direction, the image sensor (153) receives the reflected light on a region of the original document (MS) in the sub scanning direction under each lighting condition during the length specifying operation. |
