Patent ID: 8515329

Claim:
An image forming apparatus comprising: an image forming unit that performs image forming processing on a sheet; a sheet feed unit having an arrangement for placing a sheet thereon and configured to feed the sheet to the image forming unit; a first sensor configured to detect first information indicative of a first size in a first direction of a sheet placed on the sheet feed unit; a second sensor configured to detect second information indicative of a second size in a second direction perpendicular to the first direction of a sheet placed on the sheet feed unit; a sheet sensor configured to detect presence or absence of a sheet on the sheet feed unit; a monitoring unit configured to monitor the sheet sensor so as to check whether the sheet sensor has detected presence of a sheet; a timer unit configured to begin counting a first time from a time point at which the sheet sensor detects presence of a sheet; an identifying unit configured to identify, when the first time exceeds a first set time, a size of the sheet based on the first information and the second information; and a control unit configured to control the sheet feed unit not to start feeding the sheet to the image forming unit until the identifying unit identifies the size of the sheet, wherein the monitoring unit monitors whether the second information output from the second sensor has changed or has not changed, the monitoring unit monitors whether the first information output from the first sensor has changed or has not changed, the timer unit begins counting a second time from a time point at which the monitoring unit determines that both the first information and the second information have not changed, and the identifying unit tentatively identifies a tentative size of the sheet based on at least one of the first information and the second information when the second time exceeds a second set time.