Image forming device and image forming method which prevents misalignment between front end of formed image and front end of sheet

An image forming device that forms an image on a rotating image carrier, comprising:

• a feeder operable to cause a sheet to pass between a first rotating member for feeding the sheet and a separator pressed against the first rotating member in a pressed position, and a pair of second rotating members to transport the sheet fed from the first rotating member with the sheet held therebetween;
• a third rotating member that is pressed against the image carrier in a transfer position, transports the sheet that has been transported from the pair of second rotating members, with the sheet held between the third rotating member and the image carrier, and transfers the image formed on the image carrier onto the sheet;
• a first controller operable to relatively control timing when the image formation is started and timing when the pair of second rotating members start the sheet transport toward the transfer position;
• and
• a second controller operable, during the sheet transport, to suspend rotation of the first rotating member when a portion of the sheet passes the pressed position, the portion of the sheet being away from a rear end of the sheet by a predetermined distance L, wherein
• provided that a length of a first sheet size in a transport direction is greater than or equal to a length (M+L), where M is a distance from the pressed position to the transfer position on a transport path, and a length of a second sheet size in the transport direction is smaller than the length (M+L),
• the first controller determines whether the sheet has the first sheet size or the second sheet size, and in response to the first controller determining that the sheet has the second sheet size, the first controller performs at least one of delaying the start of the image formation and advancing the start of the sheet transport, by a predetermined time period as compared to when the sheet has the first sheet size.