Image reading apparatus that guides document from common transport route to one of curved transport route and linear transport route, by controlling action of switching device, and image forming apparatus

An image reading apparatus comprising:

• a document tray;
• a common transport route;
• a curved transport route and a linear transport route branched from the common transport route;
• a switching device provided at a branch point between the curved transport route and the linear transport route;
• a document transport device that draws out a document from the document tray on which the document is placed, transports the document along the common transport route, and delivers the document transported along the common transport route to one of the curved transport route and the linear transport route, with the switching device;
• a first image sensor that reads an image of the document being transported along the curved transport route;
• a second image sensor that reads an image of the document being transported along the linear transport route;
• a trailing edge detector provided on the common transport route, to detect a trailing edge of the document;
• a multi feed detector provided on the common transport route, to detect whether multi feed of documents is occurring;
• a leading edge detector provided on the common transport route, at a position downstream of the trailing edge detector and the multi feed detector in a transport direction of the document, to detect a leading edge of the document;
• and
• a controller including a processor, and configured to (i) determine, when the processor executes a control program, a length of the document in the transport direction, on a basis of a detection time point that the leading edge detector has detected the leading edge of the document, a detection time point that the trailing edge detector has detected the trailing edge of the document, and a non-detection time point that a detection status of the multi feed detector has been switched to a non-detection state, and (ii) guide the document to one of the curved transport route and the linear transport route from the common transport route, according to the length of the document in the transport direction, by controlling an action of the switching device.