Image reading device for reading image of document, image forming apparatus, and image reading method

An image reading device comprising:

• a first document placement portion on which a document can be placed;
• a document feed portion including the first document placement portion and configured to feed the document placed on the first document placement portion, to a predetermined reading position;
• a size detection portion configured to detect a size of the document placed on the first document placement portion;
• a storage processing portion configured to store size information indicating the size of the document detected by the size detection portion, into a predetermined storage medium;
• a second document placement portion on which the document can be placed, the second document placement portion being different from the first document placement portion;
• an image reading portion configured to perform a reading process of scanning a read surface of the document placed on the second document placement portion, to read an image;
• a cover member configured to open/close between a closed attitude in which the cover member covers a sheet placement surface of the second document placement portion, and an open attitude in which the cover member is separated from the sheet placement surface, the cover member including the first document placement portion at a side opposite to an opposing surface opposing the sheet placement surface;
• an attitude detection portion configured to detect an attitude of the cover member;
• a first determination portion configured to determine, on a basis of a detection signal outputted from the attitude detection portion, whether a first operation of making the cover member in the closed attitude into the open attitude and then returning the cover member to the closed attitude has been performed in a period from a time when the size information is stored into the storage medium by the storage processing portion to a time when a predetermined standby time elapses, in order to determine whether the document has been placed on the second document placement portion;
• and
• a setting portion configured to, when the first determination portion determines that the first operation has been performed, set the size information stored into the storage medium by the storage processing portion, as size information to be used for the reading process by the image reading portion, wherein
• the storage medium has a first storage area in which size information inputted to the image reading device is stored as the size information to be used for the reading process by the image reading portion;
• and a second storage area in which the size information indicating the size of the document detected by the size detection portion is stored, and
• when the size information is stored into the second storage area, the setting portion preferentially sets the size information stored in the second storage area over the size information stored in the first storage area, as the size information to be used for the reading process by the image reading portion.