Paper feeding device

A document feeding device for an image-forming machine, to feed a document in a document-feeding direction into the image-forming machine from a document tray mounted on the image-forming machine, said document feeding device comprising:

• a preliminary feed roller unit;
• first mounting means rotatably mounting said preliminary feed roller unit on the image-forming machine adjacent the downstream end of the document tray, with respect to the document-feeding direction, when the document tray is mounted on the image-forming machine, while permitting said preliminary feed roller unit to freely move up and down with respect to the document tray;
• a second feed roller unit;
• second mounting means rotatably mounting said second feed roller unit on the image-forming machine downstream of said preliminary feed roller unit, with respect to the document feeding direction;
• drive means responsive to presence of a stack of one or more documents on the document tray for rotating said preliminary feed roller unit to feed the top document of the stack in the document-feeding direction from the document tray toward said second feed roller unit;
• and
• a guide member mounted on the image-forming machine and including means responsive to rotation of said preliminary feed roller unit during feeding of documents from the stack for moving said preliminary feed roller unit up with respect to the document tray, against the downward force of gravity,
• whereby upon placement of a stack of one or more documents on the document tray, said preliminary feed roller unit is moved up in a substantially horizontal position and rotated to feed the top document of the stack toward the image-forming machine and into contact with the second feed roller regardless of the height of the stack of documents.