9. The image forming apparatus according to claim 6 , comprising a conveying roller pair having rotation axes extending in the direction orthogonal to the document feeding direction, the conveying roller pair being a pair of conveying rollers with which a leading edge of a document that has passed through the first and second document detectors is brought into contact by the document conveying unit, the conveying roller pair configured to feed the document whose leading edge has been brought into contact therewith while holding the document in the nip between the conveying rollers.
9. The image forming apparatus according to claim 6 , comprising a conveying roller pair having rotation axes extending in the direction orthogonal to the document feeding direction, the conveying roller pair being a pair of conveying rollers with which a leading edge of a document that has passed through the first and second document detectors is brought into contact by the document conveying unit, the conveying roller pair configured to feed the document whose leading edge has been brought into contact therewith while holding the document in the nip between the conveying rollers. 10. The image forming apparatus according to claim 9 , wherein the conveying roller pair is a registration roller pair configured to regulate the timing of feeding a document.