Patent ID: 8194295

Claim:
A duplex scanning apparatus for scanning an image of a document, said duplex scanning apparatus comprising: an automatic document feeder for transporting said document, said automatic document feeder comprising: a document feeder case; a scanning glass plate disposed in a first scan region; and a first light source disposed beside said first scan region for emitting a first light beam, which is projected on a first side of said document; and a flatbed image scanner for scanning said document, said flatbed image scanner comprising: a scanner case disposed under said document feeder case, and comprising a first perforation and a second perforation, wherein said first perforation is arranged under said first scan region, and said second perforation is arranged under a second scan region; a glass platform covering said first perforation and said second perforation; a second light source disposed beside said second scan region for emitting a second light beam, which is projected on a second side of said document; and a scanning module for scanning said document, and comprising a movable reflective mirror, a plurality of fixed reflective mirrors for reflecting said first light beam or said second light beam, an optical sensing module for receiving said first light beam or said second light beam, and a transmission mechanism connected with said movable reflective mirror for rotating said movable reflective mirror by a first angle or a second angle, wherein said first light beam is reflected by said movable reflective mirror when said movable reflective mirror is rotated by said first angle, and said second light beam is reflected by said movable reflective mirror when said movable reflective mirror is rotated by said second angle, wherein the optical path length of said first light beam is substantially equal to that of said second light beam.