Patent ID: 7130077

Claim:
A document reading apparatus for reading both sides of a document sheet by two image reading units at an equal reading speed, said apparatus comprising: a first image reading unit for reading one side of the document sheet; a second image reading unit for reading another side of the document sheet; a first speed changing unit for writing into a line buffer the image data read by the first image reading unit at the same speed as the reading speed of the first image reading unit, and reading the image data from the line buffer at double the reading speed; a second speed changing unit for writing into another line buffer the image data read by the second image reading unit at the same speed as the reading speed of the second image reading unit, and reading the image data from the line buffer at double the reading speed; and an image synthesizing unit for synthesizing a first image data from the first speed changing unit and a second image data from the second speed changing unit in a main scanning period of one of the two image reading units.