Patent ID: 7027194

Claim:
An image reading apparatus for reading images on two surfaces of a document transferred by an automatic document feeder one by one, comprising: a document detection sensor for detecting the document transported by the automatic document feeder; a first image sensor to read an image on one surface of the document; a second image sensor to read an image on the other surface of the document; and a control device connected to the first and second image sensors and the document detection sensor, said control device controlling the first image sensor and the second image sensor to take images based on a situation that the document detection sensor detects a leading edge of the document, said control device having counter means for counting time when the document detection sensor detects the leading edge of the document, and memory means for storing image data, said control device operating the counting means to start counting after the document detection sensor senses the leading edge of the document, starting to take the image data as effective data from the first image sensor when a counter value of the counter means reaches a predetermined first counter number, and starting to take image data from the second image sensor to the memory means when the counter value of the counter means reaches a predetermined second counter number different from the first counter number.