Patent ID: 7916364

Claim:
An image reading device comprising: a clock generator configured to generate a first clock signal having a first cycle and a second clock signal having a second cycle shorter than the first cycle; an image sensor configured to detect an image formed on a document to generate an image signal; a plurality of switches including a first switch and a second switch, the image signal being inputted into the first switch and the second switch by rotation, the first switch and the second switch being capable of switching to simultaneously or alternately output the image signal in synchronization with the first clock; a reader configured to read the image signal outputted from the first switch and the second switch; a first controller configured to control the first switch to output the image signal to the reader during a first period and to control the second switch to output the image signal to the reader during a second period; and a second controller configured to control the clock generator to generate the first clock signal during the first period and the second period and to generate the second clock signal during a third period that is between the first period and the second period and that is longer than a predetermined period mT and shorter than (k×T1), the T1 being the first cycle, the k being a minimum integer that satisfies mT<(k×T1).