Patent ID: 9723164
Date: 2017-08-01
CPC Classifications: H04N

Claim:
1. An image reading device comprising: a plate on which a document to be scanned is placed; a cover that is movable between an open position and a closed position at which the cover contacts the document; a position sensor configured to detect a position of the cover, the position sensor including a rotation member that rotates as the cover moves, a first detector configured to output a signal of detecting the rotation member, and a second detector disposed at a position different from the first detector in a rotational direction of the rotation member and configured to output a signal of detecting the rotation member; an imaging unit configured to emit light towards the plate and having an image sensor configured to detect light reflected by the document; and a controller configured to determine whether or not a region of the plate is covered by the document based on a detection result of the position sensor and a detection result of the image sensor, and determine a size of the document based on the determination of whether or not the region of the plate is covered by the document, wherein the region of the plate is determined to be covered by the document, when a detection value of the image sensor is greater than a first value and when the detection value of the image sensor is smaller than a second value.