Image Reader

An image reader comprising:

• a first reading unit that comprises:
• a first light emitting portion configured to emit light onto a first side of a document sheet;
• and
• a first light receiving portion configured to receive the light reflected from the first side of the document sheet, so as to read out an image having a plurality of pixels arranged along a main scanning direction from the first side of the document sheet;
• a second reading unit that comprises:
• a second light emitting portion configured to emit light onto a second side opposite to the first side of the document sheet;
• and
• a second light receiving portion configured to receive the light reflected from the second side of the document sheet, so as to read out an image having a plurality of pixels arranged along the main scanning direction from the second side of the document sheet;
• a feeder configured to feed the document sheet along a feeding path in a sub scanning direction perpendicular to the main scanning direction;
• a light guide unit that forms an optical path to guide the light emitted by the first light emitting portion to the second light receiving portion,
• wherein the optical path passes across the feeding path in a detection position such that the document sheet, which passes through the detection position on the feeding path, blocks the light that is guided on the optical path from the first light emitting portion to the second light receiving portion;
• and
• a controller configured to determine that one of a leading end and a trailing end of the document sheet passes through the detection position, in response to detecting a change in a light receiving state of the second light receiving portion when the document sheet passes through the detection position in a state where the first light emitting portion is set ON to emit the light and the second light emitting portion is set OFF not to emit the light.