Patent ID: 8020848

Claim:
A paper feeder comprising: a first paper cassette where paper can be stacked, the first paper cassette configured to be set at a specific position; a second paper cassette located upstream of the first paper cassette in a paper feed path and where paper can be stacked; a paper detector including a detecting sensor located on the second paper cassette, the paper detector configured to detect whether paper is present in the second paper cassette and outputs a paper present signal upon detecting presence of a paper in the second paper cassette, and outputs a paper absent signal upon detecting absence of paper in the second paper cassette, and the detecting sensor of the paper detector configured to detect whether the first paper cassette is set at the specific position; and a signal switching unit including a part located on the first paper cassette, the signal switching unit configured to switch a paper present signal output from the paper detector to a paper absent signal indicative of absence of a paper in the second paper cassette, the part of the signal switching unit being engaged with the second paper cassette when the first paper cassette is set at the specific position, and being disengaged from the second paper cassette when the first paper cassette is pulled out from the specific position, wherein when the part of signal switching unit is disengaged from the second paper cassette, the signal switching unit switches a paper present signal to a paper absent signal so that the paper detector outputs absent signal upon the signal switching unit switching, irrespective of presence or absence of paper in the second paper cassette.